Lua Polymorphism Tutorial – Complete Guide

Embarking on a coding journey might feel overwhelming at first, but with the right tools and determination anyone can become proficient. In this tutorial, we’ll delve into ‘Lua Polymorphism’, a fundamental programming concept essential for game creation and more. Whether you are a beginner or an experienced coder eager to expand your knowledge, this detailed and engaging guide is tailored just for you.

What is Lua Polymorphism?

Polymorphism in Lua, a lightweight and efficient scripting language, allows us to create diverse objects from the same blueprint. This powerful concept acts like a jack-of-all-trades, capable of handling different data types and functions with similar signature.

What is it for?

Polymorphism is crucial to streamlining complex scripts. By intuitively managing various data types and functions, it opens up a new world of flexibility and code reuse, reducing redundancy and enhancing scalability.

Why should I learn it?

Understanding Lua Polymorphism sets you up for mastering game mechanics, artificial intelligence, and intricate software systems. Its myriad applications in the 21st-century tech space make it an invaluable addition to your coding toolkit.

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Basics of Lua Polymorphism

Now let’s dive into the specifics of Lua polymorphism by setting up the basic examples. Remember, each step is important; understanding these core concepts is key to using polymorphism in more advanced applications.

Creating a Basic Polymorphic Function

Let’s start with crafting a simple polymorphic function that can handle different data types:

function display(input)
  if type(input) == "number" then
    print("The number is " .. input)
  elseif type(input) == "string" then
    print("The string is " .. input)

This function display can accept both numbers and strings, displaying a different message for each respective type. When you run this code, it will first print “The number is 4” and then “The string is Hello”.

Polymorphism and Object-Oriented Programming

Polymorphism has vast applications in Object-Oriented Programming (OOP). Let’s now create a simple class with polymorphic methods:

Animal = {
  type = "animal",
  display_type = function(self)
    print("This is a " .. self.type)

Dog = Animal:new()
Dog.type = "dog"

Dog:display_type() -- Prints "This is a dog"

In this example, we create a basic class called Animal with a method display_type that prints the type of the animal. We then create a new ‘Dog’ object from the Animal blueprint and modify its type to ‘Dog’. When the Dog’s display_type method is called, it now prints “This is a dog”.

Polymorphism with Shared Function Names

Polymorphism allows different objects to share function names. Let’s illustrate this with another example using our Animal class:

Cat = Animal:new()
Cat.type = "cat"
Cat.display_type = function(self)
  print("This is a cute " .. self.type)

Dog:display_type() -- Prints "This is a dog"
Cat:display_type() -- Prints "This is a cute cat"

We create a new ‘Cat’ object, set its type to ‘Cat’ and override the display_type method with a custom message. Even though Dog and Cat share the display_type method name, each object uses its own version of the function.

Advanced Use of Lua Polymorphism

To fully appreciate the power and flexibility of Lua polymorphism, let’s look at some advanced use cases.

Using Polymorphism for Different Shapes

Consider the case where we want to calculate the area for different geometric shapes. Instead of writing separate functions for each shape, we can utilize polymorphism to create one ‘CalculateArea’ function applicable to all shapes:

Shape = {
  name = "shape",
  CalculateArea = function(self)

Circle = Shape:new()
Circle.radius = 5
Circle.CalculateArea = function(self)
  return 3.14 * self.radius * self.radius

Rectangle = Shape:new()
Rectangle.length = 6
Rectangle.width = 4
Rectangle.CalculateArea = function(self)
  return self.length * self.width

print(Circle:CalculateArea())   -- Prints 78.5
print(Rectangle:CalculateArea()) -- Prints 24

Here, the Shape class acts as a blueprint for Circle and Rectangle classes. We create individual CalculateArea() methods for each of the child classes that follow the rules for calculating circle and rectangle areas, respectively.

Efficient Code Organization

Another great advantage of Lua polymorphism is better code organization. Consider a game where you have different enemy types:

Enemy = {
  name = "enemy",
  Attack = function(self)

Goblin = Enemy:new() = "goblin"
Goblin.Attack = function(self)
  print( .. " attacks with a club!")

Dragon = Enemy:new() = "dragon"
Dragon.Attack = function(self)
  print( .. " breathes fire!")

Goblin:Attack()     -- Prints "goblin attacks with a club!"
Dragon:Attack()     -- Prints "dragon breathes fire!"

