Expand description
Used to do a cheap mutable-to-mutable reference conversion.
This trait is similar to AsRef but used for converting between mutable
references. If you need to do a costly conversion it is better to
implement From with type &mut T or write a custom function.
Note: This trait must not fail. If the conversion can fail, use a
dedicated method which returns an Option<T> or a Result<T, E>.
Generic Implementations
AsMutauto-dereferences if the inner type is a mutable reference (e.g.:foo.as_mut()will work the same iffoohas type&mut Fooor&mut &mut Foo)
Examples
Using AsMut as trait bound for a generic function we can accept all mutable references
that can be converted to type &mut T. Because Box<T> implements AsMut<T> we can
write a function add_one that takes all arguments that can be converted to &mut u64.
Because Box<T> implements AsMut<T>, add_one accepts arguments of type
&mut Box<u64> as well:
fn add_one<T: AsMut<u64>>(num: &mut T) {
*num.as_mut() += 1;
}
let mut boxed_num = Box::new(0);
add_one(&mut boxed_num);
assert_eq!(*boxed_num, 1);