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PHP8.1的十大新功能,快用起来吧!

藏色散人
藏色散人 转载
2021-12-08 14:05:58 4441浏览

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。

PHP 8.1 提供的 10 大功能

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()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

10.新的IntlDatePatternGenerator

1. 枚举

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 &#39;string&#39; or &#39;int&#39; 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    = &#39;1&#39;;
    case GUEST    = &#39;2&#39;;
    case WRITER   = &#39;3&#39;;
    case EDITOR   = &#39;4&#39;;
}

/**
 * You can access a case by using
 * the &#39;::&#39; scope resolution operator.
 * And, to get the name of the enum case, you
 * can use the &#39;->&#39; followed by the attribute &#39;name&#39;.
 */
echo UserRole::WRITER->name;

/**
 * To get the value of the enum case, you can
 * use the &#39;->&#39; followed by the attribute &#39;value&#39;.
 */
echo UserRole::WRITER->value;

?>

2. Fiber(纤维)

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";

?>

3.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()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(&#39;https://www.google.com&#39;);

?>

4.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;

?>

5. 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 = &#39;1&#39;;
}

/**
 * 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 = &#39;2&#39;;
}

?>

6. 新的 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 => &#39;apple&#39;, 1 => 2, 2 => 3]
 */
array_is_list([&#39;apple&#39;, 2, 3]);
/**
 * Returns true as the first key is zero, and keys are in sequential order.
 * It is same as [0 => &#39;apple&#39;, 1 => &#39;scissor&#39;]
 */
array_is_list([&#39;apple&#39;, &#39;orange&#39;]);
/**
 * Returns true as the first key is zero, and keys are in sequential order.
 * It is same as [0 => &#39;apple&#39;, 1 => &#39;scissor&#39;]
 */
array_is_list([0 => &#39;apple&#39;, &#39;orange&#39;]);
/**
 * Returns true as the first key is zero, and keys are in sequential order.
 */
array_is_list([0 => &#39;rock&#39;, 1 => &#39;scissor&#39;]);

?>

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 => &#39;apple&#39;, &#39;orange&#39;]);
/**
 * Returns false as the first key does not start from zero.
 */
array_is_list([1 => &#39;apple&#39;, 0 => &#39;orange&#39;]);
/**
 * Returns false as all keys are not integer.
 */
array_is_list([0 => &#39;apple&#39;, &#39;fruit&#39; => &#39;orange&#39;]);
/**
 * Returns false as the keys are not in sequential order.
 */
array_is_list([0 => &#39;apple&#39;, 2 => &#39;orange&#39;]); 

?>

7. 新的fsync()fdatasync()函数

PHP 8.1 添加了对fsync()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()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 = &#39;notes.txt&#39;;
/**
 * Create the file with read and write permission.
 */
$file = fopen($fileName, &#39;w+&#39;);
/**
 * Add some text into the file.
 */
fwrite($file, &#39;Paragraph 1&#39;);
/**
 * Add a line break into the file.
 */
fwrite($file, "\r\n");
/**
 * Add some more text into the file.
 */
fwrite($file, &#39;Paragraph 2&#39;);
/**
 * You can use both the fsync() or fdatasync() functions 
 * to commit changs to disk.
 */
fsync($file); // or fdatasync($file).
/**
 * Close the open file pointer.
 */
fclose($file);

?>

8. 对字符串键数组解包的支持

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 = [&#39;Jonathan Apples&#39;, &#39;Sapote&#39;];
/**
 * Declare another array
 */
$fruits2 = [&#39;Pomelo&#39;, &#39;Jackfruit&#39;];
/**
 * Merge above two arrays using array unpacking.
 */
$unpackedFruits = [...$fruits1, ...$fruits2, ...[&#39;Red Delicious&#39;]];
/**
 * Print the above unpacked array.
 * This will print:
 * array(5) {
 * [0]=>
 * string(15) "Jonathan Apples"
 * [1]=>
 * string(6) "Sapote"
 * [2]=>
 * string(6) "Pomelo"
 * [3]=>
 * string(9) "Jackfruit"
 * [4]=>
 * string(13) "Red Delicious"
 * }
 */
var_dump($unpackedFruits);

?>

9.  $_FILES 新的用于目录上传的 full_path

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[&#39;REQUEST_METHOD&#39;] === &#39;POST&#39;) {
    /**
     * 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>

10. 新的IntlDatePatternGenerator

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(&#39;Y-m-d&#39;, date(&#39;Y-m-d&#39;));
/**
 * ===========================
 * PRINTING DATE IN USA FORMAT
 * ===========================
 * Initiate an instance for the IntlDatePatternGenerator class
 * and provide the locale information.
 * In the below example, I&#39;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&#39;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

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