byte compiled files

[Guido van Rossum]

Mark Robinson <m.1.robinson at herts.ac.uk> writes:

> can anyone shed some light on the mysterious behaviour of my byte 
> compiled files. I am currently working on a python script which analyses 
> patterns in a DNA sequence. I have a function which checks a pattern (a 
> substring of approx 6 chars) to ensure only valid charactors are 
> present. When I first run this program it runs fine, but if I 
> immediately rerun the program (i.e using the pre-byte compiled file) it 
> finds all patterns non-valid. If I delete the .pyc file between runs 
> this problem does not occur. Can anyone explain what is happening here 
> to me and how to prevent it?

Which Python version?  Which platform?  Please also show the regular
expression you are using and how you compile it.

--Guido van Rossum (home page: http://www.python.org/~guido/)