Hey, My biggest pain points with the Observable runtime have always been mutable state and the implicitness of reactivity in general. Mutable and viewof feel like hacks that completely circumnavigate the reactive parts, relying on an additional event/notification mechanism that is then reintegrated…

Using this you can do something like: dependentState = { let i = this ? this[0] : 0; while (true) { yield [i++, changingState]; } } it probably doesn’t answer your request but it’s another way to solve the issue.

Yeah, this however suffers from its inversion of control and makes code quite messy and hard to understand, especially when showing it to people new to observable. Edit: Also your changes introduced a subtle bug, which nicely illustrates the point :smiley: . Due to the i++ you will “loose” one inc…

Can you provide a more “real world” example to motivate this use case? It’s not clear to me why knowing the number of times that changingState has changed (since the notebook loaded? since the changingState cell was edited?) is useful. There are a variety of ways to accomplish things like this, but…

Here’s a related technique I sometimes use, if it helps: [image] Reference Tracking Using a mutable, you can maintain an array of “live” instances of a particular thing. For example, here I declare four things: And below I show a table of the currently-known things. If you edit the cells …

Hey Mike, Thanks for taking the time :smiley:! As for a concrete example of the generator use case: I’m writing the GUI for a NLP parser in observable, including a visualisation for the search graph, and would like to keep a d3.simulation object in one cell with the current nodes and their positi…

This sounds like you are fighting the representation issue between: a stream of states Vs. a stream of delta updates If you underlying state is a set of objects. you can either transmit ADD/DELETE operations (stream of updates) OR, you can transmit the whole set each time (stream of states). Thi…

@tomlarkworthy Interesting but a bit besides the point :sweat_smile:. The contents of the stream (snapshots vs. deltas), are orthogonal to the mechanics of processing them (with stateful operators). In my concrete example I’m also streaming the entire snapshot of node positions. The issue is that …

For stateful DOM I “reconcile” against “this” Hypertext literal reconciliation with nanomorph / Tom Larkworthy / Observable . I think thats one of the few good uses of ‘this’ as it pushes the state management to a general library component.

[image] somethingelseentire: Your example notebook doesn’t work for me (things don’t get removed when I delete them), but I get the idea. Ah, whoops, I was generating a Text node rather than an Element, so it should work now…

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mootari April 19, 2021, 7:25pm 10

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