MoneyFowler.cpp

class Money {
  Amount m_amount;
  Currency m_currency;
	
public:
  Money(Amount const& amount, Currency const& currency)
    : m_amount(amount)
    , m_currency(currency)
  {}
		
  Amount amount() const { return m_amount; }
  Currency currency() const { return m_currency; }
};

bool operator==(Money const& lhs, Money const& rhs)
{
  return lhs.amount() == rhs.amount() && lhs.currency() == rhs.currency();
}

bool operator!=(Money const& lhs, Money const& rhs)
{
  return !(lhs == rhs);
}

Money add(Money const& lhs, Money const& rhs)
{
  if (lhs.currency() != rhs.currency())
    throw std::logic_error("Currency should be equal");
  return Money(lhs.amount() + rhs.amount(), lhs.currency());
}