/*
   Ken Moore 3/22/2005
   Did not want to waste lecture time developing this code - 
   went home did this demo on c-tor's/value based symantics.
*/

#include <iostream>
#include <cstdlib>
using namespace std;

class testCons{
public:
	int thirty;
	testCons(){thirty = 30;cout << " in default c-tor" << endl;}
	testCons(testCons & tcr){thirty = tcr.thirty; cout << " in copy c-tor" << endl;}
/* 
   // If in, causes error 
   // What happens is this:
   //   returnLocalAsRef is returning a non protected variable.
   //   Without this assignment operator, nothing affects the program stack before 
   //     assignment in main to tc.
   //   When the assignment operator is used, it gets pushed on the program stack before
   //   the assignment, showing the folly of returning a local variable by reference.

	testCons& operator=(const testCons& rhs){
		thirty = rhs.thirty; 
		cout << "in assignment overload" << endl; 
		return *this;
	}
*/
};


// show that pass by value calls copy c-tor.
void passByValue(testCons x){
	cout << " In pass by value" << endl;
}

// create potential mistake - add = operator to show mistake.
testCons& returnLocalAsRef(){
	cout << " In returnLocalAsRef " << endl;
	testCons tcr;
	tcr.thirty = 14;
	return tcr;// generates warning.
}
// show that return by value calls copy constructor.
testCons returnLocalByValue(){
	cout << " In returnLocalByValue " << endl;
	testCons tcr;
	tcr.thirty = 44;
	return tcr;// generates warning.  Actually corrupts program when = operator in.
}


testCons* returnPtr(){
	cout << " In returnPtr " << endl;
	testCons *ptc = new testCons();
	return ptc;
}
int main(void){
	testCons *ptc, tc;
	passByValue(tc); // causes call to copy constructor!
	tc = returnLocalByValue(); // returns invalid
	cout << " After returnLocalByValue tc.thirty = " << tc.thirty << endl; // thirty?
	tc = returnLocalAsRef(); // returns invalid
	cout <<  " After returnLocalAsRef tc.thirty = " << tc.thirty << endl; // thirty?
	ptc = returnPtr();
	delete ptc;

	return EXIT_SUCCESS;
}