making Control a cooperative class #490
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I used the observer pattern to propagate changes in a usercontrol object. For that purpose my widget derives from UserControl and another class. Calling super().__init__() in my class did not work because I had the wrong order in the class calls, i.e., class MyWidget(UserControl, Subject), rather than class MyWidget(Subject, UserControl). By including super().__init__() in the Control class such points of confusion are easy to prevent. Here is a further discussion: https://rhettinger.wordpress.com/2011/05/26/super-considered-super/
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Interesting. Is that 'Subject' class your own? What problem were you solving? Is there something from your solution you can share with the rest of Flet community? |
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First, thanks for making flet. It's a great tool.
Here is the class that I used:
https://www.geeksforgeeks.org/observer-method-python-design-patterns/. It's
not my own.
When changing some widget, I wanted to update another widget that presented
just another view on the data. Exampe: in widget one I append a number to a
list, and then widget two presents the sum of the list. This second widget
has to update itself if the list gets changed in widget one.
If I am not mistaken, Qt implements this with signal and slots. Some
general support for the observer pattern would certainly be a useful
extension in flet. However, it's not hard to implement oneself, in
particular if UserControl becomes a cooperative class :-)
…On Mon, 17 Oct 2022 at 21:47, Feodor Fitsner ***@***.***> wrote:
Interesting. Is that 'Subject' class your own? What problem were you
solving? Is there something from your solution you can share with the rest
of Flet community?
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Got it, thanks! |
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I used the observer pattern to propagate changes in a usercontrol object. For that purpose my widget derives from UserControl and another class, called Subject. Calling super().init() in my class did not work because I had the wrong order in the class calls, i.e., class MyWidget(UserControl, Subject), rather than class MyWidget(Subject, UserControl). By including super().init() in the Control class such points of confusion are easy to prevent. Here is a further discussion:
https://rhettinger.wordpress.com/2011/05/26/super-considered-super/