Lesson 9
No Object is an Island
Chapter 8: Python packages
Packages
In the previous lesson, you have seen how a Python module is simply a script that you can import and use.
Let’s say you have now created a large collection of useful modules, each in a separate file, all in a single folder. That must be quite a mess!
Wouldn’t it be nice if you can organise them better, for example into folders, in a nice hierarchy? You can then ship them as a single package for others to easily use!
The good news is that you can! Python allows you to organise your modules into a package.
A package is a collection of modules and sub-packages, organised in a nice hierarchy.
Taking the example from the official documentation, you might want to organise your audio utility library that you just created. Perhaps in a nice hierarchy divided by their category.
main.py
sound/
formats/
wavread.py
wavwrite.py
...
effects/
echo.py
surround.py
...
filters/
equalizer.py
vocoder.py
...
You can access your highly organised modules from main.py by importing them as usual, using dot notation to get to your module.
In the example below, assume that there is:
- a
generate_surround()function defined ineffects/surround.py - a
WavWriterclass defined informats/wavread.py - a
SoundEqualizerclass defined infilters/equalizer.py
Notice how much you have to write in your code depending on how you import the packages!
import sound.formats.wavread
import sound.effects.surround
import sound.formats.wavwrite as ww
from sound.filters.equalizer import SoundEqualizer
surround = sound.effects.surround.generate_surround()
writer = ww.WavWriter()
sound_eq = SoundEqualizer()
Packages also add a natural namespacing to your modules, so that you can have two modules with the same name (but in different packages).