Comment by jerf
10 years ago
That's not a closure. That's returning a struct. That struct is an object that has several instance members that are functions, which you've created as closures, but note you're still returning a struct. To return a closure, you need to return a function type, which then has exactly one way to call it, which is the claim here about functions.
Of course you can dispatch anything you like within that call, turning a closure back into "methods", although in most languages that's a fairly painful way to operate even though if it is possible. Personally over the years I've come more around to tel's point of view, which is that as related as objects and closures may be, they aren't quite just two sides of the same coin, as further evidenced by the fact that pretty much all modern OO languages also include closures. If they really were the same thing in two guises somebody would probably have fully unified them by now, but they aren't the same thing. As much fun as the koan is, I think it's false wisdom.
> which you've created as closures, but note you're still returning a struct
a struct of three closures :)
EDIT:
I'm not sure I understand your point. Here's how to return three closures without the struct.
http://play.golang.org/p/9UtJ7ZBMzb
Yes, I said that. Please try less hard for the "gotchas". There's no ambiguity here, the Go type system does not permit it; something is either a struct or a closure (or exactly one of the other valid types; even "interfaces" are actually a specific type in Go), and the linked code returns a struct. (Python, for instance, can create something that acts as both object and closure at the same time with an object that implements the __call__ magic method.)