Running GUI and "GObject.mainloop.run()" together?

[Ajay Garg]

I would like to elaborate more on my more findings of case b) and c); I
hope to be as thorough as possible ::



*
I have almost confirmed from my side, that is impossible to run two loops
in a single thread of execution.

So, for example, once the GUI sets in via
                                       Gtk.main()

that's it.. the thread will now not proceed to any further of code.


Same happens, if the other loop, is run via ::

dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
                                       session_bus = dbus.SessionBus()
                                       name =
dbus.service.BusName("org.example.Sample", session_bus)
                                       object = ExampleObject(session_bus,
'/ExampleObject')
                                       mainloop = GObject.MainLoop()

So, if two different loops need to be run, we need to have threads. Period.

PLEASE LET ME KNOW IF MY ASSERTIONS ARE CORRECT :)



*
Now, when I tried running the two loops in two different threads, I
enountered strange errors.
I dare say that they seem to be due to inappropriate specification of the
event sources for the two loops (which in turn is wholly due to my limited
knowledge of dbus-loops).

Which brings me to the following related questions ::

            1)
            As per
http://www.pygtk.org/pygtk2reference/class-gobjectmainloop.html, it seems
that we must be able to add event sources to
            gobject.mainloop; however, I do not see any way to that.

            HOW CAN EVENT SOURCES BE ADDED?


            2)
            Once the event sources are added, each instance of
gobject.mainloop (in its particular thread), will cater  to only those
sources.

            PLEASE LET ME KNOW IF MY ASSERTION IS CORRECT.


            3)
            How is dbus."mainloop.glib.DBusGMainLoop(set_as_default=True)"
related to gobject.mainloop?


            4)
            How is dbus."mainloop.glib.DBusGMainLoop(set_as_default=False)"
related to gobject.mainloop?


            5)
            Is it necessary at all to specify
"mainloop.glib.DBusGMainLoop(set_as_default=True)" or
            "mainloop.glib.DBusGMainLoop(set_as_default=False)" when using
gobject.mainloop?


I know some of the answers are obvious (like points 2 and 5), but I notice
whatever I have searched on the net, people are just happy to get things
working.
This is ok if there is just  a single thread with a single
gobject.mainloop, but things get monstrous when two loops (one a
"Gtk.main()", and other "gobject.mainloop") come in; as now things won't
work unless there is a clear understanding of what each line of
bootstrapping-code does.


I will be grateful to receive any in-sights in this.








On Mon, Dec 24, 2012 at 1:56 PM, Ajay Garg <ajaygargnsit at gmail.com> wrote:

> Hi all.
>
> This is another question that arises as part of my efforts to run a GUI
> application, as well as a dbus-service within the same process.
> (The other question being at
> http://mail.python.org/pipermail/python-dev/2012-December/123287.html)
>
> For a recap of the brief history, I have a parent process, that is
> spawning  a child process via "subprocess".
> Currently, the child-process is a GUI process; however, I intend to
> "behave" it as a dbus-service as well.
>
> Thus,
>
> a)
> I subclassed the child-process "main" class with  "dbus.service.Object";
> however, I then got the error
> "metaclass conflict: the metaclass of a derived class must be a (non-
> strict) subclass of the metaclasses of all its bases"
>
>
> b)
> I then used composition, wherein another  class, "RemoteListener"
> deriving  from "dbus.service.Object" was made an attribute of the "main"
> class. That worked.
> However, when  I do
>
>                dbus.mainloop.glib.DBusGMainLoop(set_as_default=True)
>                GObject.mainloop.run()
>
> in the "RemoteListener"'s __init__ method, the GUI of the "main" class
> fails to load (apparently, because the "mainloop.run()" causes the
> singular, main-thread to go into busy-wait).
>
>
> c)
> I tried option b), but now instantiating "RemoteListener" in a separate
> thread; however, no improvement :(
>
>
>
>
> Is there a way to run GUI and a dbus-service together? Or is a
> dbus-service pure "backend" process? :P
>
> I will be grateful for any pointers; if you need me to test anything else,
> please let me know, I will be more than willing :)
>
>
>
>
> Regards,
> Ajay
>



Regards,
Ajay
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