[Python-Dev] PEP 498 f-string: please remove the special case for spaces

[MRAB]

On 2015-08-10 23:54, Victor Stinner wrote:
>
>     PEP 498:
>
> """
>
>
>     Leading whitespace in expressions is skipped
>     <https://www.python.org/dev/peps/pep-0498/#id28>
>
> Because expressions may begin with a left brace ('{'), there is a
> problem when parsing such expressions. For example:
>
>>>> f'{{k:v for k, v in [(1, 2), (3, 4)]}}'  '{k:v for k, v in [(1, 2), (3, 4)]}'
>
> """
>
> For me, this example is crazy. You should not add a special case (ignore
> spaces) just to support a corner case.
>
Is it a special case? Don't we already ignore leading spaces in
bracketed expressions?

> This example can easily be rewritten using a temporary variable and it
> makes the code simpler.
>
> items={k:v for k, v in [(1, 2), (3, 4)]; f'{items}'
>
> Seriously, a dict-comprehension inside a f-string should be considered
> as an abuse of the feature. Don't you think so?
>
True. Or we can wrap it in parentheses. :-)