pythonfunctional-programmingclosures

Can you explain closures (as they relate to Python)?


I've been reading a lot about closures and I think I understand them, but without clouding the picture for myself and others, I am hoping someone can explain closures as succinctly and clearly as possible. I'm looking for a simple explanation that might help me understand where and why I would want to use them.


Solution

  • Closure on closures

    Objects are data with methods attached, closures are functions with data attached.

    def make_counter():
        i = 0
        def counter(): # counter() is a closure
            nonlocal i
            i += 1
            return i
        return counter
    
    c1 = make_counter()
    c2 = make_counter()
    
    print (c1(), c1(), c2(), c2())
    # -> 1 2 1 2