On 11/22/2017 11:01 AM, Ivan Levkivskyi wrote:
I think how to formulate these rules more "precisely" so that they will be all consistent even if there is a `yield` inside. The key idea is that neither comprehensions nor generator expressions should create a function scope surrounding the `expr` in (expr for ind in iterable) and [expr for ind in iterable]. (this still can be some hidden implementation detail)
So as Serhiy proposed in one of his first posts any comprehensions and generator expressions with `yield` are not valid outside functions. If such comprehension or generator expression is inside a function, then it makes it a generator, and all the `yield`s are yielded from that generator, for example:
Whether it's inside or outside a function should be irrelevant -- a comprehension / generator expression should have no influence on the type of the resulting function (and at least synchronous comprehensions / generator expressions should be able to live outside of a function).
def fun_gen(): return list((yield i) for i in range(3))
The return says it's returning a list, so that's what it should be returning.
should work as following:
g = func_gen()
g.send(42) 0 g.send(43) 1 g.send(44) 2 try: g.send(45) except StopIteration as e: assert e.value == [42, 43, 44]
And exactly the same with
def fun_comp(): [(yield i) for i in range(3)]
I hope with this we can close the no-async part of the problem. Currently this is not how it works, and should be fixed. Do you agree?
No. NB: If we go with making yield inside a comprehension / generator expression a SyntaxError then this subthread can die. -- ~Ethan~