22.11.17 15:25, Ivan Levkivskyi пише:
I think this is indeed a problem.. For me the biggest surprise was that
`yield` inside a comprehension does not turn a surrounding function into
comprehension, see also
https://stackoverflow.com/questions/29334054/why-am-i-getting-different-results-when-using-a-list-comprehension-with-coroutin
In fact there is a b.p.o. issue for this
https://bugs.python.org/issue10544, it is assigned to me since July, but
I was focused on other things recently.
My plan was to restore the Python 2 semantics while still avoiding the
leak of comprehension variable to the enclosing scope (the initial
reason of introducing auxiliary "_make_list" function IIUC).
So that:
1) g = [(yield i) for i in range(3)] outside a function will be a
SyntaxError (yield outside a function)
2) g = [(yield i) for i in range(3)] inside a function will turn that
enclosing function into generator.
3) accessing i after g = [(yield i) for i in range(3)] will give a
NameError: name 'i' is not defined
If you have time to work on this, then I will be glad if you take care
of this issue, you can re-assign it.
I have the same plan. I know how implement this for comprehensions, but
the tricky question is what to do with generator expressions? Ideally
result = [expr for i in iterable]
and
result = list(expr for i in iterable)
should have the same semantic. I.e. if expr is "(yield i)", this should
turn the enclosing function into a generator function, and fill the list
with values passed to the generator's .send(). I have no idea how
implement this.
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