Imperative workflow in C++/Qml application

[anda_skoa]

As you've said yourself there are quite a number of ways to do that.

One approach that i find rather elegant myself is the request handler pattern used for example by the QML API of WebEngineView.

The C++ side emits a signal that transports a request context, which is then used by the QML side to communicate the result back.

See for example http://doc.qt.io/qt-5/qml-qtwebengin...quested-signal

If you know or require that the QML side uses a modal dialog and thus a nested event loop, then you can retrieve the user's input right after the emit returns.

RequestContext context;
 
emit requestDialog(&context);
 
// continue in "linear" workflow

RequestContext context;

emit requestDialog(&context);

// continue in "linear" workflow

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If you want to handle the nested event loop on the C++ side, it will look more like this:

RequestContext context;
QEventLoop loop;
 
connect(&context, &RequestContext::done, &loop, &QEventLoop::quit);
 
emit requestDialog(&context);
 
// check if dialog has not already been
if (!context.isDone() {
    loop.exec();
}
 
// continue in "linear" workflow

RequestContext context;
QEventLoop loop;

connect(&context, &RequestContext::done, &loop, &QEventLoop::quit);

emit requestDialog(&context);

// check if dialog has not already been
if (!context.isDone() {
    loop.exec();
}

// continue in "linear" workflow

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Cheers,
_