PHP 8.1 現已推出，它附帶了新功能與效能改良－最令人興奮的是新的 JIT 編譯器。它最近於 2021 年 11 月 25 日發布。
我將詳細示範 PHP 8.1 提供的 10 大特性，以便您可以開始在您的專案中使用它們，並改善您的 PHP 體驗。初學者和有經驗的開發人員可以從本文中受益。
#1.列舉
2.Fiber（纖維）
3.never傳回型別
4.readonly屬性
#5.final類別常數
array_is_list()函數
fsync()和fdatasync()函數
$_FILES新的用於目錄上傳的full_path鍵
IntlDatePatternGenerator類別
enum 。它是一種逐項類型，包含固定數量的可能值。請參閱以下程式碼片段以了解如何使用枚舉。
<?php
/**
* Declare an enumeration.
* It can also contain an optional 'string' or 'int' value. This is called backed Enum.
* Backed enums (if used) should match the following criteria:
* - Declare the scalar type, whether string or int, in the Enum declaration.
* - All cases have values.
* - All cases contain the same scalar type, whether string or int.
* - Each case has a unique value.
*/
enum UserRole: string {
case ADMIN = '1';
case GUEST = '2';
case WRITER = '3';
case EDITOR = '4';
}
/**
* You can access a case by using
* the '::' scope resolution operator.
* And, to get the name of the enum case, you
* can use the '->' followed by the attribute 'name'.
*/
echo UserRole::WRITER->name;
/**
* To get the value of the enum case, you can
* use the '->' followed by the attribute 'value'.
*/
echo UserRole::WRITER->value;
?>Fiber 的支持，這是一個低階元件，允許在 PHP 中執行並發程式碼。 Fiber 是一個程式碼區塊，它包含自己的變數和狀態堆疊。這些 Fiber 可以被視為應用程式線程，可以從主程式啟動。一旦啟動，主程式將無法掛起或終止 Fiber。它只能從 Fiber 程式碼區塊內部暫停或終止。在 Fiber 掛起後，控制權再次返回主程序，它可以從掛起的點繼續執行 Fiber。
Fiber 本身不允許同時執行多個 Fiber 或主執行緒和一個 Fiber。但是，對於 PHP 框架來說，高效管理執行堆疊並允許非同步執行是一個巨大的優勢。請參閱以下程式碼片段以了解如何使用 Fiber。
<?php
/**
* Initialize the Fiber.
*/
$fiber = new Fiber(function(): void {
/**
* Print some message from inside the Fiber.
* Before the Fiber gets suspended.
*/
echo "Welcome to Fiber!\n";
/**
* Suspend the Fiber.
*/
Fiber::suspend();
/**
* Print some message from inside the Fiber.
* After the Fiber gets resumed.
*/
echo "Welcome back to Fiber!\n";
});
/**
* Print a message before starting a Fiber.
*/
echo "Starting a Fiber\n";
/**
* Start the Fiber.
*/
$fiber->start();
/**
* Fiber has been suspened from the inside.
* Print some message, and then resume the Fiber.
*/
echo "Fiber has been suspended\n";
echo "Resuming the Fiber\n";
/**
* Resume the Fiber.
*/
$fiber->resume();
/**
* End of the example.
*/
echo "Fiber completed execution\n";
?>傳回類型never的回傳類型。此never類型可用於指示函數將在執行一組指定的任務後終止程式執行。這可以透過拋出異常、呼叫exit()或die()函數來完成。
請參閱以下程式碼片段以了解如何使用 never 傳回類型。never
傳回類型類似於void傳回類型。但是，void傳回類型在函數完成一組指定的任務後繼續執行。
<?php
/**
* Route Class
*/
class Route {
/**
* Constructor of the class
* @return void
*/
public function __construct() {
}
/**
* Redirect To a Page
* This function redirects to an URL specified by the user.
* @method redirect()
* @param string $url
* @param integer $httpCode
* @author Tara Prasad Routray <someemailaddress@example.com>
* @access public
* @return never
*/
public static function redirect($url, $httpCode = 301): never {
/**
* Redirect to the URL specified.
*/
header("Location: {$url}", true, $httpCode);
die;
}
}
Route::redirect('https://www.google.com');
?>屬性readonly的類別屬性。已聲明為唯讀的類別屬性只能初始化一次。裡面設定的值不能改變。如果嘗試強行更新該值，應用程式將拋出錯誤。請參閱以下程式碼片段以了解如何使用唯讀屬性。
<?php
/**
* User Class
*/
class User {
/**
* Declare a variable with readonly property.
* @var $authUserID
* @access public
*/
public readonly int $authUserID;
/**
* Constructor of the class.
* @param integer $userID
* @return void
*/
public function __construct($userID) {
/**
* Change the value of the property as specified.
* Updating the value of readonly properties are
* allowed only through the constructor.
*/
$this->authUserID = $userID;
}
/**
* Update Auth User ID
* This function tries to update the readonly property (which is not allowed).
