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Rust interface for Apple's C language extension of blocks.
For more information on the specifics of the block implementation, see Clang's documentation: http://clang.llvm.org/docs/Block-ABI-Apple.html
Invoking blocks
The Block
struct is used for invoking blocks from Objective-C. For example,
consider this Objective-C function:
int32_t sum(int32_t (^block)(int32_t, int32_t)) {
return block(5, 8);
}
We could write it in Rust as the following:
Note the extra parentheses in the call
method, since the arguments must be
passed as a tuple.
Creating blocks
Creating a block to pass to Objective-C can be done with the ConcreteBlock
struct. For example, to create a block that adds two i32
s, we could write:
let block = new;
let mut block = block.copy;
assert!;
It is important to copy your block to the heap (with the copy
method) before
passing it to Objective-C; this is because our ConcreteBlock
is only meant
to be copied once, and we can enforce this in Rust, but if Objective-C code
were to copy it twice we could have a double free.