overload operators

[anjita]

Why do we need to overload operators?

[DeaD_EyE]

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.
  

[rinu]

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

[ichabod801]

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

[buran]

@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