On Tue, Jun 15, 2021 at 5:23 AM Jach Feng <jf...@ms4.hinet.net> wrote: > > >>> def foo(): > ... # do something > ... > >>> a = [] > >>> for i in range(3): > ... a.append(foo()) > ... > >>> a > [] > >>> >
Barring shenanigans like messing with globals, no, there is no way for a function to return a lack of value. Fundamentally, EVERY expression in Python has to have a value, and that value must be a single object. The only exception - pun intended - is if the function doesn't return at all, eg if "# do something" is "raise Exception". But if that happens, you won't have the output you're looking for either, unless you wrap the append in a try/except. So, no. There is no "return emptiness" concept. You can be 100% confident that "a.append(foo())" will always append exactly one value, if the following line of code is indeed executed. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
