Fixes for metaclass syntax

IPython/core/formatters.py

@@ -36,7 +36,7 from IPython.lib import pretty
 from IPython.utils.traitlets import (
     Bool, Dict, Integer, Unicode, CUnicode, ObjectName, List,
 )
-from IPython.utils.py3compat import unicode_to_str
+from IPython.utils.py3compat import unicode_to_str, with_metaclass
 
 
 #-----------------------------------------------------------------------------
@@ -176,7 +176,7 class DisplayFormatter(Configurable):
 #-----------------------------------------------------------------------------
 
 
-class FormatterABC(object):
+class FormatterABC(with_metaclass(abc.ABCMeta, object)):
     """ Abstract base class for Formatters.
 
     A formatter is a callable class that is responsible for computing the
@@ -184,7 +184,6 class FormatterABC(object):
     an HTML formatter would have a format type of `text/html` and would return
     the HTML representation of the object when called.
     """
-    __metaclass__ = abc.ABCMeta
 
     # The format type of the data returned, usually a MIME type.
     format_type = 'text/plain'

IPython/core/inputtransformer.py

@@ -6,6 +6,7 from io import StringIO
 from IPython.core.splitinput import LineInfo
 from IPython.utils import tokenize2
 from IPython.utils.openpy import cookie_comment_re
+from IPython.utils.py3compat import with_metaclass
 from IPython.utils.tokenize2 import generate_tokens, untokenize, TokenError
 
 #-----------------------------------------------------------------------------
@@ -33,9 +34,8 ESC_SEQUENCES = [ESC_SHELL, ESC_SH_CAP, ESC_HELP ,\
                  ESC_QUOTE, ESC_QUOTE2, ESC_PAREN ]
 
 
-class InputTransformer(object):
+class InputTransformer(with_metaclass(abc.ABCMeta, object)):
     """Abstract base class for line-based input transformers."""
-    __metaclass__ = abc.ABCMeta
     
     @abc.abstractmethod
     def push(self, line):

IPython/core/interactiveshell.py

@@ -68,7 +68,8 from IPython.utils.ipstruct import Struct
 from IPython.utils.path import get_home_dir, get_ipython_dir, get_py_filename, unquote_filename
 from IPython.utils.pickleshare import PickleShareDB
 from IPython.utils.process import system, getoutput
-from IPython.utils.py3compat import builtin_mod, unicode_type, string_types
+from IPython.utils.py3compat import (builtin_mod, unicode_type, string_types,
+                                     with_metaclass)
 from IPython.utils.strdispatch import StrDispatch
 from IPython.utils.syspathcontext import prepended_to_syspath
 from IPython.utils.text import (format_screen, LSString, SList,
@@ -3157,8 +3158,7 class InteractiveShell(SingletonConfigurable):
         self.restore_sys_module_state()
 
 
-class InteractiveShellABC(object):
+class InteractiveShellABC(with_metaclass(abc.ABCMeta, object)):
     """An abstract base class for InteractiveShell."""
-    __metaclass__ = abc.ABCMeta
 
 InteractiveShellABC.register(InteractiveShell)

IPython/kernel/channelsabc.py

@@ -11,19 +11,18
 # Imports
 #-----------------------------------------------------------------------------
 
-# Standard library imports
 import abc
 
+from IPython.utils.py3compat import with_metaclass
+
 #-----------------------------------------------------------------------------
 # Channels
 #-----------------------------------------------------------------------------
 
 
-class ChannelABC(object):
+class ChannelABC(with_metaclass(abc.ABCMeta, object)):
     """A base class for all channel ABCs."""
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractmethod
     def start(self):
         pass

IPython/kernel/clientabc.py

@@ -11,14 +11,15
 # Imports
 #-----------------------------------------------------------------------------
 
-# Standard library imports
 import abc
 
+from IPython.utils.py3compat import with_metaclass
+
 #-----------------------------------------------------------------------------
 # Main kernel client class
 #-----------------------------------------------------------------------------
 
-class KernelClientABC(object):
+class KernelClientABC(with_metaclass(abc.ABCMeta, object)):
     """KernelManager ABC.
 
