[makspll]

Context: a value provided to a subtree and read by any component below, instead of passed through the props of every component in between.

local Theme = ui.create_context({ accent = "#ffcc00" })          -- the default value

ui.provide(Theme, { accent = "#00ccff" }, { ui.element(Inventory) })

local Slot = ui.component("Slot", function(props)
    local theme = ui.use_context(Theme)                          -- nearest provided value, or the default
    ...
end)

• provide is a node whose children (and what they mount later: components, show and list regions) see the value
• what is provided is remembered where each component and region is mounted (a shared linked list, no copy), so re-renders and regions running later see the same values
• the value is read when a component renders: provide a signal for a value which changes

Stacked on #727. Tested in Lua and Rune (a component inside a show region mounted after the first render, and after a reload).

[semanticdiff-com]

Review changes with  

Changed Files

File	Status
assets/tests/reactive_ui/inventory/inventory.lua	62% smaller
crates/bevy_mod_scripting_reactive_ui/src/runtime.rs	9% smaller
assets/tests/reactive_ui/inventory_rune/inventory.rn	Unsupported file format
crates/bevy_mod_scripting_reactive_ui/src/element.rs	0% smaller
crates/bevy_mod_scripting_reactive_ui/src/lib.rs	0% smaller

[github-actions]

Bencher Report

Project	Bevy Scripting
Branch	agent/reactive-ui-context
Testbed	linux-gha

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