Python cryptography, Rust, and Gentoo

> Yes, I wanted it to be mutable after init; it's a cache of state between multiple HTTP requests. So I need a Mutex, and how do you initialize a Mutex safely without lazy_static?

To answer your question:

We're currently adding an equivalent to lazy_static in the standard library: https://doc.rust-lang.org/std/lazy/index.html . It's currently available on nightly, and folks are working towards marking it stable.

We're generally very careful before adding something to the Rust standard library. We have strong stability guarantees for anything in the standard library, and once we add something it's subject to those same guarantees. The Python project has the philosophy that "the standard library is where code goes to die", for much the same reason; there are various pieces of the Python standard library for which the standard wisdom is "don't use it, use this third-party module instead". We want to avoid that situation in Rust whenever we can, even if that means that some common functionality requires a crate. It's very easy to add a dependency on a crate from the crates.io ecosystem.

Now, separate from the answer to your question, there are two reasons you might not want to use a global mutex-guarded variable as the cache for your HTTP requests. First, you might want to use a concurrent data structure instead, such as "dashmap", a fast concurrent hashmap. And second, you might consider putting that data structure in one of your library's objects instead, so that you (or other code calling into your code) can use multiple such objects concurrently without global state. All that said, you *can* use a global mutex-guarded variable if you want to, and std::lazy should let you do that using just the standard library.