// test_safe2.cc  second of sequence, shows SAFE design of a class
//                 test_safe1.cpp does not have
//                 copy constructor, 'explicit' AND operator=
//                 all three are needed to be safe !!!

#include <iostream>
using namespace std;

int main()
{
  cout << "test_safe2.cc is SAFE" << endl;
  
  class safe2
  {
    public:
      explicit safe2(){i=0; a=0;} // add explicit, make 'i' items in a
      explicit safe2(safe2 & x) // add explicit and copy constructor
        {i = x.get();
         a = new int[i];
         for(int j=0; j<i; j++){*(a+j)=x.get(j);} }
      ~safe2(){delete a;}
      void set(int ii){i=ii;}
      int get(){return i;}
      void set(int *aa){a=aa;}
      int *get(int *aa){return aa;}
      void set(int index, int val){if(index<0 | index>=i) throw "BAD index";
                                   *(a+index)=val;}
      int get(int index){if(index<0 | index>=i) throw "BAD index";
                         return *(a+index);}
      safe2 & operator=(safe2 &x){i = x.get();
                                  a = new int[i];
                                  for(int j=0; j<i; j++){*(a+j)=x.get(j);}
                                  return *this;}
    private:
      int i;  // single variables OK
      int *a; // bad news, pointer (array)
  };
  
  int d1[3]={1, 2, 3};

  safe2 U1;
  safe2 U2;
  //  try{         // comment out 'try' block for g++
  //    cout << "illegal index" << U1.get(1) << endl;
  //  }catch(...){cout << "caught illegal index." << endl;}
       
  U1.set(d1);
  U1.set(3); // size (don't have to trust user with STL container!
  cout << "index 1 of U1 is 2== " << U1.get(1) << endl;
  U2=U1; // GOOD builds a copy
  cout << "index 1 of U2 is 2== " << U2.get(1) << endl;
  // safe2 U3 = U1; // GOOD illegal because of 'explicit'
  // cout << "index 1 of U3 is 2== " << U3.get(1) << endl;
  safe2 U4(U1); // GOOD uses a copy constructor
  cout << "index 1 of U4 is 2== " << U4.get(1) << endl;
  
  cout << "now U1.set(1,5) does NOT change U2, U3 or U4" << endl;
  U1.set(1,5); // set index 1 to value 5
  cout << "index 1 of U1 is 5== " << U1.get(1) << endl;
  cout << "index 1 of U2 is 2== " << U2.get(1) << " GOOD" << endl; 
  // cout << "index 1 of U3 is 2== " << U3.get(1) << " GOOD" << endl;
  cout << "index 1 of U4 is 2== " << U4.get(1) << " GOOD" << endl;
   
  cout << "end test_safe2" << endl;
  
  return 0;
}
//Output from executing program
// test_safe2.cc is SAFE
// index 1 of U1 is 2== 2
// index 1 of U2 is 2== 2
// index 1 of U4 is 2== 2
// now U1.set(1,5) does NOT change U2, U3 or U4
// index 1 of U1 is 5== 5
// index 1 of U2 is 2== 2 GOOD
// index 1 of U4 is 2== 2 GOOD
// end test_safe2