PHP 8引入了多項重要新特性，顯著提升了性能、代碼可讀性和開發(fā)體驗。 1. JIT編譯提升執(zhí)行速度，尤其適用于CPU密集型任務(wù)，通過php.ini配置控制；2. 聯(lián)合類型支持更靈活的類型聲明，允許直接定義多個參數(shù)類型；3. 命名參數(shù)增強函數(shù)調(diào)用的可讀性和安全性，避免順序錯誤；4. match表達式提供比switch更簡潔的條件返回方式，具備嚴格比較和無穿透特性；5. 構(gòu)造函數(shù)屬性提升減少樣板代碼，使類定義更簡潔；此外還包括throw表達式、屬性替代注解等改進，整體讓PHP 8更現(xiàn)代、強大且易用，升級雖需投入但值得。

PHP 8 brought a bunch of notable changes and new features that improve performance, code readability, and developer experience. If you're working with PHP or planning to upgrade, here are the most impactful additions worth knowing.

1. JIT Compilation – Faster Execution

One of the biggest highlights in PHP 8 is the introduction of JIT (Just-In-Time) compilation . This feature compiles parts of PHP code into native machine code at runtime, reducing interpretation overhead.

• It doesn't speed up every script equally — it shines more in CPU-intensive tasks like heavy math operations or large-scale APIs.
• You can control how it works using settings in php.ini , such as opcache.jit_buffer_size and opcache.jit .

Keep in mind: for most web applications, the performance boost might be subtle unless your app does heavy processing.

2. Union Types – More Flexible Type Declarations

Before PHP 8, if you wanted to accept multiple types in a function parameter or property, you had to rely on comments or skip type checking. Now, union types let you specify that directly:

 public function setResponse(string|int|float $value): void {
    // ...
}

This makes type declarations clearer and safer without needing custom logic or loose typing.

Also, PHP 8.1 adds support for never , true , false , and even array | null combinations, giving you fine-grained control over what values are allowed.

3. Named Arguments – Cleaner and Safer Function Calls

Named arguments allow you to pass parameters by name instead of position:

 function createPost(string $title, string $content, bool $published = false) { ... }

createPost(title: "Hello World", content: "My first post", published: true);

Why this matters:

• Improves readability, especially when calling functions with many optional parameters.
• Reduces mistakes from passing arguments in the wrong order.
• Works with both built-in and custom functions.

It's especially useful when skipping optional parameters — no need to fill them with null just to reach the one you want to set.

4. Match Expressions – A Smarter Alternative to Switch

Match expressions offer a cleaner way to handle conditional returns. They're similar to switch but more concise and expressive:

 $status = match($code) {
    200 => 'OK',
    404 => 'Not Found',
    500 => 'Server Error',
    default => 'Unknown',
};

Key differences:

• Returns a value directly.
• Uses strict comparison ( === ) by default.
• No fall-through behavior, so no need for break .

They help reduce boilerplate and make logic easier to follow.

5. Constructor Property Promotion – Less Boilerplate

If you're writing classes with a lot of properties initialized via constructors, this change saves time:

 class User {
    public function __construct(
        public string $name,
        public int $age
    ) {}
}

Instead of declaring properties and assigning them separately, you do it all in the constructor signature. Makes object-oriented code much cleaner and easier to maintain.

There are other smaller improvements too — like better error handling with throw expressions, attributes replacing docblock annotations, and stricter type checks across the board.

All these changes together make PHP 8 feel more modern and powerful while staying approachable. Upgrading might take some effort depending on your codebase, but the benefits in clarity, safety, and performance are definitely worth it.

基本上就這些。

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