Re: [g++-4.1] Strange problem with overloading

[Pierre Barbier de Reuille]

Armel Asselin wrote:
>> I have a strange problem with recent g++ while trying to get a pointer
>> on an overloaded function.
>>
>> To extract one specific version of the overloaded function I tried :
>>
>> float ( *v2d_cross )( const Vector2& , const Vector2&  ) = cross;
>>
>> But then I get this error:
>>
>> src/wrappers/export_vertex.cpp|120| error: no matches converting
>> function 'cross' to type 'float (*)(const class Vector2&, const class
>> Vector2&)'
>> src/utils/amap_util_vector.h|236| error: candidates are: float
>> cross(const Vector2&, const Vector2&)
>> src/utils/amap_util_vector.h|514| error:                 Vector3
>> cross(const Vector3&, const Vector3&)
> 
> don't know if you could ever get that to work, but at least i'm sure it does 
> not work with most c++ compilers: there is no selection of a function 
> through a 'to-be-casted-to' rule, to use pointers to members/pointers to 
> function, you must have different names: you cannot 'overload'. Calling 
> directly disambiguates/works because you have tangible argument to 
> disambiguate. But casting does not give these arguments so the compiler 
> cannot choose.
> 
> Armel
> 
> 

However, that's the recommended way to do for Boost.Python overloading :

http://boost.org/libs/python/doc/tutorial/doc/html/python/functions.html#python.overloading

And I used it for more than two years without problem.

Furthermore, according to the ISO standard C++ (§13.4 - Address of an
overloaded function):

"A use of an overloaded function name without arguments is resolved in
certain contexts to a function, a pointer to function or a pointer to
member function for a specific function from the overload set. A func-
tion template name is considered to name a set of overloaded functions
in such contexts. The function selected is the one whose type matches
the target type required in the context. The target can be [...] an
explicit type conversion."

So, as far as I understand it should work, isn't it ?

Pierre