Does one create an event to notify parent window/GUI of something?

Chris Green cl at isbd.net
Sun Mar 12 17:32:48 EDT 2017


Vlastimil Brom <vlastimil.brom at gmail.com> wrote:
> 2017-03-12 13:14 GMT+01:00 Chris Green <cl at isbd.net>:
> ...
> >
> > This question relates to how one communicates between windows/GUIs.
> >
> > When the program starts theres a main GUI, class name abookgui.  If
> > you want to add new entries or modify existing entries an edit GUI is
> > started in a separate window, class abookeditgui.
> >
> > I need the abookeditgui window to be able to tell the parent abookgui
> > window that it has completed whatever it was doing.
> ...
> >
> > --
> > Chris Green
> > ·
> > --
> > https://mail.python.org/mailman/listinfo/python-list
> 
> Hi,
> I am not sure, whether it counts as the "bad way" of doing it, you
> mentined, but the most obvious approach seems to be passing a
> reference to the parent object on creation of the child object (e.g.
> dialog window), that way you can have event handlers in the child
> class/gui, which can call methods of the parent class; it can then
> handle e.g. saving the data.

Yes, I saw this as one way of doing it but I wondered whether there
was a neater way.

What I have actually done is to pass a function as a paraemeter into
the Edit GUI so that when the Edit GUI completes it can call the
function that the 'parent' has passed to it.  Similar really to what
you have suggested.


> Other than that, you can use specialised mechanisms like pubsub,
> especially for more complex requirements of event handling.
> I don't have experience with pygtk, but I believe, there might be
> similar principles like in other gui toolkits.
> You may find this more comprehensive explanation (refering to tkinter) useful:
> http://stackoverflow.com/a/33650527
> 
> The concept of controller is be more flexible for some usecases,
> however at the very basics you can couple the child class to the
> parent directly, such as in the following sample:
> http://stackoverflow.com/a/30690881
> 
> Note especially the referencing of objects between classes in the
> mentioned code:
> 
> class Widgets(tk.Frame):
>     def __init__(self, parent):
>     ...
>         self.parent = parent
>   ...
>         self.button = tk.Button(text='hello', command=self.parent.get_details)
> 
> 
> 
> ...
> 
> class App(tk.Frame):
> ...
>         self.widgets = Widgets(self)
>   ...
>    def get_details(self): ...
> 
> 
> And of course, you could probably also use a global variable to
> reference the respective objects, but this would most likely count as
> the bad way to do it in some respect.
> 
Yes! :-)


> I believe, others might give more specific answers, with respect to
> the gui you are using.
> 
> hth,

Yes, thank you.

-- 
Chris Green
·


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