Re: Question about interfaces

From:
"Daniel T." <daniel_t@earthlink.net>
Newsgroups:
comp.lang.c++
Date:
Sun, 29 Jun 2008 10:16:10 -0400
Message-ID:
<daniel_t-110507.10161029062008@earthlink.vsrv-sjc.supernews.net>
sip.address@gmail.com wrote:

When creating interfaces and implementations, the usual thing is doing
somethign like

class Interface {
public:
  virtual void f() = 0;
  virtual void g() = 0;
};

class Imp1 : public Interface {
public:
  void f();
  void g();
};

So we can have Interface* if = new Imp1; and so on..

But we could also use private inheritance:

class Imp1 {
protected:
  void f();
  void g();
};

class Interface : private Imp1 {
public:
  void f() { Imp1::f(); }
  ...
};


Note, the above is effectively the same as composition.

class Imp1 {
public:
   void f();
   void g();
};

class Interface {
   Imp1 imp;
public:
   void f() { imp.f(); }
};

What are the advantages/disadvantages of each?


The old "inheritance versus composition" question. This isn't strictly a
C++ question. Do a Google search on that term and you will get a
plethora of opinions.

Any advise?


"Favor object composition over class inheritance" (GoF)

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