How can I access the list of modules that Python's help('modules') displays?

Question

How can I access the list of modules that Python's help('modules') displays? It shows the following:

>>> help('modules')

Please wait a moment while I gather a list of all available modules...

...[list of modules]...
MySQLdb             codeop              mailman_sf          spwd
OpenSSL             collections         markupbase          sqlite3
Queue               colorsys            marshal             sre
...[list of modules]...

Enter any module name to get more help.  Or, type "modules spam" to search
for modules whose descriptions contain the word "spam".

>>>

I can view the list in the output but would like to access this as a list from within a Python program. How can I do this?

Answer 1

You can mimic all the help does by yourself. Built-in help uses pydoc, that uses ModuleScanner class to get information about all available libs - see line 1873 in pydoc.py.

Here is a bit modified version of code from the link:

>>> modules = []
>>> def callback(path, modname, desc, modules=modules):
    if modname and modname[-9:] == '.__init__':
        modname = modname[:-9] + ' (package)'
    if modname.find('.') < 0:
        modules.append(modname)

>>> def onerror(modname):
    callback(None, modname, None)

>>> from pydoc import ModuleScanner 
>>> ModuleScanner().run(callback, onerror=onerror)
>>> len(modules)
379
>>> modules[:10]
['__builtin__', '_ast', '_bisect', '_codecs', '_codecs_cn', '_codecs_hk', '_codecs_iso2022', '_codecs_jp', '_codecs_kr', '_codecs_tw']
>>> len(modules)
379