Recap - Health System

Part of the Object Oriented Programming section of Coddy's GDScript journey. Lesson 39 of 65.

Challenge

Easy

Build a health system in which the health component announces every change and a health bar reacts to it.

Health (health.gd) stores max_hp and hp (both start at the value given to the constructor) and declares three signals: damaged(amount, hp), healed(amount, hp) and died.

take_damage(amount) lowers hp, never below 0, and emits damaged with the HP actually lost and the new hp. When hp reaches 0, it also emits died.
heal(amount) raises hp, never above max_hp, and emits healed with the HP actually restored and the new hp. Healing at full health emits nothing.
Once hp is 0, both methods do nothing.

HealthBar (health_bar.gd) has watch(health), which connects all three signals to its own methods. They print -8 HP [12/20], +5 HP [17/20] and Game over. The bar stores the maximum HP it needs as a number; do not keep a reference to the Health object.

The supplied code reads the maximum HP and how many commands follow (damage 8, heal 5), then prints the final HP. For a maximum of 20 and damage 8, heal 5, heal 10, damage 30, heal 5 it prints:

-8 HP [12/20]
+5 HP [17/20]
+3 HP [20/20]
-20 HP [0/20]
Game over
Final HP: 0

Your code goes in health.gd and health_bar.gd. main.gd holds the supplied input/output code and cannot be edited.

Try it yourself

extends Node

func _ready():
	# Supplied input/output code: keep it as it is
	var health := Health.new(int(OS.read_string_from_stdin()))
	var bar := HealthBar.new()
	bar.watch(health)
	var count := int(OS.read_string_from_stdin())
	for i in count:
		var parts := OS.read_string_from_stdin().split(" ")
		if parts[0] == "damage":
			health.take_damage(int(parts[1]))
		elif parts[0] == "heal":
			health.heal(int(parts[1]))
	print("Final HP: ", health.hp)