A typesafe store keyed by types and containing different types of values.
It provides functionality similar to AnyMap, but is more flexible because it allows for key-value pairs, rather than enforcing that keys and values are the same type.
Key-value associations are defined through the Key trait, which uses an
associated type parameter and trait coherence rules to enforce the invariants
of TypeMap.
#[deriving(Show, PartialEq)]
struct KeyType;
#[deriving(Show, PartialEq)]
struct Value(i32);
impl Key for KeyType { type Value = Value; }
#[test] fn test_pairing() {
let mut map = TypeMap::new();
map.insert::<KeyType>(Value(12));
assert_eq!(*map.find::<KeyType>().unwrap(), Value(12);
}