How to implement Python __lt__ __gt__ custom (overloaded) 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 __lt__(self, other):
    in1=self.ft*12+self.inch
    in2=other.ft*12+other.inch
    if in1<in2:
      return "first object smaller than other"
    else:
      return "first object not smaller than other"

  def __gt__(self, other):
    in1=self.ft*12+self.inch
    in2=other.ft*12+other.inch
    if in1<in2:
      return "first object greater than other"
    else:
      return "first object not greater 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 shows implementation of __lt__ and _gt__ magic methods

first object not greater than other
first object not smaller than other
first object smaller than other

Pythonista

Updated on: 02-Mar-2020

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