signals-slots

I am new to Qt and GUI programming overall but i have done a fair bit of coding in python - writing modules and so on. I need to develop simple GUIs for some of my old modules. What i am trying to do can be represented by the following simple example: def f(x, y): z = x + y return z For this function i will give two line-edits for x and y and one for z. Now i create a push-button 'calculate' and when i do that i want it to take x and y from the line-edits run the function f(x,y) and give the output to z. Is there any way to do this directly in Qt Designer by adding the function f(x,y) written

This question already has an answer here: C++ Qt signal and slot not firing 3 answers I have been working on learning C++ and Qt4 recently, but I have hit a stumbling block. I have the following class and implementation: class Window : public QWidget { public: Window(); public slots: void run(); private: //... }; and Window::Window() { //... connect(runBtn,SIGNAL(clicked()),this,SLOT(run())); //... } Window::run() { //... } However, when I attempt to build and run it, although it builds just fine, it immediately exits out with the message Object::connect: No such slot QWidget::run() Unless I

QtCore.QObject.connect(my_button, QtCore.SIGNAL('clicked()'), my_func) and my_button.clicked.connect(my_func) I usually use the first option, but then I found the second one and want to know what is a difference between them. The first option is the old-style signal and slot syntax , which is now obsolete. You can still use it in PyQt4, but it is not supported at all in PyQt5. The second option is the new-style signal and slot syntax , which can be used in PyQt5 and all recent versions of PyQt4 (it was introduced in v4.5). The PyQt docs lists the following disadvantages of the old-style syntax

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 acted on the smaller widget, the MainWindow won't go into its mousePressEvent. Some document says that

The QML TreeView has an signal named: doubleClicked(QModelIndex) ref: https://doc.qt.io/qt-5.10/qml-qtquick-controls-treeview.html#doubleClicked-signal Its possible connect that existing signal in a C++ QObject::connect() ?? I tried this: QQmlApplicationEngine engine; QObject *myTreeMenu = engine.rootObjects().at(0)->findChild<QObject*>("myTreeMenu"); connect(myTreeMenu , SIGNAL(doubleClicked(QModelIndex)), this, SLOT(slotModelClicked(QModelIndex))); But i receive this return error: QObject::connect: No such signal TreeView_QMLTYPE_63_QML_68::doubleClicked(QModelIndex) in '...' QObject: