[Python-Dev] Docstrings on builtins
Chris Barker
chris.barker at noaa.gov
Tue Jun 5 10:56:47 EDT 2018
OK,
looking a bit deeper:
In [69]: timedelta.__new__.__doc__
Out[69]: 'Create and return a new object. See help(type) for accurate
signature.'
In [70]: timedelta.__init__.__doc__
Out[70]: 'Initialize self. See help(type(self)) for accurate signature.'
In [71]: timedelta.__doc__
Out[71]: 'Difference between two datetime values.'
So the none of the docstrings have the proper information. And:
help(timedelta) returns:
Help on class timedelta in module datetime:
class timedelta(builtins.object)
| Difference between two datetime values.
|
| Methods defined here:
|
| __abs__(self, /)
| abs(self)
|
| __add__(self, value, /)
| Return self+value.
....
So no signature either.
I'm guessing this is because argument clinic has not been properly applied
-- so Ihave a PR to work on.
but where does help() get its info anyway?
I always thought docstrings were supposed to be used for the basic, well,
docs. And between the class and __new__ and __init__, somewhere in there
you should learn how to initialize an instance, yes?
-CHB
On Mon, Jun 4, 2018 at 6:21 PM, Matthias Bussonnier <
bussonniermatthias at gmail.com> wrote:
>
>
> On Mon, 4 Jun 2018 at 17:29, Ivan Pozdeev via Python-Dev <
> python-dev at python.org> wrote:
>
>> On 05.06.2018 3:09, Matthias Bussonnier wrote:
>>
>> This may even be a bug/feature of IPython,
>>
>> I see that inspect.signature(timedelta) fails, so if timedelta? says
>> Init signature: timedelta(self, /, *args, **kwargs)
>> Then this may be some IPython internal logic. The timedelta class seem to
>> use __new__ instead of __init__ (not sure why)
>>
>> Because it's an immutable type.
>>
> Ah, yes, thanks.
>
>
>> and __new__ have a meaningful signature,
>> So maybe we should fallback on that during signature inspection.
>>
>> According to https://stackoverflow.com/questions/4374006/check-for-
>> mutability-in-python ,
>> there are no reliable tests for mutability.
>>
> Sure, but we can test if the signature of __init__ is (self,/, *args,
> **kwargs), and if it is, it is useless we can attempt to get the signature
> from __new__ and show that instead. We do similar things for docstrings,
> if __init__ have no docstring we look at the class level docstring.
> --
> M
>
>
>
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--
Christopher Barker, Ph.D.
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Emergency Response Division
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Chris.Barker at noaa.gov
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