[Python-ideas] Accessing the result of comprehension's expression from the conditional

[Calvin Spealman]

On Sat, Jun 20, 2009 at 9:22 AM, MRAB<python at mrabarnett.plus.com> wrote:
> Ben Finney wrote:
>>
>> Jim Jewett <jimjjewett at gmail.com> writes:
>>
>>> On Fri, Jun 19, 2009 at 3:39 AM, Lie Ryan<lie.1296 at gmail.com> wrote:
>>>
>>>> res = [x**x as F for x in nums if F < 100]
>>>
>>> This, I have wanted.
>>
>> You have it:
>>
>>    res = [f for f in (x**x for x in nums) if f < 100]
>>
>> In addition to the fact that this works now in existing Python, I find
>> it clearer than the above syntax you say you want.
>>
> How about:
>
>   res = [F for x in nums with x**x as F if F < 100]
>
> :-)

That toggles the first part of the comprehensions to be or not be an
expression, depending on if there is a with clause later. You could
miss this when you read it, and it opens the door to doing more
strange things, like:

  res = [F/2 for x in nums with x**x as F if F < 100]

This is basically a strangely syntaxed nested loop

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