interpolate_idents

Warning! This crate uses a procedural macro (known today as a compiler plugin) and can only be used with Rust's nightly distribution.

You cannot currently define a struct, enum, function, or field using concat_idents! due to the way macros are parsed by the Rust compiler. This will hopefully change in the future, but interpolate_idents! sloppily solves a side effect of the currently lacking macro system today.

#![feature(plugin)]
#![plugin(interpolate_idents)]

macro_rules! make_fn {
    ($x:ident) => ( interpolate_idents! {
        fn [my_ $x _fn]() -> u32 { 1000 }
    } )
}

Now make_fn!(favorite); is equivalent to fn my_favorite_fn() -> u32 { 1000 }.

In short, surround multiple space-separated identifiers (or macro identifer variables) with square brackets to concatenate the identifiers. Check tests/tests.rs for another example.

This plugin was quickly hacked together. It is likely not performant and most certainly not readable.

Crate upkeep

I'm not actively developing on nightly, so I haven't been using this plugin too often. I understand that libsyntax is a fickle beast, so please file an issue or PR if interpolate_idents fails to compile on the latest nightly!