GDScript Constructor Tutorial – Complete Guide

Welcome to this comprehensive tutorial about the GDScript constructor. If you’re a game development enthusiast or an aspiring game developer, this guide offers you the knowledge you need to grasp this fundamental concept. With beginner-friendly instructions and engaging examples revolving around simple game mechanics, mastering the GDScript constructor will be an adventurous and rewarding learning journey.

Understanding GDScript Constructor

The GDScript constructor is a critical function in the GDScript programming language, which is primarily used in the Godot game engine. It’s crucial in initializing objects when they’re created.

Why the GDScript Constructor?

Efficient utilization of the GDScript constructor can make a significant difference to your coding efficiency and game performance. It’s valuable for initializing game characters, objects or any game elements with specific attributes upon their creation. Understanding and mastering the GDScript constructor can make creating complex game mechanics easier and more efficient.

The Power of GDScript Constructor

Learning GDScript constructor empowers you to produce cleaner and more manageable code. It’s a skill that every game developer aiming to make a mark in using Godot game engine must possess.

Accessibility of GDScript Constructor

Regardless of your level of coding proficiency, this tutorial ensures that everyone from beginners to experienced coders can grasp and harness the power of the GDScript constructor. Endeavor to understand and master this valuable instrument as we journey through this tutorial.

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Writing Your First Constructor in GDScript

Let’s begin with writing a basic constructor in GDScript for a game character. This constructor will initialize the character with attributes like name, health, and speed.

class GameCharacter:
    var name
    var health
    var speed

    func _init(_name, _health, _speed):
        name = _name
        health = _health
        speed = _speed

This simple constructor uses the _init function, which is called whenever a new object of GameCharacter is created. It takes three parameters – _name, _health, and _speed – and assigns them to the object’s variables.

Creating Objects Using the Constructor

Now, let’s use our constructor to create a new game character object.

var character ="Hero", 100, 10)

This creates a new GameCharacter object with the name ‘Hero’, health ‘100’ and speed ’10’.

Accessing Data From Constructor

Once you’ve created an object using a constructor, you can access the data initialized by the constructor. Here’s an example:

print( // Outputs: Hero
print(character.speed) // Outputs: 10

These operations output the name and speed of our character object, confirming that the object was correctly initialized using our GDScript constructor.

Working With Multiple Constructors

In some cases, you might want multiple constructors for different kinds of initialization. In GDScript, we can use default argument values to accomplish this.

class GameCharacter:
    var name
    var health
    var speed

    func _init(_name = "Unknown", _health = 0, _speed = 0):
        name = _name
        health = _health
        speed = _speed

This allows you to create a GameCharacter object with no supplied arguments, as seen here:

var character2 =
print( // Outputs: Unknown

In this case, the GameCharacter object will be initialized with default values specified in the constructor. This gives you flexibility when initializing new objects.

Using Constructors to Customize Game Logic

Constructors in GDScript can add a layer of dynamism to your game logic. Take, for example, a situation where the game character can choose between different weapons, each with unique attributes. A constructor can be utilized to ensure each weapon object is initialized properly.

class Weapon:
    var name
    var damage
    var range

    func _init(_name = "Default Weapon", _damage = 0, _range = 1):
        name = _name
        damage = _damage
        range = _range

var sword ="Sword", 50, 2)
var bow ="Bow", 30, 5)
var axe ="Axe", 70, 1)

In this scenario, we have different weapons initialized with distinct attributes. This allows each game character to select a weapon that best fits their combat style, creating a more engaging gaming experience.

Accessing Nested Constructors

When working with nested objects, you can also access and manipulate them using their constructors. Here’s how:

class GameCharacter:
    var name
    var health
    var speed
    var weapon

    func _init(_name, _health, _speed, _weapon):
        name = _name
        health = _health
        speed = _speed
        weapon = _weapon

var sword ="Sword", 50, 2)
var character ="Hero", 100, 10, sword)

This example demonstrates how to use a constructor to initialize a game character with a Weapon object.

Constructor-based Initialization of Array Elements

GDScript constructors can be used creatively to initialize array elements or lists with specific properties. Here’s an illustrative example:

class GameCharacter:
    var name
    var health
    var speed

    func _init(_name, _health, _speed):
        name = _name
        health = _health
        speed = _speed

var characters = ["Hero-1", 100, 10),"Hero-2", 110, 12),"Hero-3", 80, 15)

In this example, we have an array of game character objects, each initialized using the constructor of the GameCharacter class. This efficient use of constructors facilitates cleaner organization of game data, potentially enhancing game development speed.

