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~
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