Re: Address of an object

From:

"Daniel T." <daniel_t@earthlink.net>

Newsgroups:

comp.lang.c++

Date:

Wed, 01 Aug 2007 01:24:34 GMT

Message-ID:

<daniel_t-B7DDC1.21243531072007@news.earthlink.net>

raan <palakadan@gmail.com> wrote:

Please see the following program. I uses Windows XP/VS2003 as my
environment.

I have two classes inherited from a base class called Interfaces. I
have a class named General in which I have instantiated objects for A
and B. I have instantiated two objects ga, gb of type A and B
respectively in my main function. I wish ga and gb, in my main,
points to the same address space that a and b occupies.

Can't be done. 'ga' and 'gb' are not pointers, so you can't change what
they point to.

My ultimate aim is to have () operator overloaded in class A and class
B so that I can call ga() and gb() (functors) from my main program.
Basically the main program will be replaced by another class and
should use the objects intantiated in General class to carry out its
functionality. Calling it as (*ga)() and (*gb)() doesn't look cool .
Hope you guys get the point, why I want it this way.

You can create a wrapper for that, but frankly there is probably a
better way to do what you are trying to do:

class Interface {
public:
   virtual ~Interface() { }
   virtual void invoke() = 0;
};

class Wrapper {
   Interface* a;
public:
   Wrapper(): a( 0 ) { }
   void set( Interface* i ) {
      a = i;
   }
   void operator()() {
      if ( a )
         a->invoke();
   }
};

class A : public Interface {
public:
   void invoke() { cout << "invoke A\n"; }
};

class B : public Interface {
public:
   void invoke() { cout << "invoke B\n"; }
};

int main() {
   A a;
   B b;
   Wrapper wrap;

   wrap.set( &a );
   wrap();

   wrap.set( &b );
   wrap();
}