[Zope3-dev] zope3 doesn't like the python datetime module?

[Tim Peters]

[Anthony Baxter]
> When trying to use zope.interface outside Zope, without the
> src/datetime package, tests fail with:
>
>   File "test.py", line 487, in get_suite
>     mod = package_import(modname)
>   File "test.py", line 479, in package_import
>     mod = __import__(modname)
>   File "zope/interface/common/tests/test_idatetime.py", line 22, in ?
>     from zope.interface.common.idatetime import ITimeDelta,
>   ITimeDeltaClass File "zope/interface/common/idatetime.py", line
>     574, in ? directlyProvides(timedelta, ITimeDeltaClass)
>   File "zope/interface/declarations.py", line 969, in directlyProvides
>     object.__provides__ = ProvidesSpecification(*interfaces)
> TypeError: can't set attributes of built-in/extension type
> 'datetime.timedelta'
>
> This makes me sad.  Can anyone suggest a fix?  It looks like the
> implemented-in-C datetime code breaks when fed into the interface
> code.

Actually, it looks more like this part of the Zope interface code breaks
when it's fed the C datetime types, yes?

> Assuming that a) Zope3 doesn't want to maintain it's own datetime
> package for ever,

It does not.

> and/or b) Zope3 wants to use the C code version at some point for
> speed,

More so for memory frugality, I think.  The C datetime types have small
memory requirements compared to the Python implementation.

> this is a problem.

Yup.  Offhand I don't know what causes the problem.  I would *like* to see
Zope Corp require Python 2.3 for Zope3.  That would force the issue in such
a way that it must be solved.  So long as we dilute our efforts wrestling
with artificial Python 2.2 compatibility requirements too, I doubt that this
one is going to make it to the top of my todo list (it can rise to crisis
status so long as "use the Python implementation" remains a blessed
alternative).

BTW, it's generally true that you can't set attributes on an object of a
builtin type (the datetime types aren't unique that way), so if you want to
pursue this now I'd look for code that manages to use, e.g., dicts with
interfaces now.