How do i use classes in python?



  • The main purpose of python classes is for the reuse of code.

    To try and help explain classes, part of object oriented programming, an analogy using cakes, see diagram:

    0_1528951402485_oop-2-2.png

    Now the explanation part. All recipes have ingredients, the thing or object you are making is a "cake", using various ingredients, you can make different cakes.

    How does this relate to classes in python? Check the diagram below:

    0_1528949465189_oop-3.png

    • The python class is the recipe.
    • The python object is the thing the class is describing.
    • The python instances are the various cakes (each can be different, but use the same class)

    A very simple code example:

    class Cake(object):
    
        def __init__(self, type, base):
            self.type = type
            self.base = base
    
    i1 = Cake('carrot', 'sponge')
    print(i1.type)
    print(i1.base)
    
    i2 = Cake('fruit', 'sponge')
    print(i2.type)
    print(i2.base)
    

    0_1528951431012_oop-5.png

    Looking into it a little more the class is made up of methods and variables. Just as a recipe is made up of various types of ingredients. In the code above, there's a method called "init" this is the first code executed when a new instance of the class is created, the init methods; the first parameter is self, but not used when calling the method, As can be seen in the code "i1 = Cake('carrot', 'sponge')".


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