__init__.py function in Python package

During the creation of the Python package, the IDE creates a __init__.py file in the package root directory, which is empty by default. The directory structure is as follows:

The package tree structure under Pycharm:

The directory structure in the Finder:

As you can see from the directory in the Finder, each package is actually a directory, so how does the IDE recognize it as a package? Yes, the first function of __init__.py is the package 's identity , which, if not, is not considered to be a catalog.

The packages and modules in Python are imported in two ways: precise import and fuzzy import:

Precise import:

 from Import Pack1class Import Root.Pack1.Pack1Class

Fuzzy import:

 from Import *

The modules in the fuzzy import are defined by __all__, and another function of __init__.py is to define the __all__ in the package, which is used to blur the import , such as __init__.py:

__all__ = ["pack1class","pack1class1"]

Called Outside the package:

 from Import *= Pack1class.pack1_aa ("Alvin") A.printname () 

__init__.py is first a python file, and all can also be used to write Python modules , but it is not recommended to do so, try to ensure that __init__.py is light enough:

__init__.py:

__all__= ["Pack1class","Pack1class1","Init_aa"]class init_aa:def __init__(self,name): Self.name=namedefgreeting (self):Print("Hello", Self.name)

Called in the test:

 from Import *= Init_aa ("test") b.greeting ()

Summarize:

As can be seen from the above example, the main function of __init__.py is:

1. The identity of the package in Python cannot be deleted

2. Define __all__ for fuzzy import

3. Writing Python code (not recommended to write Python modules in __init__, you can create additional modules in the package to write, as far as possible to ensure __init__.py simple)

__init__.py function in Python package