php 枚举

<?php

enum Color: string {
    case Red = 'red';
    case Green = 'green';
    case Blue = 'blue';
}

enum Status: int {
    case Pending = 0;
    case Completed = 1;
    case Cancelled = 2;
}

function printColor(Color $color): void {
    echo "The color is: {$color->value}\n";
}

function printStatus(Status $status): void {
    echo "The status is: {$status->value}\n";
}

$color = Color::Red;
$status = Status::Completed;

printColor($color);
printStatus($status);
?>

// 错误示例
$invalidColor = Color::Yellow; // Yellow 未定义

// 正确示例
$validColor = Color::Red;

// 错误示例
printColor('red'); // 'red' 不是 Color 枚举类型

// 正确示例
printColor(Color::Red);