What do double parentheses mean in a function call? e.g. func(stuff)(stuff)?

Question

Original title:

"Help me understand this weird Python idiom? sys.stdout = codecs.getwriter(\'utf-8\')(sys.stdout)"

Answer 1

.getwriter returns a functioncallable object; you are merely calling it in the same line.

Example:

def returnFunction():
    def myFunction():
        print('hello!')
    return myFunction

Demo:

>>> returnFunction()()
hello!

You could have alternatively done:

>>> result = returnFunction()
>>> result()
hello!

---

Visualization:

evaluation step 0: returnSomeFunction()()
evaluation step 1: |<-somefunction>-->|()
evaluation step 2: |<----result-------->|