lperlaki / astr-rs Goto Github PK

Context

The primary goal of this crate seems to be to avoid needless allocations for small constant-sized strings. Some of these strings can include IDs, UUIDs, PINs, MAC addresses, RGB hex colors etc. which may have a compact in-memory representation and a less compact string representation whose length is strictly constant (i.e. a UUID will always be 36 bytes long in string form). The "compact" representation often comes with a Debug or Display implementation which is solely responsible for the conversion.

Feature request

I think it would be convenient to have a way to build an AStr from any type that implements Display, given an expected total length. If the Display implementation writes too few or too much characters, an error is returned instead.

Implementation

The additional constructor could look something like AStr::from_fmt(fmt: &dyn std::fmt::Display). An equivalent method for the Debug trait is superfluous as calling format_args!("{something:?}") will return a Displayable Arguments<'_> instance that calls the Debug implementation of "something". With a macro as explained below, you wouldn't even call this function manually most of the time.

I have a working implementation in one of my projects, which also comes with a format_astr!() macro to build AStrs even faster. I would love to open a PR, but if you're interested, I would like guidance on the exact constructor name and signature that you would like, whether a format_astr! macro is in-scope for this PR, and whether or not the macro should take an optional parameter to specify the expected length (or else, type inference would do the job alone).