Python modules can be organized into packages. A package is a namespace which contains a set of modules. Packages are useful for organizing modules, especially when an application is large and contains a lot of modules. To create a package, create a directory and add python files to it. The directory must contain an __init__.py file in order to be recognized as a package.<\/p>\n
Example:<\/p>\n
<\/pre>\n\npkg1
\n __init__.py
\n mod1.py
\n mod2.py
\napp.py<\/p>\n\nModules, which are part of a package, can then be imported using the dot notation:<\/p>\n
<\/pre>\n\nimport pkg1.mod1<\/p>\n
\nModules can also be imported as follows:<\/p>\n
<\/pre>\n\nfrom pkg1 import mod1<\/p>\n
\nSpecific module members can be directly imported:<\/p>\n
<\/pre>\n\nfrom pkg1.mod1 import do_something<\/p>\n
or<\/p>\n
from pkg1.mod1 import do_something as do<\/p>\n
\nThe __init__.py file defines package initialization code. It can be empty or define a list of modules which are imported on initialization. This can be done individually:<\/p>\n
<\/pre>\n\nimport pkg1.mod1
\nimport pkg1.mod2<\/p>\nor using __all__ to define a list of modules to import:<\/p>\n
<\/pre>\n\n__all__ = [“mod1”, “mod2”]<\/p>\n
\nUsing<\/p>\n
<\/pre>\n\nfrom pkg1 import *<\/p>\n
\nwould then import mod1 and mod2 at once.<\/p>\n
\nPackages can contain subpackages by creating sub directories:<\/p>\n
<\/pre>\n\npkg1
\n __init__.py
\n subpkg1
\n __init__.py
\n mod1.py
\n mod2.py
\n subpkg2
\n __init__.py
\n moda.py
\n modb.py<\/p>\n\nmoda would be imported as:<\/p>\n
<\/pre>\n\nimport pkg1.subpkg2.moda<\/p>\n
\nEach subpackage also needs to contain in __init__.py file, which may or may not be empty.<\/p>\n
\nFull Example:<\/h4>\n
app.py:<\/p>\n
<\/pre>\n\nimport pkg1
\nfrom pkg1 import mod2<\/p>\npkg1.mod1.print_mod_name()
\nmod2.print_mod_name()<\/p>\n\npkg1\/__init__.py:<\/p>\n
<\/pre>\n\nimport pkg1.mod1
\nimport pkg1.mod2<\/p>\n\npkg1\/mod1.py:<\/p>\n
<\/pre>\n\ndef print_mod_name():
\n print(‘Mod 1’)<\/p>\n\npkg1\/mod2.py:<\/p>\n
<\/pre>\n\ndef print_mod_name():
\n print(‘Mod 2’)<\/p>\n