[Cython] "embedsignature" and "autotestdict" features in Py3.4

[Robert Bradshaw]

On Fri, Nov 29, 2013 at 8:03 AM, Stefan Behnel <stefan_ml at behnel.de> wrote:
> Hi,
>
> recent changes in Py3.4 affect the functionality of the two directives
> "embedsignature" and "autotestdict".
>
> The so-called "argument clinic" extracts any embedded signatures from
> docstrings and moves them into a new property "__text_signature__". This is
> done at runtime, i.e. when either "__doc__" or "__text_signature__" are
> requested.
>
> http://hg.python.org/cpython/file/6a3e09cd96f3/Objects/methodobject.c#l182
>
> I personally consider this a feature (and it works nicely with the
> signatures that Cython embeds), but you may or may not agree. It broke some
> of our own doctests, at least, because the "__doc__" value that we tested
> for was no longer the same.

I'm fine with this new behavior.

> Regarding the "autotestdict", CPython also got smarter and now finds
> doctests embedded in C implemented functions all by itself. This is clearly
> an improvement compared to the previous behaviour. However, this also means
> that it now executes both the doctest of the function itself and its copy
> in the generated "__test__" dict (stored in the module under that name),
> meaning that it executes all function doctests twice. This also broke some
> of Cython's own doctests for us, which modified global state and thus
> failed the second time.
>
> I'm yet unsure if we should try to do something about this. Currently, the
> explicit doctest dict is generated by default, so all code that uses
> doctests in function docstrings suffers from this. We might be able to make
> Cython a bit smarter so that these docstrings are left out of the test dict
> when (C-)compiling in CPython 3.4. Deciding which ones are still needed
> might be a bit tricky, though...

I think it makes sense to exclude these from the __test__ dict at C
compile time--is it the cpdef ones that it can pick up now?

- Robert