Limited member function templates?

[Bill Baxter]

Janice Caron wrote:
> I get why member function templates would be a bad idea in general.
> They'd be a nightmare to implement! But it occurs to me that if we
> insist on some limitations, it might be quite feasible, within those
> limitations. The limitation I have in mind is explicit instantiation.
> 
> Here's an example of what I'm thinking of.
> 
>     class A
>     {
>         string s;
> 
>         int f(T)(T t) { s = toUTF8(t); } /* template member function */
> 
>         alias f!(string) fs; /* explicit instantiation */
>         alias f!(wstring) fw; /* explicit instantiation */
>     }
> 
> The trick is that the instantiation must be done *within the class
> definition*. We can still disallow anything not explicitly
> instantiated inside the class definition, so
> 
>     A a;
>     a.fs("hello"); /* OK - uses alias*/
> 
>     a.f!(string)("hello") /* OK - template is instantiated for string */
> 
>     string s;
>     a.f(s); /* OK - type deduction */
> 
>     a.f!(dstring)("hello"d) /* Not OK - template not instantiated for dstring */
> 
> Thoughts?

Member function templates have worked fine as long as I've been around. 
  The only thing you can't have is _virtual_ member function templates. 
  Is making them virtual what you are talking about?

--bb