In a "has-a" class relationship does the contained class have to be implemented inside the class that contains it or can it be written entirely separately in a different file?
For example:
let's say:
class Pen
{
public:
.
.
.
private:
Ball point;
};
Can class Ball be in a separate header file or do I have to implement it within class Pen?
Yes, Ball can be in it's own file:
Ball.h
class Ball
{
} // eo class Ball
Pen.h
#include "ball.h"
class Pen
{
private:
Ball point;
} // eo clas Pen
It can be either way. If class Ball is not for use only within class Pen you should implement it separately - as a separate class in the same file or in another file.
Anyway C++ doesn't care how many files the implementations reside. Do as it feels convenient.
