PHP 8.1 现已推出,它附带了新功能和性能改进——最令人兴奋的是新的 JIT 编译器。它最近于 2021 年 11 月 25 日发布。
我将详细演示 PHP 8.1 提供的 10 大特性,以便您可以开始在您的项目中使用它们,并改善您的 PHP 体验。初学者和有经验的开发人员可以从本文中受益。
1.枚举
2.Fiber(纤维)
3.never
返回类型
4.readonly
属性
5.final
类常量
6.新的array_is_list()
函数
7.新的fsync()
和fdatasync()
函数
8.对字符串键数组解包的支持
9.$_FILES
新的用于目录上传的full_path
键
10.新的IntlDatePatternGenerator
类
PHP 8.1 添加了对枚举的支持,简写为 enum
。它是一种逐项类型,包含固定数量的可能值。请参阅以下代码片段以了解如何使用枚举。
<?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; ?>
PHP 8.1 添加了对 Fiber
的支持,这是一个低级组件,允许在 PHP 中执行并发代码。Fiber 是一个代码块,它包含自己的变量和状态堆栈。这些 Fiber 可以被视为应用程序线程,可以从主程序启动。一旦启动,主程序将无法挂起或终止 Fiber。它只能从 Fiber 代码块内部暂停或终止。在 Fiber 挂起后,控制权再次返回到主程序,它可以从挂起的点继续执行 Fiber。
Fiber 本身不允许同时执行多个 Fiber 或主线程和一个 Fiber。但是,对于 PHP 框架来说,高效管理执行堆栈并允许异步执行是一个巨大的优势。
请参阅以下代码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"; ?>
never
返回类型PHP 8.1 添加了名为never
的返回类型。该never
类型可用于指示函数将在执行一组指定的任务后终止程序执行。这可以通过抛出异常、调用exit()
或die()
函数来完成。
never
返回类型类似于void
返回类型。但是,void
返回类型在函数完成一组指定的任务后继续执行。
请参阅以下代码片段以了解如何使用 never 返回类型。
<?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'); ?>
readonly
属性PHP 8.1 添加了名为readonly
的类属性。已声明为只读的类属性只能初始化一次。里面设置的值不能改变。如果尝试强行更新该值,应用程序将抛出错误。请参阅以下代码片段以了解如何使用只读属性。
<?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; ?>
final
类常量PHP 8.1 添加了对名为final
的类常量的支持。最终类常量不能被修改,即使是通过继承,这意味着它们不能被子类扩展或覆盖。
这个标志不能用于私有常量,因为它不能在类之外被访问。声明 final 和 private 常量将导致致命错误。
请参阅以下代码片段以了解如何使用最终标志。
<?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'; } ?>
array_is_list()
函数PHP 8.1 添加了名为array_is_list()
的数组函数。它标识指定的数组是否具有从 0 开始的所有连续整数。如果数组是值的语义列表(一个数组,其键从 0 开始,都是整数,并且之间没有间隙),则此函数返回 true。对于空数组,它也返回 true。请参阅以下代码片段以了解如何使用 array_is_list() 函数。
<?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']); ?>
键不是从 0 开始的数组,或者键不是整数,或者键是整数但不按顺序出现的数组将评估为 false。
<?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']); ?>
fsync()
和fdatasync()
函数PHP 8.1 添加了对fsync()
和fdatasync()
函数的支持。两者都与现有fflush()
函数有相似之处,该函数当前用于将缓冲区刷新到操作系统中。然而,fsync()
和fdatasync()
刷新该缓冲区到物理存储。它们之间的唯一区别是该fsync()
函数在同步文件更改时包含元数据,而该fdatasync()
函数不包含元数据。
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