On Fri, 7 Aug 2020 at 16:21, David Mertz <me...@gnosis.cx> wrote:
>
> On Fri, Aug 7, 2020 at 4:58 AM Brendan Barnwell <brenb...@brenbarn.net> wrote:
>>
>> It seems that the rationale that was used in the PEP was fairly
>> narrowly focused on the comparison with things like dict.get() and the
>> idea of EAFP. A somewhat broader justification might be something along
>> these lines:
>
>
> For an example. Anyone is free to use, but I'm not claiming it's necessarily
> the best. This is from... well, probably not yesterday like I said in other
> comment, but a couple days ago. The module `jsonschema` has an API where it
> raises an exception if `validate()` doesn't succeed (None if things are
> happy). I don't love that API, so want to wrap it.
>
> def not_valid(instance, schema):
> try:
> return validate(instance, schema)
> except ValidationError as err:
> return str(err)
>
> I really wanted that to be one line rather than a helper function, and it
> really feels like it should be possible... and yet.
I did basically the same yesterday:
def is_valid_specifier(s):
try:
packaging.specifiers.SpecifierSet(s)
return True
except packahing.specifiers.InvalidSpecifier:
return False
The function was only for use in a [s for s in strings if
is_valid_specifier(s)] comprehension, so an in-line expression would
have been ideal.
Paul
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