[Python-Dev] Tricky way of of creating a generator via a comprehension expression (original) (raw)
Greg Ewing greg.ewing at canterbury.ac.nz
Wed Nov 22 17:14:41 EST 2017
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Ivan Levkivskyi wrote:
while
g = list((yield i) for i in range(3))is defined as this code:_def gen(): for i in range(3): yield (yield i) _g = list(gen())
Since this is almost certainly not what was intended, I think that 'yield' inside a generator expression should simply be disallowed.
The problem with making it work intuitively is that there's no way to distinguish between the implicit yields producing values for the generator comprehension and the explicit ones that the programmer is expecting to be passed through and yielded from the enclosing generator function.
Fixing that would require adding another whole layer of complexity similar to what Yuri did to support async generators, and I can't see that being worth the effort.
-- Greg
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