core::ops::deref::DerefMut

pub trait DerefMut

#[derive(Copy, Drop)]
struct MutWrapper {
    value: T
}

impl MutWrapperDerefMut> of DerefMut> {
    type Target = T;
    fn deref_mut(ref self: MutWrapper) -> T {
        self.value
    }
}

// This will work since x is mutable
let mut x = MutWrapper { value: 42 };
let val = x.deref_mut();
assert!(val == 42);

// This would fail to compile since y is not mutable
let y = MutWrapper { value: 42 };
let val = y.deref_mut(); // Compile error

fn deref_mut(ref self: T) -> DerefMutTarget

type Target;