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# encoding: utf-8
"""A fancy version of Python's builtin :func:`dir` function.
"""
# Copyright (c) IPython Development Team.
# Distributed under the terms of the Modified BSD License.
import inspect
import types
def safe_hasattr(obj, attr):
"""In recent versions of Python, hasattr() only catches AttributeError.
This catches all errors.
"""
try:
getattr(obj, attr)
return True
except:
return False
def dir2(obj):
"""dir2(obj) -> list of strings
Extended version of the Python builtin dir(), which does a few extra
checks.
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.
try:
words = set(dir(obj))
except Exception:
# TypeError: dir(obj) does not return a list
words = set()
if safe_hasattr(obj, '__class__'):
words |= set(dir(obj.__class__))
# filter out non-string attributes which may be stuffed by dir() calls
# and poor coding in third-party modules
words = [w for w in words if isinstance(w, str)]
return sorted(words)
def get_real_method(obj, name):
"""Like getattr, but with a few extra sanity checks:
- If obj is a class, ignore everything except class methods
- Check if obj is a proxy that claims to have all attributes
- Catch attribute access failing with any exception
- Check that the attribute is a callable object
Returns the method or None.
"""
try:
canary = getattr(obj, '_ipython_canary_method_should_not_exist_', None)
except Exception:
return None
if canary is not None:
# It claimed to have an attribute it should never have
return None
try:
m = getattr(obj, name, None)
except Exception:
return None
if inspect.isclass(obj) and not isinstance(m, types.MethodType):
return None
if callable(m):
return m
return None
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