Python 3 compatibility for identifiers.

IPython/core/interactiveshell.py

@@ -1258,13 +1258,9 b' class InteractiveShell(SingletonConfigurable, Magic):'
         """
         oname = oname.strip()
         #print '1- oname: <%r>' % oname  # dbg
-        if not py3compat.PY3:
-            try:
-                oname = oname.encode('ascii')
-                #print '2- oname: <%r>' % oname  # dbg
-            except UnicodeError:
-                print 'Python identifiers can only contain ascii characters.'
-                return dict(found=False)
+        if not py3compat.isidentifier(oname.lstrip(ESC_MAGIC), dotted=True):
+            print 'Python identifiers can only contain ascii characters.'
+            return dict(found=False)
 
         alias_ns = None
         if namespaces is None:

IPython/utils/py3compat.py

@@ -1,3 +1,5 b''
+# coding: utf-8
+"""Compatibility tricks for Python 3. Mainly to do with unicode."""
 import sys
 
 def no_code(x, encoding=None):
@@ -32,6 +34,11 b' if sys.version_info[0] >= 3:'
     str_to_bytes = encode
     bytes_to_str = decode
     
+    def isidentifier(s, dotted=False):
+        if dotted:
+            return all(isidentifier(a) for a in s.split("."))
+        return s.isidentifier()
+
 else:
     PY3 = False
     
@@ -42,6 +49,13 b' else:'
     unicode_to_str = encode
     str_to_bytes = no_code
     bytes_to_str = no_code
+    
+    import re
+    _name_re = re.compile(r"[a-zA-Z_][a-zA-Z0-9_]*$")
+    def isidentifier(s, dotted=False):
+        if dotted:
+            return all(isidentifier(a) for a in s.split("."))
+        return bool(_name_re.match(s))
 
 def execfile(fname, glob, loc=None):
     loc = loc if (loc is not None) else glob

IPython/utils/traitlets.py

@@ -1008,12 +1008,12 b' class ObjectName(TraitType):'
     This does not check that the name exists in any scope."""
     info_text = "a valid object identifier in Python"
 
-    if sys.version_info[0] < 3:
+    if py3compat.PY3:
+        # Python 3:
+        coerce_str = staticmethod(lambda _,s: s)
+    
+    else:
         # Python 2:
-        _name_re = re.compile(r"[a-zA-Z_][a-zA-Z0-9_]*$")
-        def isidentifier(self, s):
-            return bool(self._name_re.match(s))
-        
         def coerce_str(self, obj, value):
             "In Python 2, coerce ascii-only unicode to str"
             if isinstance(value, unicode):
@@ -1023,15 +1023,10 b' class ObjectName(TraitType):'
                     self.error(obj, value)
             return value
     
-    else:
-        # Python 3:
-        isidentifier = staticmethod(lambda s: s.isidentifier())
-        coerce_str = staticmethod(lambda _,s: s)
-    
     def validate(self, obj, value):
         value = self.coerce_str(obj, value)
         
-        if isinstance(value, str) and self.isidentifier(value):
+        if isinstance(value, str) and py3compat.isidentifier(value):
             return value
         self.error(obj, value)
 
@@ -1040,8 +1035,7 b' class DottedObjectName(ObjectName):'
     def validate(self, obj, value):
         value = self.coerce_str(obj, value)
         
-        if isinstance(value, str) and all(self.isidentifier(x) \
-                                                    for x in value.split('.')):
+        if isinstance(value, str) and py3compat.isidentifier(value, dotted=True):
             return value
         self.error(obj, value)