Where to define C++ class member template function and functors that instantiate it?

Question

I have a class Foo which is used in a small standalone project. It has a class definition in Foo.h with the implementation for the class\' member functions in an implementat

Answer 1

The template method definition should indeed be in the header file of it the class it belongs to.

Like this:

class MyClass
{
    template 
    void foo(const T&)
    {
        // Definition
    }
};

Or like this (note that the template method definition can be included from separate file after the class declaration)

class MyClass
{
    template  void foo(const T&);
};

template 
void MyClass::foo(const T&)
{
    // Definition
}

The rest is depends on the style you agreed on and your needs.

I would put the functor declaration (or even the definition if they are simple) into the header if I use them not only in Foo or if Foo has them as class member.