Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
1.3k views
in Technique[技术] by (71.8m points)

qt - Passing an argument to a slot

I want to override mouseReleaseEvent with a bunch of QActions and QMenus...

connect(action1, SIGNAL(triggered()), this, SLOT(onStepIncreased()));

connect(action5, SIGNAL(triggered()), this, SLOT(onStepIncreased()));

connect(action10, SIGNAL(triggered()), this, SLOT(onStepIncreased()));

connect(action25, SIGNAL(triggered()), this, SLOT(onStepIncreased()));

connect(action50, SIGNAL(triggered()), this, SLOT(onStepIncreased()));

So I want to pass an argument to the slot onStepIncreased (as you can imagine they are 1,5,10,25,50). Do you know how I can do it?

Question&Answers:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

With Qt 5 and a C++11 compiler, the idiomatic way to do such things is to give a functor to connect:

connect(action1,  &QAction::triggered, this, [this]{ onStepIncreased(1); });
connect(action5,  &QAction::triggered, this, [this]{ onStepIncreased(5); });
connect(action10, &QAction::triggered, this, [this]{ onStepIncreased(10); });
connect(action25, &QAction::triggered, this, [this]{ onStepIncreased(25); });
connect(action50, &QAction::triggered, this, [this]{ onStepIncreased(50); });

The third argument to connect is nominally optional. It is used to set up the thread context in which the functor will execute. It is always necessary when the functor uses a QObject instance. If the functor uses multiple QObject instances, they should have some common parent that manages their lifetime and the functor should refer to that parent, or it should be ensured that the objects will outlive the functor.

On Windows, this works in MSVC2012 & newer.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...