工廠模式用於封裝對象創(chuàng)建邏輯，使代碼更靈活、易維護(hù)、松耦合。其核心答案是：通過集中管理對象創(chuàng)建邏輯，隱藏實現(xiàn)細(xì)節(jié)，支持多種相關(guān)對象的創(chuàng)建。具體描述如下：工廠模式將對象創(chuàng)建交給專門的工廠類或方法處理，避免直接使用new Class()；適用於多類型相關(guān)對象創(chuàng)建、創(chuàng)建邏輯可能變化、需隱藏實現(xiàn)細(xì)節(jié)的場景；例如支付處理器中通過工廠統(tǒng)一創(chuàng)建Stripe、PayPal等實例；其實現(xiàn)包括工廠類根據(jù)輸入?yún)?shù)決定返回的對象，所有對象實現(xiàn)共同接口；常見變體有簡單工廠、工廠方法和抽象工廠，分別適用於不同複雜度的需求。

The Factory pattern is a design pattern used in software development to encapsulate the logic of creating objects. Instead of directly instantiating classes with constructors like new Class() , the Factory pattern delegates the responsibility of object creation to a separate method or class—often referred to as a "factory." This helps make your code more flexible, easier to maintain, and less tightly coupled.

Why Use the Factory Pattern?

One of the main reasons to use the Factory pattern is to centralize object creation logic. This becomes especially useful when:

• You have multiple types of related objects that need to be created.
• The creation logic might change over time.
• You want to hide implementation details from the calling code.

For example, imagine you're building an application that works with different types of payment processors—like Stripe, PayPal, and Square. Instead of scattering checks like if type == 'stripe' then new StripeProcessor() throughout your codebase, you can encapsulate this logic inside a factory.

How Does It Work in Practice?

At its core, the Factory pattern typically involves:

• A Factory class or static method that decides which object to return based on input.
• A common interface or base class that all created objects implement or extend.

Here's a simple example in pseudocode:

 class PaymentProcessorFactory {
    public function createProcessor($type) {
        if ($type === 'stripe') {
            return new StripeProcessor();
        } elseif ($type === 'paypal') {
            return new PayPalProcessor();
        }
        throw new Exception("Unknown processor type");
    }
}

This way, whenever you need a processor, you just ask the factory for one, and it handles the details.

When Should You Use It?

You'll find the Factory pattern useful in situations like:

• Your app needs to support multiple implementations of a feature (eg, logging to file vs. database).
• Object creation requires extra setup steps or configuration that you want to keep out of the main calling code.
• You want to simplify testing by allowing factories to return mock objects during tests.

That said, don't reach for it by default. If your object creation logic is straightforward and unlikely to change, using a factory might add unnecessary complexity.

Common Variations

There are a few variations of the Factory pattern that you might come across:

• Simple Factory : Not technically a formal design pattern but commonly used. It's basically a single class with a method that returns different instances based on parameters.
• Factory Method : Defines an interface for creating an object but lets subclasses alter the type of objects that will be created.
• Abstract Factory : Goes a step further and provides an interface for creating families of related or dependent objects without specifying their concrete classes.

Each variation has its own use case, so pick the one that best fits your current situation.

基本上就這些。

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