embed_kernel: give a clear error message on pyzmq ImportError

IPython/__init__.py

@@ -1,61 +1,63 b''
 # encoding: utf-8
 """
 IPython: tools for interactive and parallel computing in Python.
 
 http://ipython.org
 """
 #-----------------------------------------------------------------------------
 #  Copyright (c) 2008-2011, IPython Development Team.
 #  Copyright (c) 2001-2007, Fernando Perez <[e-mail]>
 #  Copyright (c) 2001, Janko Hauser <[e-mail]>
 #  Copyright (c) 2001, Nathaniel Gray <[e-mail]>
 #
 #  Distributed under the terms of the Modified BSD License.
 #
 #  The full license is in the file COPYING.txt, distributed with this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 from __future__ import absolute_import
 
 import os
 import sys
 
 #-----------------------------------------------------------------------------
 # Setup everything
 #-----------------------------------------------------------------------------
 
 # Don't forget to also update setup.py when this changes!
 if sys.version[0:3] < '2.6':
     raise ImportError('Python Version 2.6 or above is required for IPython.')
 
 # Make it easy to import extensions - they are always directly on pythonpath.
 # Therefore, non-IPython modules can be added to extensions directory.
 # This should probably be in ipapp.py.
 sys.path.append(os.path.join(os.path.dirname(__file__), "extensions"))
 
 #-----------------------------------------------------------------------------
 # Setup the top level names
 #-----------------------------------------------------------------------------
 
 from .config.loader import Config
 from .core import release
 from .core.application import Application
 from .frontend.terminal.embed import embed
 try:
     from .zmq.ipkernel import embed_kernel
 except ImportError:
-    pass
+    def embed_kernel(*args, **kwargs):
+        raise ImportError("IPython.embed_kernel requires pyzmq >= 2.14")
+
 from .core.error import TryNext
 from .core.interactiveshell import InteractiveShell
 from .testing import test
 from .utils.sysinfo import sys_info
 
 # Release data
 __author__ = ''
 for author, email in release.authors.itervalues():
     __author__ += author + ' <' + email + '>\n'
 __license__  = release.license
 __version__  = release.version