def create() -> socket.socket:
    return sock

def create_(func: callable)-> None:

What are the names of those two interfaces between* a socket creator and code using that socket?

Perhaps touch on situations in which one is considerably more appropriate.

* - sockets are just an example application

2 Answers 2


With respect to functional programming, I think the term you may be looking for is continuation-passing style. This is contrasted with returning a result directly like in your first example.

  • Cool, you named both: continuation-passing style; returning a result directly. That's an answer.
    – Vorac
    Commented Dec 15, 2020 at 0:02
  • In object oriented programming this is called message passing to an output port. Commented Dec 15, 2020 at 6:59

In your code example, func is commonly called a callback function.

As far as I'm aware, there's no real name for the method itself, other than describing it as using a callback function. Continuation methods fill the same functional requirement but their implementation is conceptually different.

  • +1 return an object vs accept a callback is a valid answer. I am accepting the other one because it taught me the term continuation-passing.
    – Vorac
    Commented Dec 15, 2020 at 0:05
  • This only names the structure used. Just because you have a callback function doesn't mean you have to pass it a result. Commented Dec 15, 2020 at 7:01
  • One difference in a callback function is that they typically take two arguments, one of which is null: the result, and an error. This make them more applicable in older procedural or OO style languages.
    – user949300
    Commented Feb 8, 2022 at 7:53
  • @user949300: It's significantly more common to have two callbacks (success and error), not a single callback where you have to nullcheck to see which parameter is not null.
    – Flater
    Commented Feb 8, 2022 at 9:01

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