Qt5 Signal Slots
方式二 Qt5后推荐的写法，如果编译的时候信号或槽不存在是无法编译通过的，相当于编译时检查，不容易出错，还有就是槽的写法可以直接写在public控制域下，不一定非要写在public slots:控制域下； 方式三 采用了lambda表达式的写法，更加方便快捷。.
Qt Signal Slot Queue
Graphical applications (GUI) are event-driven, unlike console or terminal applications. A users action like clicks a button or selecting an item in a list is called an event.
Nd the index of the signal and of the slot Keep in an internal map which signal is connected to what slots When emitting a signal, QMetaObject::activate is called. It calls qt metacall (generated by moc) with the slot index which call the actual slot. In the header file, we have declared two slots. The slots is not a C keyword, it is a Qt5 extension. These extensions are handled by the preprocessor, before the code is compiled. When we use signals and slots in our classes, we must provide a QOBJECT macro at the beginning of the class definition. Otherwise, the preprocessor would complain.
If an event takes place, each PyQt5 widget can emit a signal. A signal does not execute any action, that is done by a slot.
Related course:
Create GUI Apps with PyQt5
Signals and slot introduction
Consider this example:
The button click (signal) is connected to the action (slot). In this example, the method slot_method will be called if the signal emits.
Qt Signal Slots
This principle of connecting slots methods or function to a widget, applies to all widgets,
or we can explicitly define the signal:
PyQt supports many type of signals, not just clicks.
Example
We can create a method (slot) that is connected to a widget. A slot is any callable function or method.
On running the application, we can click the button to execute the action (slot).
Qt Signal Slot Dll
Qt5 Signal Slots App
If you are new to programming Python PyQt, I highly recommend this book.