Write @nogc text

Use SmallBuffer plus sparkles.base.text.writers when a hot path needs formatted text but must not allocate through the garbage collector.

Format into an output range

The writers accept any output range. SmallBuffer!(char, N) is the usual choice for short-lived text:

#!/usr/bin/env dub
/+ dub.sdl:
    name "base_write_nogc_text"
    dependency "sparkles:base" version="*"
+/
import core.time : dur;
import std.stdio : writeln;

import sparkles.base.smallbuffer : SmallBuffer;
import sparkles.base.text.writers : writeBytes, writeDuration, writeIntegerPadded;

@safe nothrow @nogc
void render(ref SmallBuffer!(char, 128) out_)
{
    out_ ~= "job=";
    writeIntegerPadded(out_, 42, 4);
    out_ ~= " rss=";
    writeBytes(out_, 1536);
    out_ ~= " elapsed=";
    writeDuration(out_, dur!"msecs"(90_000));
}

void main()
{
    SmallBuffer!(char, 128) buf;
    render(buf);
    writeln(buf[]);
}

job=0042 rss=1.5KiB elapsed=1.5m

Keep fallbacks explicit

writeValue supports primitive values and user types with @nogctoString hooks. Unsupported types fall back to allocating conversion, so prefer direct writer functions in code that must stay @nogc.