python functions, classes, modules, packages

A module can contain variables, functions, classes or C, C++ extensions, etc.

Now I define a model.py module, which defines variables, functions, and classes

The file name is model.py, and the module noun is model

1. Module definition: is a py file (module name.py)

model module

Module usage: Take the above model module as an example, create a new module user_model.py

1、 import model: import module

# user_model.py file, the module name is called user_model

import model
print(model.member)  #Call the variables in the model module
model.func()  #Call the function in the model module
p = model.Person()  #Instantiate the Person class in the model
p.fun()  #Call methods in the Person class

2、 from model import Person: Import a single member

# user_model.py file, the module name is called user_model

from model import member
from model import func
from model import Person
print(member)  #Return: Interpretation of global variables: call variables in the model module
func()  #Return: a function interpretation: call the function in the model module
p =Person()  #Interpretation: instantiate the Person class in the model
p.fun()  #Return: A method interpretation: call a method in the Person class

3、 from model import *: import all members

# user_model.py file, the module name is called user_model

from model import*print(member)  #Return: Interpretation of global variables: call variables in the model module
func()  #Return: a function interpretation: call the function in the model module
p =Person()  #Interpretation: instantiate the Person class in the model
p.fun()  #Return: A method interpretation: call a method in the Person class

4、 from model import Person as P: Add an alias to Person

# user_model.py file, the module name is called user_model

from model import member as M
from model import func  as F
from model import Person as P
print(M)  #Return: Interpretation of global variables: call variables in the model module
F()  #Return: a function interpretation: call the function in the model module
p =P()  #Interpretation: instantiate the Person class in the model
p.fun()  #Return: A method interpretation: call a method in the Person class

5、 Import multiple modules (modules are only imported once, and written multiple times are only imported once)

# Two ways, the second method is recommended
import sys, os    #The first way

import sys    #The second way
import os

2. Package definition: The folder organizes modules through the init.py file (init.py can be empty)

pkg package and web package

Package usage: call members in the model module in the page module

1、 import pkg: When importing a package, only the init.py file in the package is executed

# pkg package__init__.py file

from pkg import model

# page.py file, module page

import pkg   #If this__init__.The py file is empty, so the import cannot be used
print(pkg.model.member)  #Interpretation: call variables in the model module
pkg.model.func()  #Interpretation: call the function in the model module
p = pkg.model.Person()  #Interpretation: instantiate the Person class in the model
p.fun()  #Interpretation: call methods in the Person class

2、 from pkg import model: import module

# page.py file, module page

from pkg import model
print(model.member)  #Interpretation: call variables in the model module
model.func()  #Interpretation: call the function in the model module
p = model.Person()  #Interpretation: instantiate the Person class in the model
p.fun()  #Interpretation: call methods in the Person class

3、 from pkg.model import Person: Import members

# page.py file, module page

from pkg.model import member
from pkg.model import func
from pkg.model import Person
print(member)  #Interpretation: call variables in the model module
func()  #Interpretation: call the function in the model module
p =Person()  #Interpretation: instantiate the Person class in the model
p.fun()  #Interpretation: call methods in the Person class

4、 from ... import ... as ...; all imports can add as alias

1000 words omitted here

5、 Import multiple modules (modules are only imported once, and written multiple times are only imported once)

# Import module: two ways, the second method is recommended
from pkg import model, user_model  #The first way

from pkg import model  #The second way
from pkg import user_model

# Import members: two ways, the second method is recommended
form pkg.model import member, func, Person  #The first way

from pkg.model import member  #The second way
from pkg.model import func
from pkg.model import Person

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