[Python-Dev] Removing PendingDeprecationWarning

Inada Naoki songofacandy at gmail.com
Fri Mar 22 07:23:32 EDT 2019


On Fri, Mar 22, 2019 at 7:36 PM Serhiy Storchaka <storchaka at gmail.com> wrote:
>
> >
> > How do you think?  May I do it in Python 3.8?
>
> What is wrong with PendingDeprecationWarning? What problem do you want
> to solve at the cost of removing this feature?
>

The main problem is complexity.  In other words, learning cost.

All Python library developer would like to know how to deprecate something.

They will understand "deprecated" means "will be removed in the future
version" easily.

Then, "will be deprecated" [1] is easy to understand?  "will be (will
be removed)"
is very curious.  To understand what PendingDeprecationWarning is for, they
need to learn history which is not documented in clearly.

[1]: https://docs.python.org/3/library/exceptions.html#PendingDeprecationWarning

If we deprecate PendingDeprecationWarning, people don't have to understand
what it is for.


> Now, when DeprecationWarning is displayed by default in the interactive
> session, in __main__ and in development runtime mode (and this list can
> be extended), PendingDeprecationWarning is useful again. Even if the
> interpreter itself would not use it, it is used in third-party projects.
>

This benefits seems too small compared to the learning cost.

-- 
Inada Naoki  <songofacandy at gmail.com>


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