[Python-Dev] pathlib - current status of discussions

[Brett Cannon]

On Wed, 13 Apr 2016 at 13:40 Chris Barker <chris.barker at noaa.gov> wrote:

> so are we worried that __fspath__ will exist and be callable, but  might
> raise an AttributeError somewhere inside itself? if so isn't it broken
> anyway, so should it be ignored?
>

It should propagate instead of swallowing up the exception, otherwise it's
hard to debug why __fspath__ seems to be ignored.


>
> and I know it's asking permission rather than forgiveness, but what's
> wrong with:
>
> if hasattr(path, "__fspath__"):
>     path = path.__fspath__()
>
> if you really want to check for the existence of the attribute first?
>
>
Nothing.


> or even:
>
> path = path.__fspath__ if hasattr(path, "__fspath__") else path
>
>
That also works.


>
> (OK, really a Pythonic style question now....)
>

Yes, this is getting a bit side-tracked over some example code to just get
a concept across.

-Brett


>
> -CHB
>
>
>
> On Wed, Apr 13, 2016 at 12:54 PM, Brett Cannon <brett at python.org> wrote:
>
>>
>>
>> On Wed, 13 Apr 2016 at 12:39 Fred Drake <fred at fdrake.net> wrote:
>>
>>> On Wed, Apr 13, 2016 at 3:24 PM, Chris Angelico <rosuav at gmail.com>
>>> wrote:
>>> > Is that the intention, or should the exception catching be narrower? I
>>> > know it's clunky to write it in Python, but AIUI it's less so in C:
>>> >
>>> > try:
>>> >     callme = path.__fspath__
>>> > except AttributeError:
>>> >     pass
>>> > else:
>>> >     path = callme()
>>>
>>> +1 for this variant; I really don't like masking errors inside the
>>> __fspath__ implementation.
>>>
>>
>> Don't read too much into the code in that gist. I just did them quickly
>> to get the point across of the proposals in terms of str/bytes, not what
>> will be proposed in any final patch.
>>
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>
>
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>
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