[Zope-dev] Python 2.7 disables deprecation warnings by default

[Tres Seaver]

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Jim Fulton wrote:
> I'm guessing that this has already been noticed and discussed, but
> Python 2.7 disables deprecation warnings by default.
> 
> This will cause many tests to fail that checked that deprecation were
> issued.
> 
> This change seems likely to make Python's deprecation system useless
> and thus unused.
> 
> I noticed this yesterday when testing a project with Python 2.7 that
> had some deprecation tests. I modified the test runner script to call:
> 
>    warnings.simplefilter('default')
> 
> to renable deprecation warnings.  This allowed my tests to pass and
> also, ironically, showed new useful deprecation warnings in asyncore.
> 
> I'm not sure what the best way to handle this is.  My initial thought
> is that all test runners should enable deprecations by default.  This
> seems hard to enforce.
> 
> Individual test modules can do this, but I'm uncomfortable having a
> test script make a global setting like this and the warning module
> doesn't seem to provide a way to capture the current state so it can
> be reset after running tests.

As of Python 2.6, the warnings module sports a context manager::

  with warnings.catch_warnings():
    warnings.simplefilter("default")
    fxn()


Tres.
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Tres Seaver          +1 540-429-0999          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
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