Cast closures/blocks

Question

In Objective-C, I often pass around blocks. I use them very often to implement patterns that help avoid storing stuff into instance variables, thus avoiding threading/timing

Answer 1

How about a generic Block parameterized with the function type?

class Block {
  let f : T
  init (_ f: T) { self.f = f }
}

Allocate one of these; it will be a subtype of AnyObject and thus be assignable into dictionaries and arrays. This doesn't seem too onerous especially with the trailing closure syntax. In use:

  5> var b1 = Block<() -> ()> { print ("Blocked b1") }
b1: Block<() -> ()> = {
  f = ...
}
  6> b1.f()
Blocked b1

and another example where the Block type is inferred:

 11> var ar = [Block { (x:Int) in print ("Block: \(x)") }]
ar: [Block<(Int) -> ()>] = 1 value {
  [0] = {
    f = ...
  }
}
 12> ar[0].f(111)
Block: 111