Python (12)-modules and packages of advanced features of Python

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Preface

1. Modules in python

• The python module is essentially a python file
• The file name of the custom python file must not conflict with the existing module
• Importing a module is essentially loading and executing the content of the module

1.1 Several ways to import modules

• method one

hello.py
digits='0123'

import hello
print(hello.digits)
输出：
0123

• Way two

hello.py ## 模块文件
digits='0123'

def info():
    print('打印信息')

import hello
print(hello.digits)
hello.info()
输出：
0123
打印信息

• Way three

from hello import info
info()
输出：
打印信息

• Way Four

from hello import info as f
f()
输出：
打印信息

• Way Five

from hello import *
print(digits)
输出：
0123

1.2 Other information of the module

import sys
print(sys.path)  ## 模块的查询路径
import hello
print(dir(hello)) ## 查看hello模块可以使用的变量和函数
print(hello.__doc__)  ## 查看模块的说明文档
print(hello.__file__)  ## 显示模块的绝对路径
print(hello.__name__) ## __name__当模块被导入时，显示的是模块的名称。

1.3 Special usage of name

hello.py file: When executed inside the module, the value of __name__ is __main__; when the module is imported, the value of __name__ is hello (module name)

digits='0123'

def info():
    print('打印信息')
if __name__ == '__main__':
    print(__name__)

The code that needs to be executed when the module is executed internally. When the module is imported, it is not executed.

import hello
print(hello.digits)
hello.info()
print(hello.__name__)
输出：
0123
打印信息
hello

2. Package management

1. The package is essentially a directory containing the __init__.py file.
2. The essence of importing the package is to execute the content init.py file of __init__.py in the package

print('正在加载__init__')

import sdk
输出：正在加载__init__

Ways to import packages

Create the python package sdk, create two sub-files age.py and name.py

age.py
def create():
    print('name添加成功')
    name.py
def create():
    print('age添加成功')

• method one

from sdk import age
from sdk import name
age.create()
name.create()
输出：
age创建成功
name添加成功

• Way two

Need to add import information in the package __init__.py

from . import name
from . import age

import sdk
sdk.name.create()
sdk.age.create()
输出：
name添加成功
age创建成功

This article ends here