Pass additional parameter through event_generate?

Question

Is there any way to pass a custom parameter (string for instance) through the event_generate() method?

The problem is that i have two threads. one of them should pass a variable which is required by event handler in the other one. I've tried to declare eventHandler with additional parameter e.g. def refreshCanvas(self, event, param) but then I am unable to pass param through event_generate().

I've also tried to pass it as an existing parameter 'state', which supposed to be a string, but it does not work either.

Class that generates an event:

class GameThread(Thread):
    def __init__(self, gameInstance, gui):
        Thread.__init__(self)

        self.__gameInstance = gameInstance
        gui.event_generate("<<refresh>>", when="tail", state=str(self.__gameInstance.getState()))

The class which suppose to catch this event:

class App(ttk.Frame):
    def __init__(self, parent=None):
        ttk.Frame.__init__(self, parent)
        parent.bind("<<refresh>>", self.refreshCanvas)

    def refreshCanvas(self, event):
        #something
        pass

related: how to use Tcl/Tk bind function on Tkinter's widgets in Python? — jfs
– jfs, Commented Feb 19, 2018 at 8:01

Bicker x 2 · Accepted Answer · 2014-01-27 17:31:02Z

2

I would suggest using the data option as http://www.tcl.tk/man/tcl/TkCmd/event.htm#M16 says

-data string String may be any value; it specifies the user_data field for the event. Only valid for virtual events. Corresponds to the %d substitution for virtual events in binding scripts.

However I've found that it's not yet in Python (see: http://bugs.python.org/issue3405) for now I would suggest use something like a queue and pass the data to the queue and then generate the event and pull the data from the queue in your handler method

EDIT:

A side note I would be careful about using any threading with Tkinter in general. I would suggest looking into using mtTkinter to be on the safe side. mtTkinter is a wrapper around Tkinter that makes it thread safe.

edited Jan 27, 2014 at 17:31

answered Jan 20, 2014 at 12:36

Bicker x 2

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