8.2 Packages

• >A folder with a module named "__init__().py" file is a Python package. Any sub-directories containing "__init__().py" file is also a package (we can call them sub-packages). A Package is a collection of modules (.py files) and is a way to structure the modules under a single package's namespace. To import a module from a package use the "<package_name>.<module_name>" signature. To import a package, import it by its name, that'll import the "__init__().py" module from that package.
• >One common practice you might spot in open-source packages is "__init__().py" importing all classes/functions from all of its current directory's modules, this helps in getting all classes/functions under a single package's namespace, so you don't have to call them by following the module names, like instead of "<package_name>.<module_name>.<function_name>" you can directly call by "<package_name>.<function_name>".
• >You can find all popular open-source Python packages on Python Package Index (PyPI), it is an official third-party software repository for Python. You can install a package simply by running "pip install <package-name>" command in the command prompt.
  Note: "pip" comes pre-bundled with Python, some installation may require you use "pip3" instead of "pip", you can check with "which pip" or "which pip3" command, if you see some directory, it's already installed or you can install "pip" by following the official guide.
• >You can also create your own packages, create the given below example directory structure.

./mypackage
__init__.py
mymodule.py
./myfolder
  __init__.py
  somemodule.py
./somepackage
others.py

# Here 'mypackage' folder contains '__init__.py' so it's s a package,
# Similarly 'myfolder' is also a package (or sub-package).
# Note: From Python 3.3 and up it is optional to have '__init__.py'
# to be called package, so now 'somepackage' directory is also a package.

• >Importing from such a directory/package is very straightforward using the "." operator. Create a "test.py" outside of the "./mypackage" directory and try the following code. Note you also need to create additional .py files as shown in the above example directory and also define "MyClass" and "myfunction" inside "mymodule" with some code (or just define them with pass statement).

## Importing a module from package
import mypackage.mymodule

# now use the '<module_name>' to call its classes/functions
mymodule.myfunction()


## Importing the package by name
import mypackage
# this will call './mypackage/__init__.py' module


## But to import specific classes/functions from that module you
# need to use 'from...import', say import a class from 'mymodule'
from mypackage.mymodule import MyClass
# similarly a function
from mypackage.mymodule import myfunction

• >Furthermore you can create your own distribution archives (.whl file) with your package, follow this guide.