[Python-ideas] Add a command line option to adjust sys.path? (was Re: Add a site.cfg to keep a persistent list of paths) (original) (raw)

Nick Coghlan ncoghlan at gmail.com
Thu Oct 21 04:32:32 CEST 2010

On Thu, Oct 21, 2010 at 4:46 AM, Ron Adam <rrr at ronadam.com> wrote:

On 10/20/2010 08:38 AM, Nick Coghlan wrote: A different idea along these lines that I've been pondering is an actual -p path option for the interpreter command line, that allowed a sequence of directories to be provided that would be prepended to PYTHONPATH (and hence included in sys.path).

So if you're wanting to test two different versions of a module (from a parent directory containing the two versions in separate subdirectories): python -p versionA runtests.py python -p versionB runtests.py For more permanent additions to sys.path, PYTHONPATH (possibly in conjunction with virtualenv) is reasonable answer. Zipfile and directory execution covers execution of more complex applications containing multiple files as if they were simple scripts. The main piece I see missing from the puzzle is the ability to easily switch back and forth between multiple versions of a support package or library without mucking with persistent state like the environment variables or the filesystem. Yes, I don't like changing the system wide environment variables and file system options. It's too easy to break other things that depend on them. How about adding the ability to use a .pth file from the current program directory?

A simple check to see if a supplied path was a directory or not would let us do both with one new option:

-p Specify a directory or a .pth file (see site module docs) to be prepended to sys.path

distutils2 could then provide a way to generate an appropriate .pth file instead of installing a distribution.

Cheers, Nick.

-- Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

More information about the Python-ideas mailing list