block 0.0.2

Rust interface for Apple's C language extension of blocks.
docs.rs failed to build block-0.0.2
Please check the build logs for more information.
See Builds for ideas on how to fix a failed build, or Metadata for how to configure docs.rs builds.
If you believe this is docs.rs' fault, open an issue.
Visit the last successful build: block-0.1.6

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:

fn sum(block: &mut Block<(i32, i32), i32>) -> i32 {
    block.call((5, 8))
}

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 i32s, we could write:

let block = ConcreteBlock::new(|a: i32, b: i32| a + b);
let mut block = block.copy();
assert!(block.call((5, 8)) == 13);

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.