Operator overloading in Python.

overload.py

# In this script, we'll overload '+' operator to add two classes.

class CurrenciesDoNotMatchError(TypeError):
    def __init__(self, message):
        super().__init__(message)
        

class Currency:
    def __init__(self, currency, amount):
        self.currency = currency
        self.amount = amount
    
    def __repr__(self):
        return repr((self.currency, self.amount))
    
    def __add__(self, other):
        if self.currency != other.currency:
            raise CurrenciesDoNotMatchError(self.currency + " " + other.currency)
        total_amount = self.amount + other.amount
        return Currency(self.currency, total_amount)
    
value1 = Currency("USD", 20)
value2 = Currency("USD", 30)
print(value1 + value2)