use istype instead of isinstance for canning tuples/lists

and add explicit support for namedtuples

IPython/kernel/zmq/serialize.py

@@ -34,7 +34,8 b' except:'
 from IPython.utils import py3compat
 from IPython.utils.data import flatten
 from IPython.utils.pickleutil import (
-    can, uncan, can_sequence, uncan_sequence, CannedObject
+    can, uncan, can_sequence, uncan_sequence, CannedObject,
+    istype, sequence_types,
 )
 
 if py3compat.PY3:
@@ -91,11 +92,11 b' def serialize_object(obj, buffer_threshold=MAX_BYTES, item_threshold=MAX_ITEMS):'
     [bufs] : list of buffers representing the serialized object.
     """
     buffers = []
-    if isinstance(obj, (list, tuple)) and len(obj) < item_threshold:
+    if istype(obj, sequence_types) and len(obj) < item_threshold:
         cobj = can_sequence(obj)
         for c in cobj:
             buffers.extend(_extract_buffers(c, buffer_threshold))
-    elif isinstance(obj, dict) and len(obj) < item_threshold:
+    elif istype(obj, dict) and len(obj) < item_threshold:
         cobj = {}
         for k in sorted(obj.iterkeys()):
             c = can(obj[k])
@@ -129,7 +130,7 b' def unserialize_object(buffers, g=None):'
         # a zmq message
         pobj = bytes(pobj)
     canned = pickle.loads(pobj)
-    if isinstance(canned, (list, tuple)) and len(canned) < MAX_ITEMS:
+    if istype(canned, sequence_types) and len(canned) < MAX_ITEMS:
         for c in canned:
             _restore_buffers(c, bufs)
         newobj = uncan_sequence(canned, g)

IPython/utils/pickleutil.py

@@ -18,6 +18,7 b' __docformat__ = "restructuredtext en"'
 import copy
 import logging
 import sys
+from collections import namedtuple
 from types import FunctionType
 
 try:
@@ -249,7 +250,7 b' def can_class(obj):'
 
 def can_dict(obj):
     """can the *values* of a dict"""
-    if isinstance(obj, dict):
+    if istype(obj, dict):
         newobj = {}
         for k, v in obj.iteritems():
             newobj[k] = can(v)
@@ -257,9 +258,11 b' def can_dict(obj):'
     else:
         return obj
 
+sequence_types = (list, tuple, set)
+
 def can_sequence(obj):
     """can the elements of a sequence"""
-    if isinstance(obj, (list, tuple)):
+    if istype(obj, sequence_types):
         t = type(obj)
         return t([can(i) for i in obj])
     else:
@@ -285,7 +288,7 b' def uncan(obj, g=None):'
     return obj
 
 def uncan_dict(obj, g=None):
-    if isinstance(obj, dict):
+    if istype(obj, dict):
         newobj = {}
         for k, v in obj.iteritems():
             newobj[k] = uncan(v,g)
@@ -294,7 +297,7 b' def uncan_dict(obj, g=None):'
         return obj
 
 def uncan_sequence(obj, g=None):
-    if isinstance(obj, (list, tuple)):
+    if istype(obj, sequence_types):
         t = type(obj)
         return t([uncan(i,g) for i in obj])
     else: