Qt/C++: What's the best way to call a method asynchronously in Qt event loop without having to write its name as string?

Question

The normal way is with invokeMethod:

QMetaObject::invokeMethod(this, "methodName", Qt::QueuedConnection);

which works fine, except that I don't want to write methods in strings. Like ever. Why? Because this is a refactoring nightmare. Imagine having to change a method name for some reason. The software will malfunction and I'll have to notice in stderr that the method doesn't exist.

My solution?

I use QTimer. Like this:

QTimer::singleShot(0, this, &ClassName::methodName);

which seems to work fine. What I like about this is that you can replace the &ClassName::methodName part with a lambda/bind and it'll still be bound to the correct object (in case I need to use it with QThread) with the expected variable referencing we understand in standard C++:

QTimer::singleShot(0, threadObject, [this, param1, &param2](){ this->methodName(param1, param2); });

Better solutions exist?

But... I'm hoping there's a better way to do this because someone reading my code will not understand why I'm using a QTimer here... so I gotta comment everything.

Is there a better way to do this that's compatible with versions of Qt down to 5.9 or 5.7? What's the best solution you know?

Answer 1

Since Qt 5.10 there are functor-based overloads of QMetaObject::invokeMethod.

This means that you can ditch the string-based approach and use the modern way of calling methods with invokeMethod too.