Consolidate code to check for method in IPython.utils.dir2

IPython/core/completer.py

@@ -71,7 +71,7 b' from IPython.core.latex_symbols import latex_symbols, reverse_latex_symbol'
 from IPython.utils import generics
 from IPython.utils import io
 from IPython.utils.decorators import undoc
-from IPython.utils.dir2 import dir2, safe_hasattr
+from IPython.utils.dir2 import dir2, get_real_method
 from IPython.utils.process import arg_split
 from IPython.utils.py3compat import builtin_mod, string_types, PY3
 from traitlets import CBool, Enum
@@ -472,19 +472,6 b' def _safe_isinstance(obj, module, class_name):'
     return (module in sys.modules and
             isinstance(obj, getattr(__import__(module), class_name)))
 
-def _safe_really_hasattr(obj, name):
-    """Checks that an object genuinely has a given attribute.
-
-    Some objects claim to have any attribute that's requested, to act as a lazy
-    proxy for something else. We want to catch these cases and ignore their
-    claim to have the attribute we're interested in.
-    """
-    if safe_hasattr(obj, '_ipy_proxy_check_dont_define_this_'):
-        # If it claims this exists, don't trust it
-        return False
-
-    return safe_hasattr(obj, name)
-
 
 def back_unicode_name_matches(text):
     u"""Match unicode characters back to unicode name
@@ -937,8 +924,9 b' class IPCompleter(Completer):'
         def get_keys(obj):
             # Objects can define their own completions by defining an
             # _ipy_key_completions_() method.
-            if _safe_really_hasattr(obj, '_ipython_key_completions_'):
-                return obj._ipython_key_completions_()
+            method = get_real_method(obj, '_ipython_key_completions_')
+            if method is not None:
+                return method()
 
             # Special case some common in-memory dict-like types
             if isinstance(obj, dict) or\

IPython/core/displayhook.py

@@ -13,7 +13,6 b' import sys'
 import io as _io
 import tokenize
 
-from IPython.core.formatters import _safe_get_formatter_method
 from traitlets.config.configurable import Configurable
 from IPython.utils import io
 from IPython.utils.py3compat import builtin_mod, cast_unicode_py2

IPython/core/formatters.py

@@ -22,6 +22,7 b' from decorator import decorator'
 from traitlets.config.configurable import Configurable
 from IPython.core.getipython import get_ipython
 from IPython.utils.sentinel import Sentinel
+from IPython.utils.dir2 import get_real_method
 from IPython.lib import pretty
 from traitlets import (
     Bool, Dict, Integer, Unicode, CUnicode, ObjectName, List,
@@ -32,29 +33,6 b' from IPython.utils.py3compat import ('
 )
 
 
-#-----------------------------------------------------------------------------
-# The main DisplayFormatter class
-#-----------------------------------------------------------------------------
-
-
-def _safe_get_formatter_method(obj, name):
-    """Safely get a formatter method
-    
-    - Classes cannot have formatter methods, only instance
-    - protect against proxy objects that claim to have everything
-    """
-    if inspect.isclass(obj):
-        # repr methods only make sense on instances, not classes
-        return None
-    method = pretty._safe_getattr(obj, name, None)
-    if callable(method):
-        # obj claims to have repr method...
-        if callable(pretty._safe_getattr(obj, '_ipython_canary_method_should_not_exist_', None)):
-            # ...but don't trust proxy objects that claim to have everything
-            return None
-        return method
-
-
 class DisplayFormatter(Configurable):
 
     # When set to true only the default plain text formatter will be used.
@@ -338,7 +316,7 b' class BaseFormatter(Configurable):'
             else:
                 return printer(obj)
             # Finally look for special method names
-            method = _safe_get_formatter_method(obj, self.print_method)
+            method = get_real_method(obj, self.print_method)
             if method is not None:
                 return method()
             return None
@@ -904,7 +882,7 b' class IPythonDisplayFormatter(BaseFormatter):'
                 printer(obj)
                 return True
             # Finally look for special method names
-            method = _safe_get_formatter_method(obj, self.print_method)
+            method = get_real_method(obj, self.print_method)
             if method is not None:
                 method()
                 return True

IPython/utils/dir2.py

@@ -2,21 +2,11 b''
 """A fancy version of Python's builtin :func:`dir` function.
 """
 
-#-----------------------------------------------------------------------------
-#  Copyright (C) 2008-2011  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
-#-----------------------------------------------------------------------------
-from .py3compat import string_types
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
 
-#-----------------------------------------------------------------------------
-# Code
-#-----------------------------------------------------------------------------
+import inspect
+from .py3compat import string_types
 
 
 def safe_hasattr(obj, attr):
@@ -56,3 +46,36 b' def dir2(obj):'
 
     words = [w for w in words if isinstance(w, string_types)]
     return sorted(words)
+
+
+def get_real_method(obj, name):
+    """Like getattr, but with a few extra sanity checks:
+
+    - If obj is a class, ignore its 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.
+    """
+    if inspect.isclass(obj):
+        return 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 callable(m):
+        return m
+
+    return None