What to do with pyc files when Django or python is used with Mercurial?

Question

Just started to use Mercurial. Wow, nice application. I moved my database file out of the code directory, but I was wondering about the .pyc files. I didn't include them on the initial commit. The documentation about the .hgignore file includes an example to exclude *.pyc, so I think I'm on the right track.

I am wondering about what happens when I decide to roll back to an older fileset. Will I need to delete all the .pyc files then? I saw some questions on Stack Overflow about the issue, including one gentleman that found old .pyc files were being used. What is the standard way around this?

Answer 1

As mentioned in ms4py's answer, *.pyc are compiled files that will be regenerated on the fly. You wouldn't want to include these when distributing a project.

However, if it happens you have modules that existed before when you roll back changes and *.pyc files are left lying around, strange bugs can appear as pyc files can be execute even if the original python file doesn't exist anymore. This has bitten me a few times in Django when adding and removing apps in a project and switching branches with git.

To clean things up, you can delete every compiled files in your project's directory by running the following shell command in you project's directory:

find . -name '*.pyc' -exec rm {} \;

Answer 2

Usually you are safe, because *.pyc are regenerated if the corresponding *.py changes its content.

It is problematic if you delete a *.py file and you are still importing from it in another file. In this case you are importing from the *.pyc file if it is existing. But this will be a bug in your code and is not really related to your mercurial workflow.

Conclusion: Every famous Python library is ignoring their *.pyc files, just do it ;)