Python Functools – total_ordering()

Functools module in python helps in implementing higher-order functions. Higher-order functions are dependent functions that call other functions. Total_ordering provides rich class comparison methods that help in comparing classes without explicitly defining a function for it. So, It helps in the redundancy of code.

The six rich class comparison methods are:

• object.__lt__(self, other)
• object.__le__(self, other)
• object.__eq__(self, other)
• object.__ne__(self, other)
• object.__gt__(self, other)
• object.__ge__(self, other)

There are 2 essential conditions to implement these comparison methods:

• At least one of the comparison methods must be defined from lt(less than), le(less than or equal to), gt(greater than) or ge(greater than or equal to).
• The eq function must also be defined.

Example:

from functools import total_ordering


@total_ordering
class Students:
    def __init__(self, cgpa):
        self.cgpa = cgpa

    def __lt__(self, other):
        return self.cgpa<other.cgpa

    def __eq__(self, other):
        return self.cgpa == other.cgpa

    def __le__(self, other):
        return self.cgpa<= other.cgpa

    def __ge__(self, other):
        return self.cgpa>= other.cgpa

    def __ne__(self, other):
        return self.cgpa != other.cgpa

Arjun = Students(8.6)

Ram = Students(7.5)

print(Arjun.__lt__(Ram))
print(Arjun.__le__(Ram))
print(Arjun.__gt__(Ram))
print(Arjun.__ge__(Ram))
print(Arjun.__eq__(Ram))
print(Arjun.__ne__(Ram))

Output

False
False
True
True
False
True

Note: Since the __gt__ method is not implemented, it shows “Not

Example 2:

from functools import total_ordering

@total_ordering
class num:

    def __init__(self, value):
        self.value = value

    def __lt__(self, other):
        return self.value < other.value

    def __eq__(self, other):

        # Changing the functionality
        # of equality operator
        return self.value != other.value

# Driver code
print(num(2) < num(3))
print(num(2) > num(3))
print(num(3) == num(3))
print(num(3) == num(5))

Output:

True
False
False
True