Python operator overriding: __ge__ result is not as expected -

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problem python operator overriding: __ge__ (corresponding '>=') result not expected

class book:     title = ''     pages = 0      def __init__(self, title='', pages=0):         self.title = title         self.pages = pages      def __str__(self):         return self.title      def __radd__(self, other):         '''         enables book1 + book2         '''         return self.pages + other      def __lt__(self, other):         '''         less          '''         return self.pages < other      def ___le__(self, other):         '''         less or equals          '''         return self.pages <= other      def __eq__(self, other):         '''         equals          '''         return self.pages == other      def __ne__(self, other):         '''         not equals         '''         return self.pages != other      def __ge__(self, other):         '''         larger or equals         '''         return self.pages >= other      def __gt__(self, other):         '''         larger         '''         return self.pages > other   book1 = book('fluency', 381.3) book2 = book('the martian', 385) book3 = book('ready player one', 386) summation = sum([book1, book2, book3])  print book1 + book2  print book1 > book2 print book1 >= book2

the result 1 console is:

766.3  false  true

the last statement incorrect: 381.3 > 385 , 381.3 >= 385 both false, last printed line true.

is caused implementation bugs inside book class, or inner bugs of python? using python 2.7.10.3

the problem typo: ___le__() should __le__().

however, that's unusual way implement comparison operators. compare 2 objects of same type instead of comparing number book object. that's why confusing: > operator calling __lt__() method, , >= doesn't find __le__() method. reason direction reversed number on left side of of comparison operator doesn't implement rich comparison methods, book on right does. causes reversed comparison method called.

there no swapped-argument versions of these methods (to used when left argument not support operation right argument does); rather, __lt__() , __gt__() each other’s reflection, __le__() , __ge__() each other’s reflection, , __eq__() , __ne__() own reflection.

i think easier understand if class implemented __cmp__().


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