/******************************************************************************
 ***   FILE: error_handler.cpp
 ***   DATE: 03/17/2004
 *** AUTHOR: Daniel Dementiev
 ***   GOAL: This program illustrates how to use user defined error handlers.
 ***         Line:
 ***           typedef void (*error_handler_ptr)(char*)
 ***         defines a new type 'error_handler_ptr' that is a pointer to a
 ***         function that takes one argument of the char* type and returns
 ***         no value (void).
 ***         Class Array has a private member err_handler of this new type,
 ***         and this member is used in the method Item():
 ***           (*err_handler)("argument")
 ******************************************************************************/
#include <iostream>
#include <assert.h>
using namespace std;

class Array {
   private:
      int count;
      int data[10];
      int size;
      typedef void (*error_handler_ptr)(char*);
      error_handler_ptr err_handler;
   public:
      Array() : count(0), size(10), err_handler(NULL) {};
      int Count() const { return count; };
      int Size() const { return size; };
      int& Item(int index);
      void SetErrorHandler(error_handler_ptr err) { err_handler = err; };
};

int& Array::Item(int index)
{
   if( (index<0 || index>=10) && err_handler!=NULL )
      (*err_handler)("Index is out of range in Array::Item() method");
   return data[index];
}


// this function will be invoked if any error occurs in the Array class methods
void MyErrFunction(char *msg)
{
   cerr<<"Error: "<<msg<<endl;
}


void main()
{
   Array a;
   cout<<"count = "<<a.Count()<<endl;
   cout<<" size = "<<a.Size()<<endl;
   a.SetErrorHandler( MyErrFunction );
   a.Item(10) = 5;
   cout<<"After running 'a.Item(10) = 5':\n";
   cout<<"count = "<<a.Count()<<endl;
   cout<<" size = "<<a.Size()<<endl;
}