Python Forum

Why do we need to overload operators?

Do you mean overloading functions by it's call signature?
Sometimes it's useful to have one function, which depends on input type.
https://docs.python.org/3/library/functo...ledispatch
I never used it in real applications.

Another cool feature are the magic methods. You control the behavior of an object.
But I guess this does not answer your question.

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class Nodes:
    def __init__(self):
        self.nodes = []
    def copy(self):
        new_nodes = self.__class__()
        new_nodes.extend(self.nodes)
        return new_nodes
    def add(self, node):
        self.nodes.append(node)
    def extend(self, nodes):
        self.nodes.extend(nodes)
    def __getitem__(self, index):
        return self.nodes[index]
    def __setitem__(self, index, node):
        self.nodes[index] = node
    def __delitem__(self, index):
        del self.nodes[index]
    def __len__(self):
        return len(self.nodes)
    def __iter__(self):
        for node in self.nodes:
            yield node
    def __eq__(self, other):
        return self.nodes == other.nodes
    def __repr__(self):
        return '{}(nodes={})'.format(self.__class__.__name__, len(self))

nodes = Nodes()
nodes.add('Baz')
nodes.add('Foo')
other_nodes = nodes.copy()

This class supports:

get a node by it's index value: node[0]
assign a node to an index: nodes[0]='Foo'
delete items: del nodes[0]
getting the count of nodes: len(nodes)
equality check: nodes == new_nodes
representation of the object: print(nodes)
sorting, because __iter__or __len__ and __getitem__ is supported.

To compare two objects, we can overload operators in Python. We understand 3>2. But what is orange>apple? Let’s compare apples and oranges now.

>>> class fruit:
       def __init__(self,type,size):
               self.type='fruit'
               self.type=type
               self.size=size
       def __gt__(self,other):
               if self.size>other.size:
                        return True
               return False
>>> orange=fruit('orange',7)
>>> apple=fruit('apple',8)
>>> apple>orange
True

>>> orange>apple
False

Please use python and output tags when posting code and results. Here are instructions on how to use them.

@~~rinu~~, just note that

def __gt__(self,other):
    if self.size>other.size:
        return True
    return False

can be just

def __gt__(self, other):
    return self.size > other.size

anjita

DeaD_EyE

rinu

ichabod801

buran