Source code for taurus.qt.qtcore.communication.communication

#!/usr/bin/env python

#############################################################################
##
# This file is part of Taurus
##
# http://taurus-scada.org
##
# Copyright 2011 CELLS / ALBA Synchrotron, Bellaterra, Spain
##
# Taurus is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
##
# Taurus is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
##
# You should have received a copy of the GNU Lesser General Public License
# along with Taurus.  If not, see <http://www.gnu.org/licenses/>.
##
#############################################################################

"""
comunications.py:
"""

from __future__ import print_function

from taurus.external.qt import QtCore, compat

import weakref

_DEBUG = False


[docs]def get_signal(obj, signalname): """Return signal from object and signal name.""" if '(' not in signalname: return getattr(obj, signalname) name, dtype = signalname.strip(')').split('(') dtype = tuple(dtype.split(',')) return getattr(obj, name)[dtype]
[docs]class DataModel(QtCore.QObject): ''' An object containing one piece of data which is intended to be shared. The data will be identified by its UID (a unique identifier known to objects that intend to access the data) In general, you are not supposed to instantiate objects of this class directly. Instead, you should interact via the :class:`SharedDataManager`, which uses :meth:`SharedDataManager.__getDataModel` to ensure that the DataModels are singletons. ''' dataChanged = QtCore.pyqtSignal(compat.PY_OBJECT) def __init__(self, parent, dataUID, defaultData=None): ''' creator :param parent: (QObject) the object's parent :param dataUID: (str) a unique identifier for the Data Model ''' QtCore.QObject.__init__(self, parent) self.__dataUID = dataUID self.__data = defaultData self.__isDataSet = False self.__readerSlots = [] self.__writerSignals = [] def __repr__(self): return '<DataModel object with dataUID="%s">' % self.dataUID()
[docs] def dataUID(self): ''' returns the data unique identifier :return: (str) ''' return self.__dataUID
[docs] def getData(self): ''' Returns the data object. :return: (object) the data object ''' return self.__data
[docs] def setData(self, data): ''' sets the data object and emits a "dataChanged" signal with the data as the parameter :param data: (object) the new value for the Model's data ''' self.__data = data self.__isDataSet = True self.dataChanged.emit(self.__data)
[docs] def connectReader(self, slot, readOnConnect=True): ''' Registers the given slot method to receive notifications whenever the data is changed. :param slot: (callable) a method that will be called when the data changes. This slot will be the receiver of a signal which has the data as its first argument. :param readOnConnect: (bool) if True (default) the slot will be called immediately with the current value of the data if the data has been already initialized .. seealso:: :meth:`connectWriter`, :meth:`getData` ''' self.dataChanged.connect(slot) if readOnConnect and self.__isDataSet: slot(self.__data) obj = getattr(slot, '__self__', slot) self.__readerSlots.append((weakref.ref(obj), slot.__name__))
[docs] def connectWriter(self, writer, signalname): ''' Registers the given writer object as a writer of the data. The writer is then expected to emit a `QtCore.SIGNAL(signalname)` with the new data as the first parameter. :param writer: (QObject) object that will change the data :param signalname: (str) the signal name that will notify changes of the data .. seealso:: :meth:`connectReader`, :meth:`setData` ''' try: get_signal(writer, signalname).connect(self.setData) except AttributeError: # support old-style signal self.connect(writer, QtCore.SIGNAL(signalname), self.setData) self.__writerSignals.append((weakref.ref(writer), signalname))
[docs] def disconnectWriter(self, writer, signalname): '''unregister a writer from this data model :param writer: (QObject) object to unregister :param signalname: (str) the signal that was registered .. seealso:: :meth:`SharedDataManager.disconnectWriter` ''' ok = get_signal(writer, signalname).disconnect(self.setData) self.__writerSignals.remove((weakref.ref(writer), signalname))
[docs] def disconnectReader(self, slot): ''' unregister a reader :param slot: (callable) the slot to which this was connected .. seealso:: :meth:`SharedDataManager.disconnectReader`, :meth:`getData` ''' ok = self.dataChanged.disconnect(slot) self.__readerSlots.remove((weakref.ref(slot.__self__), slot.__name__))
[docs] def isDataSet(self): '''Whether the data has been set at least once or if it is uninitialized :return: (bool) True if the data has been set. False it is uninitialized''' return self.__isDataSet
[docs] def info(self): readers = ["%s::%s" % (repr(r()), s) for r, s in self.__readerSlots] writers = ["%s::%s" % (repr(r()), s) for r, s in self.__writerSignals] return "UID: %s\n\t Readers (%i):%s\n\t Writers (%i):%s\n" % (self.__dataUID, len(readers), readers, len(writers), writers)
[docs] def readerCount(self): '''returns the number of currently registered readers of this model :return: (int) ''' return len(self.__readerSlots)
