signals-slots

问题 Lets consider this simple example: Class Emitter: public QObject { ... signal: surfaceDestroyed(QObject*); public: void emittingMethod(QObject* surface) { emit surfaceDestroyed(surface); delete surface; } } I have a queued connection for this case connect(emitterObject, SIGNAL(surfaceDestroyed(QObject*), receiverObject, SLOT(onSurfaceDestroyed(QObject*)), Qt::QueuedConnection); In onSurfaceDestroyed method the received QObject is dereferenced and used So the question is how safe this code is?

问题 Lets consider this simple example: Class Emitter: public QObject { ... signal: surfaceDestroyed(QObject*); public: void emittingMethod(QObject* surface) { emit surfaceDestroyed(surface); delete surface; } } I have a queued connection for this case connect(emitterObject, SIGNAL(surfaceDestroyed(QObject*), receiverObject, SLOT(onSurfaceDestroyed(QObject*)), Qt::QueuedConnection); In onSurfaceDestroyed method the received QObject is dereferenced and used So the question is how safe this code is?

来源： https://stackoverflow.com/questions/20561690/pyqt-auto-connect-signal

问题 I have a variable t t = 0 I want to start an event whenever t value is changed. How ? There's no valuechanged.connect properties or anything for variables... 回答1: For a global variable, this is not possible using assignment alone. But for an attribute it is quite simple: just use a property (or maybe __getattr__/__setattr__). This effectively turns assignment into a function call, allowing you to add whatever additional behaviour you like: class Foo(QWidget): valueChanged = pyqtSignal(object)

问题 I have a variable t t = 0 I want to start an event whenever t value is changed. How ? There's no valuechanged.connect properties or anything for variables... 回答1: For a global variable, this is not possible using assignment alone. But for an attribute it is quite simple: just use a property (or maybe __getattr__/__setattr__). This effectively turns assignment into a function call, allowing you to add whatever additional behaviour you like: class Foo(QWidget): valueChanged = pyqtSignal(object)

问题 I've ready many posts on how to connect multiple signals to the same event handler in python and pyqt. For example, connecting several buttons or comboboxes to the same function. Many examples show how to do this with QSignalMapper, but it is not applicable when the signal carries a parameter, as with combobox.currentIndexChanged Many people suggest it can be made with lambda. It is a clean and pretty solution, I agree, but nobody mentions that lambda creates a closure, which holds a

问题 I've ready many posts on how to connect multiple signals to the same event handler in python and pyqt. For example, connecting several buttons or comboboxes to the same function. Many examples show how to do this with QSignalMapper, but it is not applicable when the signal carries a parameter, as with combobox.currentIndexChanged Many people suggest it can be made with lambda. It is a clean and pretty solution, I agree, but nobody mentions that lambda creates a closure, which holds a

问题 It seem that the only implementation that provide Safe Cross-Thread Signals for both the Signal class and what's being called in the slot is QT. (Maybe I'm wrong?). But I cannot use QT in the project I'm doing. So how could I provide safe Slots call from a different thread (Using Boost::signals2 for example)? Are mutex inside the slot the only way? I think signals2 protect themself but not what's being done inside the slot. Thanks 回答1: You can combine boost::bind and boost ASIO to create

问题 I have a QMainWindow, and want to handle the "clicked" signal from a smaller widget (such as tableview) inside it. Originally I connect the signal to a slot of this QMainWindow, this is the most common approach. Now I need to tell which mouse button is clicked, and do different things for left and right button, I found that the "clicked" signal don't have the mouse event information. I tried to implement the "mousePressEvent" function,but there are still some problem. if the mouse action is

问题 There's singleton class in python: from PyQt5.QtCore import QObject, pyqtSignal import logging class Singleton(QObject): _instance = None def __new__(cls, *args, **kwargs): if not isinstance(cls._instance, cls): cls._instance = QObject.__new__(cls, *args, **kwargs) return cls._instance class DataStatus(Singleton, QObject): ''' ''' dataChanged = pyqtSignal(str) __val = 'init' def __init__(self): super().__init__() def setVal(self, val): self.dataChanged.emit('emit: ' + val) logging.debug('emit