1  # encoding: utf-8
   2  """A fancy version of Python's builtin :func:`dir` function.
   3  """
   4  
   5  # Copyright (c) IPython Development Team.
   6  # Distributed under the terms of the Modified BSD License.
   7  
   8  import inspect
   9  import types
  10  
  11  
  12  def safe_hasattr(obj, attr):
  13      """In recent versions of Python, hasattr() only catches AttributeError.
  14      This catches all errors.
  15      """
  16      try:
  17          getattr(obj, attr)
  18          return True
  19      except:
  20          return False
  21  
  22  
  23  def dir2(obj):
  24      """dir2(obj) -> list of strings
  25  
  26      Extended version of the Python builtin dir(), which does a few extra
  27      checks.
  28  
  29      This version is guaranteed to return only a list of true strings, whereas
  30      dir() returns anything that objects inject into themselves, even if they
  31      are later not really valid for attribute access (many extension libraries
  32      have such bugs).
  33      """
  34  
  35      # Start building the attribute list via dir(), and then complete it
  36      # with a few extra special-purpose calls.
  37  
  38      try:
  39          words = set(dir(obj))
  40      except Exception:
  41          # TypeError: dir(obj) does not return a list
  42          words = set()
  43  
  44      if safe_hasattr(obj, "__class__"):
  45          words |= set(dir(obj.__class__))
  46  
  47      # filter out non-string attributes which may be stuffed by dir() calls
  48      # and poor coding in third-party modules
  49  
  50      words = [w for w in words if isinstance(w, str)]
  51      return sorted(words)
  52  
  53  
  54  def get_real_method(obj, name):
  55      """Like getattr, but with a few extra sanity checks:
  56  
  57      - If obj is a class, ignore everything except class methods
  58      - Check if obj is a proxy that claims to have all attributes
  59      - Catch attribute access failing with any exception
  60      - Check that the attribute is a callable object
  61  
  62      Returns the method or None.
  63      """
  64      try:
  65          canary = getattr(obj, "_ipython_canary_method_should_not_exist_", None)
  66      except Exception:
  67          return None
  68  
  69      if canary is not None:
  70          # It claimed to have an attribute it should never have
  71          return None
  72  
  73      try:
  74          m = getattr(obj, name, None)
  75      except Exception:
  76          return None
  77  
  78      if inspect.isclass(obj) and not isinstance(m, types.MethodType):
  79          return None
  80  
  81      if callable(m):
  82          return m
  83  
  84      return None
  85