Moved twisted import into a function, so base exception classes in kernel

can be imported without twisted present.

IPython/kernel/__init__.py

@@ -1,25 +1,25 b''
 # encoding: utf-8
 """The IPython1 kernel.
 
 The IPython kernel actually refers to three things:
 
  * The IPython Engine
  * The IPython Controller
  * Clients to the IPython Controller
 
 The kernel module implements the engine, controller and client and all the 
 network protocols needed for the various entities to talk to each other.
 
 An end user should probably begin by looking at the `client.py` module
 if they need blocking clients or in `asyncclient.py` if they want asynchronous,
 deferred/Twisted using clients.
 """
 __docformat__ = "restructuredtext en"
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
-from IPython.kernel.error import TaskRejectError
  No newline at end of file
+from IPython.kernel.error import TaskRejectError

IPython/kernel/error.py

@@ -1,207 +1,207 b''
 # encoding: utf-8
 
 """Classes and functions for kernel related errors and exceptions."""
 
 __docformat__ = "restructuredtext en"
 
 # Tell nose to skip this module
 __test__ = {}
 
 #-------------------------------------------------------------------------------
 #  Copyright (C) 2008  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-------------------------------------------------------------------------------
 
 #-------------------------------------------------------------------------------
 # Imports
 #-------------------------------------------------------------------------------
-from twisted.python import failure
-
 from IPython.kernel.core import error
 
 #-------------------------------------------------------------------------------
 # Error classes
 #-------------------------------------------------------------------------------
 
 class KernelError(error.IPythonError):
     pass
 
 class NotDefined(KernelError):
     def __init__(self, name):
         self.name = name
         self.args = (name,)
 
     def __repr__(self):
         return '<NotDefined: %s>' % self.name
     
     __str__ = __repr__
 
 class QueueCleared(KernelError):
     pass
 
 class IdInUse(KernelError):
     pass
 
 class ProtocolError(KernelError):
     pass
 
 class ConnectionError(KernelError):
     pass
 
 class InvalidEngineID(KernelError):
     pass
     
 class NoEnginesRegistered(KernelError):
     pass
     
 class InvalidClientID(KernelError):
     pass
     
 class InvalidDeferredID(KernelError):
     pass
     
 class SerializationError(KernelError):
     pass
     
 class MessageSizeError(KernelError):
     pass
     
 class PBMessageSizeError(MessageSizeError):
     pass
     
 class ResultNotCompleted(KernelError):
     pass
     
 class ResultAlreadyRetrieved(KernelError):
     pass
     
 class ClientError(KernelError):
     pass
 
 class TaskAborted(KernelError):
     pass
 
 class TaskTimeout(KernelError):
     pass
 
 class NotAPendingResult(KernelError):
     pass
 
 class UnpickleableException(KernelError):
     pass
 
 class AbortedPendingDeferredError(KernelError):
     pass
 
 class InvalidProperty(KernelError):
     pass
 
 class MissingBlockArgument(KernelError):
     pass
 
 class StopLocalExecution(KernelError):
     pass
 
 class SecurityError(KernelError):
     pass
 
 class FileTimeoutError(KernelError):
     pass
 
 class TaskRejectError(KernelError):
     """Exception to raise when a task should be rejected by an engine.
     
     This exception can be used to allow a task running on an engine to test
     if the engine (or the user's namespace on the engine) has the needed
     task dependencies.  If not, the task should raise this exception.  For
     the task to be retried on another engine, the task should be created
     with the `retries` argument > 1.
     
     The advantage of this approach over our older properties system is that
     tasks have full access to the user's namespace on the engines and the
     properties don't have to be managed or tested by the controller.
     """
 
 class CompositeError(KernelError):
     def __init__(self, message, elist):
         Exception.__init__(self, *(message, elist))
         # Don't use pack_exception because it will conflict with the .message
         # attribute that is being deprecated in 2.6 and beyond.
         self.msg = message
         self.elist = elist
 
     def _get_engine_str(self, ev):
         try:
             ei = ev._ipython_engine_info
         except AttributeError:
             return '[Engine Exception]'
         else:
             return '[%i:%s]: ' % (ei['engineid'], ei['method'])
 
     def _get_traceback(self, ev):
         try:
             tb = ev._ipython_traceback_text
         except AttributeError:
             return 'No traceback available'
         else:
             return tb
 
     def __str__(self):
         s = str(self.msg)
         for et, ev, etb in self.elist:
             engine_str = self._get_engine_str(ev)
             s = s + '\n' + engine_str + str(et.__name__) + ': ' + str(ev)
         return s
 
     def print_tracebacks(self, excid=None):
         if excid is None:
             for (et,ev,etb) in self.elist:
                 print self._get_engine_str(ev)
                 print self._get_traceback(ev)
                 print
         else:
             try:
                 et,ev,etb = self.elist[excid]
             except:
                 raise IndexError("an exception with index %i does not exist"%excid)
             else:
                 print self._get_engine_str(ev)
                 print self._get_traceback(ev)
     
     def raise_exception(self, excid=0):
         try:
             et,ev,etb = self.elist[excid]
         except:
             raise IndexError("an exception with index %i does not exist"%excid)
         else:
             raise et, ev, etb
 
 def collect_exceptions(rlist, method):
+    from twisted.python import failure
+
     elist = []
     for r in rlist:
         if isinstance(r, failure.Failure):
             r.cleanFailure()
             et, ev, etb = r.type, r.value, r.tb
             # Sometimes we could have CompositeError in our list.  Just take
             # the errors out of them and put them in our new list.  This 
             # has the effect of flattening lists of CompositeErrors into one
             # CompositeError
             if et==CompositeError:
                 for e in ev.elist:
                     elist.append(e)
             else:
                 elist.append((et, ev, etb))
     if len(elist)==0:
         return rlist
     else:
         msg = "one or more exceptions from call to method: %s" % (method)
         # This silliness is needed so the debugger has access to the exception
         # instance (e in this case)
         try:
             raise CompositeError(msg, elist)
         except CompositeError, e:
             raise e