Qt connect signal slot twice

By Mark Zuckerberg

Signals and Slots - Qt Documentation

Connecting in Qt 5. There are several ways to connect a signal in Qt 5. Old syntax. Qt 5 continues to support the old string-based syntax for connecting signals and slots defined in a QObject or any class that inherits from QObject (including QWidget) . connect( sender, SIGNAL( valueChanged( QString, QString ) ), receiver, SLOT( updateValue( QString ) ) ); Qt for Python Signals and Slots - Qt Wiki Traditional syntax: SIGNAL and SLOT() QtCore.SIGNAL() and QtCore.SLOT() macros allow Python to interface with Qt signal and slot delivery mechanisms. This is the old way of using signals and slots. The example below uses the well known clicked signal from a QPushButton.The connect method has a non python-friendly syntax. Signals & SlotsQt for Python Signals and slots are loosely coupled: A class which emits a signal neither knows nor cares which slots receive the signal. Qt’s signals and slots mechanism ensures that if you connect a signal to a slot, the slot will be called with the signal’s parameters at the right time. Signals and slots can take any number of arguments of any type. PyQt Signals and Slots - Tutorials Point

I have defined a signal and connect it to a slot. I found that the slot would be invoked twice and I trace into the Qt source code. It seems that the QMetaObject::activate will call QAbstractDeclarativeData::signalEmitted() to relay the signal from working thread to main thread (PS.

QTimer Class | Qt Core 5.12.3 Creates a connection from the timeout() signal to slot to be placed in a specific event loop of context, and returns a handle to the connection. This method is provided for convenience. It's equivalent to calling QObject::connect(timer, &QTimer::timeout, context, slot, connectionType). This function was introduced in Qt 5.12. [SOLVED] Connecting signal and slot between ... - Qt Forum

Qt Signals and Slot connected twice... what happens ...

Сигналы и слоты в Qt - это механизм, который используются для взаимодействия между несколькими объектами. Фактически, сигналы и слоты помогают нам реализовать шаблон "Наблюдатель" (скоро описание этого шаблона будет добавлено в блог, если в скором времени... Сигнально-слотовые соединения | Программирование Qt Сигналы и слоты в Qt реализованы с механизмом надежности работы в потоках, а это означает, что вы можете высылать сигналы и получать, не заботясь о блокировке ресурсов. Вы можете перемещать объект, созданный в одном потоке, в другой. Если вдруг получится так, что...

Signals and slots are loosely coupled: A class which emits a signal neither knows nor cares which slots receive the signal. Qt's signals and slots mechanism ensures that if you connect a signal to a slot, the slot will be called with the signal's parameters at the right time. Signals and slots can take any number of arguments of any type.

Signals and Slots - Qt Documentation Signals and slots are loosely coupled: a class which emits a signal neither knows nor cares which slots receive the signal. Qt's signals and slots mechanism ensures that if you connect a signal to a slot, the slot will be called with the signal's parameters at the right time. Signals and slots can take any number of arguments of any type. They are completely typesafe: no more callback core dumps! c++ - Qt: QLineEdit editingFinished signal twice when changing focus ... In my case I am a bit stuck as I am getting the editFinished signal twice even when my slot handler is doing nothing. For a test, I have an array of QLineEdit which use a signalMapper to connect the editingFinished() signals to a single slot. Signals and slots Connect | Qt Forum