what happened to EventfulList and friends? about traitlets HOT 6 CLOSED

Eventful was kept with widgets, which is the only thing in IPython that used it:

https://github.com/ipython/ipywidgets/blob/master/ipython_widgets/widgets/eventful.py

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I need eventful containers (List, Dict and Set) in my application. The link above is not working. Can anyone suggest what is the recommended module to use now in 2017?

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@jmsuresh I am unsure of why they were removed. However there is a pull request to implement them again - jupyter-widgets/ipywidgets#1071

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The above PR uses spectate under the hood:

pip install spectate

Check out the examples and let me know what you think.

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Thanks for this. I was trying to test this but could not as it depends on FrozenBunch which is not available in the version I have. Any suggestions?
I am trying to use this eventful container to do a clean MVC pattern for a GUI. I am wondering why there is no popular way to do this as this requirement should be very common.

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@jmsuresh, I am trying to find time to uncouple the pull request from its dependance on the (as yet) unreleased 5.0 version of traitlets. However even when I do, that branch will probably be unstable since its a WIP and will need to respond to changes during review.

The reason eventful traits haven't been done before is twofold:

1. It's hard and requires a deep knowledge of traitlets to implement (which few people have).
2. It is possible to trigger change notifications if you assign a new instance to the trait.
   • this is obviously not ideal though.

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