#!/usr/bin/env dub
/+ dub.sdl:
name "property_tree_edit_commands"
targetPath "build"
dflags "-preview=in" "-preview=dip1000"
buildType "checked" {
buildOptions "optimize" "inline" "debugInfo"
}
+/
/**
* The mutation contract (fork D5), with read-write as the default
* and read-only as a policy (fork D6, as decided).
*
* Under test:
* C12. An edit is a VALUE — `(path, newValue, phase)` — not a callback.
* Applying one returns its INVERSE, so undo/redo is a host-owned stack
* of the same value type and the component contains no transaction
* machinery. (The corpus rule "undo belongs to the host", made cheap.)
* C13. `@readOnly` and a component-level policy both refuse the write at the
* SAME place — inside the generated dispatch — so no view can bypass it.
* C14. `phase` separates a drag's previews from its commit (Unreal's
* `SetValue` flags). Previews mutate; only a commit yields an undo
* entry. This is the distinction Godot's `changing` flag does NOT make.
* C15. The D-specific wrinkle: `SumType.opAssign` is `@system` when another
* member has indirections, so a variant switch needs one `@trusted`
* seam — and the edit vocabulary needs a `variant` case, because a
* switch is not an assignment of any leaf type.
*
* Run: `dub run --single edit-commands.d`
*/
module (module) property_tree_edit_commandsThe mutation contract (fork D5), with read-write as the default
and read-only as a policy (fork D6, as decided).
Under test:
C12. An edit is a VALUE — (path, newValue, phase) — not a callback.
Applying one returns its INVERSE, so undo/redo is a host-owned stack
of the same value type and the component contains no transaction
machinery. (The corpus rule "undo belongs to the host", made cheap.)
C13. @readOnly and a component-level policy both refuse the write at the
SAME place — inside the generated dispatch — so no view can bypass it.
C14. phase separates a drag's previews from its commit (Unreal's
SetValue flags). Previews mutate; only a commit yields an undo
entry. This is the distinction Godot's changing flag does NOT make.
C15. The D-specific wrinkle: SumType.opAssign is @system when another
member has indirections, so a variant switch needs one @trusted
seam — and the edit vocabulary needs a variant case, because a
switch is not an assignment of any leaf type.
Run
dub run --single edit-commands.d
property_tree_edit_commands;
import (package) stdstd.(module) std.convA one-stop shop for converting values from one type to another.
Category Functions Generic asOriginalType castFrom parse to toChars bitCast Strings text wtext dtext writeText writeWText writeDText hexString Numeric octal roundTo signed unsigned Exceptions ConvException ConvOverflowException
Source
std/conv.d
conv : (alias template) property_tree_edit_commands.text = std.conv.text(T...)(T args) if (T.length > 0)Convenience functions for converting one or more arguments
of any type into text (the three character widths).
text, (alias template) property_tree_edit_commands.to = std.conv.to(T)The to template converts a value from one type to another.
The source type is deduced and the target type must be specified, for example the
expression to`!int(42.0)` converts the number 42 from
`double` to `int`. The conversion is "safe", i.e.,
it checks for overflow; to!int(4.2e10) would throw the
ConvOverflowException exception. Overflow checks are only
inserted when necessary, e.g., ``to!double(42) does not do
any checking because any int fits in a double.
Conversions from string to numeric types differ from the C equivalents
atoi() and atol() by checking for overflow and not allowing whitespace.
For conversion of strings to signed types, the grammar recognized is:
Integer:
Sign UnsignedInteger
UnsignedInteger
Sign:
+
-
For conversion to unsigned types, the grammar recognized is:
UnsignedInteger:
DecimalDigit
DecimalDigit UnsignedInteger
to;
import (package) stdstd.(module) std.sumtypeSumType is a generic discriminated union implementation that uses
design-by-introspection to generate safe and efficient code. Its features
include:
Pattern matching.
Support for self-referential types.
Full attribute correctness (pure, @safe, @nogc, and nothrow are
inferred whenever possible).
A type-safe and memory-safe API compatible with DIP 1000 (scope).
No dependency on runtime type information (TypeInfo).
Compatibility with BetterC.
List of examples
Memory corruption (why assignment can be @system)
Source
std/sumtype.d
Examples
Basic usage
import std.math.operations : isClose;
struct Fahrenheit { double value; }
struct Celsius { double value; }
struct Kelvin { double value; }
alias Temperature = SumType!(Fahrenheit, Celsius, Kelvin);
// Construct from any of the member types.
Temperature t1 = Fahrenheit(98.6);
Temperature t2 = Celsius(100);
Temperature t3 = Kelvin(273);
// Use pattern matching to access the value.
Fahrenheit toFahrenheit(Temperature t)
{
return Fahrenheit(
t.match!(
(Fahrenheit f) => f.value,
(Celsius c) => c.value * 9.0/5 + 32,
(Kelvin k) => k.value * 9.0/5 - 459.4
)
);
}
assert(toFahrenheit(t1).value.isClose(98.6));
assert(toFahrenheit(t2).value.isClose(212));
assert(toFahrenheit(t3).value.isClose(32));
// Use ref to modify the value in place.
void freeze(ref Temperature t)
{
t.match!(
(ref Fahrenheit f) => f.value = 32,
(ref Celsius c) => c.value = 0,
(ref Kelvin k) => k.value = 273
);
}
freeze(t1);
assert(toFahrenheit(t1).value.isClose(32));
// Use a catch-all handler to give a default result.
bool isFahrenheit(Temperature t)
{
return t.match!(
(Fahrenheit f) => true,
_ => false
);
}
assert(isFahrenheit(t1));
assert(!isFahrenheit(t2));
assert(!isFahrenheit(t3));
Matching with an overload set
Instead of writing match handlers inline as lambdas, you can write them as
overloads of a function. An alias can be used to create an additional
overload for the SumType itself.
For example, with this overload set:
string handle(int n) { return "got an int"; }
string handle(string s) { return "got a string"; }
string handle(double d) { return "got a double"; }
alias handle = match!handle;
Usage would look like this:
alias ExampleSumType = SumType!(int, string, double);
ExampleSumType a = 123;
ExampleSumType b = "hello";
ExampleSumType c = 3.14;
assert(a.handle == "got an int");
assert(b.handle == "got a string");
assert(c.handle == "got a double");
Recursive SumTypes
This example makes use of the special placeholder type This to define a
recursive data type: an
abstract syntax tree for
representing simple arithmetic expressions.
import std.functional : partial;
import std.traits : EnumMembers;
import std.typecons : Tuple;
enum Op : string
{
Plus = "+",
Minus = "-",
Times = "*",
Div = "/"
}
// An expression is either
// - a number,
// - a variable, or
// - a binary operation combining two sub-expressions.
alias Expr = SumType!(
double,
string,
Tuple!(Op, "op", This*, "lhs", This*, "rhs")
);
// Shorthand for Tuple!(Op, "op", Expr*, "lhs", Expr*, "rhs"),
// the Tuple type above with Expr substituted for This.
alias BinOp = Expr.Types[2];
// Factory function for number expressions
Expr* num(double value)
{
return new Expr(value);
}
// Factory function for variable expressions
Expr* var(string name)
{
return new Expr(name);
}
// Factory function for binary operation expressions
Expr* binOp(Op op, Expr* lhs, Expr* rhs)
{
return new Expr(BinOp(op, lhs, rhs));
}
// Convenience wrappers for creating BinOp expressions
alias sum = partial!(binOp, Op.Plus);
alias diff = partial!(binOp, Op.Minus);
alias prod = partial!(binOp, Op.Times);
alias quot = partial!(binOp, Op.Div);
// Evaluate expr, looking up variables in env
double eval(Expr expr, double[string] env)
{
return expr.match!(
(double num) => num,
(string var) => env[var],
(BinOp bop)
{
double lhs = eval(*bop.lhs, env);
double rhs = eval(*bop.rhs, env);
final switch (bop.op)
{
static foreach (op; EnumMembers!Op)
{
case op:
return mixin("lhs" ~ op ~ "rhs");
}
}
}
);
}
// Return a "pretty-printed" representation of expr
string pprint(Expr expr)
{
import std.format : format;
return expr.match!(
(double num) => "%g".format(num),
(string var) => var,
(BinOp bop) => "(%s %s %s)".format(
pprint(*bop.lhs),
cast(string) bop.op,
pprint(*bop.rhs)
)
);
}
Expr* myExpr = sum(var("a"), prod(num(2), var("b")));
double[string] myEnv = ["a":3, "b":4, "c":7];
assert(eval(*myExpr, myEnv) == 11);
assert(pprint(*myExpr) == "(a + (2 * b))");
sumtype : (alias template) property_tree_edit_commands.match = std.sumtype.match(handlers...)Calls a type-appropriate function with the value held in a SumType.
For each possible type the SumType can hold, the given handlers are
checked, in order, to see whether they accept a single argument of that type.
The first one that does is chosen as the match for that type. (Note that the
first match may not always be the most exact match.
See "Avoiding unintentional matches" for
one common pitfall.)
Every type must have a matching handler, and every handler must match at
least one type. This is enforced at compile time.
Handlers may be functions, delegates, or objects with opCall overloads. If
a function with more than one overload is given as a handler, all of the
overloads are considered as potential matches.
Templated handlers are also accepted, and will match any type for which they
can be implicitly instantiated.
(Remember that a function literal
without an explicit argument type is considered a template.)
If multiple SumTypes are passed to match, their values are passed to the
handlers as separate arguments, and matching is done for each possible
combination of value types. See "Multiple dispatch" for
an example.
match, (alias struct) property_tree_edit_commands.SumType = std.sumtype.SumType(Types...) if (is(NoDuplicates!Types == Types) && (Types.length > 0))A tagged union that can hold a
single value from any of a specified set of types.
The value in a SumType can be operated on using pattern matching.
To avoid ambiguity, duplicate types are not allowed (but see the
"basic usage" example for a workaround).
The special type This can be used as a placeholder to create
self-referential types, just like with Algebraic. See the
"Recursive SumTypes" example for usage.
A SumType is initialized by default to hold the .init value of its
first member type, just like a regular union. The version identifier
SumTypeNoDefaultCtor can be used to disable this behavior.
SumType;
import (package) stdstd.(module) std.traitsTemplates which extract information about types and symbols at compile time.
Category Templates Symbol Name traits fullyQualifiedName mangledName moduleName packageName Function traits isFunction arity functionAttributes hasFunctionAttributes functionLinkage FunctionTypeOf isSafe isUnsafe isFinal ParameterDefaults ParameterIdentifierTuple ParameterStorageClassTuple Parameters ReturnType SetFunctionAttributes variadicFunctionStyle Aggregate Type traits BaseClassesTuple BaseTypeTuple classInstanceAlignment EnumMembers FieldNameTuple Fields hasAliasing hasElaborateAssign hasElaborateCopyConstructor hasElaborateDestructor hasElaborateMove hasIndirections hasMember hasStaticMember hasNested hasUnsharedAliasing InterfacesTuple isInnerClass isNested MemberFunctionsTuple RepresentationTypeTuple TemplateArgsOf TemplateOf TransitiveBaseTypeTuple Type Conversion CommonType AllImplicitConversionTargets ImplicitConversionTargets CopyTypeQualifiers CopyConstness isAssignable isCovariantWith isImplicitlyConvertible isQualifierConvertible Type Constructors InoutOf ConstOf SharedOf SharedInoutOf SharedConstOf SharedConstInoutOf ImmutableOf QualifierOf Categories of types allSameType ifTestable isType isAggregateType isArray isAssociativeArray isAutodecodableString isBasicType isBoolean isBuiltinType isCopyable isDynamicArray isEqualityComparable isFloatingPoint isIntegral isNarrowString isConvertibleToString isNumeric isOrderingComparable isPointer isScalarType isSigned isSIMDVector isSomeChar isSomeString isStaticArray isUnsigned Type behaviours isAbstractClass isAbstractFunction isCallable isDelegate isExpressions isFinalClass isFinalFunction isFunctionPointer isInstanceOf isIterable isMutable isSomeFunction isTypeTuple General Types ForeachType KeyType Largest mostNegative OriginalType PointerTarget Signed Unconst Unshared Unqual Unsigned ValueType Promoted Misc lvalueOf rvalueOf Select select User-Defined Attributes hasUDA getUDAs getSymbolsByUDA
Source
std/traits.d
traits : (alias template) property_tree_edit_commands.hasUDA = std.traits.hasUDA(alias symbol, alias attribute)Determine if a symbol has a given
user-defined attribute.
hasUDA, (alias template) property_tree_edit_commands.isAggregateType = std.traits.isAggregateType(T)Detect whether type T is an aggregate type.
isAggregateType, (alias template) property_tree_edit_commands.isArray = std.traits.isArray(T)Detect whether type T is an array (static or dynamic; for associative
arrays see isAssociativeArray).
isArray, (alias template) property_tree_edit_commands.isSomeString = std.traits.isSomeString(T)Detect whether T is one of the built-in string types.
