====== Python ======

Python is the preferred scripting language of the CP2K project.

===== Self-Testing =====
All python scripts should support self-testing. This means that the script can be invoked with ''%%--selftest%%'' as its sole argument. 

Ideally, a script's self-test consists of an exhaustive suite of unit-tests. At the very least, it should not crash or break anything. Even an empty self-test will still reveal syntax and import errors, which are the most common Python 3 compatibility issues.

Once per night all Python executable are [[https://dashboard.cp2k.org/archive/python/index.html|self-tested automatically]].

===== Language Versions =====

All scripts should work with **Python 2.7 or later**. In particular the scripts should be future-proof and also work with Python 3.x . 
Additionally, a small set of //essential scripts// should work with Python 2.4 as well. Essential scripts are those required for building CP2K plus ''prettify.py'' and ''instantiateTemplates.py''.

For more information on how to achieve Python 2+3 compatibility see:
  * http://python3porting.com/noconv.html
  * http://python-future.org/compatible_idioms.html
  * http://sebastianraschka.com/Articles/2014_python_2_3_key_diff.html