Reactive Props V2 - Githubissues

The original reactive props system was based on a naive implementation (a hard-coded pattern match for the shared and props tables in a prop and a metatable to detect reads/writes on the shared table) that was proving difficult to extend further. This PR rebuilds the reaction system to be based on a new primitive, basalt.reactive, which is not coupled to the environment. It also does away with the naive pattern matching. Any global variable can now be accessed in a reactive prop. Additionally, reactive props are now full Lua expressions, which are computed to return a value. This makes it possible to do things like this:

<script>
  local basalt = require("basalt")
  getCount, setCount = basalt.reactive(0)
</script>

<button text={"Times clicked: " .. getCount()}>
  <onClick>
    setCount(getCount() + 1)
  </onClick>
</button>

<label text={"Times clicked * 2 = " .. getCount() * 2} />

Internally, this works in much the same way that Signals work in Solid.js. We populate a list of observers for a reactive value on the first pass render, based on calls to their respective get functions. A subsequent call of the set function will then update all these observers.

Other changes

Removed the shared table, there's no need for it anymore
Removed basalt from layout envs, because if it's needed it can just be imported. Unnecessary global variables are bad!
Also removed the main variable from layouts loaded into a Frame

Pyroxenium / Basalt

Reactive Props V2 #71