The built-in string types are Char[], where Char is any of char,
wchar or dchar, with or without qualifiers.
Static arrays of characters (like char[80]) are not considered
built-in string types.
isSomeString;
@safe:
enum (enum) property_tree_edit_commands.readOnlyreadOnly;
// ── the edit vocabulary (C12) ────────────────────────────────────────────────
enum (enum) property_tree_edit_commands.PhasePhase : ubyte { (enum value) property_tree_edit_commands.Phase.preview = cast(ubyte)0upreview, (enum value) property_tree_edit_commands.Phase.commit = 1commit }
/// Every leaf the component can produce an edit for, as one value type.
struct (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue
{
enum (enum) property_tree_edit_commands.EditValue.KindKind : ubyte { (enum value) property_tree_edit_commands.EditValue.Kind.none = cast(ubyte)0unone, (enum value) property_tree_edit_commands.EditValue.Kind.boolean = 1boolean, (enum value) property_tree_edit_commands.EditValue.Kind.integral = 2integral, (enum value) property_tree_edit_commands.EditValue.Kind.floating = 3floating, (enum value) property_tree_edit_commands.EditValue.Kind.text = 4text, (enum value) property_tree_edit_commands.EditValue.Kind.variant = 5variant }
(enum) property_tree_edit_commands.EditValue.KindKind (field) property_tree_edit_commands.EditValue.Kind property_tree_edit_commands.EditValue.kindkind;
bool (field) bool property_tree_edit_commands.EditValue.bb; long (field) long property_tree_edit_commands.EditValue.ii; double (field) double property_tree_edit_commands.EditValue.ff; (alias) object.string = stringstring (field) string property_tree_edit_commands.EditValue.ss;
static (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(bool v) @safeof(bool (parameter) bool vv) => (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue((enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.boolean = 1boolean, (parameter) bool vv);
static (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(long v) @safeof(long (parameter) long vv) => (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue((enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.integral = 2integral, false, (parameter) long vv);
static (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(double v) @safeof(double (parameter) double vv) => (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue((enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.floating = 3floating, false, 0, (parameter) double vv);
static (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(string v) @safeof((alias) object.string = stringstring (parameter) string vv) => (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue((enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.text = 4text, false, 0, 0, (parameter) string vv);
static (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.variantOf(string name) @safevariantOf((alias) object.string = stringstring (parameter) string namename)
=> (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue((enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.variant = 5variant, false, 0, 0, (parameter) string namename);
(alias) object.string = stringstring string property_tree_edit_commands.EditValue.toString() const pure @safetoString() const pure
{
final switch ((field) property_tree_edit_commands.EditValue.Kind property_tree_edit_commands.EditValue.kindkind)
{
case (enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.none = cast(ubyte)0unone: return "∅";
case (enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.boolean = 1boolean: return (field) bool property_tree_edit_commands.EditValue.bb ? "true" : "false";
case (enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.integral = 2integral: return (field) long property_tree_edit_commands.EditValue.ii.string std.conv.to!string.to!(const(long))(const(long) __param_0) pure nothrow @safeThe to template converts a value from one type to another.
The source type is deduced and the target type must be specified, for example the
expression to`!int(42.0)` converts the number 42 from
`double` to `int`. The conversion is "safe", i.e.,
it checks for overflow; to!int(4.2e10) would throw the
ConvOverflowException exception. Overflow checks are only
inserted when necessary, e.g., ``to!double(42) does not do
any checking because any int fits in a double.
Conversions from string to numeric types differ from the C equivalents
atoi() and atol() by checking for overflow and not allowing whitespace.
For conversion of strings to signed types, the grammar recognized is:
Integer:
Sign UnsignedInteger
UnsignedInteger
Sign:
+
-
For conversion to unsigned types, the grammar recognized is:
UnsignedInteger:
DecimalDigit
DecimalDigit UnsignedInteger
Examples
Converting a value to its own type (useful mostly for generic code)
simply returns its argument.
int a = 42;
int b = to!int(a);
double c = to!double(3.14); // c is double with value 3.14
Converting among numeric types is a safe way to cast them around.
Conversions from floating-point types to integral types allow loss of
precision (the fractional part of a floating-point number). The
conversion is truncating towards zero, the same way a cast would
truncate. (To round a floating point value when casting to an
integral, use roundTo.)
import std.exception : assertThrown;
int a = 420;
assert(to!long(a) == a);
assertThrown!ConvOverflowException(to!byte(a));
assert(to!int(4.2e6) == 4200000);
assertThrown!ConvOverflowException(to!uint(-3.14));
assert(to!uint(3.14) == 3);
assert(to!uint(3.99) == 3);
assert(to!int(-3.99) == -3);
When converting strings to numeric types, note that D hexadecimal and binary
literals are not handled. Neither the prefixes that indicate the base, nor the
horizontal bar used to separate groups of digits are recognized. This also
applies to the suffixes that indicate the type.
To work around this, you can specify a radix for conversions involving numbers.
auto str = to!string(42, 16);
assert(str == "2A");
auto i = to!int(str, 16);
assert(i == 42);
Conversions from integral types to floating-point types always
succeed, but might lose accuracy. The largest integers with a
predecessor representable in floating-point format are 2^24-1 for
float, 2^53-1 for double, and 2^64-1 for real (when
real is 80-bit, e.g. on Intel machines).
// 2^24 - 1, largest proper integer representable as float
int a = 16_777_215;
assert(to!int(to!float(a)) == a);
assert(to!int(to!float(-a)) == -a);
Conversion from string types to char types enforces the input
to consist of a single code point, and said code point must
fit in the target type. Otherwise, ConvException is thrown.
import std.exception : assertThrown;
assert(to!char("a") == 'a');
assertThrown(to!char("ñ")); // 'ñ' does not fit into a char
assert(to!wchar("ñ") == 'ñ');
assertThrown(to!wchar("😃")); // '😃' does not fit into a wchar
assert(to!dchar("😃") == '😃');
// Using wstring or dstring as source type does not affect the result
assert(to!char("a"w) == 'a');
assert(to!char("a"d) == 'a');
// Two code points cannot be converted to a single one
assertThrown(to!char("ab"));
Converting an array to another array type works by converting each
element in turn. Associative arrays can be converted to associative
arrays as long as keys and values can in turn be converted.
import std.string : split;
int[] a = [1, 2, 3];
auto b = to!(float[])(a);
assert(b == [1.0f, 2, 3]);
string str = "1 2 3 4 5 6";
auto numbers = to!(double[])(split(str));
assert(numbers == [1.0, 2, 3, 4, 5, 6]);
int[string] c;
c["a"] = 1;
c["b"] = 2;
auto d = to!(double[wstring])(c);
assert(d["a"w] == 1 && d["b"w] == 2);
Conversions operate transitively, meaning that they work on arrays and
associative arrays of any complexity.
This conversion works because to`!short` applies to an `int`, to!wstring
applies to a string, to`!string` applies to a `double`, and
to!(double[]) applies to an int[]. The conversion might throw an
exception because ``to!short might fail the range check.
int[string][double[int[]]] a;
auto b = to!(short[wstring][string[double[]]])(a);
Object-to-object conversions by dynamic casting throw exception when
the source is non-null and the target is null.
import std.exception : assertThrown;
// Testing object conversions
class A {}
class B : A {}
class C : A {}
A a1 = new A, a2 = new B, a3 = new C;
assert(to!B(a2) is a2);
assert(to!C(a3) is a3);
assertThrown!ConvException(to!B(a3));
Stringize conversion from all types is supported.
String to string conversion works for any two string types having
(char, wchar, dchar) character widths and any
combination of qualifiers (mutable, const, or immutable).
Converts array (other than strings) to string.
Each element is converted by calling ``to!T.
Associative array to string conversion.
Each element is converted by calling ``to!T.
Object to string conversion calls toString against the object or
returns "null" if the object is null.
Struct to string conversion calls toString against the struct if
it is defined.
For structs that do not define toString, the conversion to string
produces the list of fields.
Enumerated types are converted to strings as their symbolic names.
Boolean values are converted to "true" or "false".
char, wchar, dchar to a string type.
Unsigned or signed integers to strings.
: Convert integral value to string in radix radix.
radix must be a value from 2 to 36.
value is treated as a signed value only if radix is 10.
The characters A through Z are used to represent values 10 through 36
and their case is determined by the letterCase parameter.
All floating point types to all string types.
Pointer to string conversions convert the pointer to a size_t value.
If pointer is char*, treat it as C-style strings.
In that case, this function is @system.
See formatValue on how toString should be defined.
// Conversion representing dynamic/static array with string
long[] a = [ 1, 3, 5 ];
assert(to!string(a) == "[1, 3, 5]");
// Conversion representing associative array with string
int[string] associativeArray = ["0":1, "1":2];
assert(to!string(associativeArray) == `["0":1, "1":2]` ||
to!string(associativeArray) == `["1":2, "0":1]`);
// char* to string conversion
assert(to!string(cast(char*) null) == "");
assert(to!string("foo\0".ptr) == "foo");
// Conversion reinterpreting void array to string
auto w = "abcx"w;
const(void)[] b = w;
assert(b.length == 8);
auto c = to!(wchar[])(b);
assert(c == "abcx");
Strings can be converted to enum types. The enum member with the same name as the
input string is returned. The comparison is case-sensitive.
A ConvException is thrown if the enum does not have the specified member.
import std.exception : assertThrown;
enum E { a, b, c }
assert(to!E("a") == E.a);
assert(to!E("b") == E.b);
assertThrown!ConvException(to!E("A"));
to!(alias) object.string = stringstring;
case (enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.floating = 3floating: return (field) double property_tree_edit_commands.EditValue.ff.string std.conv.to!string.to!(const(double))(const(double) __param_0) pure @safeThe to template converts a value from one type to another.
The source type is deduced and the target type must be specified, for example the
expression to`!int(42.0)` converts the number 42 from
`double` to `int`. The conversion is "safe", i.e.,
it checks for overflow; to!int(4.2e10) would throw the
ConvOverflowException exception. Overflow checks are only
inserted when necessary, e.g., ``to!double(42) does not do
any checking because any int fits in a double.
Conversions from string to numeric types differ from the C equivalents
atoi() and atol() by checking for overflow and not allowing whitespace.
