Getting a list of all modules

Ian Kelly ian.g.kelly at
Wed Jul 30 16:29:04 CEST 2014

On Jul 30, 2014 4:37 AM, "Robert Kern" <robert.kern at> wrote:
> On 2014-07-30 09:46, Peter Otten wrote:
>> Steven D'Aprano wrote:
>>> I'm looking for a programmatic way to get a list of all Python modules
>>> and packages. Not just those already imported, but all those which
>>> *could* be imported.
>>> I have a quick-and-dirty function which half does the job:
>>> def get_modules():
>>>      extensions = ('.py', '.pyc', '.pyo', '.so', '.dll')
>>>      matches = set()
>>>      for location in sys.path:
>>>          if location == '': location = '.'
>>>          if os.path.isdir(location):
>>>              for name in os.listdir(location):
>>>                  base, ext = os.path.splitext(name)
>>>                  if ext in extensions:
>>>                      matches.add(base)
>>>      return sorted(matches)
>>> but I know it's wrong (it doesn't handle packages correctly, or zip
>>> files, doesn't follow .pth files, has a very naive understanding of
>>> platform issues, fails to include built-in modules that don't live in
>>> file system, and probably more).
>>> Is this problem already solved? Can anyone make any suggestions?
>> $ python3 -m pydoc -b
>> shows a page with modules that I think is more complete than what you
>> A quick glance at the implementation suggests that the hard work is done
>> pkgutil.iter_modules()
> There are two niggles to this answer: it omits builtin modules, but those
are easily discovered through sys.builtin_module_names. It can also include
spurious script .py files that cannot be imported because their names are
not Python identifiers: e.g. Those are easy to filter
out, fortunately.

It will also omit any modules provided by a custom module finder that
doesn't implement iter_modules, which is not a required part of the
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