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 (Click here for a personal note from Marshall Cline.) |
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Section 24:
| 24.1 | How do you express "private inheritance"? |
| 24.2 | How are "private inheritance" and "composition" similar? |
| 24.3 | Which should I prefer: composition or private inheritance? |
| 24.4 | Should I pointer-cast from a private derived class to its base class? |
| 24.5 | How is protected inheritance related to private inheritance? |
| 24.6 | What are the access rules with private and protected inheritance? |
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[24.6] What are the access rules with private and protected inheritance?
Take these classes as examples:
class B { /*...*/ };
class D_priv : private B { /*...*/ };
class D_prot : protected B { /*...*/ };
class D_publ : public B { /*...*/ };
class UserClass { B b; /*...*/ };
None of the derived classes can access anything that is private in B. In
D_priv, the public and protected parts of B are private. In
D_prot, the public and protected parts of B are protected. In
D_publ, the public parts of B are public and the protected parts of
B are protected (D_publ is-a-kind-of-a B). class UserClass can
access only the public parts of B, which "seals off" UserClass from B.
To make a public member of B public in D_priv or D_prot, state the name of the member with a B:: prefix. E.g., to make member B::f(int,float) public in D_prot, you would say:
class D_prot : protected B {
public:
using B::f; // Note: Not using B::f(int,float)
};