openerp-expert-framework team mailing list archive

[Alexandre Fayolle <alexandre.fayolle@xxxxxxxxxxxxxx>]

On mar. 18 sept. 2012 19:00:33 CEST, Xavier Morel wrote:
> On 2012-09-18, at 17:17 , Alexandre Fayolle wrote:
>
>> Hello,
>>
>> I wanted to bring to your attention the proposal I made in
>> https://bugs.launchpad.net/openobject-server/+bug/1052392 and for which
>> I proposed an implementation in
>> https://code.launchpad.net/~c2c/openobject-server/trunk-deprecate-osv_osv
>>
>> This is about using python stdlib DeprecationWarning and warnings module
>> to tag deprecated features, rather than just putting a comment in the
>> source code where it will likely be missed by most developers.
>
> The problem of this approach is that most developers are no more likely to
> notice them with these improvements (which I support anyway) considering:
>
> 1. OpenERP's launch scripts do not (as far as I know) allow manipulations
>    of the warnings filter (although it might be possible to use the Python
>    interpreter explicitly and the -W flag, I'm not aware of anybody who
>    does that ever, let alone on a regular basis)
> 2. From Python 2.7 onwards, DeprecationWarning is silenced by default
> 3. I don't believe there's any support for logging.captureWarnings either,
>   it only exists in Python 2.7 anyway and (I believe) respects the
>    warnings filter which you can't set (as per 1.)
>
> With all that, I rather doubt adding deprecation warnings in the code
> would do anything more than the equivalent comments.

Well if you look at the merge proposals, you'll see that there is 
support to set this from the command line and that by default, 
DeprecationWarnings are logged, but they can also be written to stderr 
or ignored. It is a start, and I'll gladly change the way things are 
done in there if people request for enhancements.

Indeed I used the warnings.captureWarnings function to achieve this, 
which won't work with python < 2.7. OpenERP 6.1 apparently changed the 
minimum required Python version to 2.6. If we want to keep it that way 
in 2.7 I can write the required code to emulate captureWarnings in 2.6. 
Note to OpenERP folks: could you clarify the minimum required Python 
version for the next release? I think this deserves a mention in the 
README file (cf. 
https://bugs.launchpad.net/openobject-server/+bug/1052783)

The point in this behavior is that it allows to see what is deprecated 
in the runbot logs (e.g. 
http://runbot.openerp.com/c2c-trunk-deprecate-osv-osv-17452/logs/server.txt). 
There could even be an additional filter saying if there are some 
deprecation warnings triggered by the test or not.

Given all that, I think educated developers will be able to look for 
such warnings and fix them in their code. Everyone will benefit from 
this, as it will reduce breakage when deprecated features are removed 
altogether (and it lowers the risks of making people unhappy when the 
removal occurs). With the deprecation policy and a clear tagging of the 
warnings I talked about in the OP, it becomes possible run the test 
base with settings that will trigger exceptions (and thus break the 
tests) when some code uses a feature that is going to completely 
disappear in the next stable release, meaning that it is time to bite 
the bullet and finally fix this code, which is important for 
integrators who wish to keep a single code base for extensions who need 
to support several releases.

This applies to both the framework itself (I'm thinking of the API 
revamp that was presented at the community days last spring) and to the 
certified addons.

Best regards,

--
Alexandre Fayolle
Chef de Projet
Tel : + 33 (0)4 79 26 57 94

Camptocamp France SAS
Savoie Technolac, BP 352
73377 Le Bourget du Lac Cedex
http://www.camptocamp.com