Struct alloc::boxed::IntermediateBox

pub struct IntermediateBox<T: ?Sized> { /* fields omitted */ }

🔬 This is a nightly-only experimental API. (placement_in #27779)

placement box design is still being worked out.

IntermediateBox represents uninitialized backing storage for Box.

FIXME (pnkfelix): Ideally we would just reuse Box<T> instead of introducing a separate IntermediateBox<T>; but then you hit issues when you e.g. attempt to destructure an instance of Box, since it is a lang item and so it gets special handling by the compiler. Easier just to make this parallel type for now.

FIXME (pnkfelix): Currently the box protocol only supports creating instances of sized types. This IntermediateBox is designed to be forward-compatible with a future protocol that supports creating instances of unsized types; that is why the type parameter has the ?Sized generalization marker, and is also why this carries an explicit size. However, it probably does not need to carry the explicit alignment; that is just a work-around for the fact that the align_of intrinsic currently requires the input type to be Sized (which I do not think is strictly necessary).

Trait Implementations

impl<T> Place<T> for IntermediateBox<T>

fn pointer(&mut self) -> *mut T

🔬 This is a nightly-only experimental API. (placement_new_protocol #27779)

Returns the address where the input value will be written. Note that the data at this address is generally uninitialized, and thus one should use ptr::write for initializing it.

impl<T> BoxPlace<T> for IntermediateBox<T>

fn make_place() -> IntermediateBox<T>

🔬 This is a nightly-only experimental API. (placement_new_protocol #27779)

Creates a globally fresh place.

impl<T> InPlace<T> for IntermediateBox<T>

type Owner = Box<T>

🔬 This is a nightly-only experimental API. (placement_new_protocol #27779)

Owner is the type of the end value of PLACE <- EXPR

Important traits for Box<I>

impl<I: Iterator + ?Sized> Iterator for Box<I> type Item = I::Item;

unsafe fn finalize(self) -> Box<T>

🔬 This is a nightly-only experimental API. (placement_new_protocol #27779)

Converts self into the final value, shifting deallocation/cleanup responsibilities (if any remain), over to the returned instance of Owner and forgetting self.

impl<T: ?Sized> Drop for IntermediateBox<T>

fn drop(&mut self)

Executes the destructor for this type.