Example analysis of self principle in Python

Source: Internet
Author: User

This example describes the self principle in Python. Share to everyone for your reference. The specific analysis is as follows:

The methods of a class have only one particular difference from a normal function-they must have an extra first parameter name, but you don't assign a value to this parameter when you call the method, and Python provides that value. This particular variable refers to the object itself, and by convention its name is self.

Suppose you have a class called MyClass and an instance of this class MyObject. When you call the object's method Myobject.method (Arg1, arg2), it automatically transitions from Python to Myclass.method (MyObject, Arg1, arg2)-that's the principle of self.

This also means that if you have a method that does not require a parameter, you still have to define a self parameter for the method.

Sample programs:


1 2 3 4 5 6 7 8 9 >>> class P: ... def selfdemo (self): ... print ' Python, why self? ' ... >>> p = p () >>> p.se Lfdemo () Python, why self? >>>

Swap the arguments in the Selfdemo () to something else, such as Selfdemo (x), and output the same result.

If you do not add parameters, the error:


1 2 3 4 5 6 7 8 9 10 11 >>> class P:. Def selfdemo (): # have no arguments ... print ' Python, why self? ' ... >>> p = P () & Gt;>> P.selfdemo () traceback (most recent call last): File ' <stdin> ', line 1, in <module> Typeerror:sel Fdemo () takes no arguments (1 given) >>>

I hope this article will help you with your Python programming.

Note < > : More Wonderful tutorials please focus on Triple programming

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