For conversion of strings to signed types, the grammar recognized is:
Integer:
Sign UnsignedInteger
UnsignedInteger
Sign:
+
-
For conversion to unsigned types, the grammar recognized is:
UnsignedInteger:
DecimalDigit
DecimalDigit UnsignedInteger
Examples
Converting a value to its own type (useful mostly for generic code)
simply returns its argument.
int a = 42;
int b = to!int(a);
double c = to!double(3.14); // c is double with value 3.14
Converting among numeric types is a safe way to cast them around.
Conversions from floating-point types to integral types allow loss of
precision (the fractional part of a floating-point number). The
conversion is truncating towards zero, the same way a cast would
truncate. (To round a floating point value when casting to an
integral, use roundTo.)
import std.exception : assertThrown;
int a = 420;
assert(to!long(a) == a);
assertThrown!ConvOverflowException(to!byte(a));
assert(to!int(4.2e6) == 4200000);
assertThrown!ConvOverflowException(to!uint(-3.14));
assert(to!uint(3.14) == 3);
assert(to!uint(3.99) == 3);
assert(to!int(-3.99) == -3);
When converting strings to numeric types, note that D hexadecimal and binary
literals are not handled. Neither the prefixes that indicate the base, nor the
horizontal bar used to separate groups of digits are recognized. This also
applies to the suffixes that indicate the type.
To work around this, you can specify a radix for conversions involving numbers.
auto str = to!string(42, 16);
assert(str == "2A");
auto i = to!int(str, 16);
assert(i == 42);
Conversions from integral types to floating-point types always
succeed, but might lose accuracy. The largest integers with a
predecessor representable in floating-point format are 2^24-1 for
float, 2^53-1 for double, and 2^64-1 for real (when
real is 80-bit, e.g. on Intel machines).
// 2^24 - 1, largest proper integer representable as float
int a = 16_777_215;
assert(to!int(to!float(a)) == a);
assert(to!int(to!float(-a)) == -a);
Conversion from string types to char types enforces the input
to consist of a single code point, and said code point must
fit in the target type. Otherwise, ConvException is thrown.
import std.exception : assertThrown;
assert(to!char("a") == 'a');
assertThrown(to!char("ñ")); // 'ñ' does not fit into a char
assert(to!wchar("ñ") == 'ñ');
assertThrown(to!wchar("😃")); // '😃' does not fit into a wchar
assert(to!dchar("😃") == '😃');
// Using wstring or dstring as source type does not affect the result
assert(to!char("a"w) == 'a');
assert(to!char("a"d) == 'a');
// Two code points cannot be converted to a single one
assertThrown(to!char("ab"));
Converting an array to another array type works by converting each
element in turn. Associative arrays can be converted to associative
arrays as long as keys and values can in turn be converted.
import std.string : split;
int[] a = [1, 2, 3];
auto b = to!(float[])(a);
assert(b == [1.0f, 2, 3]);
string str = "1 2 3 4 5 6";
auto numbers = to!(double[])(split(str));
assert(numbers == [1.0, 2, 3, 4, 5, 6]);
int[string] c;
c["a"] = 1;
c["b"] = 2;
auto d = to!(double[wstring])(c);
assert(d["a"w] == 1 && d["b"w] == 2);
Conversions operate transitively, meaning that they work on arrays and
associative arrays of any complexity.
This conversion works because to`!short` applies to an `int`, to!wstring
applies to a string, to`!string` applies to a `double`, and
to!(double[]) applies to an int[]. The conversion might throw an
exception because ``to!short might fail the range check.
int[string][double[int[]]] a;
auto b = to!(short[wstring][string[double[]]])(a);
Object-to-object conversions by dynamic casting throw exception when
the source is non-null and the target is null.
import std.exception : assertThrown;
// Testing object conversions
class A {}
class B : A {}
class C : A {}
A a1 = new A, a2 = new B, a3 = new C;
assert(to!B(a2) is a2);
assert(to!C(a3) is a3);
assertThrown!ConvException(to!B(a3));
Stringize conversion from all types is supported.
String to string conversion works for any two string types having
(char, wchar, dchar) character widths and any
combination of qualifiers (mutable, const, or immutable).
Converts array (other than strings) to string.
Each element is converted by calling ``to!T.
Associative array to string conversion.
Each element is converted by calling ``to!T.
Object to string conversion calls toString against the object or
returns "null" if the object is null.
Struct to string conversion calls toString against the struct if
it is defined.
For structs that do not define toString, the conversion to string
produces the list of fields.
Enumerated types are converted to strings as their symbolic names.
Boolean values are converted to "true" or "false".
char, wchar, dchar to a string type.
Unsigned or signed integers to strings.
: Convert integral value to string in radix radix.
radix must be a value from 2 to 36.
value is treated as a signed value only if radix is 10.
The characters A through Z are used to represent values 10 through 36
and their case is determined by the letterCase parameter.
All floating point types to all string types.
Pointer to string conversions convert the pointer to a size_t value.
If pointer is char*, treat it as C-style strings.
In that case, this function is @system.
See formatValue on how toString should be defined.
// Conversion representing dynamic/static array with string
long[] a = [ 1, 3, 5 ];
assert(to!string(a) == "[1, 3, 5]");
// Conversion representing associative array with string
int[string] associativeArray = ["0":1, "1":2];
assert(to!string(associativeArray) == `["0":1, "1":2]` ||
to!string(associativeArray) == `["1":2, "0":1]`);
// char* to string conversion
assert(to!string(cast(char*) null) == "");
assert(to!string("foo\0".ptr) == "foo");
// Conversion reinterpreting void array to string
auto w = "abcx"w;
const(void)[] b = w;
assert(b.length == 8);
auto c = to!(wchar[])(b);
assert(c == "abcx");
Strings can be converted to enum types. The enum member with the same name as the
input string is returned. The comparison is case-sensitive.
A ConvException is thrown if the enum does not have the specified member.
import std.exception : assertThrown;
enum E { a, b, c }
assert(to!E("a") == E.a);
assert(to!E("b") == E.b);
assertThrown!ConvException(to!E("A"));
to!(alias) object.string = stringstring;
case (enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.text = 4text: return `"` ~ (field) string property_tree_edit_commands.EditValue.ss ~ `"`;
case (enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.variant = 5variant: return "=" ~ (field) string property_tree_edit_commands.EditValue.ss;
}
}
}
/// The whole mutation API surface: one value.
struct (struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit
{
(alias) object.string = stringstring (field) string property_tree_edit_commands.Edit.pathpath;
(struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue (field) property_tree_edit_commands.EditValue property_tree_edit_commands.Edit.valuevalue;
(enum) property_tree_edit_commands.PhasePhase (field) property_tree_edit_commands.Phase property_tree_edit_commands.Edit.phasephase = (enum) property_tree_edit_commands.PhasePhase.(enum value) property_tree_edit_commands.Phase.commit = 1commit;
}
/// Why a write was refused — the view renders this, it is not an exception.
enum (enum) property_tree_edit_commands.RefusalWhy a write was refused — the view renders this, it is not an exception.
Refusal : ubyte { (enum value) property_tree_edit_commands.Refusal.none = cast(ubyte)0unone, (enum value) property_tree_edit_commands.Refusal.noSuchPath = 1noSuchPath, (enum value) property_tree_edit_commands.Refusal.readOnlyField = 2readOnlyField, (enum value) property_tree_edit_commands.Refusal.readOnlyPolicy = 3readOnlyPolicy, (enum value) property_tree_edit_commands.Refusal.typeMismatch = 4typeMismatch }
struct (struct) property_tree_edit_commands.AppliedApplied
{
(enum) property_tree_edit_commands.RefusalWhy a write was refused — the view renders this, it is not an exception.
Refusal (field) property_tree_edit_commands.Refusal property_tree_edit_commands.Applied.refusalrefusal;
(struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit (field) property_tree_edit_commands.Edit property_tree_edit_commands.Applied.inversevalid when refusal == none && phase == commit
inverse; /// valid when refusal == none && phase == commit
bool bool property_tree_edit_commands.Applied.ok() const pure nothrow @nogc @safeok() const pure nothrow @nogc => (field) property_tree_edit_commands.Refusal property_tree_edit_commands.Applied.refusalrefusal == (enum) property_tree_edit_commands.RefusalWhy a write was refused — the view renders this, it is not an exception.
Refusal.(enum value) property_tree_edit_commands.Refusal.none = cast(ubyte)0unone;
}
// ── applying an edit ─────────────────────────────────────────────────────────
struct (struct) property_tree_edit_commands.PolicyPolicy { bool (field) bool property_tree_edit_commands.Policy.readOnlyreadOnly; }
/// Assigns `v` from an `EditValue` when the types line up; reports the old
/// value as an `EditValue` so the caller can build the inverse.
private bool bool property_tree_edit_commands.assignLeaf!double(ref double v, in property_tree_edit_commands.EditValue e, out property_tree_edit_commands.EditValue old) @safeAssigns v from an EditValue when the types line up; reports the old
value as an EditValue so the caller can build the inverse.
assignLeaf(V)(ref (alias) V = doubleV (parameter) double vv, in (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue (parameter) const(property_tree_edit_commands.EditValue) ee, out (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue (parameter) property_tree_edit_commands.EditValue oldold)
{
static if (is((alias) V = doubleV == bool))
{
if ((parameter) const(property_tree_edit_commands.EditValue) ee.(field) property_tree_edit_commands.EditValue.Kind property_tree_edit_commands.EditValue.kindkind != (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.(enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.boolean = 1boolean) return false;
(parameter) property_tree_edit_commands.EditValue oldold = (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(bool v) @safeof((parameter) bool vv); (parameter) bool vv = (parameter) const(property_tree_edit_commands.EditValue) ee.(field) bool property_tree_edit_commands.EditValue.bb; return true;
}
else static if (is((alias) V = doubleV == enum))
{
if ((parameter) const(property_tree_edit_commands.EditValue) ee.(field) property_tree_edit_commands.EditValue.Kind property_tree_edit_commands.EditValue.kindkind != (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.(enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.text = 4text) return false;
(parameter) property_tree_edit_commands.EditValue oldold = (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(string v) @safeof((parameter) property_tree_edit_commands.Cap vv.string std.conv.to!string.to!(property_tree_edit_commands.Cap)(property_tree_edit_commands.Cap __param_0) pure @safeThe to template converts a value from one type to another.
The source type is deduced and the target type must be specified, for example the
expression to`!int(42.0)` converts the number 42 from
`double` to `int`. The conversion is "safe", i.e.,
it checks for overflow; to!int(4.2e10) would throw the
ConvOverflowException exception. Overflow checks are only
inserted when necessary, e.g., ``to!double(42) does not do
any checking because any int fits in a double.
Conversions from string to numeric types differ from the C equivalents
atoi() and atol() by checking for overflow and not allowing whitespace.
For conversion of strings to signed types, the grammar recognized is:
Integer:
Sign UnsignedInteger
UnsignedInteger
Sign:
+
-
For conversion to unsigned types, the grammar recognized is:
UnsignedInteger:
DecimalDigit
DecimalDigit UnsignedInteger
Examples
Converting a value to its own type (useful mostly for generic code)
simply returns its argument.
int a = 42;
int b = to!int(a);
double c = to!double(3.14); // c is double with value 3.14
Converting among numeric types is a safe way to cast them around.
Conversions from floating-point types to integral types allow loss of
precision (the fractional part of a floating-point number). The
conversion is truncating towards zero, the same way a cast would
truncate. (To round a floating point value when casting to an
integral, use roundTo.)
import std.exception : assertThrown;
int a = 420;
assert(to!long(a) == a);
assertThrown!ConvOverflowException(to!byte(a));
assert(to!int(4.2e6) == 4200000);
assertThrown!ConvOverflowException(to!uint(-3.14));
assert(to!uint(3.14) == 3);
assert(to!uint(3.99) == 3);
assert(to!int(-3.99) == -3);
When converting strings to numeric types, note that D hexadecimal and binary
literals are not handled. Neither the prefixes that indicate the base, nor the
horizontal bar used to separate groups of digits are recognized. This also
applies to the suffixes that indicate the type.
