Best way to avoid stale *.pyc files?

Question

What's the best way to avoid stale *.pyc files? Sometimes, especially when switching branches in version control, some *.pyc files are left there and are used by Python instead of the source files I have.

What's the best strategy for making sure I don't create or unknowingly use stale *.pyc files?

Answer 1

Similar to khampson, git and mercurial (and likely others) allow client side hooks. You can sprinkle around scripts that do

find -iname "*.pyc" -exec rm -f {} \; 

on linux at least. Search "git hooks" and "mercurial hooks" for more details.

Answer 2

There is a useful environment variable for that: PYTHONDONTWRITEBYTECODE

export PYTHONDONTWRITEBYTECODE=true

Answer 3

I would recommend a combined approach.

First, add *.pyc to your .gitignore file, which should help to avoid issues when switching branches (at least for cases where the cause is that a .pyc file somehow got committed). I generally always add both *.pyc and *.log to my .gitignore so as not to potentially commit any of those files accidentally, and so they don't clutter my git status output.

Second, create a wrapper shell script which first removes all .pyc files (recursively if your source directory structure calls for it) and then invokes your actual script. That should ensure any resulting .pyc files are newly created using the current source.

i.e. something like (without the & if you want the script to wait):

#!/bin.sh
rm -f *.pyc
./foo.py &