ECS Example in Dart using OOP

ECSExampleInDartOOPStyle.dart

class Point {
    final num x;
    final num y;
    const Point(this.x, this.y);
    Point operator + (Point p) {
        return new Point(p.x + x, p.y + y);
    }
    Point scale(num factor){
        return new Point(x * factor, y * factor);
    }
}


compose(f,g){
    return (x) => f(g(x));
}

abstract class Position {
    Point position;
}

abstract class Velocity {
    Point velocity;
}

abstract class Life {
    bool life;
}

abstract class Mass {
    num mass;
}

abstract class Controllability {
    bool controllability;
}

abstract class Groundedness {
    bool groundedness;
}

abstract class Flying {
    bool flying;
}

abstract class Destructability {
    bool destructability;
}

abstract class Entity {
    Entity copy();
}

class Mario extends Entity implements Position, Velocity, Life, Mass, Controllability, Groundedness {
    Point position = new Point(0,0);
    Point velocity = new Point(0,0);
    bool life = true;
    num mass = 20;
    bool controllability = true;
    bool groundedness = true;
    
    @override Mario copy(){
        var marioCopy = new Mario()
            ..position = this.position
            ..velocity = this.velocity
            ..life     = this.life
            ..mass     = this.mass
            ..controllability = this.controllability
            ..groundedness = this.groundedness;
        
        return marioCopy;
    }
}

class Goomba extends Entity implements Position, Velocity, Life, Mass, Groundedness {
    Point position = new Point(20,0);
    Point velocity = new Point(-1,0);
    bool life = true;
    num mass = 20;
    bool groundedness = true;
    
    @override Goomba copy(){
        var goombaCopy = new Goomba()
            ..position = this.position
            ..velocity = this.velocity
            ..life = this.life
            ..mass = this.mass
            ..groundedness = this.groundedness;
        return goombaCopy;
    }
}

class LakituCloud extends Entity implements Position, Velocity, Life, Flying {
    Point position = new Point(0,100);
    Point velocity = new Point(-2, 0);
    bool life = true;
    bool flying = true;
    
    @override LakituCloud copy(){
        var lakituCloudCopy = new LakituCloud()
            ..position = this.position
            ..velocity = this.velocity
            ..life = this.life
            ..flying = this.flying;
        return lakituCloudCopy;
    }
}

class Block extends Entity implements Position, Destructability {
    Point position = new Point(0,0);
    bool destructability = true;
    
    @override Block copy(){
        var blockCopy = new Block()
            ..position = this.position
            ..destructability = this.destructability;
        return blockCopy;
    }
}

Entity move(Entity entity){
    if ((entity is Position) && (entity is Velocity)){
        var outputEntity = entity.copy();
        outputEntity.position = (entity as Position).position + (entity as Velocity).velocity;
        return outputEntity;
    }else{
        return entity;
    }
}

typedef Entity PointToEntity(Point);
PointToEntity applyGravity(Point force){
    return (Entity entity){
        if ((entity is Mass) && (entity is Velocity)){
            var outputEntity = entity.copy();
            outputEntity.velocity = (entity as Velocity).velocity + force.scale((entity as Mass).mass);
            return outputEntity;
        }else{
            return entity;
        }       
    };
}

final update = compose(move, applyGravity(new Point(0, -9.81)));

void main() {
  final Mario mario = new Mario();
  final Goomba goomba = new Goomba();
  final LakituCloud lakituCloud = new LakituCloud();
  final Block block = new Block();
  
  final List<Entity> entities = [mario, goomba, lakituCloud, block];  
  
  final List<Entity> updatedEntities = new List.from(entities.map(update));
}