Whither dispatch_once in Swift 3?

Question

Okay, so I found out about the new Swifty Dispatch API in Xcode 8. I\'m having fun using DispatchQueue.main.async, and I\'ve been browsing around the Disp

Answer 1

While the "lazy var" pattern allows me to stop caring about dispatch tokens and is generally more convenient than dispatch_once() was, I don't like how it looks at call site:

_ = doSomethingOnce

I would expect this statement to look more like a function call (since it implies action), but it doesn't look so at all. Also, having to write _ = to explicitly discard the result is unnecessary and annoying.

There is a better way:

lazy var doSomethingOnce: () -> Void = {
  print("executed once")
  return {}
}()

Which makes the following possible:

doSomethingOnce()

This might be less efficient (since it calls an empty closure instead of just discarding a Void), but improved clarity is totally worth it for me.