[Python-Dev] Docstrings on builtins

Matthias Bussonnier bussonniermatthias at gmail.com
Mon Jun 4 21:21:02 EDT 2018

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.
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