Factory Pattern

Factory Pattern nima?

Factory Pattern — bu creational design pattern bo‘lib, object (obyekt) yaratish jarayonini alohida funksiyaga ajratib beradi. Ya’ni, new operatorini har joyda ishlatish o‘rniga, obyektlarni factory orqali yaratamiz.

Bu yondashuv kodni:

• tushunarliroq
• kengaytirish osonroq
• kam bog‘langan (loosely coupled)

qiladi.

Oddiy object yaratish (Factorysiz)

Avval oddiy usulni ko‘rib chiqamiz:

const car1 = {
  type: "sedan",
  speed: 180,
};

const car2 = {
  type: "suv",
  speed: 220,
};

Muammo:

• Kod doimiy ravishda takrorlanadi
• Yangi object (obyekt) qo‘shish qiyinlashadi
• Logika markazlashmagan

Oddiy Factory Function

Endi object yaratishni bitta funksiyaga o‘tkazamiz:

function createCar(type, speed) {
  return {
    type,
    speed,
    drive() {
      console.log(`${type} ${speed} km/soat tezlikda yurmoqda`);
    },
  };
}

const car1 = createCar("sedan", 180);
const car2 = createCar("suv", 220);

car1.drive(); // sedan 180 km/soat tezlikda yurmoqda
car2.drive(); // suv 220 km/soat tezlikda yurmoqda

Factory funksiya orqali object yaratish bitta joyda amalga oshmoqda va bu nafaqat kodni o’zgartirishga qulay, balki kod takrorlanmayapti ham.

Pros

DRY: Factory pattern bir xil xususiyatlarga ega bo‘lgan bir nechta kichik object’larni yaratishimiz kerak bo‘lganda foydali bo‘ladi. Factory function joriy environment yoki user’ga xos configuration’ga qarab moslashtirilgan custom object’ni osonlik bilan return qilishi mumkin.

Cons

Not really a pattern: JavaScript’da factory pattern asosan new keyword’idan foydalanmasdan object qaytaradigan function’dan iborat. ES6 arrow function’lar bizga har safar implicit ravishda object return qiladigan kichik factory function’larni yaratish imkonini beradi.

Biroq, ko‘p hollarda har safar yangi object yaratish o‘rniga yangi instance’lar yaratish xotira (memory) jihatidan samaraliroq bo‘lishi mumkin.

class Car {
  constructor(type, speed, company) {
    this.type = type;
    this.speed = speed;
    this.company = company;
  }

  async getCars() {
    const cars = await fetch(`https://example.com/cars/${this.company}`);
    return cars;
  }
}

const car1 = new Car({
  type: "sedan",
  speed: 180,
  company: "Toyota",
});

const car2 = new Car({
  type: "suv",
  speed: 220,
  company: "Hyundai",
});

Yaratilgan barcha object’lar uchun getCars method bir xil. Yangi instance’lar yaratish orqali getCars method’i object’ning o‘zida emas, balki prototype’da joylashadi, bu esa xotirani (memory) tejaydi.