[Python-Dev] Proposal: go back to enabling DeprecationWarning by default (original) (raw)

Barry Warsaw barry at python.org
Mon Nov 6 18:56:24 EST 2017

Nick Coghlan wrote:

On the 12-weeks-to-3.7-feature-freeze thread, Jose Bueno & I both mistakenly though the async/await deprecation warnings were missing from 3.6.

Sometimes the universe just throws synchronicity right in your face.

I'm working on building an internal tool against Python 3.7 to take advantage of the very cool -X importtime feature. It's been a fun challenge, but mostly because of our external dependencies. For example, PyThreadState renamed its structure members, so both Cython and lxml needed new releases to adjust for this. That's the "easy" part; they've done it and those fixes work great.

We also depend on ldap3 <https://pypi.org/project/ldap3/>. Suddenly we get a SyntaxError because ldap3 has a module ldap3/strategy/async.py. I say "suddenly" because of course if DeprecationWarnings had been enabled by default, I'm sure someone would have noticed that those imports were telling the developers about the impending problem in Python 3.6.

https://github.com/cannatag/ldap3/issues/428

This just reinforces my opinion that even though printing DeprecationWarning by default can be a hardship in some environments, it is on the whole a positive beneficial indicator that gives developers some runway to fix such problems. These types of apparently sudden breakages are the worse of all worlds.

Cheers, -Barry

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