To work around this, you can specify a radix for conversions involving numbers.
auto str = to!string(42, 16);
assert(str == "2A");
auto i = to!int(str, 16);
assert(i == 42);
Conversions from integral types to floating-point types always
succeed, but might lose accuracy. The largest integers with a
predecessor representable in floating-point format are 2^24-1 for
float, 2^53-1 for double, and 2^64-1 for real (when
real is 80-bit, e.g. on Intel machines).
// 2^24 - 1, largest proper integer representable as float
int a = 16_777_215;
assert(to!int(to!float(a)) == a);
assert(to!int(to!float(-a)) == -a);
Conversion from string types to char types enforces the input
to consist of a single code point, and said code point must
fit in the target type. Otherwise, ConvException is thrown.
import std.exception : assertThrown;
assert(to!char("a") == 'a');
assertThrown(to!char("ñ")); // 'ñ' does not fit into a char
assert(to!wchar("ñ") == 'ñ');
assertThrown(to!wchar("😃")); // '😃' does not fit into a wchar
assert(to!dchar("😃") == '😃');
// Using wstring or dstring as source type does not affect the result
assert(to!char("a"w) == 'a');
assert(to!char("a"d) == 'a');
// Two code points cannot be converted to a single one
assertThrown(to!char("ab"));
Converting an array to another array type works by converting each
element in turn. Associative arrays can be converted to associative
arrays as long as keys and values can in turn be converted.
import std.string : split;
int[] a = [1, 2, 3];
auto b = to!(float[])(a);
assert(b == [1.0f, 2, 3]);
string str = "1 2 3 4 5 6";
auto numbers = to!(double[])(split(str));
assert(numbers == [1.0, 2, 3, 4, 5, 6]);
int[string] c;
c["a"] = 1;
c["b"] = 2;
auto d = to!(double[wstring])(c);
assert(d["a"w] == 1 && d["b"w] == 2);
Conversions operate transitively, meaning that they work on arrays and
associative arrays of any complexity.
This conversion works because to`!short` applies to an `int`, to!wstring
applies to a string, to`!string` applies to a `double`, and
to!(double[]) applies to an int[]. The conversion might throw an
exception because ``to!short might fail the range check.
int[string][double[int[]]] a;
auto b = to!(short[wstring][string[double[]]])(a);
Object-to-object conversions by dynamic casting throw exception when
the source is non-null and the target is null.
import std.exception : assertThrown;
// Testing object conversions
class A {}
class B : A {}
class C : A {}
A a1 = new A, a2 = new B, a3 = new C;
assert(to!B(a2) is a2);
assert(to!C(a3) is a3);
assertThrown!ConvException(to!B(a3));
Stringize conversion from all types is supported.
String to string conversion works for any two string types having
(char, wchar, dchar) character widths and any
combination of qualifiers (mutable, const, or immutable).
Converts array (other than strings) to string.
Each element is converted by calling ``to!T.
Associative array to string conversion.
Each element is converted by calling ``to!T.
Object to string conversion calls toString against the object or
returns "null" if the object is null.
Struct to string conversion calls toString against the struct if
it is defined.
For structs that do not define toString, the conversion to string
produces the list of fields.
Enumerated types are converted to strings as their symbolic names.
Boolean values are converted to "true" or "false".
char, wchar, dchar to a string type.
Unsigned or signed integers to strings.
: Convert integral value to string in radix radix.
radix must be a value from 2 to 36.
value is treated as a signed value only if radix is 10.
The characters A through Z are used to represent values 10 through 36
and their case is determined by the letterCase parameter.
All floating point types to all string types.
Pointer to string conversions convert the pointer to a size_t value.
If pointer is char*, treat it as C-style strings.
In that case, this function is @system.
See formatValue on how toString should be defined.
// Conversion representing dynamic/static array with string
long[] a = [ 1, 3, 5 ];
assert(to!string(a) == "[1, 3, 5]");
// Conversion representing associative array with string
int[string] associativeArray = ["0":1, "1":2];
assert(to!string(associativeArray) == `["0":1, "1":2]` ||
to!string(associativeArray) == `["1":2, "0":1]`);
// char* to string conversion
assert(to!string(cast(char*) null) == "");
assert(to!string("foo\0".ptr) == "foo");
// Conversion reinterpreting void array to string
auto w = "abcx"w;
const(void)[] b = w;
assert(b.length == 8);
auto c = to!(wchar[])(b);
assert(c == "abcx");
Strings can be converted to enum types. The enum member with the same name as the
input string is returned. The comparison is case-sensitive.
A ConvException is thrown if the enum does not have the specified member.
import std.exception : assertThrown;
enum E { a, b, c }
assert(to!E("a") == E.a);
assert(to!E("b") == E.b);
assertThrown!ConvException(to!E("A"));
to!(alias) object.string = stringstring);
switch ((parameter) const(property_tree_edit_commands.EditValue) ee.(field) string property_tree_edit_commands.EditValue.ss)
{
static foreach (m; __traits(allMembers, V))
{
case (constant) string property_tree_edit_commands.assignLeaf!(property_tree_edit_commands.Cap).m = "butt"m: (parameter) property_tree_edit_commands.Cap vv = __traits(getMember, V, m); return true;
}
default: return false;
}
}
else static if (__traits(isIntegral, (unresolved type) VV))
{
if ((parameter) const(property_tree_edit_commands.EditValue) ee.(field) property_tree_edit_commands.EditValue.Kind property_tree_edit_commands.EditValue.kindkind != (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.(enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.integral = 2integral) return false;
(parameter) property_tree_edit_commands.EditValue oldold = (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(long v) @safeof(cast(long) (parameter) int vv); (parameter) int vv = cast((alias) V = intV) (parameter) const(property_tree_edit_commands.EditValue) ee.(field) long property_tree_edit_commands.EditValue.ii; return true;
}
else static if (__traits(isFloating, (unresolved type) VV))
{
if ((parameter) const(property_tree_edit_commands.EditValue) ee.(field) property_tree_edit_commands.EditValue.Kind property_tree_edit_commands.EditValue.kindkind != (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.(enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.floating = 3floating) return false;
(parameter) property_tree_edit_commands.EditValue oldold = (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(double v) @safeof(cast(double) (parameter) double vv); (parameter) double vv = cast((alias) V = doubleV) (parameter) const(property_tree_edit_commands.EditValue) ee.(field) double property_tree_edit_commands.EditValue.ff; return true;
}
else static if ((template instance) std.traits.isSomeString!stringisSomeString!(alias) V = stringV)
{
if ((parameter) const(property_tree_edit_commands.EditValue) ee.(field) property_tree_edit_commands.EditValue.Kind property_tree_edit_commands.EditValue.kindkind != (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.(enum) property_tree_edit_commands.EditValue.KindKind.(enum value) property_tree_edit_commands.EditValue.Kind.text = 4text) return false;
// dip1000 earns its keep: an `in Edit` is scope, so its text cannot
// be stored into the subject without a copy. The compiler says so.
(parameter) property_tree_edit_commands.EditValue oldold = (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(string v) @safeof((parameter) string vv.string object.idup!(immutable(char))(string a) pure nothrow @property @safeProvide the .idup array property, which creates an immutable duplicate.
idup); (parameter) string vv = (parameter) const(property_tree_edit_commands.EditValue) ee.(field) string property_tree_edit_commands.EditValue.ss.string object.idup!(immutable(char))(string a) pure nothrow @property @safeProvide the .idup array property, which creates an immutable duplicate.
idup; return true;
}
else
return false;
}
/// The generated dispatch: one walk, parameterised by TYPE only ([`open-set-descent.d`](./open-set-descent.d)).
/// `@readOnly` is consulted HERE (C13) — a view cannot route around it.
private (enum) property_tree_edit_commands.RefusalWhy a write was refused — the view renders this, it is not an exception.
Refusal property_tree_edit_commands.Refusal property_tree_edit_commands.applyAt!(property_tree_edit_commands.Cap)(ref property_tree_edit_commands.Cap subject, in property_tree_edit_commands.Seg[] segs, ulong at_, in property_tree_edit_commands.Edit e, in property_tree_edit_commands.Policy pol, out property_tree_edit_commands.EditValue old) pure nothrow @nogc @safeThe generated dispatch: one walk, parameterised by TYPE only (open-set-descent.d).
@readOnly is consulted HERE (C13) — a view cannot route around it.
applyAt(T)(ref (alias) T = property_tree_edit_commands.CapT (parameter) property_tree_edit_commands.Cap subjectsubject, in (struct) property_tree_edit_commands.SegSeg[] (parameter) const(property_tree_edit_commands.Seg[]) segssegs, (alias) object.size_t = ulongsize_t (parameter) ulong at_at_,
in (struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit (parameter) const(property_tree_edit_commands.Edit) ee, in (struct) property_tree_edit_commands.PolicyPolicy (parameter) const(property_tree_edit_commands.Policy) polpol, out (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue (parameter) property_tree_edit_commands.EditValue oldold)
{
static if (is((alias) T = property_tree_edit_commands.CapT == U*, U))
{
if (subject is null) return Refusal.noSuchPath;
return applyAt(*subject, segs, at_, e, pol, old);
}
else static if ((template instance) std.traits.isAggregateType!(property_tree_edit_commands.Cap)isAggregateType!(alias) T = property_tree_edit_commands.CapT && !(template instance) isSomeString!TisSomeString!(alias) T = property_tree_edit_commands.StrokeT)
{
if ((parameter) ulong at_at_ >= (parameter) const(property_tree_edit_commands.Seg[]) segssegs.(field) ulong const(property_tree_edit_commands.Seg[]).lengthlength || (parameter) const(property_tree_edit_commands.Seg[]) segssegs[(parameter) ulong at_at_].(field) bool property_tree_edit_commands.Seg.isIndexisIndex) return (enum) property_tree_edit_commands.RefusalWhy a write was refused — the view renders this, it is not an exception.
Refusal.(enum value) property_tree_edit_commands.Refusal.noSuchPath = 1noSuchPath;
switch ((parameter) const(property_tree_edit_commands.Seg[]) segssegs[(parameter) ulong at_at_].(field) string property_tree_edit_commands.Seg.namename)
{
static foreach (name; __traits(allMembers, T))
{{
alias (alias field) property_tree_edit_commands.applyAt!(property_tree_edit_commands.Stroke).F = double property_tree_edit_commands.Stroke.widthF = __traits(getMember, T, name);
static if (__traits(compiles, typeof((field) double property_tree_edit_commands.Stroke.widthF))
&& !is(typeof((field) double property_tree_edit_commands.Stroke.widthF) == function))
{
case (constant) string property_tree_edit_commands.applyAt!(property_tree_edit_commands.Stroke).name = "width"name:
static if ((template instance) property_tree_edit_commands.Stroke.hasUDA!(width, property_tree_edit_commands.readOnly)hasUDA!((field) double property_tree_edit_commands.Stroke.widthF, (enum) property_tree_edit_commands.readOnlyreadOnly))
return (enum) property_tree_edit_commands.RefusalWhy a write was refused — the view renders this, it is not an exception.
