Python Resources

Tutorials

Understanding Python Decorators in 12 Easy Steps! for decorators and lots of background
A guide to Python's function decorators for a more concise explanation of decorators
Python metaclasses by example for an explanation of metaclasses with examples
A Primer on Python Metaclasses for an introduction to and examples of how to use metaclasses
Advanced use of Python decorators and metaclasses for cool things that can be done with these
Python 3 Metaprogramming (YouTube Video) for a very comprehensive guide on metaprogramming

Reference

The Python 2.x Language Reference for the official language reference for 2.x
The Python 3.x Language Reference for the official language reference for 3.x

The Python 2.x Standard Library for the official Python 2.x library reference
The Python 3.x Standard Library for the official Python 3.x library reference

Libraries

Python unittest module for documentation on how to use the builtin unittest module
Nose for executing Python unittests written with the unittest module or other formats
PyHamcrest for powerful matchers that simplify writing test assertions
Python unittest.mock module for creating mock objects for tests
Flexmock for an alternative to unittest.mock for writing test mocks

Protocol Bufers for cross-languages/cross-platform data serialization
MessagePack for a cross-platform/cross-language alternative to protocol buffers
Pickle for Python object serialization (security note: can invoke application code; only use with trusted data)

Spark for a high-level mechanism for creating parallel data processing pipelines
Python subprocess module for low-level process creation
Python multiprocessing module for invoking specific Python functions in a subprocess
Python threading module for a low-level multithreading library useful for concurrency in I/O bound tasks

Python urllib module for very basic, simple fetching of network resources by URL
Python httplib module for issuing more advanced HTTP requests
Google App Engine for a Platform as a Service (PaaS) for running Python servers (not a library, but useful)
Webapp2 for an implementation of the Web Server Gateway Interface (WSGI) for writing servers
Flask for another WSGI-compliant framework for writing servers
Bottle for yet another WSGI-compliant server framework
gRPC for a high-performance remote procedure call (RPC) system based on protocol buffers
ProtoRPC (NOT RECOMMENDED) an RPC system based on protocol bufers predating gRPC

Jinja2 for template system that you can use to generate / emit HTML
Mako for an alternative templating engine that can likewise be used for emitting HTML
Kivy for writing cross-platform user interfaces in Python that run on Android, Mac OS X, Windows, and Linux
PySide for writing cross-platform desktop GUIs using the Qt framework

Python Image Library (PIL) for image processing in Python
Pillow for a more frequently updated, modern fork of PIL
OpenCV-Python for a more advanced (but also more complex) image processing library

PyGame for writing cross-platform games in Python
PyGame Subset for Android for using PyGame on Android via Python for Android

Tools

CPython for the standard, official interpreter
PyPy for an alternative implementation, focused on speed
Jython for an alternative implementation, focused on interoperation with Java
Iron Python for an alternative implementation, focused on interoperation with C# / .NET

Bazel and Subpar for building many Python files, libraries into a single, self-contained executable file
Scons for a build system implemented in Python that can be used to run preprocessing / packaging steps
PyInstaller for distributing a self-contained Python app as a single folder or single file
Setuptools for the recommended way to distribute Python libraries
Py2Exe for packaging Python code into a *.exe file for distribution to Windows users
Py2App for packaging Python code into a *.app folder for distribution to Mac users