core::mem::MaybeUninit - Rust
Description: API documentation for the Rust `MaybeUninit` union in crate `core`.
Keywords: rust, rustlang, rust-lang, MaybeUninit

# [−][src]Union core::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 const fn uninitialized() -> MaybeUninit<T>`

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🔬 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)`

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🔬 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 the `MaybeUninit` really is in an initialized state, otherwise this will immediately cause undefined behavior.

####

`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 the `MaybeUninit` really is in an initialized state, otherwise this will immediately cause undefined behavior.

####

`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 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, U> Into for T where U: From<T>,`

[src]

####

`fn into(Self) -> U`

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Performs the conversion.

###

`impl<T> From for T`

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####

`fn from(T) -> T`

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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>`

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

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(U) -> Result<T, <T as TryFrom<U>>::Error>`

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

Performs the conversion.

###

`impl<T> Borrow for T where T: ?Sized,`

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####

`fn borrow(&Self) -> &T`

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Immutably borrows from an owned value. Read more

###

`impl<T> BorrowMut for T where T: ?Sized,`

[src]

####

`fn borrow_mut(&mut Self) -> &mut T`

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Mutably borrows from an owned value. Read more

###

`impl<T> Any for T where T: 'static + ?Sized,`

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####

`fn get_type_id(&Self) -> TypeId`

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🔬 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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