[Python-Dev] Deprecation policy

[Raymond Hettinger]

On Oct 24, 2011, at 5:58 AM, Ezio Melotti wrote:

> Hi,
> our current deprecation policy is not so well defined (see e.g. [0]), and it seems to me that it's something like:
>  1) deprecate something and add a DeprecationWarning;
>  2) forget about it after a while;
>  3) wait a few versions until someone notices it;
>  4) actually remove it;
> 
> I suggest to follow the following process:
>  1) deprecate something and add a DeprecationWarning;
>  2) decide how long the deprecation should last;
>  3) use the deprecated-remove[1] directive to document it;
>  4) add a test that fails after the update so that we remember to remove it[2];

How about we agree that actually removing things is usually bad for users.
It will be best if the core devs had a strong aversion to removal.
Instead, it is best to mark APIs as obsolete with a recommendation to use something else instead.
There is rarely a need to actually remove support for something in the standard library.
That may serve a notion of tidyness or somesuch but in reality it is a PITA for users making it more difficult to upgrade python versions and making it more difficult to use published recipes.


Raymond
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