paths in modules

[Larry Bates]

Brandon Mintern wrote:
> I am developing a project in Python which uses several external utilities.
> For convenience, I am wrapping these accesses in a module. The problem is
> that I cannot be sure where these modules are imported from, so I am
> trying to figure out how to reliably execute e.g. a popen call.  Example
> layout:
> 
> toplevel_dir
> +-main script
> +-wrapper_dir
>   +-some_wrapper
>   +-utility_dir
>     +-some_external_utility
> 
> So in my main script, I might say:
> 
> from wrapper_dir import some_wrapper
> 
> some_wrapper.use_external_utility()
> 
> 
> And then in some_wrapper, I would have code like:
> 
> import os
> 
> def use_external_utility():
>   f = os.popen('utility_dir/some_external_utility')
>   lines = f.readlines()
>   f.close()
>   return lines
> 
> 
> Of course, the problem with that approach is that it fails because there
> is no utility_dir in the CWD, which is actually top_level_dir.  So my
> question is whether there is any way to specify that specified paths are
> relative to the module's directory rather than the importing file's
> directory.  I would really like to avoid kludging together some solution
> that involves passing variables or having knowledge of where my module is
> being imported from.
> 
> I am hoping that there is some simple solution to this problem that I
> simply haven't found in my searches so far.  If so, I will humbly accept
> any ridicule that comes along with said simple solution :-).
> 
> Thanks in advance,
> Brandon

Normally this would be:

f = os.popen('./wrapper_dir/utility_dir/some_external_utility')

-Larry