Do templates maintain separation?

[Clayton Weaver]

By separation, I simply mean declaration/definition (.h/.cpp). Every book I know of stresses separating the definition from the declaration. Upon learning templates I read that they force you to include everything in the header file:

template<typename T>

class Vec{

         T val;

    public:

        T funct() const { return val; }

};

Then I found a site where a person did this:

// collection.h

template<typename T>

class Collection{

     public:     

          bool isempty() const;

};

// collection.cpp

template<typename T>

bool Collection<T>::isempty()const

{

     //....

}

//main.cpp

Collection<int> col1;

Collection<string> col2; // etc.

Due to that site I'm confused. Do templates allow to maintain declaration/definition separation or not? 

Sincerely,

Clayton Weaver

[Thiago Macieira]

On quinta-feira, 12 de janeiro de 2017 17:27:45 PST Clayton Weaver wrote:
> Due to that site I'm confused. Do templates allow to maintain
> declaration/definition separation or not?

Yes, but there's a caveat:

In the header, you need to declare which instantiations will appear in the
.cpp file.

In the .cpp, you need to instantiate them.

And you cannot use any instantiation that isn't in the .cpp.

--
Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
Software Architect - Intel Open Source Technology Center

[Clayton Weaver]

Thank you for clearing that up for me.