c++ - Named? parameters in templates, functions

Question

Is there any update in the upcoming C++0x standard on named parameters in templates and/or functions? For example, I would like to be able to write the following:

having defined previously:

template<class T = int,class Policy_1, class Policy_2>
class X
{
};

then in main:

X<Policy_2: NoReturn> x;

this same with functions; having:

void f(int arg_1 = 0, int arg_2 = 1, int arg_3 = 2)
{
}

then in main:

f(arg_3: 55);

Answer 1

For functions you can use the Named Parameters Idiom (in both C++98 and C++0x).

See C++ FAQ item 10.20 What is the "Named Parameter Idiom"?.

For template arguments I think you can use the idea of wrapping, using "type carrier" types that by their type encode which template argument they are. It gets complex. You might check out the Boost Parameters library for ideas, but essentially, for template arguments I do not think it's worth spending time on (not to mention actually using) -- it's academic.

Cheers & hth.,