Refusal.(enum value) property_tree_edit_commands.Refusal.readOnlyField = 2readOnlyField;
else
{
if ((parameter) ulong at_at_ + 1 == (parameter) const(property_tree_edit_commands.Seg[]) segssegs.(field) ulong const(property_tree_edit_commands.Seg[]).lengthlength)
return bool property_tree_edit_commands.assignLeaf!double(ref double v, in property_tree_edit_commands.EditValue e, out property_tree_edit_commands.EditValue old) @safeAssigns v from an EditValue when the types line up; reports the old
value as an EditValue so the caller can build the inverse.
assignLeaf(__traits(getMember, subject, name),
(parameter) const(property_tree_edit_commands.Edit) ee.(field) property_tree_edit_commands.EditValue property_tree_edit_commands.Edit.valuevalue, (parameter) property_tree_edit_commands.EditValue oldold)
? (enum) property_tree_edit_commands.RefusalWhy a write was refused — the view renders this, it is not an exception.
Refusal.(enum value) property_tree_edit_commands.Refusal.none = cast(ubyte)0unone : (enum) property_tree_edit_commands.RefusalWhy a write was refused — the view renders this, it is not an exception.
Refusal.(enum value) property_tree_edit_commands.Refusal.typeMismatch = 4typeMismatch;
return property_tree_edit_commands.Refusal property_tree_edit_commands.applyAt!double(ref double subject, in property_tree_edit_commands.Seg[] segs, ulong at_, in property_tree_edit_commands.Edit e, in property_tree_edit_commands.Policy pol, out property_tree_edit_commands.EditValue old) pure nothrow @nogc @safeThe generated dispatch: one walk, parameterised by TYPE only (open-set-descent.d).
@readOnly is consulted HERE (C13) — a view cannot route around it.
applyAt(__traits(getMember, subject, name),
(parameter) const(property_tree_edit_commands.Seg[]) segssegs, (parameter) ulong at_at_ + 1, (parameter) const(property_tree_edit_commands.Edit) ee, (parameter) const(property_tree_edit_commands.Policy) polpol, (parameter) property_tree_edit_commands.EditValue oldold);
}
}
}}
default: return (enum) property_tree_edit_commands.RefusalWhy a write was refused — the view renders this, it is not an exception.
Refusal.(enum value) property_tree_edit_commands.Refusal.noSuchPath = 1noSuchPath;
}
}
else static if ((template instance) std.traits.isArray!(property_tree_edit_commands.Cap)isArray!(alias) T = property_tree_edit_commands.CapT && !(template instance) isSomeString!TisSomeString!(alias) T = stringT)
{
if (at_ >= segs.length || !segs[at_].isIndex
|| segs[at_].index >= subject.length) return Refusal.noSuchPath;
if (at_ + 1 == segs.length)
return assignLeaf(subject[segs[at_].index], e.value, old)
? Refusal.none : Refusal.typeMismatch;
return applyAt(subject[segs[at_].index], segs, at_ + 1, e, pol, old);
}
else
return (enum) property_tree_edit_commands.RefusalWhy a write was refused — the view renders this, it is not an exception.
Refusal.(enum value) property_tree_edit_commands.Refusal.noSuchPath = 1noSuchPath;
}
/// The public verb. Read-only policy is refused before the walk (C13).
(struct) property_tree_edit_commands.AppliedApplied property_tree_edit_commands.Applied property_tree_edit_commands.apply!(property_tree_edit_commands.Layer)(ref property_tree_edit_commands.Layer subject, in property_tree_edit_commands.Edit e, in property_tree_edit_commands.Policy pol = Policy(false)) @safeThe public verb. Read-only policy is refused before the walk (C13).
apply(T)(ref (alias) T = property_tree_edit_commands.LayerT (parameter) property_tree_edit_commands.Layer subjectsubject, in (struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit (parameter) const(property_tree_edit_commands.Edit) ee, in (struct) property_tree_edit_commands.PolicyPolicy (parameter) const(property_tree_edit_commands.Policy) polpol = (struct) property_tree_edit_commands.PolicyPolicy.(constant) property_tree_edit_commands.Policy property_tree_edit_commands.Policy.init = Policy(false)init)
{
if ((parameter) const(property_tree_edit_commands.Policy) polpol.(field) bool property_tree_edit_commands.Policy.readOnlyreadOnly) return (struct) property_tree_edit_commands.AppliedApplied((enum) property_tree_edit_commands.RefusalWhy a write was refused — the view renders this, it is not an exception.
Refusal.(enum value) property_tree_edit_commands.Refusal.readOnlyPolicy = 3readOnlyPolicy);
(struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue (local variable) property_tree_edit_commands.EditValue oldold;
const (local variable) const(property_tree_edit_commands.Refusal) rr = property_tree_edit_commands.Refusal property_tree_edit_commands.applyAt!(property_tree_edit_commands.Layer)(ref property_tree_edit_commands.Layer subject, in property_tree_edit_commands.Seg[] segs, ulong at_, in property_tree_edit_commands.Edit e, in property_tree_edit_commands.Policy pol, out property_tree_edit_commands.EditValue old) @safeThe generated dispatch: one walk, parameterised by TYPE only (open-set-descent.d).
@readOnly is consulted HERE (C13) — a view cannot route around it.
applyAt((parameter) property_tree_edit_commands.Layer subjectsubject, property_tree_edit_commands.Seg[] property_tree_edit_commands.segments(scope const(char)[] path) pure @safesegments((parameter) const(property_tree_edit_commands.Edit) ee.(field) string property_tree_edit_commands.Edit.pathpath), 0, (parameter) const(property_tree_edit_commands.Edit) ee, (parameter) const(property_tree_edit_commands.Policy) polpol, (local variable) property_tree_edit_commands.EditValue oldold);
if ((local variable) const(property_tree_edit_commands.Refusal) rr != (enum) property_tree_edit_commands.RefusalWhy a write was refused — the view renders this, it is not an exception.
Refusal.(enum value) property_tree_edit_commands.Refusal.none = cast(ubyte)0unone) return (struct) property_tree_edit_commands.AppliedApplied((local variable) const(property_tree_edit_commands.Refusal) rr);
// C12: the inverse is the same value type, built from what was there.
return (struct) property_tree_edit_commands.AppliedApplied((enum) property_tree_edit_commands.RefusalWhy a write was refused — the view renders this, it is not an exception.
Refusal.(enum value) property_tree_edit_commands.Refusal.none = cast(ubyte)0unone, (struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit((parameter) const(property_tree_edit_commands.Edit) ee.(field) string property_tree_edit_commands.Edit.pathpath, (local variable) property_tree_edit_commands.EditValue oldold, (enum) property_tree_edit_commands.PhasePhase.(enum value) property_tree_edit_commands.Phase.commit = 1commit));
}
// ── path segments ([`path-addressing.d`](./path-addressing.d), verbatim) ────────────────────────────────────────
struct (struct) property_tree_edit_commands.SegSeg { (alias) object.string = stringstring (field) string property_tree_edit_commands.Seg.namename; (alias) object.size_t = ulongsize_t (field) ulong property_tree_edit_commands.Seg.indexindex; bool (field) bool property_tree_edit_commands.Seg.isIndexisIndex; }
(struct) property_tree_edit_commands.SegSeg[] property_tree_edit_commands.Seg[] property_tree_edit_commands.segments(scope const(char)[] path) pure @safesegments(scope const(char)[] (parameter) const(char)[] pathpath) pure
{
(struct) property_tree_edit_commands.SegSeg[] (local variable) property_tree_edit_commands.Seg[] segssegs;
(alias) object.size_t = ulongsize_t (local variable) ulong ii;
while ((local variable) ulong ii < (parameter) const(char)[] pathpath.(field) ulong const(char)[].lengthlength)
{
if ((parameter) const(char)[] pathpath[(local variable) ulong ii] == '.') { (local variable) ulong ii++; continue; }
if ((parameter) const(char)[] pathpath[(local variable) ulong ii] == '[')
{
(alias) object.size_t = ulongsize_t (local variable) ulong jj = ++(local variable) ulong ii;
while ((local variable) ulong jj < (parameter) const(char)[] pathpath.(field) ulong const(char)[].lengthlength && (parameter) const(char)[] pathpath[(local variable) ulong jj] != ']') (local variable) ulong jj++;
(local variable) property_tree_edit_commands.Seg[] segssegs ~= (struct) property_tree_edit_commands.SegSeg(null, ulong std.conv.to!ulong.to!(const(char)[])(const(char)[] __param_0) pure @safeThe to template converts a value from one type to another.
The source type is deduced and the target type must be specified, for example the
expression to`!int(42.0)` converts the number 42 from
`double` to `int`. The conversion is "safe", i.e.,
it checks for overflow; to!int(4.2e10) would throw the
ConvOverflowException exception. Overflow checks are only
inserted when necessary, e.g., ``to!double(42) does not do
any checking because any int fits in a double.
Conversions from string to numeric types differ from the C equivalents
atoi() and atol() by checking for overflow and not allowing whitespace.
For conversion of strings to signed types, the grammar recognized is:
Integer:
Sign UnsignedInteger
UnsignedInteger
Sign:
+
-
For conversion to unsigned types, the grammar recognized is:
UnsignedInteger:
DecimalDigit
DecimalDigit UnsignedInteger
Examples
Converting a value to its own type (useful mostly for generic code)
simply returns its argument.
int a = 42;
int b = to!int(a);
double c = to!double(3.14); // c is double with value 3.14
Converting among numeric types is a safe way to cast them around.
Conversions from floating-point types to integral types allow loss of
precision (the fractional part of a floating-point number). The
conversion is truncating towards zero, the same way a cast would
truncate. (To round a floating point value when casting to an
integral, use roundTo.)
import std.exception : assertThrown;
int a = 420;
assert(to!long(a) == a);
assertThrown!ConvOverflowException(to!byte(a));
assert(to!int(4.2e6) == 4200000);
assertThrown!ConvOverflowException(to!uint(-3.14));
assert(to!uint(3.14) == 3);
assert(to!uint(3.99) == 3);
assert(to!int(-3.99) == -3);
When converting strings to numeric types, note that D hexadecimal and binary
literals are not handled. Neither the prefixes that indicate the base, nor the
horizontal bar used to separate groups of digits are recognized. This also
applies to the suffixes that indicate the type.
To work around this, you can specify a radix for conversions involving numbers.
auto str = to!string(42, 16);
assert(str == "2A");
auto i = to!int(str, 16);
assert(i == 42);
Conversions from integral types to floating-point types always
succeed, but might lose accuracy. The largest integers with a
predecessor representable in floating-point format are 2^24-1 for
float, 2^53-1 for double, and 2^64-1 for real (when
real is 80-bit, e.g. on Intel machines).
// 2^24 - 1, largest proper integer representable as float
int a = 16_777_215;
assert(to!int(to!float(a)) == a);
assert(to!int(to!float(-a)) == -a);
Conversion from string types to char types enforces the input
to consist of a single code point, and said code point must
fit in the target type. Otherwise, ConvException is thrown.
import std.exception : assertThrown;
assert(to!char("a") == 'a');
assertThrown(to!char("ñ")); // 'ñ' does not fit into a char
assert(to!wchar("ñ") == 'ñ');
assertThrown(to!wchar("😃")); // '😃' does not fit into a wchar
assert(to!dchar("😃") == '😃');
// Using wstring or dstring as source type does not affect the result
assert(to!char("a"w) == 'a');
assert(to!char("a"d) == 'a');
// Two code points cannot be converted to a single one
assertThrown(to!char("ab"));
Converting an array to another array type works by converting each
element in turn. Associative arrays can be converted to associative
arrays as long as keys and values can in turn be converted.
import std.string : split;
int[] a = [1, 2, 3];
auto b = to!(float[])(a);
assert(b == [1.0f, 2, 3]);
string str = "1 2 3 4 5 6";
auto numbers = to!(double[])(split(str));
assert(numbers == [1.0, 2, 3, 4, 5, 6]);
int[string] c;
c["a"] = 1;
c["b"] = 2;
auto d = to!(double[wstring])(c);
assert(d["a"w] == 1 && d["b"w] == 2);
Conversions operate transitively, meaning that they work on arrays and
associative arrays of any complexity.
