what is the type of op1 in Equality<Derived> const& op1 ?

[analyst123]

Equality<Derived> const& op1

what is the type of op1 in above variable

[Guest]

You mean spelled out in English? Because the type is right there in front of you. Reference to const Equality<Derived>.

[MutantJohn]

It's funny, I spent a couple years programming in C and C++ before I learned that you could put the const to the right of the type :P

Also, keep in mind that template classes aren't actually fully realized until your provide the template parameter.

Like,

template <typename T>
class my_class
{

};

isn't actually a real type until you do:

my_class<int>

Templates are neat because you can think of them as giving the compiler information to someday create a type.

[Elysia]

Also, keep in mind that template classes aren't actually fully realized until your provide the template parameter.

Like,

isn't actually a real type until you do:

Oh no, it's a type alright. A different one:

template<typename T> class foo {};
template<typename T> void bar1(T) {}
template<template<typename> class T> void bar2(T) {}

bar1<foo>(); // Error
bar1<foo<int>>(); // OK
bar2<foo>(); // OK
bar2<foo<int>>(); // Error

(I did not check for syntax errors.)

[MutantJohn]

Yeah, I'm not really familiar with nested templates....

Trying to make sense of that code is interesting. You can also pass around the templated class definition...