Question

I want to hide an implementation in implementation file. If the object is not public, I don’t want the object’s header to leak everywhere my class is used.

Suppose I have header file A.h for my class A:

#include "Foo.h"

class A{
    private:
        Foo foo;
    public:
        do_stuff();
};

Now wherever I would include A.h, Foo.h also would be included. But I have no use for class Foo anywhere outside of class A. I would rather not have this #include "Foo.h" line. Is there any way to move the declaration of ‘foo’ variable inside the implementation A.cpp?

I suspect one possible solution involves adding a layer of abstract class (interface analogy). Is it the best solution?

Thank you.

Answer 1

Use a pointer to Foo and allocate it dynamically, rather than using a member object. Then you only need to include Foo.h in A.cpp.

class Foo;

class A{
    private:
        Foo* foo;
    public:
        do_stuff();
}