[Python-Dev] Breaking undocumented API

[Brett Cannon]

On Mon, Nov 8, 2010 at 13:45,  <exarkun at twistedmatrix.com> wrote:
> On 09:25 pm, brett at python.org wrote:
>>
>> On Mon, Nov 8, 2010 at 13:03,  <exarkun at twistedmatrix.com> wrote:
>>>
>>> On 07:58 pm, brett at python.org wrote:
>>>>>
>>>>> I don't think a strict don't remove without deprecation policy is
>>>>> workable.  For example, is trace.rx_blank constant part of the trace
>>>>> module API that needs to be preserved indefinitely?  I don't even know
>>>>> if it is possible to add a deprecation warning to it, but
>>>>> CoverageResults._blank_re would certainly be a better place for it.
>>>>
>>>> The deprecation policy obviously cannot apply to module-level
>>>> attributes.
>>>
>>> I'm not sure why this is.  Can you elaborate?
>>
>> There is no way to directly trigger a DeprecationWarning for an
>> attribute. We can still document it, but there is just no way to
>> programmatically enforce it.
>
> What about `deprecatedModuleAttribute`
> (<http://twistedmatrix.com/documents/current/api/twisted.python.deprecate.html>)
> or zope.deprecation
> (<http://docs.zope.org/zope3/Book/deprecation/show.html>) which inspired it?

Just checked the code and it looks like it substitutes the module for
some proxy object? To begin that break subclass checks. After that I
don't know the ramifications without really digging into the
ModuleType code.