* @method updateAuthUserID()
* @param integer $userID
* @author Tara Prasad Routray <someemailaddress@example.com>
* @access public
* @return void
*/
public function updateAuthUserID($userID) {
/**
* Change the value of the property as specified.
* Executing this function will throw the following error;
* PHP Fatal error: Uncaught Error: Cannot modify readonly property User::$authUserID
*/
$this->authUserID = $userID;
}
}
/**
* Initialize the class and update the value of the readonly property.
*/
$user = new User(30);
/**
* Print the readonly property value.
* This will print 30.
*/
echo $user->authUserID;
/**
* Call another function inside the class and try to update the class property.
*/
$user->updateAuthUserID(50);
/**
* Print the readonly property value.
*/
echo $user->authUserID;
?>類別常數final的類別常數的支援。最終類別常數不能被修改，即使是透過繼承，這意味著它們不能被子類別擴展或覆蓋。
這個標誌不能用於私有常數，因為它不能在類別之外被存取。聲明 final 和 private 常數將導致致命錯誤。請參閱以下程式碼片段以了解如何使用最終標誌。
<?php
/**
* UserRole Class
*/
class UserRole {
/**
* Declare a final class constant with a value.
*/
final public const ADMIN = '1';
}
/**
* User Class extending the UserRole Class
*/
class User extends UserRole {
/**
* Declare another constant with the same name
* as of the parent class to override the value.
*
* Note: Overriding the value will throw the following error:
* PHP Fatal error: User::ADMIN cannot override final constant UserRole::ADMIN
*/
public const ADMIN = '2';
}
?> 函數array_is_list()的陣列函數。它標識指定的陣列是否具有從 0 開始的所有連續整數。如果數組是值的語意列表（一個數組，其鍵從 0 開始，都是整數，並且之間沒有間隙），則此函數傳回 true。對於空數組，它也傳回 true。請參閱以下程式碼片段以了解如何使用 array_is_list() 函數。
<?php /** * Returns true for empty array. */ array_is_list([]); /** * Returns true for sequential set of keys. */ array_is_list([1, 2, 3]); /** * Returns true as the first key is zero, and keys are in sequential order. * It is same as [0 => 'apple', 1 => 2, 2 => 3] */ array_is_list(['apple', 2, 3]); /** * Returns true as the first key is zero, and keys are in sequential order. * It is same as [0 => 'apple', 1 => 'scissor'] */ array_is_list(['apple', 'orange']); /** * Returns true as the first key is zero, and keys are in sequential order. * It is same as [0 => 'apple', 1 => 'scissor'] */ array_is_list([0 => 'apple', 'orange']); /** * Returns true as the first key is zero, and keys are in sequential order. */ array_is_list([0 => 'rock', 1 => 'scissor']); ?>
<?php /** * Returns false as the first key does not start from zero. */ array_is_list([1 => 'apple', 'orange']); /** * Returns false as the first key does not start from zero. */ array_is_list([1 => 'apple', 0 => 'orange']); /** * Returns false as all keys are not integer. */ array_is_list([0 => 'apple', 'fruit' => 'orange']); /** * Returns false as the keys are not in sequential order. */ array_is_list([0 => 'apple', 2 => 'orange']); ?>
和fdatasync()函數##PHP 8.1 新增了對和fdatasync()函數的支援。兩者都與現有fflush()函數有相似之處，該函數目前用於將緩衝區刷新到作業系統中。然而，fsync()和fdatasync()刷新該緩衝區到實體儲存。它們之間的唯一差異是該fsync()函數在同步檔案變更時包含元數據，而該fdatasync()函數不包含元資料。 <blockquote><p><code>fsync()函数将采用文件指针并尝试将更改提交到磁盘。成功时返回 true，失败时返回 false，如果资源不是文件，则会发出警告。fdatasync()函数的工作方式相同，但速度稍快一些，因为 fsync() 将尝试完全同步文件的数据更改和有关文件的元数据（上次修改时间等），这在技术上是两次磁盘写入。
请参阅以下代码片段以了解如何使用 fsync() 和 fdatasync() 函数。
<?php /** * Declare a variable and assign a filename. */ $fileName = 'notes.txt'; /** * Create the file with read and write permission. */ $file = fopen($fileName, 'w+'); /** * Add some text into the file. */ fwrite($file, 'Paragraph 1'); /** * Add a line break into the file. */ fwrite($file, "\r\n"); /** * Add some more text into the file. */ fwrite($file, 'Paragraph 2'); /** * You can use both the fsync() or fdatasync() functions * to commit changs to disk. */ fsync($file); // or fdatasync($file). /** * Close the open file pointer. */ fclose($file); ?>
PHP 8.1 添加了对字符串键数组解包的支持。为了解压数组，PHP 使用展开(…)运算符。PHP 7.4 中引入了这个运算符来合并两个或多个数组，但语法更简洁。但在 PHP 8.1 之前，展开运算符仅支持带数字键的数组。请参阅以下代码片段以了解如何将展开运算符用于字符串键控数组。
<?php
/**
* Declare an array
*/
$fruits1 = ['Jonathan Apples', 'Sapote'];
/**
* Declare another array
*/
$fruits2 = ['Pomelo', 'Jackfruit'];
/**
* Merge above two arrays using array unpacking.
