lazy_static about lru-rs

[jeromefroe]

Here's an example program:

#[macro_use]
extern crate lazy_static;

extern crate lru;

use lru::LruCache;

lazy_static! {
    static ref LRU: LruCache<u32, &'static str> = {
        let mut cache = LruCache::new(2);
        cache.put(0, "foo");
        cache
    };
    static ref COUNT: usize = LRU.len();
}

fn main() {
    println!("The cache has {} entries.", *COUNT);
    println!("The cache contains `0`: \"{}\".", LRU.contains(&0));
}

The catch with lazy_static though is that since the references it creates are static they are therefore immutable, so you won't be able to use most of the cache's methods, for example even get, since they manipulate the internal state of the cache. If you don't need to add elements to the cache I think it would be better to just use a Hashmap. On the other hand, if you do need to update the cache after it's created, then you won't be able to use lazy_static but will need to instead initialize during runtime.