Question

我正在为实验设置创建一个PyQt GUI。这将涉及计算量大的操作，因此我的目标是基于多处理模块的架构，并受到this answer的启发。

QMainWindow创建

子进程具有单独的“任务”队列以获取来自主进程的指令和共享的“回调”队列以将指令发送回主进程
一个QThread来轮询“回调”队列并将消息转换为连接到QMainWindow的插槽的信号

该示例使用具有任意签名self.emit(QtCore.SIGNAL(signature), args)的旧样式信号。 我的问题是：是否可以使用新式信号复制此功能？

我知道this question和this one。但是，总是用一般对象发出valueChanged信号不符合我的需要，因为我想连接到具有不同名称的插槽，具体取决于从其中一个子进程收到的签名。

这是一个有效的代码（注意，为简单起见，MainWindow中只有一个子进程和一个插槽，但在完成的代码中会有几个）：

from multiprocessing import Process, Queue
import sys
from PyQt4 import QtGui, QtCore


class CallbackQueueToSignal(QtCore.QThread):

    def __init__(self, queue, parent=None):
        super(CallbackQueueToSignal, self).__init__(parent)
        self.queue = queue

    def _emit(self, signature, args=None):
        if args:
            self.emit(QtCore.SIGNAL(signature), args)
        else:
            self.emit(QtCore.SIGNAL(signature))

    def run(self):
        while True:
            signature = self.queue.get()
            self._emit(*signature)


class WorkerProcess(Process):

    def __init__(self, callback_queue, task_queue, daemon=True):
        super(WorkerProcess, self).__init__()
        self.daemon = daemon
        self.callback_queue = callback_queue
        self.task_queue = task_queue

    def _process_call(self, func_name, args=None):
        func = getattr(self, func_name)
        if args:
            func(args)
        else:
            func()

    def emit_to_mother(self, signature, args=None):
        signature = (signature, )
        if args:
            signature += (args, )
        self.callback_queue.put(signature)

    def run(self):
        while True:
            call = self.task_queue.get()
            # print("received: {}".format(call))
            self._process_call(*call)

    def text_upper(self, text):
        self.emit_to_mother('data(PyQt_PyObject)', (text.upper(),))


class MainWin(QtGui.QMainWindow):

    def __init__(self, parent=None):
        super(MainWin, self).__init__(parent)

        self.data_to_child = Queue()
        self.callback_queue = Queue()

        self.callback_queue_watcher = CallbackQueueToSignal(self.callback_queue)
        self.callback_queue_watcher.start()

        self.child = WorkerProcess(self.callback_queue, self.data_to_child)
        self.child.start()

        self.browser = QtGui.QTextBrowser()
        self.lineedit = QtGui.QLineEdit('Type text and press <Enter>')
        self.lineedit.selectAll()
        layout = QtGui.QVBoxLayout()
        layout.addWidget(self.browser)
        layout.addWidget(self.lineedit)
        self.layout_widget = QtGui.QWidget()
        self.layout_widget.setLayout(layout)
        self.setCentralWidget(self.layout_widget)
        self.lineedit.setFocus()
        self.setWindowTitle('Upper')
        self.connect(self.lineedit, QtCore.SIGNAL('returnPressed()'), self.to_child)
        self.connect(self.callback_queue_watcher, QtCore.SIGNAL('data(PyQt_PyObject)'), self.updateUI)

    def to_child(self):
        self.data_to_child.put(("text_upper", ) + (self.lineedit.text(), ))
        self.lineedit.clear()

    def updateUI(self, text):
        text = text[0]
        self.browser.append(text)

    def closeEvent(self, event):
        result = QtGui.QMessageBox.question(
            self,
            "Confirm Exit...",
            "Are you sure you want to exit ?",
            QtGui.QMessageBox.Yes | QtGui.QMessageBox.No)
        event.ignore()

        if result == QtGui.QMessageBox.Yes:
            # self.pipeWatcher.exit()
            self.child.terminate()
            event.accept()

if __name__ == '__main__':

    app = QtGui.QApplication(sys.argv)

    form = MainWin()
    form.show()

    app.aboutToQuit.connect(app.deleteLater)
    sys.exit(app.exec_())

Answer 1

new-style signal and slot syntax要求信号预先定义为继承自QObject的类的类属性。实例化类时，会自动为实例创建绑定信号对象。绑定信号对象具有connect/disconnect/emit方法和__getitem__语法，允许选择不同的重载。

由于绑定信号是对象，因此使用旧式语法允许动态发送任意信号不再有意义。这只是因为任意信号（即不是预定义的信号）无法为连接的插槽提供相应的绑定信号对象。

但问题中的示例代码仍然可以移植到新式语法中：

class CallbackQueueToSignal(QtCore.QThread):
    dataSignal = QtCore.pyqtSignal([], [object], [object, object])   
    ...

    def _emit(self, signal, *args):
        getattr(self, signal)[(object,) * len(args)].emit(*args)

    def run(self):
        while True:
            args = self.queue.get()
            self._emit(*args)


class WorkerProcess(Process):
    ...

    def emit_to_mother(self, *args):
        self.callback_queue.put(args)

    def text_upper(self, text):
        self.emit_to_mother('dataSignal', (text.upper(),))


class MainWin(QtGui.QMainWindow):
    def __init__(self, parent=None):
        ...

        self.lineedit.returnPressed.connect(self.to_child)
        self.callback_queue_watcher.dataSignal[object].connect(self.updateUI)

发出具有任意签名的新式PyQt信号

1 个答案: