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In the following example, a class called complx is defined to model complex numbers, and the + (plus) operator is redefined in this class to add two complex numbers. where () is the function call operator and [] is the subscript operator. You cannot overload the following operators: .
The subscript operator [] is normally used to access array elements. This operator can be overloaded to enhance the existing functionality of C++ arrays.
7. Which function overloads the >> operator? Explanation: __rshift__() overloads the >> operator.
Python does not limit operator overloading to arithmetic operators only. We can overload comparison operators as well. Suppose we wanted to implement the less than symbol < symbol in our Point class.
You need to use the __getitem__ method.
class MyClass:
def __getitem__(self, key):
return key * 2
myobj = MyClass()
myobj[3] #Output: 6
And if you're going to be setting values you'll need to implement the __setitem__ method too, otherwise this will happen:
>>> myobj[5] = 1
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: MyClass instance has no attribute '__setitem__'
To fully overload it you also need to implement the __setitem__and __delitem__ methods.
edit
I almost forgot... if you want to completely emulate a list, you also need __getslice__, __setslice__ and __delslice__.
There are all documented in http://docs.python.org/reference/datamodel.html
You are looking for the __getitem__ method. See http://docs.python.org/reference/datamodel.html, section 3.4.6
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