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First acquaintance with Python class
2022-01-31 17:22:18 【A program cat】
「 This is my participation 11 The fourth of the yuegengwen challenge 15 God , Check out the activity details ：2021 One last more challenge 」
Little knowledge points ：
Object oriented and process oriented ：：：
（1） Process oriented （ Do as you please ）： Cook rice , Wash the dishes , Wash the dishes , Chopping vegetables , Stir fry , Pots having dinner
（2） object-oriented （ Everything is done by objects ）： Girl friend （ Cook rice , Wash the dishes , Wash the dishes , Chopping vegetables , Stir fry , Pots ） We directly having dinner
Take out having dinner
class （ abstract ）
Class is an independent variable （ attribute / Method ） Space .（ Encapsulate the common features of some things .） An instance is also a space for storing variables independently .（ Each instance is an independent variable space , The space between different instances is not visible ） Copy code
Class names should be capitalized , The instance name should be lowercase .
Instance name . Property name Call an instance property .
Class name . Property name Call the properties of the class encapsulated in the class .
Class coding style ：
Class names should be named using the hump naming method , Capitalize the first letter of every word in the class name , Instead of using underscores . Instance name And module names are in lowercase , And underline the words .
For each class , You should include a docstring immediately after the class definition . This document string briefly describes the of the class function , And follow the formatting conventions used when writing the documentation string for the function . Each module should also contain a documentation string , What are the classes used for .
You can use blank lines to organize your code , But don't abuse it . In class , You can use a blank line to separate methods ; And in the module , You can use two blank lines to separate classes .
When you need to import both the module in the standard library and the module you wrote , Write to import the standard library module first import sentence , Again Add a blank line , Then write to import your own module import sentence . In containing multiple import Statement in the program , This makes it easier to see where the modules used by the program come from .
class Class name ： pass Copy code
1. for example ：
class Person: # Define that the class name should be capitalized . a = ' Two hands , Two legs ' # Attributes encapsulated in a class # class , Is an independent storage variable （ attribute / Method ） Space . wumou = Person() # Instance name = Class name () example zhangmou = Person() wumou.name = " Wu " # The characteristics of the instance Instance attributes （ The characteristics of an example , It's property ） wumou.age = 18 zhangmou.age = 20 print(Person.a) # Invokes the properties of the class print(wumou.age) # Invoke instance properties Copy code
The relationship between classes and instances ：：：
（1） class ：：：
It's an abstraction of a kind of thing , It's not real , Describe the commonalities of this kind of things .
for example ：“ people ”,“ animal ”
（2） example ：：：
A specific individual of something , Is the concrete manifestation of this kind of things , It's real .
for example ：“ Wu ” It's a specific person ,
“ zhang ” It's also a specific person .
2. Private property :
stay python There are two private properties in , Add an underscore before the attribute （） And two underscores ()
An underscore can be accessed directly from the outside , The two underscores cannot be accessed directly outside .
An underline is just a simple mark .
Two are private properties , It can't be used directly .
python There is no absolute private property in the private property .
class Person: _sex = " male " __age = 18 wuhan = Person() # example print(Person._sex) # Calling class properties print(Person.__age) # Double underline will report an error , Double underlined variable names cannot be accessed directly print(Person._Person__money) # This allows you to access double underlined properties Copy code
stay python in ,_ and __ The use of is more of a norm / Appointment , There is no real limit to the purpose
Private properties in a defined class can also be inherited by subclasses
Little knowledge points ：：：
dir() You can view the method , You can put the class name inside . Copy code
author[A program cat],Please bring the original link to reprint, thank you.
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