[Zope-dev] Show Deprecation Warnings in Zope2

[Tres Seaver]

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On 02/16/2015 07:09 AM, Jens W. Klein wrote:
> In past in Zope2 it was possible to turn DeprecationWarnings on and
> off in zope.conf by adding a snippet like:
> 
> <warnfilter> action always category exceptions.DeprecationWarning 
> </warnfilter>
> 
> I wondered by this is no longer possible. So I found the code 
> responsible for adding the filter here:
> 
> https://github.com/zopefoundation/Zope/blob/master/src/Zope2/Startup/warnfilter.py#L53
>
>  It adds a custom filter at the _end_ of the filters list (last digit
> = 1). See also 
> https://docs.python.org/2/library/warnings.html#warnings.filterwarnings
>
>  Now since Python 2.7 some defaults changed. One is, that
> DeprecationWarnings are ignored by default. So the first rule in the
> default Python 2.7 filters is to ignore DeprecationWarnings.
> 
> see also https://docs.python.org/2/using/cmdline.html#cmdoption-W
> 
> and we can check this in code (naked python)
> 
>>>> import warnings warnings.filters
> [('ignore', None, <type 'exceptions.DeprecationWarning'>, None, 0), 
> ('ignore', None, <type 'exceptions.PendingDeprecationWarning'>, None,
>  0), ('ignore', None, <type 'exceptions.ImportWarning'>, None, 0), 
> ('ignore', None, <type 'exceptions.BytesWarning'>, None, 0)]
> 
> So with the zope.conf setting there is no possibility to override the
>  defaults: The list is processed from the head to tail and first match
> wins.
> 
> Is there any good reason to append the zope custom filter to the list?
>  If it would be prepended (which is also the default settings for 
> warnings.filterwarnings) all works as expected.
> 
> I can provide this tiny patch + pull request if the change is fine.

SGTM.


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