Path: utzoo!attcan!uunet!cs.utexas.edu!rutgers!mcnc!duke!macbeth!sk
From: sk@macbeth.cs.duke.edu (Srinivasan Krishnan)
Newsgroups: comp.lang.c++
Subject: detecting writes
Keywords: arrays
Message-ID: <21007@duke.cs.duke.edu>
Date: 25 Jul 90 15:45:19 GMT
Sender: news@duke.cs.duke.edu
Lines: 36


While trying to implement an array based object, I have run into 
difficulties with detection of writes on the array.

Here's part of the definition of the class:

	class IntArray {
	public :

			// allows assignments of the form A = B
		IntArray& operator=(const IntArray&);

			// returns the lvalue of the i-th element of the array
		int& operator[] (int);

	protected :
			// internal data representation
		int flag;
		int *ia;
};

I would like to be able to set the variable "flag" to zero whenever any
assignments are made to the array.

	Assignments to an array are of 2 types : 

1	A = B ; ( A and B IntArrays )
	By overloading the = operator , I am able to 
	set the flag of A to 0 

2       A[i] = somevalue;
	This is causing the problem. The [] operator is used for
	both reads and writes, and the = operator operates on integers.

Is there any way I can cause the side effect of setting flag to 0
only on memory writes while retaining the use of the [] operator?