On Tue, Jul 26, 2011 at 1:19 PM, Noah Roberts <roberts.noah@gmail.com>wrote: [...]
One thing that I think is missing is the option to check for a named callable within a type. For example, one might want to use enable_if style concept checking. So long as a type has function 'xxx' that takes arguments of type x,y,and z, and returns something convertible to type A, the concept is obeyed. I don't believe this can be done with C++03, but with C++1X I was able to do something using decltype.
[...] Actually, you can approximate it pretty well in C++03 (using derivation and using tricks) to the point that I think it will work pretty much as you expect except for nullary member functions, where your queries must be more restrictive. This is a useful query, but I believe Edward has decided it to be outside the scope of TTI. - Jeff