This conversion works because to`!short` applies to an `int`, to!wstring
applies to a string, to`!string` applies to a `double`, and
to!(double[]) applies to an int[]. The conversion might throw an
exception because ``to!short might fail the range check.
int[string][double[int[]]] a;
auto b = to!(short[wstring][string[double[]]])(a);
Object-to-object conversions by dynamic casting throw exception when
the source is non-null and the target is null.
import std.exception : assertThrown;
// Testing object conversions
class A {}
class B : A {}
class C : A {}
A a1 = new A, a2 = new B, a3 = new C;
assert(to!B(a2) is a2);
assert(to!C(a3) is a3);
assertThrown!ConvException(to!B(a3));
Stringize conversion from all types is supported.
String to string conversion works for any two string types having
(char, wchar, dchar) character widths and any
combination of qualifiers (mutable, const, or immutable).
Converts array (other than strings) to string.
Each element is converted by calling ``to!T.
Associative array to string conversion.
Each element is converted by calling ``to!T.
Object to string conversion calls toString against the object or
returns "null" if the object is null.
Struct to string conversion calls toString against the struct if
it is defined.
For structs that do not define toString, the conversion to string
produces the list of fields.
Enumerated types are converted to strings as their symbolic names.
Boolean values are converted to "true" or "false".
char, wchar, dchar to a string type.
Unsigned or signed integers to strings.
: Convert integral value to string in radix radix.
radix must be a value from 2 to 36.
value is treated as a signed value only if radix is 10.
The characters A through Z are used to represent values 10 through 36
and their case is determined by the letterCase parameter.
All floating point types to all string types.
Pointer to string conversions convert the pointer to a size_t value.
If pointer is char*, treat it as C-style strings.
In that case, this function is @system.
See formatValue on how toString should be defined.
// Conversion representing dynamic/static array with string
long[] a = [ 1, 3, 5 ];
assert(to!string(a) == "[1, 3, 5]");
// Conversion representing associative array with string
int[string] associativeArray = ["0":1, "1":2];
assert(to!string(associativeArray) == `["0":1, "1":2]` ||
to!string(associativeArray) == `["1":2, "0":1]`);
// char* to string conversion
assert(to!string(cast(char*) null) == "");
assert(to!string("foo\0".ptr) == "foo");
// Conversion reinterpreting void array to string
auto w = "abcx"w;
const(void)[] b = w;
assert(b.length == 8);
auto c = to!(wchar[])(b);
assert(c == "abcx");
Strings can be converted to enum types. The enum member with the same name as the
input string is returned. The comparison is case-sensitive.
A ConvException is thrown if the enum does not have the specified member.
import std.exception : assertThrown;
enum E { a, b, c }
assert(to!E("a") == E.a);
assert(to!E("b") == E.b);
assertThrown!ConvException(to!E("A"));
to!(alias) object.size_t = ulongsize_t((parameter) const(char)[] pathpath[(local variable) ulong ii .. (local variable) ulong jj]), true);
(local variable) ulong ii = (local variable) ulong jj + 1;
}
else
{
(alias) object.size_t = ulongsize_t (local variable) ulong jj = (local variable) ulong ii;
while ((local variable) ulong jj < (parameter) const(char)[] pathpath.(field) ulong const(char)[].lengthlength && (parameter) const(char)[] pathpath[(local variable) ulong jj] != '.' && (parameter) const(char)[] pathpath[(local variable) ulong jj] != '[') (local variable) ulong jj++;
(local variable) property_tree_edit_commands.Seg[] segssegs ~= (struct) property_tree_edit_commands.SegSeg((parameter) const(char)[] pathpath[(local variable) ulong ii .. (local variable) ulong jj].string object.idup!(const(char))(const(char)[] a) pure nothrow @property @safeProvide the .idup array property, which creates an immutable duplicate.
idup, 0, false);
(local variable) ulong ii = (local variable) ulong jj;
}
}
return (local variable) property_tree_edit_commands.Seg[] segssegs;
}
// ── the subject ──────────────────────────────────────────────────────────────
enum (enum) property_tree_edit_commands.CapCap { (enum value) property_tree_edit_commands.Cap.butt = 0butt, (enum value) property_tree_edit_commands.Cap.round = 1round, (enum value) property_tree_edit_commands.Cap.square = 2square }
struct (struct) property_tree_edit_commands.StrokeStroke { double (field) double property_tree_edit_commands.Stroke.widthwidth = 1; (enum) property_tree_edit_commands.CapCap (field) property_tree_edit_commands.Cap property_tree_edit_commands.Stroke.capcap; }
struct (struct) property_tree_edit_commands.LayerLayer
{
(alias) object.string = stringstring (field) string property_tree_edit_commands.Layer.namename = "layer";
bool (field) bool property_tree_edit_commands.Layer.visiblevisible = true;
int (field) int property_tree_edit_commands.Layer.orderorder;
(struct) property_tree_edit_commands.StrokeStroke (field) property_tree_edit_commands.Stroke property_tree_edit_commands.Layer.strokestroke;
@(enum) property_tree_edit_commands.readOnlyreadOnly ulong (field) ulong property_tree_edit_commands.Layer.idid = 42;
}
// C15: the sum type.
struct (struct) property_tree_edit_commands.SolidSolid { uint (field) uint property_tree_edit_commands.Solid.rgbargba; }
struct (struct) property_tree_edit_commands.GradientGradient { (alias) object.string = stringstring (field) string property_tree_edit_commands.Gradient.fromfrom, (field) string property_tree_edit_commands.Gradient.toto; int (field) int property_tree_edit_commands.Gradient.stopsstops = 2; }
alias (alias) property_tree_edit_commands.Paint = std.sumtype.SumType!(Solid, Gradient)Paint = (struct) std.sumtype.SumType!(property_tree_edit_commands.Solid, property_tree_edit_commands.Gradient)A tagged union that can hold a
single value from any of a specified set of types.
The value in a SumType can be operated on using pattern matching.
To avoid ambiguity, duplicate types are not allowed (but see the
"basic usage" example for a workaround).
The special type This can be used as a placeholder to create
self-referential types, just like with Algebraic. See the
"Recursive SumTypes" example for usage.
A SumType is initialized by default to hold the .init value of its
first member type, just like a regular union. The version identifier
SumTypeNoDefaultCtor can be used to disable this behavior.
SumType!((struct) property_tree_edit_commands.SolidSolid, (struct) property_tree_edit_commands.GradientGradient);
/// The one `@trusted` seam a variant switch needs, and its precondition.
/// PRECONDITION: no reference into the old payload outlives this call — which
/// the frame model guarantees, since rows are rebuilt after every edit.
void void property_tree_edit_commands.switchTo!(property_tree_edit_commands.Gradient)(ref std.sumtype.SumType!(Solid, Gradient) p, property_tree_edit_commands.Gradient v) pure nothrow @nogc @trustedThe one @trusted seam a variant switch needs, and its precondition.
PRECONDITION
no reference into the old payload outlives this call — which
the frame model guarantees, since rows are rebuilt after every edit.
switchTo(V)(ref (alias) property_tree_edit_commands.Paint = std.sumtype.SumType!(Solid, Gradient)Paint (parameter) std.sumtype.SumType!(Solid, Gradient) pp, (alias) V = property_tree_edit_commands.GradientV (parameter) property_tree_edit_commands.Gradient vv) @trusted { (parameter) std.sumtype.SumType!(Solid, Gradient) pp = std.sumtype.SumType!(Solid, Gradient) std.sumtype.SumType!(property_tree_edit_commands.Solid, property_tree_edit_commands.Gradient).opAssign(property_tree_edit_commands.Gradient rhs) pure nothrow @nogc ref @safeAssigns a value to a SumType.
If any of the SumType's members other than the one being assigned
to contain pointers or references, it is possible for the assignment
to cause memory corruption (see the
"Memory corruption" example below for an
illustration of how). Therefore, such assignments are considered
@system.
An individual assignment can be @trusted if the caller can
guarantee that there are no outstanding references to any SumType
members that contain pointers or references at the time the
assignment occurs.
Examples
Memory corruption
This example shows how assignment to a SumType can be used to
cause memory corruption in @system code. In @safe code, the
assignment s = 123 would not be allowed.
SumType!(int*, int) s = new int;
s.tryMatch!(
(ref int* p) {
s = 123; // overwrites `p`
return *p; // undefined behavior
}
);
v; }
void void D main() @safemain()
{
import (package) stdstd.(module) std.stdioCategory Symbols File handles _popen File isFileHandle openNetwork stderr stdin stdout Reading chunks lines readf readfln readln Writing toFile write writef writefln writeln Misc KeepTerminator LockType StdioException
Standard I/O functions that extend core.stdc.stdio. core.stdc.stdio
is publically imported when importing std.stdio.
There are three layers of I/O:
The lowest layer is the operating system layer. The two main schemes are Windows and Posix.
C's stdio.h which unifies the two operating system schemes.
std.stdio, this module, unifies the various stdio.h implementations into
a high level package for D programs.
Source
std/stdio.d
stdio : (alias template) writefln = std.stdio.writefln(alias fmt, A...)(A args) if (isSomeString!(typeof(fmt)))Equivalent to $(D writef(fmt, args, '\n')).
writefln, (alias template) writeln = std.stdio.writeln(T...)(T args)Equivalent to write(args, '\n'). Calling writeln without
arguments is valid and just prints a newline to the standard
output.
Params:
args = the items to write to stdout
Throws:
In case of an I/O error, throws an $(LREF StdioException).
Example:
Reads stdin and writes it to stdout with an argument
counter.
import std.stdio;
void main()
{
string line;
for (size_t count = 0; (line = readln) !is null; count++)
{
writeln("Input ", count, ": ", line);
}
}
---
writeln;
(struct) property_tree_edit_commands.LayerLayer (local variable) property_tree_edit_commands.Layer ll;
(struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit[] (local variable) property_tree_edit_commands.Edit[] undoundo;
void void property_tree_edit_commands.main.run(property_tree_edit_commands.Edit e, property_tree_edit_commands.Policy pol = Policy(false)) @saferun((struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit (parameter) property_tree_edit_commands.Edit ee, (struct) property_tree_edit_commands.PolicyPolicy (parameter) property_tree_edit_commands.Policy polpol = (struct) property_tree_edit_commands.PolicyPolicy.(constant) property_tree_edit_commands.Policy property_tree_edit_commands.Policy.init = Policy(false)init)
{
const (local variable) const(property_tree_edit_commands.Applied) rr = property_tree_edit_commands.Applied property_tree_edit_commands.apply!(property_tree_edit_commands.Layer)(ref property_tree_edit_commands.Layer subject, in property_tree_edit_commands.Edit e, in property_tree_edit_commands.Policy pol = Policy(false)) @safeThe public verb. Read-only policy is refused before the walk (C13).
apply((local variable) property_tree_edit_commands.Layer ll, (parameter) property_tree_edit_commands.Edit ee, (parameter) property_tree_edit_commands.Policy polpol);
void std.stdio.writefln!(char, string, string, property_tree_edit_commands.Phase, const(property_tree_edit_commands.Refusal), string)(in char[] fmt, string __param_1, string __param_2, property_tree_edit_commands.Phase __param_3, const(property_tree_edit_commands.Refusal) __param_4, string __param_5) @safeEquivalent to writef(fmt, args, '\n').
