On 26/05/12 21:25, Jeremy Maitin-Shepard wrote:
Steven Watanabe <watanabesj <at> gmail.com> writes:
The problem with const any<Concept, _self&> xx; is that anything that isn't specially designed to handle it will see the const and treat it as const. Some parts of the library will work with it, but in others it was just too difficult.
I can see now that there would be a problem with using concept_interface to inject member functions, since there is no way to simultaneously define both a const and non-const member function. Particularly with the introduction of member reference qualification, not being able to template on the type of "this" is a significant defect in the language. At least it can be worked around by not using member functions (except for operator overloading where it can't be avoided).
In the past I've achieved this by defining both const and non-const member functions and forwarding to a free function which then can be templated on the type of this. As you say, things get worse with member reference qualification because now three member functions are needed. I don't know whether such a technique would be applicable in this case. John