When is List Comprehension inappropriate?

[Steve Holden]

Alex Martelli wrote:
> BJörn Lindqvist <bjourne at gmail.com> wrote:
>    ...
>> even2 = [(pos, col) for pos, col in iterimage(im, width, height, 2)]
> 
> list(iterimage(etc etc))
> 
> is surely a better way to express identical semantics.  More generally,
> [x for x in whatever] (whether x is a single name or gets peculiarly
> unpacked and repacked like here) is a good example of inappropriate LC,
> to get back to the question in the subject: list(whatever) is the "one
> obvious way" to perform the same task.
> 
Clearly the comprehension you complain about is sub-optimal.

The essential difference, however, is between

   [x for x in iterimage(im, width, height, 2)]

and

   list(iterimage(im, width, height, 2))

I agree that the latter is the obvious way, but the difference isn't as 
large as your leap makes it look - and we had to await the invention of 
the generator expression for it to be a practical choice.

regards
  Steve
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