About the Python Documentation

Differences between Raytressi and Raypython

Some functions are not accessible from python scripting :

You cannot write your own procedural textures (2D or 3D) i.e. you cannot subclass FonctionReal or FonctionIntensity in Python.
You cannot declare a Map2D object. Use the Python material helper to load texture maps.
You may, but should avoid writing your own implicit functions in Python. This is damn slow.