example of python operator overloadind

And last here is the overload operators example:

 

# map() takes two (or more) arguments, a function and a list to apply the function to

# lambda can be put anywhere a function is expected

# map() calls lambada for every element in the self list

# since Vector has overloaded __getitem__ and __len__ definitions

# the Vector object can be considered a list

# the lambda function adds each other item to each item in the list

# note this only adds objects that can typicaly be added by python



# print statements added to show what is getting called

class Vector:



	def __init__(self, data):

		print "__init__"

		self.data = data



	def __call__(self, varA, varB):

		print "__call__"

		print "do something with ", varA, " and ", varB



	# overload print

	# repr returns a string containing a printable representation of an object

	# otherwise printing a Vector object would look like:

	#<__main__.Vector instance at 0x0000000017A9DF48>

	def __repr__(self):

		print "__repr__"

		return repr(self.data)



	# overload +

	def __add__(self, other):

		print "__add__"

		return Vector(map(lambda x, y: x+y, self, other))



	# overload -

	def __sub__(self, other):

		print "__sub__"

		return Vector(map(lambda x, y: x-y, self, other))



	# overload /

	def __div__(self, other):

		print "__div__"

		return Vector(map(lambda x, y: x/y, self, other))



	# overload *

	def __mul__(self, other):

		print "__mul__"

		return Vector(map(lambda x, y: x*y, self, other))



	# overload %

	def __mod__(self, other):

		print "__mod__"

		return Vector(map(lambda x, y: x%y, self, other))



	# overload []

	def __getitem__(self, index):

		print "__getitem__"

		return self.data[index]



	# overload set []

	def __setitem__(self, key, item):

		print "__setitem__"

		self.data[key] = item



	# return size to len()

	def __len__(self):

		print "__len__"

		return len(self.data)



# Execute this in the Python script tab



vecA = Vector([1, 2, 3])

>>__init__






vecA( 1, 2 )

>>__call__

>>do something with  1  and  2






print vecA

>>__repr__

>>[1, 2, 3]






vecB = vecA + vecA

>>__add__

>>__len__

>>__len__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__init__






vecB = vecA - vecA

>>__sub__

>>__len__

>>__len__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__init__






vecB = vecA / vecA

>>__div__

>>__len__

>>__len__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__init__






vecB = vecA * vecA

>>__mul__

>>__len__

>>__len__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__init__






vecB = vecA % vecA

>>__mod__

>>__len__

>>__len__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__getitem__

>>__init__






print vecB[2]

>>__getitem__

>>0






vecB[2] = 10

>>__setitem__






len(vecB)

>>__len__

>># Result: 3 #