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Lua Academy · Lesson

Mixin Composition and Interface Checks

Mix in multiple behavior tables and validate interface conformance.

What Are Mixins?

Mixins are tables of methods copied into a class. They provide behavior without requiring an inheritance relationship — perfect for cross-cutting concerns.

Simple Mixin Application

Copy methods from a mixin table into the target class.

local Serializable = {
  serialize = function(self)
    local parts = {}
    for k, v in pairs(self) do
      parts[#parts+1] = k .. "=" .. tostring(v)
    end
    return "{" .. table.concat(parts, ", ") .. "}"
  end
}
local function mixin(cls, ...)
  for _, m in ipairs({...}) do
    for k, v in pairs(m) do
      if cls[k] == nil then cls[k] = v end
    end
  end
end
mixin(Animal, Serializable)
print(cat:serialize())

All lessons in this course

  1. Base Class and Constructor Design
  2. Multi-Level Inheritance
  3. Mixin Composition and Interface Checks
  4. instanceof and Type Introspection
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