[Python-Dev] sys.path[0] (original) (raw)

Thomas Heller theller@python.net
08 Jan 2003 15:36:36 +0100

Guido van Rossum <guido@python.org> writes:

[ping]

> Exactly for this reason, changing the working directory confuses > inspect and pydoc and presumably anything else that tries to find > source code. There's no way to work around this because the true > path information is simply not available, unless we fix the > file attribute. > > I'd be in favour of setting all file attributes to absolute paths. That's what site.py does:

for m in sys.modules.values(): if hasattr(m, "file") and m.file: m.file = os.path.abspath(m.file) del m

Note that code objects have their own filename attribute, which is not directly related to file, and that's the one that causes the most problems. I truly wish we could change marshal so that when it loads a code object, it replaces the filename attribute with the filename from which the object is loaded, but that's far from easy. :-( > > > I'm disinclined to do anything about this, except perhaps warn that > > > the script directory may be given as a relative path. > > The current working directory is a piece of hidden global state. > In general, hidden global state is bad, and this particular piece > of state is especially important because it affects what Python > modules get loaded. I'd prefer for the interpreter to just set > up sys.path correctly to begin with -- what's the point in doing > it ambiguously only to fix it up later anyway? Maybe things have changed, but in the past I've been bitten by absolute path conversions. E.g. I rememeber from my time at CWI that automount caused really ugly long absulute paths that everybody hated. Also, there are conditions under which getcwd() can fail (when an ancestor directory doesn't have enough permissions) so the code doing so must be complex. That said, I'd be +0 if someone gave me a patch that fixed the path of the script (the only path that's not already absolutized by site.py).

I've submitted a patch #664376 which fixes the problem on Windows, I cannot do it for other systems.

This patch only converts sys.path[0], it doesn't touch sys.argv[0].

Thomas