Find out who triggered an aggregated channel callback

[claudiu-coman]

It would be nice if we knew what channel triggered the callback.

At the moment if you're subscribed to channels A, B, C for example and the callback is triggered, you can't tell where the changes came from. But there might be times when you might want to ignore changes from A after the initial rendering of the widget. You need A to have data in the beginning, but you don't care about it afterwards.

Some flag on each of the channels indicating whether or not the callback was triggered by them would help a lot.

[palcu]

👍 I had the same problem while debugging. However, I don't know how this should be fixed.

[aismail]

great use-case! I'll whip up a solution and come back to you

[aismail]

Who wants to implement this with a test-case? I propose an extra parameter for the aggregated channels callback, called 'cause', that will be the last one (thus optional).

Here is where we call the callback (and see a few lines above that for the second use-case). It's very simple to add the 'cause', because you have the channel triggering the callback.

[ovidiuch]

Good find, I'm sure I needed this more than once. I'm still wrapping my head around the design pattern implications, but the solution @aismail proposed is quite slick as it doesn't alter any previous code and is easy to implement.

@claudiu-coman you could create the pull request yourself if you want to give it a shot, we're here to help.