aggregates.cpp

#include <iostream>

using namespace std;

// -----------------------------------------------
//    Test the Aggregates propreties with gcc v3.4
// -----------------------------------------------

// The rules for a type for being an Aggregates are:
// - No user-defined ctor nor copy ctor.
// - No virtual functions.
// - No private or protected (non static) members or member functions.
// More?

// -----------------------------------------------
class Agg
{
public:
  int a;
  int b;
};

// -----------------------------------------------
//               "More" is also an Aggregate type.
// -----------------------------------------------
class More 
{
public:
  int a;
  Agg first;
  int b;
  Agg second;
  int c;
};

// -----------------------------------------------
//                                 Pretty printer.
// -----------------------------------------------
ostream& operator << (ostream& os, const Agg& rhs);

// -----------------------------------------------
//                Main function. Holds everything!
// -----------------------------------------------
int main()
{
  cout << "hello world." << endl;
  
  // Aggregates types enables kind of "intialiser list"
  // in pre-c++11.
  Agg test = { 1, 2 };
  cout << "Agg = " << test << endl;
  
  test.b = 10;
  cout << "Agg = " << test << endl;
  
  // test = {88, 99}; // Complier Error!
  // test = Agg ({88, 99}); // Complier Error!
  
  const More test2 = {1, {5, 6}, 2, test, 3};
  cout << "More=" << test2.a << ", "
                "(" << test2.first << "), "
                "" << test2.b << ", "
                "(" << test2.second << "), "
                "" << test2.c << endl;
}

// -----------------------------------------------
//                             Useless part below.
// -----------------------------------------------

// -----------------------------------------------
ostream& operator << (ostream& os, const Agg& rhs)
{
  return os << rhs.a << "," << rhs.b;
}