On Sat, May 12, 2018 at 1:03 AM, Ian Kelly <ian.g.ke...@gmail.com> wrote: > On Fri, May 11, 2018 at 7:40 AM, Chris Angelico <ros...@gmail.com> wrote: >> So, yes, your function's name is outright lying. But there's nothing >> about it that is *pretending* to be a normal function. It IS a normal >> function. > > The detail of whether it's a generator function affects the function's > execution and may be relevant to the caller. Here are two hypothetical > functions. They do some processing with side-effects over a bunch of > items and return the processed items. However, one is a generator > function and the other just returns a list. > > def process_items(items): > ... > > def handle_items(items): > ... > > Now, we can agree that these ought to be better documented, but say I > want to call one of these for the side effects and ignore the return > value. Just from reading the first line of the function, do I need to > iterate over the result, or not?
This is no different from anything else you might need to know about the functions. It might be essential to know that "handle_items" actually doesn't return anything at all, and signals success or failure by what exception it raises. Or that "process_items", due to internal structure and implementation, absolutely must be called from the main thread, otherwise you risk OS-level signals corrupting your data. The solution is simple: read the docstring. > Scenario 2. I have two "while True" loops. One is potentially infinite > and the other is not. > > while True: > ... > > while True: > ... > > Obviously, it's important to know whether a loop might be infinite > before I run the code that includes it. Just from reading the first > line of the loop, how do I know? You can argue that they should use > strings instead to describe what they do, which would help, although I > think that's potentially confusing. > > I don't see these two situations as being fundamentally different. Do you? Not hugely, no. But it's worth noting that we have the option to annotate a function's return value. So if you need structured information about what this function or that function returns, you can provide that. It's not easy to make program-readable information about a 'while' loop (since it's not a first-class object), but you can still have structured information about whether the loop is infinite or not, by putting it into the loop header. But I still think you're overblowing the case when you claim that a generator function isn't a function. That'd be on par with claiming that a while loop isn't a loop. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
