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# core::ops::deref::DerefMut

A trait for dereferencing in mutable contexts.
This trait is similar to `Deref` but specifically handles cases where the value
accessed is mutable. Despite its name, `DerefMut` does NOT allow modifying the
inner value - it only indicates that the container itself is mutable.

## Signature

```rust theme={null}
pub trait DerefMut
```

## Examples

```rust theme={null}
#[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
```

## Trait functions

### deref\_mut

Returns the dereferenced value.

#### Signature

```rust theme={null}
fn deref_mut(ref self: T) -> DerefMutTarget
```

## Trait types

### Target

The type of the dereferenced value.

#### Signature

```rust theme={null}
type Target;
```