how to do without polymorphism

Unity Engine
,
1

Polymorphism is the advantage of OOP，but dots has no polymorphism. with the OOP, i can show different action for different person by a function. However, in the dots,if i want to show different action, i should code different system and attach different component.

2

Correct. With an ECS approach you tend to write more systems, but each is much smaller with a well-defined purpose.

This is also the primary way to re-use logic, when you combine multiple systems in new and interesting ways.

3

OOP:

class Animal {
}

class Cat : Animal {
}

class Dog : Animal {
}

ECS:

struct Animal : IComponentData {
}

struct Cat : IComponentData {
}

struct Dog : IComponentData {
}

// A cat entity
Entity cat = entityManager.CreateEntity(typeof(Animal), typeof(Cat));

// A dog entity
Entity dog = entityManager.CreateEntity(typeof(Animal), typeof(Dog));

// A system for Animals (base class)
class CommonAnimalStuffSystem : ComponentSystem {
}

// A system only for dogs
class DogStuffSystem : ComponentSystem {
}

// A system only for cats
class CatStuffSystem : ComponentSystem {
}
1 Like