Swift for Rubyists: Optionals

Here's the source of try from active_support

    def try(*a, &b)
      if a.empty? && block_given?
        yield self
      else
        public_send(*a, &b) if respond_to?(a.first)
      end
    end

Should be easy to do the same in swift. Let me take a stab at it.

Here's an implementation of the latter try operator in swift.

    extension Optional {
        func try<U>(f: (T) -> U) -> Optional<U> {
            if let unwrapped = self {
                return f(unwrapped)
            } else {
                return nil
            }
        }
    }

https://gist.github.com/nottombrown/c6585cad9588a9dc5383

In Swift, you have to signal and guard against the nil.

In ruby, you choose whether to signal and you choose whether to guard. Here are some ruby examples that may be more clear:

Does not signal

    user = User.find_by_favorite_dinosaur("Dromiceiomimus")

    def print_favorite_dinosaur(user)
        p "User's favorite dinosaur is #{user.dino})"
    end

    def print_favorite_dinosaur(user)
        if user
            p "User's favorite dinosaur is #{user.dino})"
        else
            p "No user. (Let's assume she likes T-rexs)"
        end
    end

    possible_user = User.find_by_favorite_dinosaur("Dromiceiomimus")

    print_favorite_dinosaur(possible_user)

Nothing to do with the article, but I think it's interesting to see someone else with the "not#{first_name}#{last_name}" pattern. I didn't know that was a common thing.