[Python-Dev] Idea of the Month: Preprocessor (original) (raw)

Raymond Hettinger python@rcn.com
Mon, 18 Mar 2002 18:03:59 -0500

Enable a command line option [-p filename.py] and a related environment variable PYTHONPREPROCESS. The new behavior of the interpreter would then be to submit all of its input to the preprocess program (a module written in pure python) and then interpret the result.

The goal is to enable experimentation with proposed language features without having to write and compile a python extention or alter the parser in any way. The anti-goals are to avoid use in production programs and avoiding creating a macro system for the language as a whole. In other words, make experimentation easy while keeping the language itself pure and avoid the weirdness that macro systems make possible.

This idea would make it easy to experiment with the effects of proposed PEPs. Experimentation is important for evaluation -- a lot of folks who thought list comprehensions were a bad idea found that they came to like them after some experimentation. Right now, I'm inclined to believe that the proposed 'for i in 3:' integer iteration idea is a bad thing; however, direct experimentation could possibly convince me otherwise. For the time being, the discussion of its merits will remain abstract and ungrounded as compared to a more meaningful and concrete discussion that would ensue from some experience the idea.

Raymond Hettinger <-- No longer afraid of reptiles