Steven Watanabe <watanabesj <at> gmail.com> writes:
On 05/24/2012 04:21 PM, Jeremy Maitin-Shepard wrote:
Steven Watanabe <watanabesj <at> gmail.com> writes:
[snip]
The situation is one that isn't even allowed with C++ references:
int & const ref = i; // error
True, but a reference can be a member of a struct to which you have a const reference, in which case it is treated just like a pointer, i.e. no const propagation.
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). Maybe support for _self* or even shared_ptr<_self> (as a special syntax to indicate that internally a shared_ptr to the underlying type should be stored) could be a useful alternative?