Source code for camelot.view.action_runner

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import logging

from PyQt4 import QtCore

from camelot.admin.action import ActionStep
from camelot.core.exception import GuiException, CancelRequest
from camelot.view.model_thread import post

LOGGER = logging.getLogger( 'camelot.view.action_runner' )

[docs]class ActionRunner( QtCore.QEventLoop ): """Helper class for handling the signals and slots when an action is running. This class takes a generator and iterates it within the model thread while taking care of Exceptions raised and ActionSteps yielded by the generator. This is class is intended for internal Camelot use only. """ non_blocking_action_step_signal = QtCore.pyqtSignal(object) def __init__( self, generator_function, gui_context ): """ :param generator_function: function to be called in the model thread, that will return the generator :param gui_context: the GUI context of the generator """ super( ActionRunner, self ).__init__() self._generator_function = generator_function self._generator = None self._gui_context = gui_context self._model_context = gui_context.create_model_context() self.non_blocking_action_step_signal.connect( self.non_blocking_action_step ) post( self._initiate_generator, self.generator, self.exception ) def _initiate_generator( self ): """Create the model context and start the generator""" return self._generator_function( self._model_context ) def _iterate_until_blocking( self, generator_method, *args ): """Helper calling for generator methods. The decorated method iterates the generator until the generator yields an :class:`ActionStep` object that is blocking. If a non blocking :class:`ActionStep` object is yielded, then send it to the GUI thread for execution through the signal slot mechanism. :param generator_method: the method of the generator to be called :param *args: the arguments to use when calling the generator method. """ result = None try: result = generator_method( *args ) except CancelRequest: pass while True: if isinstance( result, (ActionStep,)): if result.blocking: return result else: self.non_blocking_action_step_signal.emit( result ) result = self._generator.next() @QtCore.pyqtSlot( object )
[docs] def non_blocking_action_step( self, action_step ): action_step.gui_run( self._gui_context )
@QtCore.pyqtSlot( object )
[docs] def exception( self, exception_info ): """Handle an exception raised by the generator""" from camelot.view.controls.exception import model_thread_exception_message_box model_thread_exception_message_box( exception_info ) self.exit()
@QtCore.pyqtSlot( object )
[docs] def generator( self, generator ): """Handle the creation of the generator""" self._generator = generator # # when model_run is not a generator, but a normal function it returns # no generator, and as such we can exit the event loop # if self._generator != None: post( self._iterate_until_blocking, self.next, self.exception, args = ( self._generator.next, ) ) else: self.exit()
def _was_canceled( self, gui_context ): """raise a :class:`camelot.core.exception.CancelRequest` if the user pressed the cancel button of the progress dialog in the gui_context. """ if gui_context.progress_dialog: if gui_context.progress_dialog.wasCanceled(): raise CancelRequest() @QtCore.pyqtSlot( object )
[docs] def next( self, yielded ): """Handle the result of the next call of the generator :param yielded: the object that was yielded by the generator in the *model thread* """ if isinstance( yielded, (ActionStep,) ): try: self._was_canceled( self._gui_context ) to_send = yielded.gui_run( self._gui_context ) self._was_canceled( self._gui_context ) post( self._iterate_until_blocking, self.next, self.exception, args = ( self._generator.send, to_send,) ) except CancelRequest, exc: post( self._iterate_until_blocking, self.next, self.exception, args = ( self._generator.throw, exc,) ) except Exception, exc: LOGGER.error( 'gui exception while executing action', exc_info=exc) # # In case of an exception in the GUI thread, propagate an # exception to make sure the generator ends. Don't propagate # the very same exception, because no references from the GUI # should be past to the model. # post( self._iterate_until_blocking, self.next, self.exception, args = ( self._generator.throw, GuiException(), ) ) elif isinstance( yielded, (StopIteration,) ): # # Process the events before exiting, as there might be exceptions # left in the signal slot queue # self.processEvents() self.exit() else: raise Exception( 'this should not happen' )

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