Picking an Interpreter¶
Which Python to use?
2.x vs 3.x¶
tl;dr: Python 2.x is the status quo, Python 3.x is the shiny new thing.
Today¶
If you’re choosing a Python interpreter to use, I highly recommend you Use Python 2.7.x, unless you have a strong reason not to.
The Future¶
As more and more modules get ported over to Python3, the easier it will be for others to use it.
Which Python to Support?¶
If you’re starting work on a new Python module, I recommend you write it for Python 2.5 or 2.6, and add support for Python3 in a later iteration.
Implementations¶
There are several popular implementations of the Python programming language on different back-ends.
CPython¶
CPython is the reference implementation of Python, written in C. It compiles Python code to intermediate bytecode which is then interpreted by a virtual machine. When people speak of Python they often mean not just the language but also this implementation. It provides the highest level of compatibility with Python packages and C extension modules.
If you are writing open-source Python code and want to reach the widest possible audience, targeting CPython is your best bet. If you need to use any packages that are rely on C extensions for their functionality (eg: numpy) then CPython is your only choice.
Being the reference implementation, all versions of the Python language are available as CPython. Python 3 is only available in a CPython implementation.
PyPy¶
PyPy is a Python interpreter implemented in a restricted statically-typed subset of the Python language called RPython. The interpreter features a just-in-time compiler and supports multiple back-ends (C, CLI, JVM).
PyPy aims for maximum compatibility with the reference CPython implementation while improving performance.
If you are looking to squeeze more performance out of your Python code, it’s worth giving PyPy a try. On a suite of benchmarks, it’s current over 5 times faster than CPython.
Currently PyPy supports Python 2.7.
Jython¶
Jython is a Python implementation that compiles Python code to Java byte code that then executes on a JVM. It has the additional advantage of being able to import and use any Java class the same as a Python module.
If you need to interface with an existing Java codebase or have other reasons to need to write Python code for the JVM, Jython is the best choice.
Currently Jython supports up to Python 2.5.
IronPython¶
IronPython is an implementation of Python for .NET framework. It can use both Python and .NET framework libraries, and can also expose Python code to other .NET languages.
Python Tools for Visual Studio integrate IronPython directly in to the Visual Studio development environment, making it an ideal choice for Windows developers.
IronPython supports Python 2.7.
