[Python-Dev] PEP 565: show DeprecationWarning in __main__ (round 2)

Serhiy Storchaka storchaka at gmail.com
Tue Nov 28 02:54:07 EST 2017

25.11.17 07:33, Nick Coghlan пише:
> * ``FutureWarning``: always reported by default. The intended audience is users
>    of applications written in Python, rather than other Python developers
>    (e.g. warning about use of a deprecated setting in a configuration file
>    format).
> Given its presence in the standard library since Python 2.3, ``FutureWarning``
> would then also have a secondary use case for libraries and frameworks that
> support multiple Python versions: as a more reliably visible alternative to
> ``DeprecationWarning`` in Python 2.7 and versions of Python 3.x prior to 3.7.

I think it is worth to say more explicitly that the primary purpose of 
FutureWarning (warn about future behavior changes that will not be 
errors) is kept. It is just added a secondary purpose: a replacement for 
DeprecationWarning if you want to be sure that it is visible to end users.

I think that showing DeprecationWarning in __main__.py is just a first 
step. In future we can extend the scope of showing DeprecationWarning.

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