Abstract Data Types - Separating Interface from Implementation

From: Anon Email (anonemail1_at_fastmail.fm)
Date: 12/22/03 

Date: 21 Dec 2003 17:29:05 -0800

Hi people,

I'm learning about header files in C++. The following is code from
Bartosz Milewski:

// Code

const int maxStack = 16;

class IStack
{
public:
    IStack () :_top (0) {}
    void Push (int i);
    int Pop ();
private:
    int _arr [maxStack];
    int _top;
};

--------------
// Header file

#include "stack.h"
#include <cassert>
#include <iostream>
using std::cout;
using std::endl;

//compile with NDEBUG=1 to get rid of assertions

void IStack::Push (int i)
{
    assert (_top < maxStack);
    _arr [_top] = i;
    ++_top;
}

int IStack::Pop ()
{
    assert (_top > 0);
    --_top;
    return _arr [_top];
}

--------------

I know this is very basic code. I also know that it's a non-standard
header filename/ file. I'm merely using this for demonstration
purposes. Let's pretend that in C++ it's possible to completely
separate the interface from the implementation. Would the header file
then look something like this?:

//compile with NDEBUG=1 to get rid of assertions

const int maxStack = 16;

class IStack
{
public:
        IStack () :_top (0) {}
            void Push (int i);
            int Pop ();

        void Push (int i)
        {
                assert (_top < maxStack);
                    _arr [_top] = i;
                ++_top;
        }

        int Pop ()
        {
                 assert (_top > 0);
                   --_top;
                  return _arr [_top];
        }

            
private:
            int _arr [maxStack];
            int _top;

};

In other words, everything that defines the class would go in the
class header, and the only code written in the implementation file
would be a call or calls to the constructor or member functions?

Cheers,

Deets

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