     The docstrings for this class can be found in the base implementation:
@@ -26,8 +27,6 class KernelClientABC(object):
     `IPython.kernel.client.KernelClient`
     """
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractproperty
     def kernel(self):
         pass

IPython/kernel/inprocess/socket.py

@@ -23,14 +23,13 import zmq
 
 # Local imports.
 from IPython.utils.traitlets import HasTraits, Instance, Int
+from IPython.utils.py3compat import with_metaclass
 
 #-----------------------------------------------------------------------------
 # Generic socket interface
 #-----------------------------------------------------------------------------
 
-class SocketABC(object):
-    __metaclass__ = abc.ABCMeta
-
+class SocketABC(with_metaclass(abc.ABCMeta, object)):
     @abc.abstractmethod
     def recv_multipart(self, flags=0, copy=True, track=False):
         raise NotImplementedError

IPython/kernel/managerabc.py

@@ -11,19 +11,18
 # Imports
 #-----------------------------------------------------------------------------
 
-# Standard library imports.
 import abc
 
+from IPython.utils.py3compat import with_metaclass
+
 #-----------------------------------------------------------------------------
 # Channels
 #-----------------------------------------------------------------------------
 
 
-class ChannelABC(object):
+class ChannelABC(with_metaclass(abc.ABCMeta, object)):
     """A base class for all channel ABCs."""
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractmethod
     def start(self):
         pass
@@ -130,7 +129,7 class HBChannelABC(ChannelABC):
 # Main kernel manager class
 #-----------------------------------------------------------------------------
 
-class KernelManagerABC(object):
+class KernelManagerABC(with_metaclass(abc.ABCMeta, object)):
     """KernelManager ABC.
 
     The docstrings for this class can be found in the base implementation:
@@ -138,8 +137,6 class KernelManagerABC(object):
     `IPython.kernel.kernelmanager.KernelManager`
     """
 
-    __metaclass__ = abc.ABCMeta
-
     @abc.abstractproperty
     def kernel(self):
         pass

IPython/qt/console/console_widget.py

@@ -21,6 +21,7 from IPython.config.configurable import LoggingConfigurable
 from IPython.core.inputsplitter import ESC_SEQUENCES
 from IPython.qt.rich_text import HtmlExporter
 from IPython.qt.util import MetaQObjectHasTraits, get_font
+from IPython.utils.py3compat import with_metaclass
 from IPython.utils.text import columnize
 from IPython.utils.traitlets import Bool, Enum, Integer, Unicode
 from .ansi_code_processor import QtAnsiCodeProcessor
@@ -69,7 +70,7 def is_letter_or_number(char):
 # Classes
 #-----------------------------------------------------------------------------
 
-class ConsoleWidget(LoggingConfigurable, QtGui.QWidget):
+class ConsoleWidget(with_metaclass(MetaQObjectHasTraits, type('NewBase', (LoggingConfigurable, QtGui.QWidget), {}))):
     """ An abstract base class for console-type widgets. This class has
         functionality for:
 
@@ -82,7 +83,6 class ConsoleWidget(LoggingConfigurable, QtGui.QWidget):
         ConsoleWidget also provides a number of utility methods that will be
         convenient to implementors of a console-style widget.
     """
-    __metaclass__ = MetaQObjectHasTraits
 
     #------ Configuration ------------------------------------------------------
 

IPython/qt/kernel_mixins.py

@@ -168,27 +168,22 class QtHBChannelMixin(ChannelQObject):
         self.kernel_died.emit(since_last_heartbeat)
 
 
-class QtKernelRestarterMixin(HasTraits, SuperQObject):
+class QtKernelRestarterMixin(MetaQObjectHasTraits('NewBase', (HasTraits, SuperQObject), {})):
 
-    __metaclass__ = MetaQObjectHasTraits
     _timer = None
 
 
-class QtKernelManagerMixin(HasTraits, SuperQObject):
+class QtKernelManagerMixin(MetaQObjectHasTraits('NewBase', (HasTraits, SuperQObject), {})):
     """ A KernelClient that provides signals and slots.
     """
 
-    __metaclass__ = MetaQObjectHasTraits
-
     kernel_restarted = QtCore.Signal()
 
 
-class QtKernelClientMixin(HasTraits, SuperQObject):
+class QtKernelClientMixin(MetaQObjectHasTraits('NewBase', (HasTraits, SuperQObject), {})):
     """ A KernelClient that provides signals and slots.
     """
 
-    __metaclass__ = MetaQObjectHasTraits
-
     # Emitted when the kernel client has started listening.
     started_channels = QtCore.Signal()
 

IPython/utils/py3compat.py

@@ -208,3 +208,28 else:
             else:
                 filename = fname
             builtin_mod.execfile(filename, *where)
+
+# Parts below taken from six:
+# Copyright (c) 2010-2013 Benjamin Peterson
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+def with_metaclass(meta, *bases):
+    """Create a base class with a metaclass."""
+    return meta("NewBase", bases, {})

IPython/utils/traitlets.py

@@ -394,9 +394,7 class MetaHasTraits(type):
                 v.this_class = cls
         super(MetaHasTraits, cls).__init__(name, bases, classdict)
 
-class HasTraits(object):
-
-    __metaclass__ = MetaHasTraits
+class HasTraits(py3compat.with_metaclass(MetaHasTraits, object)):
 
     def __new__(cls, *args, **kw):
         # This is needed because in Python 2.6 object.__new__ only accepts