// ==========================================
// * Samples
// * Member and non-member operators
// * Usage Sample Code
// ------------------------------------------
// * Language : C++
// * Content  : Program files, Log files
// * Version  : MOP-1.0
// ------------------------------------------
// * Attachments
//   - mem-nomem-operators-1-0.cpp
//   - mem-nomem-operators-1-0.log
// ==========================================

 Alex Vinokur
     email: alex DOT vinokur AT gmail DOT com
     http://mathforum.org/library/view/10978.html
     http://sourceforge.net/users/alexvn

[ mem-nomem-operators-1-0.cpp 2K ]
// ==========================================
// * Samples
// * Member and non-member operators
// * Usage Sample Code
// ------------------------------------------
// * Language : C++
// * Content  : Program files, Log files
// * Version  : MOP-1.0
// ------------------------------------------
// * Attachments
//   - mem-nomem-operators-1-0.cpp
//   - mem-nomem-operators-1-0.log
// ==========================================

#include <iostream>
using namespace std;

// ------
struct Blah
{

// ------
class Foo
{
friend Foo operator+ (const Foo& arg1, const Foo& arg2);
friend Foo operator+ (int arg1,        const Foo& arg2);
friend Foo operator+ (const Foo& arg1, int arg2);

private:
  int     m_value;

public :
  Foo () {}
  Foo (const Blah&)
  {
    cout << "Constructor: " << __PRETTY_FUNCTION__ << endl;
  }

  Foo& operator- (const Foo& arg)
  {
    m_value -= arg.m_value;
    cout << "Member:      " << __PRETTY_FUNCTION__ << endl;
    return (*this);
  }

  Foo& operator- (int arg)
  {
    m_value -= arg;
    cout << "Member:      " << __PRETTY_FUNCTION__ << endl;
    return (*this);
  }

// ------
Foo operator+ (const Foo& arg1, const Foo& arg2)
{
  Foo foo;
  foo.m_value = arg1.m_value + arg2.m_value;
  cout << "Non-Member:  " << __PRETTY_FUNCTION__ << endl;
  return foo;

// ------
Foo operator+ (int arg1, const Foo& arg2)
{
  Foo foo;
  foo.m_value = arg1 + arg2.m_value;
  cout << "Non-Member:  " << __PRETTY_FUNCTION__ << endl;
  return foo;

// ------
Foo operator+ (const Foo& arg1, int arg2)
{
  Foo foo;
  foo.m_value = arg1.m_value + arg2;
  cout << "Non-Member:  " << __PRETTY_FUNCTION__ << endl;
  return foo;

// ------
struct Bar
{
  operator Foo () { cout << "operator:    " <<  __PRETTY_FUNCTION__ << endl;}

// ------
int main ()
{
Foo f0, f1, f2;
  f0 = f1 + f2;
  f0 = f1 - f2;

  cout << endl;
int i1 = 127;
  f0 = f1 + i1;
  f0 = i1 + f1;
  f0 = f1 - i1;
  // f0 = i1 - f1;      // no match for 'operator-' in 'i1 - f1'

  cout << endl;
Blah b1;
  f0 = f1 + b1;
  f0 = b1 + f1;
  f0 = f1 - b1;
  // f0 = b1 - f1;      // no match for 'operator-' in 'b1 - f1'

  cout << endl;
Foo foo;
Bar bar;
  f0 = foo + bar;
  f0 = foo - bar;
  f0 = bar + foo;
  // f0 = bar - foo;    // no match for 'operator-' in 'bar - foo'

  return 0;

mem-nomem-operators-1-0.log < 1K Download