Local structs as template parameters

[Marcin Kalicinski]

Hi,

Why local structs/classes cannot be used as template parameters?

void f(std::list &l)
{
struct Cmp { /*...*/ };
l.sort(Cmp()); // Error here
}

Best regards,
Marcin

 

[Victor Bazarov]

Why local structs/classes cannot be used as template parameters?

In comp.lang.c++ the answer is "because the Standard says so".

If you need to know the rationale behind the decision not to allow
local classes in templates, then you should as in comp.std.c++.

IIRC, the reason is that local classes don't have linkage. I do
not remember anything useful beyond that.

Victor

 

[tom_usenet]

Hi,

Why local structs/classes cannot be used as template parameters?

Because the have internal, not external, linkage, which currently
would cause problems for template instantiation. See
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2003/n1427.pdf

Tom