when to use private inheritance?

[al pacino]

hi,
is there any advantage of using private inheritance over composition
and vice versa.
under what condition/s should we chose one over the other.

thanks in advance.

 

[Ian Collins]

hi,
is there any advantage of using private inheritance over composition
and vice versa.
under what condition/s should we chose one over the other.

I tend to prefer private inheritance

a) when 'is a' makes more sense than 'has a'.
b) it could go either way and I want to save on typing.

 

[Daniel T.]

hi,
is there any advantage of using private inheritance over composition
and vice versa.
under what condition/s should we chose one over the other.

class Base {
public:
// lots of functionality
virtual void fun();
};

Now, assume we want to write a class that can use Base's functionality
and must override fun, but shouldn't be useable as a Base*. We have two
choices.

class Derived : public Base {
public:
void fun();
};

class User {
Derived d;
public:
//stuff
};

or simply:

class User : private Base {
void fun();
public:
// stuff
};