Handling Errors in Constructors

Coding errors are intrinsic to any programming process. Being aware of how to trace and handle errors in constructors can save you valuable debugging time. For instance, it’s crucial to ensure that parameter types match the expected types. Otherwise, an error will occur.

class GameCharacter:
    var name
    var health
    var speed

    func _init(_name, _health, _speed):
        assert(typeof(_name) == TYPE_STRING)
        assert(typeof(_health) == TYPE_INT)
        assert(typeof(_speed) == TYPE_INT)
        name = _name
        health = _health
        speed = _speed

var character ="Hero", "100", 10) // This will cause an error

In this example, we have used the ‘assert’ keyword and ‘typeof’ function to ensure that the parameters passed to the constructor are of the expected types. This reduces the likelihood of errors stemming from incorrect data types.

Using Constructors as Objects’ Control Center

One strong use case for constructors is turning them into control centers for object behavior. This can help enforce default behaviors in a class, and set rules for how objects interact between each other. For example:

class GameCharacter:
    var name
    var health
    var speed
    var alive

    func _init(_name, _health, _speed):
        name = _name
        health = _health
        speed = _speed
        alive = true

    func take_damage(damage):
        if alive:
            health -= damage
            if health <= 0:
                alive = false
                print(name + " has died.")
                print(name + " took " + str(damage) + " damage.")

In this constructor-augmented class, we can now track whether or not a game character is alive, and make subsequent calls to take_damage yield different results depending on the state of the GameCharacter object..

Creating Alphabetically Sorted Characters

Let’s imagine we want to create an object for each letter of the alphabet, each with its own set properties. Constructors aid us in automating the process without manual input for every character:

class AlphabetLetter:
    var letter
    var order

    func _init(_letter, _order):
        letter = _letter
        order = _order

var alphabet = []
for i in range(26):
    alphabet.append(AlphabetLetter(chr(i + 65), i + 1))

The constructor in the class AlphabetLetter is being used to create 26 different objects, each representing a letter of the alphabet, and assigns them an order based on their position in the alphabet.

Working with Dynamic Object Attributes

Constructors come in handy when we want our objects to have dynamic attributes. We can set up our constructor to take in a dictionary, and assign attributes dynamically based on the provided dictionary.

class DynamicObject:
    func _init(attributes: Dictionary):
        for attribute in attributes.keys():
            self.set(attribute, attributes[attribute])

var dynamic ={"color": "red", "shape": "circle", "size": 2})
print(dynamic.color) // Outputs: red
print(dynamic.shape) // Outputs: circle
print(dynamic.size) // Outputs: 2

This setup allows us to create and manipulate objects with dynamic attributes, which can be especially helpful when working with data structures with varying parameters.

Managing Public and Private Data with Constructors

We can also use constructors to set up private object data (data that should only be modified by the object itself). This can play a crucial role in managing class integrity and minimizing potential bugs.

class BankAccount:
    var public_name
    var _private_balance

    func _init(_public_name):
        public_name = _public_name
        _private_balance = 0

    func deposit(amount):
        if amount > 0:
            _private_balance += amount
            print("Deposit successful!")
            print("Invalid deposit amount.")

    func balance():
        return _private_balance

var account ="John Doe")
print(account.balance()) // Outputs: 1000

Here, we’ve set up a BankAccount class where the balance can only be altered internally, through safe methods such as deposit(). This keeps the integrity of our BankAccount object intact, thus reducing scope for mismanagement and bugs.

Exploring New Learning Horizons

If you’ve found this deep-dive into the GDScript constructor insightful, it’s time to take a leap and explore more intricate aspects of game development. Luckily, we’ve got the perfect next step for you: our Godot Game Development Mini-Degree program.

The mini-degree is designed to offer a comprehensive and thorough foundation in game development using the lightweight and open-source Godot 4 engine. You’ll learn to create cross-platform games with stunning graphics and explore various game genres, from RPGs to platformers. Through practical projects, you can build a solid portfolio of real Godot projects.

This mini-degree program provides you with the flexibility of learning at your own pace. It’s suitable for both beginners who are entering the world of game development, as well as experienced coders looking to expand their expertise. Our certified instructors at Zenva, who are seasoned gamers and coders themselves, have designed this curriculum for maximum learning impact. And, if you want to explore a more extensive collection of Godot courses, our Godot Courses directory will help you take an even deeper dive. Here’s to an engaging and rewarding learning experience ahead!


In this guide, we’ve journeyed through the wonders of GDScript constructors and how they provide a foundational construct for game development using the Godot engine. Using constructors, you can bring dynamism and improved structure to your game characters, weapons, and entire game logic. Your adventure into game development doesn’t stop here, though. This is only the beginning.

If you’re ready to take the plunge into a more comprehensive, hands-on learning experience, we invite you to join our Godot Game Development Mini-Degree program. Dive into the exhilarating world of game design, development, and deployment with us at Zenva. Let’s create fantastic gaming experiences together.

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