Re: Implementing member object's virtual functions

From:
"Salt_Peter" <pj_hern@yahoo.com>
Newsgroups:
comp.lang.c++
Date:
10 Apr 2007 00:40:58 -0700
Message-ID:
<1176190858.589957.160190@b75g2000hsg.googlegroups.com>
On Apr 9, 7:36 am, "v4vijayakumar" <vijayakumar.subbu...@gmail.com>
wrote:

Is it possible to implement member object's virtual functions, in the
containing class? If not, is it possible to simulate this behavior?

ex:

class test
{
protected:
  virtual void fun() = 0;

};

class test1
{
protected:
  void fun() {}

private:
  test t1;

};


No, if the language allowed that then coupling would become a
nightmare.
Isn't class test meant to be abstract anyways?
Templates are not required but consider the implications:

#include <iostream>

class abstract
{
protected:
  virtual void fun() = 0;
};

class concrete : public abstract
{
public:
  void fun() { std::cout << "concrete::fun()\n"; }
};

class another : public concrete
{
public:
  void fun() { std::cout << "another::fun()\n"; }
};

// type M must implement void fun()
template< typename M >
class test
{
  M m;
public:
  void fun() { m.fun(); }
};

int main()
{
  test< concrete > t;
  t.fun();

  test< another > a;
  a.fun();
}

/*
concrete::fun()
another::fun()
*/

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