Design Patterns

Design Patterns in GDScript

Singleton Pattern

Singletons are objects that ensure there's only one instance of a particular class throughout the entire game. They provide global access to their data and functionality. In Godot, you can implement singletons using auto-loaded nodes. Here are some examples:

1. Player Singleton:

   • Manages player-related data such as health points (HP) and skin customization.
   • Auto-loaded node: res://Player.gd
   • Access it globally with Player.method()

2. Game Singleton:

   • Handles in-game currency (coins), current level, god mode, and cutscene state.
   • Auto-loaded node: res://Game.gd
   • Access it globally with Game.method()

3. Save Singleton:

   • Responsible for saving and loading game progress.
   • Auto-loaded node: res://Save.gd
   • Access it globally with Save.method()

Observer Pattern (Using Signals)

The observer pattern facilitates loosely coupled communication between objects. In Godot, we achieve this using signals. Here's an example:

1. Stun Ability and Enemies:

   • When Aurora uses the stun ability, emit a signal (e.g., "stun_activated").
   • All enemies within her range (that have a handle_stun function) connect to this signal.
   • No need for manual checks; the signal automatically notifies relevant enemies.

2. Enemies attacking:

• When a character enters their range, enemies receive a signal based on that signal they check if the character is the player and they start attacking

# Start chasing the player when it enters chaser's range
func _on_chase_range_body_entered(body: CharacterBody2D) -> void:
	if body.name == "Aurora":
		player = body
		Game.enter_combat()
		chasing = true


# Stop chasing the player when it leaves chaser's range
func _on_chase_range_body_exited(body: CharacterBody2D) -> void:
	if body.name == "Aurora":
		chasing = false
		Game.exit_combat()
		player = null