Feature gate: #![feature(int_format_into)]

This is a tracking issue for efficient decimal integer formatting into a fixed-size buffer.

Public API

// core::num

struct NumBuffer { .. }
impl NumBuffer {
    fn new() -> Self;
}

impl $Int {
    fn format_into(self, &mut NumBuffer) -> &str;
}

Steps / History

• ACP: Efficient integer formatting into fixed-size buffer libs-team#546
• Implementation: Implement int_format_into feature #142098
• Final comment period (FCP)¹
• Stabilization PR

Unresolved Questions

• Should this return &[ascii::Char] in the future? Efficient integer formatting into fixed-size buffer libs-team#546 (comment)
• Should NumBuffer be NumBuffer<$Int> so that the reserved space can be tailored to the specific integer's size? Not a big difference with current integer types, but may be significant if we gain u8192 in the future.
• Naming of core::num::NumBuffer.