Instead of scattering different attack functions throughout the code, we tidy things up through polymorphism. Each enemy type has the same Attack() method name, but the implementation is unique for each Enemy subclass (Dragon, Goblin etc).


By adopting polymorphism in your Lua coding techniques, you take a giant leap toward simplifying and structuring your scripts, making your work more scalable and efficient. Here at Zenva, we’re always aiming to present subjects as engaging, valuable and useful and make your learning journey as seamless as possible. Stay tuned for more tutorials!

Fostering Inheritance with Polymorphism

Polymorphism, when combined with inheritance, can create a more abstract and organized codebase. Let’s demonstrate this with an example involving birds:

Bird = {
  type = "bird",
  callSound = function(self)

Sparrow = Bird:new()
Sparrow.type = "sparrow"
Sparrow.callSound = function(self)
  print("Chirp Chirp! I am a " .. self.type)

Crow = Bird:new()
Crow.type = "crow"
Crow.callSound = function(self)
  print("Caw Caw! I am a " .. self.type)

Eagle = Bird:new()
Eagle.type = "eagle"
Eagle.callSound = function(self)
  print("Screetch! I am an " .. self.type)

Sparrow:callSound() -- Prints "Chirp Chirp! I am a sparrow"
Crow:callSound()    -- Prints "Caw Caw! I am a crow"
Eagle:callSound()   -- Prints "Screetch! I am an eagle"

Each type of bird inherits from the Bird ‘class’, and overrides the callSound() method with its own unique sound. In spite of having the same method name, each bird type (Crow, Sparrow, Eagle) has a distinct implementation.

Polymorphic Tables

Lua’s tables can also exhibit polymorphic properties. Let’s see an illustration using a simple table operation:

function draw(t)

Square = {
  draw = function(self)
    print("Drawing a square")

Circle = {
  draw = function(self)
    print("Drawing a circle")

draw(Square)     -- Prints "Drawing a square"
draw(Circle)     -- Prints "Drawing a circle"

Irrespective of the object passed to the draw() function, it always calls the respective draw method of the object. This behavior is an example of how polymorphism can be leveraged within Lua’s tables.

Using Polymorphism in Game Development

Lua’s power in game development is significantly enhanced with Polymorphism. Consider a game scenario with different character actions:

Character = {
  type = "character",
  action = function(self)

Warrior = Character:new()
Warrior.type = "warrior"
Warrior.action = function(self)
  print(self.type .. " swings sword!")

Mage = Character:new()
Mage.type = "mage"
Mage.action = function(self)
  print(self.type .. " casts spell!")

Warrior:action()     -- Prints "warrior swings sword!"
Mage:action()        -- Prints "mage casts spell!"

Polymorphism allows for the Character class to be a blueprint for Warrior and Mage classes. The action() method for each class corresponds to the action of that character in the game. This modularity and reusability make Polymorphism a significant benefit when developing games with Lua.

Where to Go Next?

Now that you’ve got a grasp on Lua Polymorphism and its potential applications, where might you take your newfound knowledge next? Engaging in project-based learning and practicing the implementation of these concepts in real-time applications will solidify your understanding.

We encourage you to explore our Roblox Game Development Mini-Degree. This comprehensive collection of courses covers game creation with Roblox Studio and Lua, diving into genres like obstacle courses, melee combat games, and FPS games. It’s an excellent platform for both novice and seasoned developers eager to build their portfolios while learning about multiplayer functionality, leaderboards, and more.

For a more extensive selection, feel free to browse our catalog of Roblox courses. With our versatile range of content, you can easily progress from beginner to professional at your own pace. Continue your learning journey with Zenva and unlock new opportunities in the thriving game market!


Mastering Lua polymorphism is a significant step towards amplifying your coding skills and unlocking advanced functionalities in game creation and beyond. Its set of unique benefits, including code reuse, scalability, and better organization, make it an indispensable tool for any developer’s toolkit.

Hard skills, like Lua, are the lifeblood of the tech ecosystem. Now that you’re a step closer to mastering this versatile scripting language, it’s time to put your knowledge into action. Explore more about game creation through Zenva’s Roblox Game Development Mini-Degree and prepare yourself to create, innovate, and impress. As pioneers in the edtech industry, we look forward to guiding you further on your journey to becoming the 21st-century tech-savvy professional.

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