https://github.com/unsafecoerce/static_str_ops

It is often asked by Rust programmer that how to create `&'static str` in Rust with non-const operations at runtime, e.g., returns the result of `format!()` as `&'static str`, rather than `String`.

The crate static_str_ops addressed this issue, by allocating a hash set under the hood, and return the reference as the result. Along with this crate, a set of utilities are provided, including `static_format!`, `static_concat!`, and `staticize_once!` which can be used to initialize static strings with the `call_once` semantic.