Comparison Magic Methods

Similarly to the mathematical magic methods, here we take self and other as arguments and compare their desired attributes. These magic methods should always return True or False.

Magic Method	Operation
`__eq__(self, other)`	`==`
`__gt__(self, other)`	`>`
`__ge__(self, other)`	`>=`
`__lt__(self, other)`	`<`
`__le__(self, other)`	`<=`
`__ne__(self, other)`	`!=`

Note

To understand the naming of these methods, look at some examples:

eq is equal.

gt is greater than.

le is less or equal.

ne is not equal.


              12345
            
a = 12.3
b = 5.7

print("a >= b is", a >= b)
print("a.__ge__(b) is", a.__ge__(b))

Look at the example of Road class:


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class Road:
    def __init__(self, length):
        self.length = length

    def __eq__(self, other):
        if isinstance(other, Road):
            return self.length == other.length  # compare with road
        return self.length == other  # compare with number

road_1 = Road(20)
road_2 = Road(30)
road_3 = Road(20)

print(road_1 == road_2)
print(road_1 == road_3)
print(road_1 == 20)
print(road_1 == 20.0)
print(road_1 == 1412)

Note

To optimize the code, you can utilize existing comparison methods. For example, if you have implemented the __lt__() method (<), by implementing the __ge__() method (>=), you can use return not (instance1 < instance2) which will return the opposite result of the already implemented < operator.

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Section 5. Chapter 4