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Documentation Index

Fetch the complete documentation index at: https://docs.sure-developer.com/llms.txt

Use this file to discover all available pages before exploring further.

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Track

The track module gives you a compact reactive state primitive inspired by signal-style APIs. A state returns a getter and setter. Effects subscribe to one or more getters and run when a subscribed state changes. 
local track = sure.getModule('track')

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State and effect

local amount, setAmount = track.state('amount', 1)

track.effect(function()
  print(('Amount changed to %s'):format(amount()))
end, { amount })

setAmount(2)
Effects are dependency based. Updating a different state will not trigger an effect unless that state’s getter is included in the dependency list.

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Tables and functional updates

When the initial value, returned value, or next value is a table, sure_lib deep-clones it at the state boundary. This prevents accidental mutation of stored state through an old table reference. 
local profile, setProfile = track.state('profile', {
  name = 'Sure',
  level = 1
})

local current = profile()
current.level = 99

setProfile({
  name = 'Sure',
  level = 2
})

print(profile().level) -- 2
Setters also accept a function. The function receives a copied current value and returns the next value. 
local notices, setNotices = track.state('notices', {})

setNotices(function(items)
  items[#items + 1] = {
    id = 'n-1',
    message = 'Saved'
  }

  return items
end)

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API

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state(stateName, initialValue)
function
required
Creates a reactive state. stateName is used internally to connect dependencies to effects.
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getter
function
Call the getter with no arguments to read the current value: amount().
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setter
function
Call the setter with a new value or a function (currentValue) -> nextValue to update state and notify dependent effects.
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effect(callback, dependencies)
function
required
Registers a callback that runs when any getter in dependencies changes.
Use track for local derived behavior inside one resource. It is not a network replication layer.