.pth in current directory: Why doesn't it work as the documentation says?

[Tim Golden]

David Lyon wrote:
> On Mon, 18 May 2009 14:34:33 +0200, Philipp Hagemeister <phihag at phihag.de>
> wrote:
>> Yes, but that processing will add /example/ to sys.path, right?
> 
> It actually works the other way around. The directories listed in
> sys.path are scanned for .pth files.
> 
> You can add packages by listing them inside a .PTH.
> 
>> I'm expecting .pth files in the current directory to be be processed,
>> according to docs/install/. Christian Heimes already pointed out this is
>> not the case; so I'm wondering whether this is a mistake in the
>> documentation or just my faulty logic.
> 
> Perphaps you don't understand them yet.
> 
> .PTH files are for adding run-time packages.
> 
> May I ask why you are playing with .PTH files? they are a fairly
> advanced sort of concept for describing where packages are located
> to the python interpreter.
> 
> If you are using .PTH files... you should be using "import .." 
> inside your code..


David: I believe you're at least over-stating the case for .pth
files as "fairly advanced" and "for adding run-time packages".

According to http://docs.python.org/install/index.html and my
own reasonably long experience of them, they're just a way of
getting extra paths into sys.path. Those paths could, of course,
support adding packages, but they might not. My own has a mixture
of network directories which contain a bunch of commonly-used
modules, and entries in my subversion checkouts dir each of which
may or may not refer to a package.

The docs referred to above do indeed say "add a path configuration 
file to a directory that’s already on Python’s path" but until I
saw Christian H's post just now, I'd never bothered to understand
exactly what the mechanism was: I just stick site.pth into c:\pythonxx
and it works for me.

TJG