[Python-Dev] Proposal: go back to enabling DeprecationWarning by default

Antoine Pitrou solipsis at pitrou.net
Tue Nov 7 04:40:28 EST 2017

On Tue, 7 Nov 2017 09:30:19 +0000
Paul Moore <p.f.moore at gmail.com> wrote:
> I understand the "but no-one actually does this" argument. And I
> understand that breakage as a result is worse than a few warnings. But
> enabling deprecation warnings by default feels to me like favouring
> the developer over the end user.

I understand this characterization.

> I'd prefer it if rather than simply switching warnings on by default,
> we worked on making it easier for the people in a position to actually
> *fix* the issue (coders writing programs, educators developing
> training materials, etc) to see the warnings. For example, encourage
> the various testing frameworks (unittest, pytest, nose, tox, ...) to
> enable warnings by default,

pytest does nowadays.  That doesn't mean warnings get swiftly fixed,
though.  There are many reasons why (see my initial reply to Nick's

> ensure that all new deprecations are
> documented in the "Porting to Python 3.x" notes, etc.

In my experience, Python deprecations are in the minority.
Most often you have to deal with deprecations in third-party libraries
rather than Python core/stdlib, because we (Python) are more reluctant
to change and deprecate APIs than the average library maintainer is.



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