PUBLIC MARKS from bcpbcp with tags scripting & 2005

Python is a programming language often used to script games. Scripts are the bit of code where most game developers romp, it is the stuff separating the 'game engine' from the elves-in-tights that dance across your screen. Scripts make the elves dance and protect (somewhat) developers from the detail of the orcs-turning-creaking-cranks in the game engine.

In this paper, an implementation of "Stackless Python" (a Python which does not keep state on the C stack) is presented. Surprisingly, the necessary changes affect just a small number of C modules, and a major rewrite of the C library can be avoided. The key idea in this approach is a paradigm change for the Python code interpreter that is not easy to understand in the first place. Recursive interpreter calls are turned into tail recursion, which allows deferring evaluation by pushing frames to the frame stack, without the C stack involved.