writefln(" %-22s %-10s %-8s → %-14s %s", (parameter) property_tree_edit_commands.Edit ee.(field) string property_tree_edit_commands.Edit.pathpath, (parameter) property_tree_edit_commands.Edit ee.(field) property_tree_edit_commands.EditValue property_tree_edit_commands.Edit.valuevalue.string property_tree_edit_commands.EditValue.toString() const pure @safetoString,
(parameter) property_tree_edit_commands.Edit ee.(field) property_tree_edit_commands.Phase property_tree_edit_commands.Edit.phasephase, (local variable) const(property_tree_edit_commands.Applied) rr.(field) property_tree_edit_commands.Refusal property_tree_edit_commands.Applied.refusalrefusal,
(local variable) const(property_tree_edit_commands.Applied) rr.bool property_tree_edit_commands.Applied.ok() const pure nothrow @nogc @safeok && (parameter) property_tree_edit_commands.Edit ee.(field) property_tree_edit_commands.Phase property_tree_edit_commands.Edit.phasephase == (enum) property_tree_edit_commands.PhasePhase.(enum value) property_tree_edit_commands.Phase.commit = 1commit
? "inverse " ~ (local variable) const(property_tree_edit_commands.Applied) rr.(field) property_tree_edit_commands.Edit property_tree_edit_commands.Applied.inversevalid when refusal == none && phase == commit
inverse.(field) property_tree_edit_commands.EditValue property_tree_edit_commands.Edit.valuevalue.string property_tree_edit_commands.EditValue.toString() const pure @safetoString : "");
if ((local variable) const(property_tree_edit_commands.Applied) rr.bool property_tree_edit_commands.Applied.ok() const pure nothrow @nogc @safeok && (parameter) property_tree_edit_commands.Edit ee.(field) property_tree_edit_commands.Phase property_tree_edit_commands.Edit.phasephase == (enum) property_tree_edit_commands.PhasePhase.(enum value) property_tree_edit_commands.Phase.commit = 1commit) (local variable) property_tree_edit_commands.Edit[] undoundo ~= (local variable) const(property_tree_edit_commands.Applied) rr.(field) property_tree_edit_commands.Edit property_tree_edit_commands.Applied.inversevalid when refusal == none && phase == commit
inverse;
}
void std.stdio.writeln!string(string __param_0) @safeEquivalent to write(args, '\n'). Calling writeln without
arguments is valid and just prints a newline to the standard
output.
Example
Reads stdin and writes it to stdout with an argument
counter.
import std.stdio;
void main()
{
string line;
for (size_t count = 0; (line = readln) !is null; count++)
{
writeln("Input ", count, ": ", line);
}
}
writeln("C12/C13 — edits as values; every write returns its inverse\n");
void std.stdio.writefln!(char, string, string, string, string, string)(in char[] fmt, string __param_1, string __param_2, string __param_3, string __param_4, string __param_5) @safeEquivalent to writef(fmt, args, '\n').
writefln(" %-22s %-10s %-8s %-14s %s",
"path", "value", "phase", "refusal", "undo");
void property_tree_edit_commands.main.run(property_tree_edit_commands.Edit e, property_tree_edit_commands.Policy pol = Policy(false)) @saferun((struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit("name", (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(string v) @safeof("background")));
void property_tree_edit_commands.main.run(property_tree_edit_commands.Edit e, property_tree_edit_commands.Policy pol = Policy(false)) @saferun((struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit("visible", (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(bool v) @safeof(false)));
void property_tree_edit_commands.main.run(property_tree_edit_commands.Edit e, property_tree_edit_commands.Policy pol = Policy(false)) @saferun((struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit("stroke.width", (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(double v) @safeof(2.5)));
void property_tree_edit_commands.main.run(property_tree_edit_commands.Edit e, property_tree_edit_commands.Policy pol = Policy(false)) @saferun((struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit("stroke.cap", (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(string v) @safeof("round")));
void property_tree_edit_commands.main.run(property_tree_edit_commands.Edit e, property_tree_edit_commands.Policy pol = Policy(false)) @saferun((struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit("id", (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(long v) @safeof(7L))); // @readOnly field
void property_tree_edit_commands.main.run(property_tree_edit_commands.Edit e, property_tree_edit_commands.Policy pol = Policy(false)) @saferun((struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit("order", (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(string v) @safeof("nope"))); // type mismatch
void property_tree_edit_commands.main.run(property_tree_edit_commands.Edit e, property_tree_edit_commands.Policy pol = Policy(false)) @saferun((struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit("stroke.nope", (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(long v) @safeof(1L))); // no such path
void property_tree_edit_commands.main.run(property_tree_edit_commands.Edit e, property_tree_edit_commands.Policy pol = Policy(false)) @saferun((struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit("name", (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(string v) @safeof("x")), (struct) property_tree_edit_commands.PolicyPolicy(readOnly: true)); // policy
void std.stdio.writefln!(char, property_tree_edit_commands.Layer)(in char[] fmt, property_tree_edit_commands.Layer __param_1) @safeEquivalent to writef(fmt, args, '\n').
writefln("\n subject now: %s", (local variable) property_tree_edit_commands.Layer ll);
void std.stdio.writeln!string(string __param_0) @safeEquivalent to write(args, '\n'). Calling writeln without
arguments is valid and just prints a newline to the standard
output.
Example
Reads stdin and writes it to stdout with an argument
counter.
import std.stdio;
void main()
{
string line;
for (size_t count = 0; (line = readln) !is null; count++)
{
writeln("Input ", count, ": ", line);
}
}
writeln("\nC12 — undo is the host replaying the inverses, newest first:");
foreach_reverse ((parameter) property_tree_edit_commands.Edit ee; (local variable) property_tree_edit_commands.Edit[] undoundo)
{
const (local variable) const(property_tree_edit_commands.Applied) rr = property_tree_edit_commands.Applied property_tree_edit_commands.apply!(property_tree_edit_commands.Layer)(ref property_tree_edit_commands.Layer subject, in property_tree_edit_commands.Edit e, in property_tree_edit_commands.Policy pol = Policy(false)) @safeThe public verb. Read-only policy is refused before the walk (C13).
apply((local variable) property_tree_edit_commands.Layer ll, (local variable) property_tree_edit_commands.Edit ee);
void std.stdio.writefln!(char, string, string, const(property_tree_edit_commands.Refusal))(in char[] fmt, string __param_1, string __param_2, const(property_tree_edit_commands.Refusal) __param_3) @safeEquivalent to writef(fmt, args, '\n').
writefln(" undo %-14s %-12s %s", (local variable) property_tree_edit_commands.Edit ee.(field) string property_tree_edit_commands.Edit.pathpath, (local variable) property_tree_edit_commands.Edit ee.(field) property_tree_edit_commands.EditValue property_tree_edit_commands.Edit.valuevalue.string property_tree_edit_commands.EditValue.toString() const pure @safetoString, (local variable) const(property_tree_edit_commands.Applied) rr.(field) property_tree_edit_commands.Refusal property_tree_edit_commands.Applied.refusalrefusal);
}
void std.stdio.writefln!(char, property_tree_edit_commands.Layer)(in char[] fmt, property_tree_edit_commands.Layer __param_1) @safeEquivalent to writef(fmt, args, '\n').
writefln(" subject restored: %s", (local variable) property_tree_edit_commands.Layer ll);
void std.stdio.writeln!string(string __param_0) @safeEquivalent to write(args, '\n'). Calling writeln without
arguments is valid and just prints a newline to the standard
output.
Example
Reads stdin and writes it to stdout with an argument
counter.
import std.stdio;
void main()
{
string line;
for (size_t count = 0; (line = readln) !is null; count++)
{
writeln("Input ", count, ": ", line);
}
}
writeln("\nC14 — a drag: previews mutate, only the commit records undo");
(local variable) property_tree_edit_commands.Edit[] undoundo = null;
foreach ((parameter) double ww; [1.5, 2.0, 2.5, 3.0])
void property_tree_edit_commands.main.run(property_tree_edit_commands.Edit e, property_tree_edit_commands.Policy pol = Policy(false)) @saferun((struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit("stroke.width", (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(double v) @safeof((local variable) double ww), (enum) property_tree_edit_commands.PhasePhase.(enum value) property_tree_edit_commands.Phase.preview = cast(ubyte)0upreview));
void property_tree_edit_commands.main.run(property_tree_edit_commands.Edit e, property_tree_edit_commands.Policy pol = Policy(false)) @saferun((struct) property_tree_edit_commands.EditThe whole mutation API surface: one value.
Edit("stroke.width", (struct) property_tree_edit_commands.EditValueEvery leaf the component can produce an edit for, as one value type.
EditValue.property_tree_edit_commands.EditValue property_tree_edit_commands.EditValue.of(double v) @safeof(3.0), (enum) property_tree_edit_commands.PhasePhase.(enum value) property_tree_edit_commands.Phase.commit = 1commit));
void std.stdio.writefln!(char, ulong, double)(in char[] fmt, ulong __param_1, double __param_2) @safeEquivalent to writef(fmt, args, '\n').
writefln(" undo entries after the whole drag: %s (width=%s)",
(local variable) property_tree_edit_commands.Edit[] undoundo.(field) ulong property_tree_edit_commands.Edit[].lengthlength, (local variable) property_tree_edit_commands.Layer ll.(field) property_tree_edit_commands.Stroke property_tree_edit_commands.Layer.strokestroke.(field) double property_tree_edit_commands.Stroke.widthwidth);
void std.stdio.writeln!string(string __param_0) @safeEquivalent to write(args, '\n'). Calling writeln without
arguments is valid and just prints a newline to the standard
output.
Example
Reads stdin and writes it to stdout with an argument
counter.
import std.stdio;
void main()
{
string line;
for (size_t count = 0; (line = readln) !is null; count++)
{
writeln("Input ", count, ": ", line);
}
}
writeln(" NOTE: the inverse of the COMMIT is the value at the drag's end,");
void std.stdio.writeln!string(string __param_0) @safeEquivalent to write(args, '\n'). Calling writeln without
arguments is valid and just prints a newline to the standard
output.
Example
Reads stdin and writes it to stdout with an argument
counter.
import std.stdio;
void main()
{
string line;
for (size_t count = 0; (line = readln) !is null; count++)
{
writeln("Input ", count, ": ", line);
}
}
writeln(" not its start — so a host that wants one undo per drag must");
void std.stdio.writeln!string(string __param_0) @safeEquivalent to write(args, '\n'). Calling writeln without
arguments is valid and just prints a newline to the standard
output.
Example
Reads stdin and writes it to stdout with an argument
counter.
import std.stdio;
void main()
{
string line;
for (size_t count = 0; (line = readln) !is null; count++)
{
writeln("Input ", count, ": ", line);
}
}
writeln(" keep the first preview's prior value. That is a spec decision.");
void std.stdio.writeln!string(string __param_0) @safeEquivalent to write(args, '\n'). Calling writeln without
arguments is valid and just prints a newline to the standard
output.
Example
Reads stdin and writes it to stdout with an argument
counter.
import std.stdio;
void main()
{
string line;
for (size_t count = 0; (line = readln) !is null; count++)
{
writeln("Input ", count, ": ", line);
}
}
writeln("\nC15 — the variant switch is not an assignment of any leaf type");
(alias) property_tree_edit_commands.Paint = std.sumtype.SumType!(Solid, Gradient)Paint (local variable) std.sumtype.SumType!(Solid, Gradient) pp = (struct) property_tree_edit_commands.SolidSolid(0xff0000ff);
void std.stdio.writefln!(char, string)(in char[] fmt, string __param_1) @safeEquivalent to writef(fmt, args, '\n').
writefln(" before: %s", (local variable) std.sumtype.SumType!(Solid, Gradient) pp.string property_tree_edit_commands.main.match!(std.sumtype.SumType!(Solid, Gradient))(ref std.sumtype.SumType!(Solid, Gradient) __param_0) pure nothrow @safeCalls a type-appropriate function with the value held in a SumType.
