From 88c105a5bd69995b6f007f04532677aa83b0aa97 2014-11-14 01:12:11
From: Thomas Kluyver <takowl@gmail.com>
Date: 2014-11-14 01:12:11
Subject: [PATCH] Fix signature with unbound methods

---

diff --git a/IPython/utils/signatures.py b/IPython/utils/signatures.py
index 0ab0a88..771899e 100644
--- a/IPython/utils/signatures.py
+++ b/IPython/utils/signatures.py
@@ -72,10 +72,13 @@ def signature(obj):
         raise TypeError('{0!r} is not a callable object'.format(obj))
 
     if isinstance(obj, types.MethodType):
-        # In this case we skip the first parameter of the underlying
-        # function (usually `self` or `cls`).
-        sig = signature(obj.__func__)
-        return sig.replace(parameters=tuple(sig.parameters.values())[1:])
+        if obj.__self__ is None:
+            # Unbound method - treat it as a function (no distinction in Py 3)
+            obj = obj.__func__
+        else:
+            # Bound method: trim off the first parameter (typically self or cls)
+            sig = signature(obj.__func__)
+            return sig.replace(parameters=tuple(sig.parameters.values())[1:])
 
     try:
         sig = obj.__signature__