Lua Academy · Lesson

Component-Based Scripting

Design game entities as tables with behavior components in Lua.

Lesson 2 of 413 steps

Component-Based Scripting is a free Lua Academy lesson on CoddyKit. This is lesson 2 of 4. Any 3 lessons of this learning path are free to read in full — after that, CoddyKit PRO unlocks every lesson, plus hands-on practice with a built-in code editor and a 24/7 AI tutor. It is part of the Lua Academy learning path, and your progress syncs across the web and the CoddyKit app. The Lua Academy course includes 4 lessons in total.

What Is Component-Based Design?

Instead of deep class hierarchies, entities are composed of components — small, focused tables of data and behavior. An entity is just a collection of components.

Entity as a Table

An entity is a table with an id and a components sub-table. Components are added and removed at runtime.

local function newEntity(id)
  return {id = id, components = {}}
end
local player = newEntity(1)

Adding Components

Attach a component by setting a named key in the components table.

player.components.position = {x=0, y=0}
player.components.health   = {hp=100, max=100}
player.components.sprite   = {image="player.png", scale=1}

Systems Process Components

A system processes all entities that have a required set of components. Systems iterate entities and update component data.

local function moveSystem(entities, dt)
  for _, e in ipairs(entities) do
    local pos = e.components.position
    local vel = e.components.velocity
    if pos and vel then
      pos.x = pos.x + vel.dx * dt
      pos.y = pos.y + vel.dy * dt
    end
  end
end

Component Scripts

Attach Lua functions as component behavior — a simple form of scripting per entity.

player.components.ai = {
  update = function(self, entity, dt)
    -- move towards target
  end
}

Component Registry

A registry maps component type names to factory functions, enabling components to be created by name (e.g., from a level file).

local registry = {}
function registry.register(name, factory)
  registry[name] = factory
end
function registry.create(name, ...)
  return registry[name](...)
end

Removing Components

Set the component to nil to remove it. The entity will then be ignored by systems that require it.

player.components.health = nil  -- entity is "dead"

World and Entity Manager

A World object stores all entities and systems, iterates systems each tick, and provides entity query APIs.

Querying Entities by Component

Provide a query function that returns all entities having all specified components.

local function query(world, ...)
  local required = {...}
  local result = {}
  for _, e in ipairs(world.entities) do
    local ok = true
    for _, comp in ipairs(required) do
      if not e.components[comp] then ok = false; break end
    end
    if ok then result[#result+1] = e end
  end
  return result
end

Prefabs

A prefab is a template table of components. Instantiate new entities from prefabs by deep-copying the template.

Benefits over Inheritance

No deep hierarchies.
Behavior mixed at runtime.
Easy to add/remove features.
Data-driven from config files.

Component Design Question

In component-based design, what does a System do?

Answer it in the interactive lesson

Recap: Component-Based Scripting

Entities are tables of components. Systems process entities with required components. This decoupled, data-driven architecture is more flexible than deep inheritance hierarchies and works naturally in Lua.

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Frequently Asked Questions

Is the “Component-Based Scripting” lesson free?

Yes — any 3 lessons of the Lua Academy learning path, including “Component-Based Scripting”, are free to read in full here on the web. After that, CoddyKit PRO unlocks every lesson, plus interactive practice with a built-in code editor and a 24/7 AI tutor. The Lua Academy course includes 4 lessons in total.

What will I learn in “Component-Based Scripting”?

Design game entities as tables with behavior components in Lua. You practise Lua Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Lua Academy?

No prior experience is required. Lua Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 2 of 4.

How long does the “Component-Based Scripting” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Lua Academy lesson?

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