Can you customize "exit" action using guizero?

[emailman]

I would like to run some code when a guizero App window is closed. I found the code below for tkinter, but I'm not sure if it can be applied to a guizero app or if guizero supports another way of doing the same thing:

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root.protocol('WM_DELETE_WINDOW', doSomething)  # root is your root window

def doSomething():
    # check if saving
    # if not:
    root.destroy()
 

[Garvan]

You can put your cleanup code after app.display() and it will run when app.display() closes.

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from guizero import App, Text

app = App()
text = Text(app, text="hello world")
app.display()
print ("Cleanup")

[emailman]

Thanks Garvan. That's a brilliantly simple solution.

[scotty101]

If you want to register a function at exit of tkinter, you can use the WM_DELETE_WINDOW method.

using the "tk" property allows you to access the underlying tkinter widget of a guizero widget.

I've now been reliably informed that guizero has an event callback for this already, see below

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def goodbye():
    print("Goodbye!")
    app.destroy()

app.when_closed = goodbye

This is better than the method proposed by Garvan since the app will still exist when this function is called. Lets say you want to save the current text in the window, if you do the Garvan method, the app will have already been destroyed and all the information lost by the time the code after the .display() is executed.

[emailman]

Hi Scotty,

Thanks for pointing out the handy, but undocumented, event handler "app.when_closed". I agree that's the way to go if you need some information from the app before it ceases to exist, not unlike the dead parrot.

Eric