Don't understand module search path...

[Chris Mellon]

On 10/4/07, mhearne808[insert-at-sign-here]gmail[insert-dot-here]com
<mhearne808 at gmail.com> wrote:
> I think I don't understand how the module search path works...
>
> Let's say I have a folders called 'test'.  Underneath it, I create two
> more folders called 'foo' and 'bar'.
>
> In 'foo', I create an empty '__init__.py' file, indicating that this
> folder is a package 'foo'.  I then create a simple python script
> 'foo.py' consisting of the following code:
>
> ----------------------------
> #!/usr/bin/python
>
> def printhello():
>     print 'Hello world!'
> ----------------------------
>
> Then in test/bar, I create 'bar.py' consisting of the following code:
> ----------------------------
> #!/usr/bin/python
> import sys
> import os
> (curpath,thisdir) = os.path.split(os.getcwd())
> foopath = os.path.join(curpath,'foo')
> sys.path.append(foopath)
> print sys.path
> os.chdir(os.path.join(os.getcwd(),'..'))
> print os.getcwd()
> from foo.foo import printhello
> ----------------------------
>
> When I try to run bar.py, I get the following:
>
> ----------------------------
> [sys.path search path, including full path to 'foo' folder]
> path/to/test
> Traceback (most recent call last):
>   File "/path/to/test/bar/testfoo.py", line 16, in <module>
> from foo.foo import printhello
> ImportError: No module named foo
> ----------------------------
>
> Why?  If 'foo' is in sys.path, shouldn't it appear when I try to
> import the foo module from it?

No. foo will be searched for modules, but foo itself won't be found
(because it's looking *inside* foo). You want "test" to be on sys.path
for this to work.

>Incidentally, when I move the script
> up to 'test' and modify it so that it just says:
> ----------------------------
> #!/usr/bin/python
>
> from foo.foo import printhello
> ----------------------------
>
> I get no errors.  I don't understand the difference...
>

The directory that the executing script is in is implicitly on
sys.path, so when you do this you place "test" in sys.path, and foo is
found.