commit	ba55bdb4233912993395377c308f1d3acb0af334	[log] [tgz]
author	Joel Galenson <jgalenson@google.com>	Wed Apr 28 22:34:25 2021 +0000
committer	Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>	Wed Apr 28 22:34:25 2021 +0000
tree	d085eaf52ac4c533290ddfff287cc1632b2bd74f
parent	9079a6e2fd188ba868011e3f05d6bd56d9e53df1 [diff]
parent	08507275f7b443865837f78415642365450dfd70 [diff]

tree: d085eaf52ac4c533290ddfff287cc1632b2bd74f

README.md

lazy-static.rs

A macro for declaring lazily evaluated statics in Rust.

Using this macro, it is possible to have statics that require code to be executed at runtime in order to be initialized. This includes anything requiring heap allocations, like vectors or hash maps, as well as anything that requires non-const function calls to be computed.

Minimum supported `rustc`

1.27.2+

This version is explicitly tested in CI and may only be bumped in new minor versions. Any changes to the supported minimum version will be called out in the release notes.

Getting Started

lazy-static.rs is available on crates.io. It is recommended to look there for the newest released version, as well as links to the newest builds of the docs.

At the point of the last update of this README, the latest published version could be used like this:

Add the following dependency to your Cargo manifest...

[dependencies]
lazy_static = "1.4.0"

...and see the docs for how to use it.

Example

#[macro_use]
extern crate lazy_static;

use std::collections::HashMap;

lazy_static! {
    static ref HASHMAP: HashMap<u32, &'static str> = {
        let mut m = HashMap::new();
        m.insert(0, "foo");
        m.insert(1, "bar");
        m.insert(2, "baz");
        m
    };
}

fn main() {
    // First access to `HASHMAP` initializes it
    println!("The entry for `0` is \"{}\".", HASHMAP.get(&0).unwrap());

    // Any further access to `HASHMAP` just returns the computed value
    println!("The entry for `1` is \"{}\".", HASHMAP.get(&1).unwrap());
}

License

Licensed under either of

Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.