Struct block2::StackBlock

#[repr(C)]
pub struct StackBlock<'f, A, R, Closure> { /* private fields */ }

An Objective-C block constructed on the stack.

This is a smart pointer that Derefs to Block.

Type parameters

The type parameters for this is a bit complex due to trait system limitations. Usually, you will not need to specify them, as the compiler should be able to infer them.

• The lifetime 'f, which is the lifetime of the block.
• The parameter A, which is a tuple representing the parameters to the block.
• The parameter R, which is the return type of the block.
• The parameter Closure, which is the contained closure type. This is usually not nameable, and you will have to use _, impl Fn() or similar.

Memory layout

The memory layout of this type is not guaranteed.

That said, it will always be safe to reintepret pointers to this as a pointer to a Block with the corresponding dyn Fn type.

Implementations

impl<'f, A, R, Closure> StackBlock<'f, A, R, Closure>

pub fn new(closure: Closure) -> Self

where A: EncodeArguments, R: EncodeReturn, Closure: IntoBlock<'f, A, R> + Clone,

Construct a StackBlock with the given closure.

Note that this requires Clone, as a C block is generally assumed to be copy-able. If you want to avoid that, put the block directly on the heap using RcBlock::new.

When the block is called, it will return the value that results from calling the closure.

Methods from Deref<Target = Block<Closure::Dyn>>

pub fn copy(&self) -> RcBlock<F>

Copy the block onto the heap as an RcBlock.

The behaviour of this function depends on whether the block is from a RcBlock or a StackBlock. In the former case, it will bump the reference-count (just as-if you’d Clone’d the RcBlock), in the latter case it will construct a new RcBlock from the StackBlock.

This distiction should not matter, except for micro-optimizations.

pub fn call(&self, args: F::Args) -> F::Output

where F: BlockFn,

Call the block.

The arguments must be passed as a tuple. The return is the output of the block.

Trait Implementations

impl<'f, A, R, Closure: Clone> Clone for StackBlock<'f, A, R, Closure>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'f, A, R, Closure> Debug for StackBlock<'f, A, R, Closure>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'f, A, R, Closure> Deref for StackBlock<'f, A, R, Closure>

where A: EncodeArguments, R: EncodeReturn, Closure: IntoBlock<'f, A, R>,

type Target = Block<<Closure as IntoBlock<'f, A, R>>::Dyn>

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<'f, A, R, Closure> RefEncode for StackBlock<'f, A, R, Closure>

where A: EncodeArguments, R: EncodeReturn, Closure: IntoBlock<'f, A, R>,

const ENCODING_REF: Encoding = Encoding::Block

The Objective-C type-encoding for a reference of this type.

impl<'f, A, R, Closure: Copy> Copy for StackBlock<'f, A, R, Closure>