17.类继承

类继承

类继承是一种机制，您可以在其中从另一个类派生一个类，以获得共享一组属性和方法的类层次结构
要从类继承，请使用extends关键字：

# Animal.gd
extends Node2D # Inherits from the Global Node2D class
class_name Animal

# Horse.gd
extends Animal # Inherits from the Global Node2D class
class_name Horse

在这种情况下，Animal 类称为超类，而 Horse 类称为子类。
当子类从超类继承时，子类获取超类的所有函数和类变量。

# Animal.gd
extends Node2D # Inherits from the Global Node2D class
class_name Animal
var health: int = 100
func getHealth() -> int:
    return health

# Horse.gd
extends Animal 
# Horse class has the health variable and the getHealth() method
class_name Horse
func newlyCreatedFunction() -> void:
    print(getHealth()) # 100

# Animal.gd
extends Node2D # Inherits from the Global Node2D class
class_name Animal
var health: int = 100
func getHealth() -> int:
    return health

# Horse.gd
extends Animal 
# Horse class has the health variable and the getHealth() method
class_name Horse
func newlyCreatedFunction() -> void:
    print(getHealth()) # 100

重写超类函数

您可以通过仅在子类中写出函数来覆盖超类函数。

# Animal.gd
extends Node2D # Inherits from the Global Node2D class
class_name Animal
func attack() -> void:
    print("Animal Attacks")

# Horse.gd
extends Animal 
# Horse class has the health variable and the getHealth() method
class_name Horse
func attack() -> void:
    print("Horse Attacks") # Override function attack()

为什么需要使用继承？

继承允许更简洁的代码，它使我们更容易定义类。
基本上，当你想重用一个类时，你会使用继承。