Packages and Package Directories

Python Tutorials - Herong's Tutorial Examples

∟Packages and Package Directories

This chapter provides introductions and tutorial examples about on packages and package directories. Topics include introduction of packages and package directories; importing package directories to create packages; accessing package members; importing package members only; importing sub-modules and sub-directories.

These sections are omitted from this Web preview version. To view the full content, see information on how to obtain the full version this book.

What Is Package

What Is Sub-Module

What Is Sub-Package

"from package import *" Statement

Using __all__ List in Package

"import" Statement Summary

What Is the __main__.py File

"python -m package|module" Command

Takeaways:

A package is a special module defined by an external directory, and may contain sub-packages and sub-modules.
A sub-module is a module defined by a module file inside a package directory.
A package directory contains a special Python code file, __init__.py, define package members: attributes (variable), functions, and classes.
Package objects are created from module files by running "import" statements.
A sub-module is a module defined by a module file inside a package directory.
A sub-package is a package defined by a sub-directory inside a package (referred as top-package) directory.
"import package_name" statement loads a package directory into memory and binds it package_name as a local variable.
"import package_name as variable_name" statement loads a package directory into memory and binds it variable_name as a local variable.
"from package_name import member_name" statement loads a package directory into memory and binds the given member to member_name as a local variable.
"from package_name import *" statement loads a package directory into memory and binds each member to member_name as a local variable.
The __all__ list can be used in package override which members are to be imported by the "from package_name import *" statement.
"import package_name.submodule_name" statement loads a package directory into memory and binds it package_name as a local variable. The given submodule is also loaded into the package.
"import package_name.subpackage_name" statement loads a package directory into memory and binds it package_name as a local variable. The given subpackage is also loaded into the package.
The __main__.py file is a special module file in a package directory that will be executed when the package directory is invoked by the "python" command line program.
"python -m package|module" command allows you to load and run a given module by the "python" command line program as the __main__ module.