# [−][src]Union std::mem::MaybeUninit

    pub union MaybeUninit<T> {
        // some fields omitted
    }

🔬 This is a nightly-only experimental API. (`maybe_uninit` #53491)

A newtype to construct uninitialized instances of `T`

## Methods

### `impl<T> MaybeUninit<T>`[src]

#### `pub fn new(val: T) -> MaybeUninit<T>`[src]

🔬 This is a nightly-only experimental API. (`maybe_uninit` #53491)

Create a new `MaybeUninit` initialized with the given value.

Note that dropping a `MaybeUninit` will never call `T`'s drop code. It is your responsibility to make sure `T` gets dropped if it got initialized.

#### `pub fn uninitialized() -> MaybeUninit<T>`[src]

🔬 This is a nightly-only experimental API. (`maybe_uninit` #53491)

Create a new `MaybeUninit` in an uninitialized state.

Note that dropping a `MaybeUninit` will never call `T`'s drop code. It is your responsibility to make sure `T` gets dropped if it got initialized.

#### `pub fn zeroed() -> MaybeUninit<T>`[src]

🔬 This is a nightly-only experimental API. (`maybe_uninit` #53491)

Create a new `MaybeUninit` in an uninitialized state, with the memory being filled with `0` bytes. It depends on `T` whether that already makes for proper initialization. For example, `MaybeUninit<usize>::zeroed()` is initialized, but `MaybeUninit<&'static i32>::zeroed()` is not because references must not be null.

Note that dropping a `MaybeUninit` will never call `T`'s drop code. It is your responsibility to make sure `T` gets dropped if it got initialized.

#### `pub fn set(&mut self, val: T)`[src]

🔬 This is a nightly-only experimental API. (`maybe_uninit` #53491)

Set the value of the `MaybeUninit`. This overwrites any previous value without dropping it.

#### `pub unsafe fn into_inner(self) -> T`[src]

🔬 This is a nightly-only experimental API. (`maybe_uninit` #53491)

Extract the value from the `MaybeUninit` container. This is a great way to ensure that the data will get dropped, because the resulting `T` is subject to the usual drop handling.

# Unsafety

It is up to the caller to guarantee that the `MaybeUninit` really is in an initialized state, otherwise this will immediately cause undefined behavior.

####
ⓘImportant traits for &'_ mut I

### Important traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W`
`pub unsafe fn get_ref(&self) -> &T`[src]

🔬 This is a nightly-only experimental API. (`maybe_uninit` #53491)

Get a reference to the contained value.

# Unsafety

It is up to the caller to guarantee that the `MaybeUninit` really is in an initialized state, otherwise this will immediately cause undefined behavior.

####
ⓘImportant traits for &'_ mut I

### Important traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W`
`pub unsafe fn get_mut(&mut self) -> &mut T`[src]

🔬 This is a nightly-only experimental API. (`maybe_uninit` #53491)

Get a mutable reference to the contained value.

# Unsafety

It is up to the caller to guarantee that the `MaybeUninit` really is in an initialized state, otherwise this will immediately cause undefined behavior.

#### `pub fn as_ptr(&self) -> *const T`[src]

🔬 This is a nightly-only experimental API. (`maybe_uninit` #53491)

Get a pointer to the contained value. Reading from this pointer will be undefined behavior unless the `MaybeUninit` is initialized.

#### `pub fn as_mut_ptr(&mut self) -> *mut T`[src]

🔬 This is a nightly-only experimental API. (`maybe_uninit` #53491)

Get a mutable pointer to the contained value. Reading from this pointer will be undefined behavior unless the `MaybeUninit` is initialized.

## Auto Trait Implementations

### `impl<T> Send for MaybeUninit<T> where
T: Send,`

### `impl<T> Sync for MaybeUninit<T> where
T: Sync,`

## Blanket Implementations

### `impl<T> From for T`[src]

#### `fn from(t: T) -> T`[src]

Performs the conversion.

### `impl<T, U> TryFrom for T where
T: From<U>,` [src]

#### `type Error = !`

🔬 This is a nightly-only experimental API. (`try_from` #33417)

The type returned in the event of a conversion error.

#### `fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>`[src]

🔬 This is a nightly-only experimental API. (`try_from` #33417)

Performs the conversion.

### `impl<T, U> TryInto for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

🔬 This is a nightly-only experimental API. (`try_from` #33417)

The type returned in the event of a conversion error.

#### `fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>`[src]

🔬 This is a nightly-only experimental API. (`try_from` #33417)

Performs the conversion.

### `impl<T, U> Into for T where
U: From<T>,` [src]

#### `fn into(self) -> U`[src]

Performs the conversion.

### `impl<T> Borrow for T where
T: ?Sized,` [src]

####
ⓘImportant traits for &'_ mut I

### Important traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W`
`fn borrow(&self) -> &T`[src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut for T where
T: ?Sized,` [src]

####
ⓘImportant traits for &'_ mut I

### Important traits for &'_ mut I

`impl<'_, I> Iterator for &'_ mut I where
I: Iterator + ?Sized, type Item = <I as Iterator>::Item;impl<'a, R: Read + ?Sized> Read for &'a mut Rimpl<'a, W: Write + ?Sized> Write for &'a mut W`
`fn borrow_mut(&mut self) -> &mut T`[src]

Mutably borrows from an owned value. Read more

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `fn get_type_id(&self) -> TypeId`[src]

🔬 This is a nightly-only experimental API. (`get_type_id` #27745)

this method will likely be replaced by an associated static

Gets the `TypeId` of `self`. Read more

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