# interpolate_idents

## Deprecation warning

Because of the introduction of stable procedural macro support in Rust 1.30.0, it is now possible to accomplish what this crate set out to accomplish using entirely stable code. Please try @dtolnay's [`paste`](https://crates.io/crates/paste) crate to see if it can fulfill all of your current use cases. `paste` can be used in stable production environments and is not nearly as prone to breakage between Rust versions.

Ideally, we will deprecate `interpolate_idents` as soon as we are confident that no users of this crate are left behind in the transition to `paste`. Please comment on [issue #45](https://github.com/SkylerLipthay/interpolate_idents/issues/45) or open a new issue with any concerns and personal experiences. Thank you!

## Summary

[![Travis-CI Status]][travis]

**Warning!** This crate uses a procedural macro (known today as a [compiler plugin](https://doc.rust-lang.org/book/compiler-plugins.html)) and can only be used with Rust's [nightly distribution](https://doc.rust-lang.org/book/nightly-rust.html).

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*.

```rust
#![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!

[travis]: https://travis-ci.org/SkylerLipthay/interpolate_idents
[Travis-CI Status]: https://travis-ci.org/SkylerLipthay/interpolate_idents.svg?branch=master