[Python-Dev] folding cElementTree behind ElementTree in 3.3 (original) (raw)

Nick Coghlan ncoghlan at gmail.com
Tue Feb 14 05:44:31 CET 2012

On Tue, Feb 14, 2012 at 2:25 PM, Eli Bendersky <eliben at gmail.com> wrote:

With the deprecation warning being silent, is there much to lose, though?

Yes, it creates problems for anyone that deliberately converts all warnings to errors when running their test suites. This forces them to spend time switching over to a Python version dependent import of either cElementTree or ElementTree that could have been spent doing something actually productive instead of mere busywork.

And, of course, even people that don't convert warnings to errors when running tests will have to make the same switch when the module is eventually removed.

Cleanups help lower the clutter and mental burden on maintainers in the long run. If nothing is ever cleaned up don't we end up with PHP :-) ?

It's a balancing act, sure. But when the maintenance burden for us is low and the cost to third parties clear, documented deprecation for eventual removal in the next release series is the better choice.

Programmatic deprecation is a significant imposition on third party developers and should really be reserved for APIs that actively encourage writing broken code (e.g. contextlib.nested) or are seriously problematic for python-dev to maintain. For cleanup stuff, documented deprecation is sufficient. A quick search of the sources for DeprecationWarning show that it's being used much more liberally than solely for stuff that encourages writing broken code. Has there been a recent policy change with regards to what's considered deprecated?

It's always been judged on a case-by-case basis, but yes, there's been a deliberate push in favour of purely documented deprecations in recent years (initially mostly from Raymond Hettinger, more recently from me as well as I came to appreciate the merit of Raymond's point of view). It mainly started with the decision to leave optparse alone (aside from a deprecation note in the docs) even after argparse was added to the standard library.

Cheers, Nick.

-- Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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