From: mksmith AT idirect DOT com (Martin Smith)
Newsgroups: comp.os.msdos.djgpp
Subject: vectors of derived objects
Message-ID: <3aa1079f.55821769@news1.on.sympatico.ca>
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Date: Sat, 03 Mar 2001 15:11:39 GMT
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

The vector<class T> template apparently casts all elements in the
vector as base objects in the situation where class T has classes
derived from it.  

I would like to ba able to have the vector elements be able to use
virtual function calls, so I guess the question is whether there is
another template other than vector that I don't know about.

In the example follows, I want the derived list member to output
"DERIVED" 

#include <iostream>
#include <vector>

class base {
public:
  virtual void show() { cout << "BASE" << endl; }
};

class derived : public base {
public:
  void show() { cout << "DERIVED" << endl; }
};

main() {

  vector<base> list;

  base b;  list.push_back(b);

  derived a;  list.push_back(a);

  list[0].show();    // output is "BASE"
  list[1].show();    // output is "BASE"

}