How to overload Python comparison operators?


Python has magic methods to define overloaded behaviour of operators. The comparison operators (<, <=, >, >=, == and !=) can be overloaded by providing definition to __lt__, __le__, __gt__, __ge__, __eq__ and __ne__ magic methods. 

Following program overloads == and >= operators to compare objects of distance class.

class distance:
      def __init__(self, x=5,y=5):
            self.ft=x
            self.inch=y

      def __eq__(self, other):
             if self.ft==other.ft and self.inch==other.inch:
                  return "both objects are equal"
             else:
                  return "both objects are not equal"

       def __ge__(self, other):
                 in1=self.ft*12+self.inch
                 in2=other.ft*12+other.inch
                 if in1>=in2:
                    return "first object greater than or equal to other"
                  else:
                    return "first object smaller than other"

d1=distance(5,5)
d2=distance()
print (d1==d2)
d3=distance()
d4=distance(6,10)
print (d1==d2)
d5=distance(3,11)
d6=distance()
print(d5>=d6)

Result of above program shows overloaded use of == and >= comparison operators

both objects are equal
both objects are equal
first object smaller than other

Updated on: 02-Mar-2020

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