Finding a module's sub modules at runtime

[Alex Martelli]

Joshua J. Kugler <joshua at eeinternet.com> wrote:

> On Thursday 29 March 2007 07:33, Alex Martelli wrote:
> 
> > Joshua J. Kugler <joshua at eeinternet.com> wrote:
> > 
> >> still be nicely portable.  It just seems that since Python is gathering
> >> that information anyway, it should make it available without me having to
> >> walk the directory tree.
> > 
> > Sorry, where is Python "gathering that information anyway"?  Unless I'm
> > mistaken, Python by default does not walk directory trees of subpackages
> > -- what makes you think it does?
> 
> Hmm...right: dynamic language, runtime binding.  It would go out and find
> whether or not Module1.Module2 existed only when import was called.  Sorry,
> my bad.  I am assuming, however, that the help function walks the directory
> tree, or else I would not get output like this:
> 
> >>> import ModTest
> >>> help(ModTest)
> Help on package ModTest:
> 
> NAME
>     ModTest
> 
> FILE
>     /usr/local/lib/python2.4/site-packages/ModTest/__init__.py
> 
> PACKAGE CONTENTS
>     AModule
>     BModule
>     CModule
> 
> Thanks for the clarification.

Sure, pydoc (which help calls under the code) does that, with a nice mix
of inspect, os, and pkgutil.iter_modules calls.  pkgutil.iter_modules
may in fact be most of what you need:

>>> help(pkgutil.iter_modules)
Help on function iter_modules in module pkgutil:

iter_modules(path=None, prefix='')
    Yields (module_loader, name, ispkg) for all submodules on path,
    or, if path is None, all top-level modules on sys.path.
    
    'path' should be either None or a list of paths to look for
    modules in.
    
    'prefix' is a string to output on the front of every module name
    on output.

You will still have to call it recursively, though, I believe.


Alex