"Python" Create and use classes

Object-oriented programming is one of the most effective methods of software writing

Create a Dog class

classDog ():" "a simple test to simulate a puppy" "    def __init__(self,name,age): Self.name=name Self.age= Agedefsit (self):" "simulated puppy is ordered to squat" "        Print(Self.name.title () +"is now sitting.")    defRoll_over (self):" "simulated puppy is ordered to roll" "        Print(Self.name.title () +"rolled over!")

1. Here we define a dog class, in Python, the name of the first capitalization refers to the class

2. Method __init__ () is a special method that Python automatically runs whenever you create a new instance according to the dog class, in which there are two underscores at the beginning and the end, which is a convention designed to avoid conflicts between the Python default method and the normal method. In this method, again, the parameter self is necessary, and must precede the other parameters, and Python calls this method to create the dog instance, automatically passes in the arguments, self, and each method call that is associated with the class is automatically passed the argument, which is a reference to the instance itself. Enables an instance to access properties and methods in a class. Self is automatically passed, just passing in the next two parameters (name and age)

3.self.name, a variable prefixed with self can be used by all methods in a class, and we can access these variables through any instance of the class, Self.name = name Gets the value stored in the parameter name and stores it in the variable name. The variable is then associated to the currently created instance. Variables such as those that can be accessed through an instance are called properties.

To create an instance from a class

My_dog = Dog ('Lucy', 3)print("" + my_ Dog.name +". " )print(" + str (my_dog.age) +"  years old. ")

We can usually assume that the handwritten letter capitalization refers to the class, the lowercase name refers to the instance created by the class

1. Calling methods

My_dog = Dog ('Lucy', 3) my_dog.sit () my_dog.roll_over ()print(" "+ My_dog.name +".   " )print(" + str (my_dog.age) +"  years old. ")

2. Create multiple instances

My_dog = Dog ('Lucy', 3) Your_dog=dog ('Michile', 4)Print("My Dog ' s name is"+ My_dog.name +".")Print("My Dog is"+ STR (my_dog.age) +"years old.") my_dog.sit ()Print("your dog ' s name is"+ Your_dog.name +".")Print("your dog is"+ STR (your_dog.age) +"years old.") your_dog.sit ()

In this example, we created 2 puppies, each named Lucy and michile. Each puppy is a separate instance with its own attributes.

"Python" Create and use classes