Refactor project state machine using pub-sub events?

[benjiwheeler]

The project state machine currently serves to trigger events in various components in a roundabout way.

The components must check if a given project state has become the current project state, in their componentDidUpdate() functions.

An alternative approach would be to use an explicit pub-sub model; have components directly subscribe to actions which correspond to project state machine transitions.

One library we could use is https://github.com/mroderick/PubSubJS (this is the most-used js pubsub library, according to npm trends).

Sample usage: https://gist.github.com/pablen/63b57ee80877712ad00ca7849643b4a2

[adroitwhiz]

What are the benefits of PubSubJS over the events module used in scratch-render and scratch-vm?

[benjiwheeler]

@adroitwhiz Thanks for pointing out the similarity! I don't work on those areas of the code -- can you point me to where that module is defined? I didn't see it in either of those repos with a quick look around.

[adroitwhiz]

It's not in the dependencies, but examining the Webpack output, it looks like they're pulling it in from the events NPM package. I remember seeing somewhere that Webpack automatically includes it in builds (and will no longer do so in Webpack 5), but can't find a source for that right now.

[benjiwheeler]

Oh, I see. Hm, not sure what advantages pubsub-js would have!