For each possible type the SumType can hold, the given handlers are
checked, in order, to see whether they accept a single argument of that type.
The first one that does is chosen as the match for that type. (Note that the
first match may not always be the most exact match.
See "Avoiding unintentional matches" for
one common pitfall.)
Every type must have a matching handler, and every handler must match at
least one type. This is enforced at compile time.
Handlers may be functions, delegates, or objects with opCall overloads. If
a function with more than one overload is given as a handler, all of the
overloads are considered as potential matches.
Templated handlers are also accepted, and will match any type for which they
can be implicitly instantiated.
(Remember that a function literal
without an explicit argument type is considered a template.)
If multiple SumTypes are passed to match, their values are passed to the
handlers as separate arguments, and matching is done for each possible
combination of value types. See "Multiple dispatch" for
an example.
Examples
Avoiding unintentional matches
Sometimes, implicit conversions may cause a handler to match more types than
intended. The example below shows two solutions to this problem.
alias Number = SumType!(double, int);
Number x;
// Problem: because int implicitly converts to double, the double
// handler is used for both types, and the int handler never matches.
assert(!__traits(compiles,
x.match!(
(double d) => "got double",
(int n) => "got int"
)
));
// Solution 1: put the handler for the "more specialized" type (in this
// case, int) before the handler for the type it converts to.
assert(__traits(compiles,
x.match!(
(int n) => "got int",
(double d) => "got double"
)
));
// Solution 2: use a template that only accepts the exact type it's
// supposed to match, instead of any type that implicitly converts to it.
alias exactly(T, alias fun) = function (arg)
{
static assert(is(typeof(arg) == T));
return fun(arg);
};
// Now, even if we put the double handler first, it will only be used for
// doubles, not ints.
assert(__traits(compiles,
x.match!(
exactly!(double, d => "got double"),
exactly!(int, n => "got int")
)
));
Multiple dispatch
Pattern matching can be performed on multiple SumTypes at once by passing
handlers with multiple arguments. This usually leads to more concise code
than using nested calls to match, as show below.
struct Point2D { double x, y; }
struct Point3D { double x, y, z; }
alias Point = SumType!(Point2D, Point3D);
version (none)
{
// This function works, but the code is ugly and repetitive.
// It uses three separate calls to match!
@safe pure nothrow @nogc
bool sameDimensions(Point p1, Point p2)
{
return p1.match!(
(Point2D _) => p2.match!(
(Point2D _) => true,
_ => false
),
(Point3D _) => p2.match!(
(Point3D _) => true,
_ => false
)
);
}
}
// This version is much nicer.
@safe pure nothrow @nogc
bool sameDimensions(Point p1, Point p2)
{
alias doMatch = match!(
(Point2D _1, Point2D _2) => true,
(Point3D _1, Point3D _2) => true,
(_1, _2) => false
);
return doMatch(p1, p2);
}
Point a = Point2D(1, 2);
Point b = Point2D(3, 4);
Point c = Point3D(5, 6, 7);
Point d = Point3D(8, 9, 0);
assert( sameDimensions(a, b));
assert( sameDimensions(c, d));
assert(!sameDimensions(a, c));
assert(!sameDimensions(d, b));
match!(s => text("Solid ", s.rgba),
g => text("Gradient ", g.stops)));
// The rule is DIRECTIONAL, and finer than "SumType assignment is @system":
// `opAssign` is unsafe when the variant being OVERWRITTEN may hold
// indirections, because a reference into the old payload would dangle.
void std.stdio.writefln!(char, string)(in char[] fmt, string __param_1) @safeEquivalent to writef(fmt, args, '\n').
writefln(" q = Gradient(...) over a maybe-Solid @safe? %s",
__traits(compiles, () @safe { (alias) property_tree_edit_commands.Paint = std.sumtype.SumType!(Solid, Gradient)Paint (local variable) std.sumtype.SumType!(Solid, Gradient) qq; (local variable) std.sumtype.SumType!(Solid, Gradient) qq = std.sumtype.SumType!(Solid, Gradient) std.sumtype.SumType!(property_tree_edit_commands.Solid, property_tree_edit_commands.Gradient).opAssign(property_tree_edit_commands.Gradient rhs) pure nothrow @nogc ref @safeAssigns a value to a SumType.
If any of the SumType's members other than the one being assigned
to contain pointers or references, it is possible for the assignment
to cause memory corruption (see the
"Memory corruption" example below for an
illustration of how). Therefore, such assignments are considered
@system.
An individual assignment can be @trusted if the caller can
guarantee that there are no outstanding references to any SumType
members that contain pointers or references at the time the
assignment occurs.
Examples
Memory corruption
This example shows how assignment to a SumType can be used to
cause memory corruption in @system code. In @safe code, the
assignment s = 123 would not be allowed.
SumType!(int*, int) s = new int;
s.tryMatch!(
(ref int* p) {
s = 123; // overwrites `p`
return *p; // undefined behavior
}
);
Gradient("a", "b"); }())
? "yes — Solid has no indirections" : "no");
void std.stdio.writefln!(char, string)(in char[] fmt, string __param_1) @safeEquivalent to writef(fmt, args, '\n').
writefln(" q = Solid(...) over a maybe-Gradient @safe? %s",
__traits(compiles, () @safe { (alias) property_tree_edit_commands.Paint = std.sumtype.SumType!(Solid, Gradient)Paint (local variable) std.sumtype.SumType!(Solid, Gradient) qq; (local variable) std.sumtype.SumType!(Solid, Gradient) qq = std.sumtype.SumType!(Solid, Gradient) std.sumtype.SumType!(property_tree_edit_commands.Solid, property_tree_edit_commands.Gradient).opAssign(property_tree_edit_commands.Solid rhs) pure nothrow @nogc ref @systemAssigns a value to a SumType.
If any of the SumType's members other than the one being assigned
to contain pointers or references, it is possible for the assignment
to cause memory corruption (see the
"Memory corruption" example below for an
illustration of how). Therefore, such assignments are considered
@system.
An individual assignment can be @trusted if the caller can
guarantee that there are no outstanding references to any SumType
members that contain pointers or references at the time the
assignment occurs.
Examples
Memory corruption
This example shows how assignment to a SumType can be used to
cause memory corruption in @system code. In @safe code, the
assignment s = 123 would not be allowed.
SumType!(int*, int) s = new int;
s.tryMatch!(
(ref int* p) {
s = 123; // overwrites `p`
return *p; // undefined behavior
}
);
Solid(1); }())
? "yes" : "no — Gradient holds strings, so the overwrite is @system");
void property_tree_edit_commands.switchTo!(property_tree_edit_commands.Gradient)(ref std.sumtype.SumType!(Solid, Gradient) p, property_tree_edit_commands.Gradient v) pure nothrow @nogc @trustedThe one @trusted seam a variant switch needs, and its precondition.
PRECONDITION
no reference into the old payload outlives this call — which
the frame model guarantees, since rows are rebuilt after every edit.
switchTo((local variable) std.sumtype.SumType!(Solid, Gradient) pp, (struct) property_tree_edit_commands.GradientGradient("black", "white", 3));
void std.stdio.writefln!(char, string)(in char[] fmt, string __param_1) @safeEquivalent to writef(fmt, args, '\n').
writefln(" after switchTo (one @trusted seam): %s",
(local variable) std.sumtype.SumType!(Solid, Gradient) pp.string property_tree_edit_commands.main.match!(std.sumtype.SumType!(Solid, Gradient))(ref std.sumtype.SumType!(Solid, Gradient) __param_0) pure nothrow @safeCalls a type-appropriate function with the value held in a SumType.
For each possible type the SumType can hold, the given handlers are
checked, in order, to see whether they accept a single argument of that type.
The first one that does is chosen as the match for that type. (Note that the
first match may not always be the most exact match.
See "Avoiding unintentional matches" for
one common pitfall.)
Every type must have a matching handler, and every handler must match at
least one type. This is enforced at compile time.
Handlers may be functions, delegates, or objects with opCall overloads. If
a function with more than one overload is given as a handler, all of the
overloads are considered as potential matches.
Templated handlers are also accepted, and will match any type for which they
can be implicitly instantiated.
(Remember that a function literal
without an explicit argument type is considered a template.)
If multiple SumTypes are passed to match, their values are passed to the
handlers as separate arguments, and matching is done for each possible
combination of value types. See "Multiple dispatch" for
an example.
Examples
Avoiding unintentional matches
Sometimes, implicit conversions may cause a handler to match more types than
intended. The example below shows two solutions to this problem.
alias Number = SumType!(double, int);
Number x;
// Problem: because int implicitly converts to double, the double
// handler is used for both types, and the int handler never matches.
assert(!__traits(compiles,
x.match!(
(double d) => "got double",
(int n) => "got int"
)
));
// Solution 1: put the handler for the "more specialized" type (in this
// case, int) before the handler for the type it converts to.
assert(__traits(compiles,
x.match!(
(int n) => "got int",
(double d) => "got double"
)
));
// Solution 2: use a template that only accepts the exact type it's
// supposed to match, instead of any type that implicitly converts to it.
alias exactly(T, alias fun) = function (arg)
{
static assert(is(typeof(arg) == T));
return fun(arg);
};
// Now, even if we put the double handler first, it will only be used for
// doubles, not ints.
assert(__traits(compiles,
x.match!(
exactly!(double, d => "got double"),
exactly!(int, n => "got int")
)
));
Multiple dispatch
Pattern matching can be performed on multiple SumTypes at once by passing
handlers with multiple arguments. This usually leads to more concise code
than using nested calls to match, as show below.
struct Point2D { double x, y; }
struct Point3D { double x, y, z; }
alias Point = SumType!(Point2D, Point3D);
version (none)
{
// This function works, but the code is ugly and repetitive.
// It uses three separate calls to match!
@safe pure nothrow @nogc
bool sameDimensions(Point p1, Point p2)
{
return p1.match!(
(Point2D _) => p2.match!(
(Point2D _) => true,
_ => false
),
(Point3D _) => p2.match!(
(Point3D _) => true,
_ => false
)
);
}
}
// This version is much nicer.
@safe pure nothrow @nogc
bool sameDimensions(Point p1, Point p2)
{
alias doMatch = match!(
(Point2D _1, Point2D _2) => true,
(Point3D _1, Point3D _2) => true,
(_1, _2) => false
);
return doMatch(p1, p2);
}
Point a = Point2D(1, 2);
Point b = Point2D(3, 4);
Point c = Point3D(5, 6, 7);
Point d = Point3D(8, 9, 0);
assert( sameDimensions(a, b));
assert( sameDimensions(c, d));
assert(!sameDimensions(a, c));
assert(!sameDimensions(d, b));
match!(s => text("Solid ", s.rgba), g => text("Gradient ", g.stops)));
void std.stdio.writeln!string(string __param_0) @safeEquivalent to write(args, '\n'). Calling writeln without
arguments is valid and just prints a newline to the standard
output.
Example
Reads stdin and writes it to stdout with an argument
counter.
import std.stdio;
void main()
{
string line;
for (size_t count = 0; (line = readln) !is null; count++)
{
writeln("Input ", count, ": ", line);
}
}
writeln(" so the edit vocabulary needs EditValue.Kind.variant, and the");
void std.stdio.writeln!string(string __param_0) @safeEquivalent to write(args, '\n'). Calling writeln without
arguments is valid and just prints a newline to the standard
output.
Example
Reads stdin and writes it to stdout with an argument
counter.
import std.stdio;
void main()
{
string line;
for (size_t count = 0; (line = readln) !is null; count++)
{
writeln("Input ", count, ": ", line);
}
}
writeln(" component needs exactly one @trusted function, not @trusted rows.");
}