IPython/utils/dir2.py

# encoding: utf-8
"""A fancy version of Python's builtin :func:`dir` function.
"""

#-----------------------------------------------------------------------------
#  Copyright (C) 2008-2009  The IPython Development Team
#
#  Distributed under the terms of the BSD License.  The full license is in
#  the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------

#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------

#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------

def get_class_members(cls):
    ret = dir(cls)
    if hasattr(cls,'__bases__'):
        for base in cls.__bases__:
            ret.extend(get_class_members(base))
    return ret


def dir2(obj):
    """dir2(obj) -> list of strings

    Extended version of the Python builtin dir(), which does a few extra
    checks, and supports common objects with unusual internals that confuse
    dir(), such as Traits and PyCrust.

    This version is guaranteed to return only a list of true strings, whereas
    dir() returns anything that objects inject into themselves, even if they
    are later not really valid for attribute access (many extension libraries
    have such bugs).
    """

    # Start building the attribute list via dir(), and then complete it
    # with a few extra special-purpose calls.
    words = dir(obj)

    if hasattr(obj,'__class__'):
        words.append('__class__')
        words.extend(get_class_members(obj.__class__))
    #if '__base__' in words: 1/0

    # Some libraries (such as traits) may introduce duplicates, we want to
    # track and clean this up if it happens
    may_have_dupes = False

    # this is the 'dir' function for objects with Enthought's traits
    if hasattr(obj, 'trait_names'):
        try:
            words.extend(obj.trait_names())
            may_have_dupes = True
        except TypeError:
            # This will happen if `obj` is a class and not an instance.
            pass

    # Support for PyCrust-style _getAttributeNames magic method.
    if hasattr(obj, '_getAttributeNames'):
        try:
            words.extend(obj._getAttributeNames())
            may_have_dupes = True
        except TypeError:
            # `obj` is a class and not an instance.  Ignore
            # this error.
            pass

    if may_have_dupes:
        # eliminate possible duplicates, as some traits may also
        # appear as normal attributes in the dir() call.
        words = list(set(words))
        words.sort()

    # filter out non-string attributes which may be stuffed by dir() calls
    # and poor coding in third-party modules
    return [w for w in words if isinstance(w, basestring)]