def g(): yield 42 return 43
I don't see how the allowing return values in generators can fail to be confusing for people new to Python. Of course, there are limits to the degree that we should let people who are bad at Python dictate our code practices, but I really just feel like this is going to confuse people endlessly. "Where did my 43 go? Why didn't it come up in my loop?" On the other hand, raising is a pretty well understood way of doing control flow, if not value passing. But I can see why "raise StopIteration(42)" might seem a bit obtuse. What if we just subclass StopIteration and make something called "ReturnValue" or some-such. Would a simple rename fix part of the problem: def g(): yield 42 raise ReturnValue(43)
Do you really think the intent of the code would be any clearer if all the returns were replaced by raising StopIteration?
Doesn't "ReturnValue(43)" pretty clearly indicate what's going on? I think part of the appeal of using "return" is that return is what's used in ordinary functions, but if you think about it, you already have to make your cooperative multitasking mini-thread different from an ordinary function anyway by sprinkling yields throughout it. If you're going that far, is it really so bad to also change the "return" to a "raise ReturnValue"? -- Carl Johnson