[Cython] Templated attributes in extensions classes in 0.17 Beta 2

[Stefan Behnel]

Brett Calcott, 20.08.2012 08:23:
> I'm not sure if this is a bug in 0.17 beta or not. But something is not working.
> 
> Default-constructed attributes in an extension definition appear to
> work (though I can't see where they are documented on the site…)
> 
> So this works:
> 
> ----test.h --------
> #include <vector>
> 
> struct Attributes
> {
>     std::vector<int> v;
> };
> 
> -----test.pyx------
> from libcpp.vector cimport vector
> 
> cdef extern from "test.h":
>     cdef cppclass Attributes:
>         vector[int] v
> 
> cdef class Test:
>     cdef Attributes a
>     def __cinit__(self, list x):
>         self.a.v = x
> 
> 
> However, if I try to put the templated attribute in directly:
> 
> ----test2.pyx------
> from libcpp.vector cimport vector
> 
> cdef class Test:
>     cdef vector[int] v
>     def __cinit__(self, list x):
>         self.v = x
> 
> cython compiles it fine, but I get an error in the cpp compilation:
> test2.cpp:722:23: error: expected a type
>   new((void*)&(p->v)) std::vector();
> 
> So it looks like it's doing the funky in place construction, but not
> getting the template parameters in there…
> 
> Should this work?

Yes, although (IIRC) not in beta 2. There was a recent fix for this, but it
broke other stuff. I'm waiting for a fix for those before I release yet
another beta (which will then hopefully be a release candidate).

In any case, thanks for the report!

Stefan