How to Create a Class

Basic Structure

Method

A method is like a normal function, except the name first parameter must be self. self is a variable that contains the instance which this method in. (for example, the value of me in the examples before) You can get attributes of the instance from self.

Read this piece of code from the example before, the method selfIntro have one parameter.(but when you invoke it, you don’t need to give it any parameter because python automatically fills the first parameter with the instance you are using) In the second line, you get the name and age attributes from self, an instance of Person, and print them out.

In the example before, when me.selfIntro() runs, python use me as the value for parameter self.

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def selfIntro(self):
    print("I'm " + self.name + " and I'm " + str(self.age) + " years' old.")

__init__ Method

__init__ Method is a special method, it invokes when you instantiate a class.

In the example before, when me = Person("pega",16,"male") runs, python invokes this method and give parameters "pega",16,"male" to it.

Because value from the parameters will disappear after this method ends, so it assign them to the attributes of the instance.(represented by self)

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def __init__(self, name, age, gender):
    self.name = name
    self.age = age
    self.gender = gender

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