*/
$unpackedFruits = [...$fruits1, ...$fruits2, ...['Red Delicious']];
/**
* Print the above unpacked array.
* This will print:
* array(5) {
* [0]=>
* string(15) "Jonathan Apples"
* [1]=>
* string(6) "Sapote"
* [2]=>
* string(6) "Pomelo"
* [3]=>
* string(9) "Jackfruit"
* [4]=>
* string(13) "Red Delicious"
* }
*/
var_dump($unpackedFruits);
?>$_FILES 新的用于目录上传的 full_path 键PHP 8.1 添加了对$_FILES全局变量中full_path新键的支持。在 PHP 8.1 之前，$_FILES没有存储到服务器的相对路径或确切目录。因此，您无法使用 HTML 文件上传表单上传整个目录。新full_path键解决了这个问题。它存储相对路径并在服务器上重建确切的目录结构，使目录上传成为可能。请参阅以下代码片段以了解如何将full_path键与$_FILES全局变量一起使用。
<?php
/**
* Check if the user has submitted the form.
*/
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
/**
* Print the $_FILES global variable. This will display the following:
* array(1) {
* ["myfiles"]=> array(6) {
* ["name"]=> array(2) {
* [0]=> string(9) "image.png"
* [1]=> string(9) "image.png"
* }
* ["full_path"]=> array(2) {
* [0]=> string(25) "folder1/folder2/image.png"
* [1]=> string(25) "folder3/folder4/image.png"
* }
* ["tmp_name"]=> array(2) {
* [0]=> string(14) "/tmp/phpV1J3EM"
* [1]=> string(14) "/tmp/phpzBmAkT"
* }
* // ... + error, type, size
* }
* }
*/
var_dump($_FILES);
}
?>
<form action="" method="POST" enctype="multipart/form-data">
<input name="myfiles[]" type="file" webkitdirectory multiple />
<button type="submit">Submit</button>
</form>IntlDatePatternGenerator类PHP 8.1 添加了对新IntlDatePatternGenerator类的支持。在 PHP 8.1 之前，只能使用IntlDateFormatter。虽然它支持昨天、今天和明天使用的八种预定义格式，但是这些格式和IntlDatePatternGenerator不太一样。这个类允许指定日期、月份和时间的格式，并且顺序将由类自动处理。请参阅以下代码片段以了解如何使用 IntlDatePatternGenerator 类。
<?php
/**
* Define a default date format.
*/
$skeleton = "YYYY-MM-dd";
/**
* Parse a time string (for today) according to a specified format.
*/
$today = \DateTimeImmutable::createFromFormat('Y-m-d', date('Y-m-d'));
/**
* ===========================
* PRINTING DATE IN USA FORMAT
* ===========================
* Initiate an instance for the IntlDatePatternGenerator class
* and provide the locale information.
* In the below example, I've used locale: en_US.
*/
$intlDatePatternGenerator = new \IntlDatePatternGenerator("en_US");
/**
* Get the correct date format for the locale: en_US.
* Following function "getBestPattern" will return:
* MM/dd/YYYY
*/
$enUSDatePattern = $intlDatePatternGenerator->getBestPattern($skeleton);
/**
* Use the "formatObject" function of IntlDateFormatter to print as per specified pattern.
* This will print the following:
* Date in en-US: 12/03/2021
*/
echo "Date in en-US: ". \IntlDateFormatter::formatObject($today, $enUSDatePattern, "en_US"). "\n";
/**
* =============================
* PRINTING DATE IN INDIA FORMAT
* =============================
* Initiate an instance for the IntlDatePatternGenerator class
* and provide the locale information.
* In the below example, I've used locale: en_IN.
*/
$intlDatePatternGenerator = new \IntlDatePatternGenerator("en_IN");
/**
* Get the correct date format for the locale: en_IN.
* Following function "getBestPattern" will return:
* dd/MM/YYYY
*/
$enINDatePattern = $intlDatePatternGenerator->getBestPattern($skeleton);
/**
* Use the "formatObject" function of IntlDateFormatter to print as per specified pattern.
* This will print the following:
* Date in en-IN: 03/12/2021
*/
echo "Date in en-IN: ". \IntlDateFormatter::formatObject($today, $enINDatePattern, "en_IN"). "\n";
?>点赞！您已经完成了 PHP 8.1 提供的功能的学习。现在您可以继续并开始在您当前或即将进行的项目中实现上述功能。
原文：https://levelup.gitconnected.com/top-10-php-8-1-features-you-should-start-using-now-7161b91275fd
