[Python-ideas] Use __all__ for dir(module) (Was: PEP 562)

Guido van Rossum guido at python.org
Sun Sep 17 22:49:31 EDT 2017

I ave to agree with the other committers who already spoke up.

I'm not using tab completion much (I have a cranky old Emacs setup), but
isn't making tab completion better a job for editor authors (or
language-support-for-editor authors) rather than for the core language?
What editor are you using that calls dir() for tab completion?

On Sun, Sep 17, 2017 at 7:34 PM, Cody Piersall <cody.piersall at gmail.com>

> On Tue, Sep 12, 2017 at 3:26 AM, Ivan Levkivskyi <levkivskyi at gmail.com>
> wrote:
> > @Cody
> >> I still think the better way
> >> to solve the custom dir()  would be to change the module __dir__
> >> method to check if __all__ is defined and use it to generate the
> >> result if it exists. This seems like a logical enhancement to me,
> >> and I'm planning on writing a patch to implement this. Whether it
> >> would be accepted is still an open issue though.
> >
> > This seems a reasonable rule to me, I can also make this patch if
> > you will not have time.
> I submitted a PR:https://github.com/python/cpython/pull/3610
> and a BPO issue: https://bugs.python.org/issue31503
> R. David Murray pointed out that this is a backwards-incompatible
> change.  This is technically true, but I don't know of any code that
> depends on this behavior.  (Of course, that does not mean it does not
> exist!)
> From my perspective, the big benefit of this change is that
> tab-completion will get better for libraries which are already
> defining __all__.  This will make for a better REPL experience.  The
> only code in the stdlib that broke were tests in test_pkg which were
> explicitly checking the return value of dir().  Apart from that,
> nothing broke.
> If a module does not have __all__ defined, then nothing changes for that
> module.
> Cody
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--Guido van Rossum (python.org/~guido)
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