Hooks

config.ts

import { createNinja, Katana, Shuriken } from './entities';

export default {
	Warrior: createNinja,
	Weapon: () => new Katana(),
	ThrowableWeapon: () => new Shuriken(),
};

entities.ts

import hook from './hook';
import { ThrowableWeapon, Warrior, Weapon } from './interfaces';

export class Katana implements Weapon {
	public hit() {
		return 'cut!';
	}
}

export class Shuriken implements ThrowableWeapon {
	public throw() {
		return 'hit!';
	}
}

export function createNinja() {
	const [
		weapon,
		throwableWeapon,
	] = hook<[Weapon, ThrowableWeapon]>('Weapon', 'ThrowableWeapon');
	return class Ninja implements Warrior {
		public fight() {
			return weapon.hit();
		}
		public sneak() {
			return throwableWeapon.throw();
		}
	}
}

hook.ts

import config from './config';

export default function hook<T extends any[]>(...keys: string[]) {
	return keys.map(key => config[key]) as T;
}

interfaces.ts

export interface Warrior {
	fight(): string;
	sneak(): string;
}

export interface Weapon {
	hit(): string;
}

export interface ThrowableWeapon {
	throw(): string;
}