Re: [boost] enable_if and non-template member functions?

Subject: Re: [boost] enable_if and non-template member functions?
From: John Maddock (boost.regex_at_[hidden])
Date: 2011-08-12 05:31:10

>From your description, I think I've done exactly this.  E.g.

--8<---------------cut here---------------start------------->8---
template <class U>
struct X
{
     // member function void f(int) becomes something like:
     template <class T>
     typename enable_if<
        mpl::and_<
            is_convertible<T,int>
          , some_condition_on<U>
        >
     >::type
     f(T x_)
     { int x = x_; ... }
};
--8<---------------cut here---------------end--------------->8---

That works as long as the function has at least one parameter that can be 
turned into a template, but I have some cases that are operators or else 
have no parameters.

So for now I think I'll stick to the old "this member can't be instantiated 
unless T models X".  It prevents explicit instantiation, but never mind I 
guess...

BTW, it would be great if all these techniques could be added to the 
enable_if docs.

Cheers, John.