[Cython] Type inference and C++

[Stefan Behnel]

Vitja Makarov, 24.07.2012 18:42:
> 2012/7/24 Stefan Behnel:
>> Vitja Makarov, 24.07.2012 14:48:
>>> 2012/7/24 Stefan Behnel:
>>>> Stefan Behnel, 24.07.2012 12:43:
>>>>> Vitja Makarov, 23.07.2012 07:13:
>>>>>> Here is part of original testcase:
>>>>>>
>>>>>> from cython.operator cimport dereference as d
>>>>>> from cython.operator cimport preincrement as incr
>>>>>> from libcpp.vector cimport vector
>>>>>>
>>>>>> def reverse_iteration_test(L):
>>>>>>     v = new vector[int]()
>>>>>>     for a in L:
>>>>>>         v.push_back(a)
>>>>>>     it = v.rbegin()
>>>>>>     while it != v.rend():
>>>>>>         a = d(it)
>>>>>>         incr(it)
>>>>>>         print(a)
>>>>>>
>>>>>> I think it's not correct to infer `a` as reverse_iterator because it's
>>>>>> not an iterator it's vector's item.
>>>>>
>>>>> Right. DereferenceNode should implement infer_type().
>>>>
>>>> ... and not only DereferenceNode. Pretty much all C++ operators do not
>>>> properly implement type inference. I'll take a look.
>>>
>>> Ok, thanks!
>>
>> Here's my fix.
>>
>> https://github.com/cython/cython/commit/43f3d87d9760d3c7e7fa6a127d0bdaf549880621
>>
>> It became a bit more involved than I had anticipated, including some
>> cleanups and fixes for a couple of quirks that I ran into.
>>
>> It's really too bad that the Sage build is currently broken. The C++ code
>> in there would be a good exercise for this change (even if it won't benefit
>> from the type inference). At least, so far, it doesn't seem like it has
>> broken more than what was broken before.
> 
> And sorry for stupid question: do we support multiple overloaded
> operators of the same kind?

I'm sure we're lacking a test for that. At least in the change above, I'm
using "lookup_operator_for_types()", which should do the right thing.

Stefan