[docs] def writerCount(self): '''returns the number of currently registered writers of this model :return: (int) ''' return len(self.__writerSignals)
[docs]class SharedDataManager(QtCore.QObject): ''' A Factory of :class:`DataModel` objects. The :meth:`__getDataModel` method ensures that the created DataModels are singletons. DataModels are not kept alive unless there at least some Reader or Writer registered to it (or another object referencing them) ''' def __init__(self, parent): QtCore.QObject.__init__(self, parent) self.__models = {} def __getDataModel(self, dataUID): ''' Returns the :class:`DataModel` object for the given data UID (which is a singleton). If it does not previously exist, it creates one). .. note:: This is a private method. You are probably more interested in using :meth:`connectReader` and :meth:`connectWriter` :param dataUID: (str) the unique identifier of the data :return: (DataModel) .. seealso:: :meth:`connectReader`, :meth:`connectWriter`, :class:`DataModel` ''' if dataUID not in self.__models: self.__models[dataUID] = DataModel(self, dataUID) return self.__models[dataUID]
[docs] def getDataModelProxy(self, dataUID, callback=None): ''' Returns a :class:`weakref.proxy` to a :class:`DataModel` object for the given data UID or None if the UID is not registered. .. note:: The underlying :class:`DataModel` object may cease to exist if all its readers and writers are unregistered. :param dataUID: (str) the unique identifier of the data :param callback: (callable) same as in :class:`weakref.ref` callback parameter :return: (weakref.proxy or None) .. seealso:: :meth:`connectReader`, :meth:`connectWriter`, :class:`DataModel` ''' if dataUID not in self.__models: return None dm = self.__getDataModel(dataUID) return weakref.proxy(dm, callback)
[docs] def connectReader(self, dataUID, slot, readOnConnect=True): ''' Registers the given slot method to receive notifications whenever the data identified by dataUID is changed. Note that it returns the :meth:`DataModel.getData` method for the given data UID, which can be used for reading the data at any moment. :param dataUID: (str) the unique identifier of the data :param slot: (callable) a method that will be called when the data changes this slot will be the receiver of a signal which has the data as its first argument. :param readOnConnect: (bool) if True (default) the slot will be called immediately with the current value of the data if the data has been already initialized :return: (callable) a callable that can be used for reading the data .. seealso:: :meth:`connectWriter`, :meth:`__getDataModel` ''' m = self.__getDataModel(dataUID) m.connectReader(slot, readOnConnect=True) if _DEBUG: # @todo: comment this line out. ONLY FOR DEBUGGING m.connectReader(self.debugReader) return m.getData
[docs] def connectWriter(self, dataUID, writer, signalname): ''' Registers the given writer object as a changer of the shared data identified by dataUID. The writer is then expected to emit a `QtCore.SIGNAL(signalname)` with the new data as the first parameter Note that it returns the :meth:`DataModel.setData` method for the given data UID, which can be used for changing the data at any moment. :param dataUID: (str) the unique identifier of the data :param writer: (QObject) object that will change the data :param signalname: (str) the signal name that will notify changes of the data :return: (callable) a callable that can be used for setting the data. When using it, one parameter has to be passed containing the new data .. seealso:: :meth:`connectWriter`, :meth:`__getDataModel` ''' m = self.__getDataModel(dataUID) m.connectWriter(writer, signalname) if _DEBUG: # @todo: comment this line out. ONLY FOR DEBUGGING m.connectReader(self.debugReader) return m.setData
[docs] def disconnectWriter(self, dataUID, writer, signalname): '''Unregister the given object as writer of the shared data :param dataUID: (str) the unique identifier of the data :param writer: (QObject) object to unregister :param signalname: (str) the signal that was registered .. seealso:: :meth:`DataModel.disconnectWriter` ''' m = self.__getDataModel(dataUID) m.disconnectWriter(writer, signalname) if m.readerCount() < 1 and m.writerCount() < 1: self.__models.pop(dataUID)
[docs] def disconnectReader(self, dataUID, slot): '''Unregister the given method as data receiver :param dataUID: (str) the unique identifier of the data :param slot: (str) the slot that was registered .. seealso:: :meth:`DataModel.disconnectReader` ''' m = self.__getDataModel(dataUID) m.disconnectReader(slot) if m.readerCount() < 1 and m.writerCount() < 1: self.__models.pop(dataUID)
[docs] def activeDataUIDs(self): ''' Returns a list of currently shared data. Note that this list only reflects the situation at the moment of calling this method: a given DataModel may die at any moment if there are no references to it. :returns: (list<str>) UIDs of currently shared data. ''' return list(self.__models.keys())
[docs] def debugReader(self, data): ''' A slot which you can connect as a reader for debugging. It will print info to the stdout ''' print("SharedDataManager: \n\tSender=: %s\n\tData=%s" % (self.sender(), repr(data)))
[docs] def info(self): s = "" for uid, m in sorted(self.__models.items()): s += m.info() + '\n' return s