[SOLVED] Acquiring a reference to the emitting widget with QtRuby

Acquiring a reference to the emitting widget with QtRuby

I'm currently connecting the signal to a function like this:

 dashboard.ui.start_button_r1.connect(:clicked, dashboard.ui.start_button_r1, :handler)

where start_button_r1 is a QPushButton

Now what I want is a reference to the sending widget within handler, since I will connect this signal to several widgets. Ideally I would like my handler function to receive a emitter argument I can play around with. I could put handlerwithin a class inheriting from Qt::Object (say HandlerContainer) and call sender(), but then how do I connect the signal to HandlerContainer's inner method? I tried instance.method(:handler), but connect doesn't receive slots in that way

I usually use this approach in PyQt, but can't figure out how to do it with Ruby. I feel like I'm doing something terribly wrong since there isn't much discussion on how to get the sender from within a slot using QtRuby. How is it usually done? I have read about QSignalMapper, but that seems awfully overkill for my use case.

Solution

You can do it with QObject::sender() function. As you've said inside handler slot, typecast sender() to the type, you expect, QPushButton in your case, and you,ve got a reference to sender object.

In c++ it could be done like this:

// inside handler method
QPushButton *tmpBtn= dynamic_cast<QPushButton*>(sender());

Edit:

 A minimal example on how to do this in Ruby:

class SlotContainer < Qt::Object
   slots "handler()"

   def handler
    puts "called by: " + sender().to_s
   end
end

if $0 == __FILE__
    app = Qt::Application.new(ARGV) 
    ui = Ui_MainWindow.new
    container = SlotContainer.new
    window = Qt::MainWindow.new
    ui.setupUi(window)
    Qt::Object.connect(ui.pushButton, SIGNAL("clicked()"), container, SLOT("handler()"))
    window.show
    app.exec
end