PHP ^8.0 - ATTRIBUTE - HOW TO USE

sample.php

<?php
declare(strict_types = 1);

/**
 * Required PHP >= 8.0
 *
 * This is a Sample
 *
 */

#[Attribute]
class Foo
{
    function __construct(){
        echo "Running " . __METHOD__ . PHP_EOL;
    }
}

#[Attribute(Attribute::TARGET_CLASS|Attribute::IS_REPEATABLE)]
class Bar {
    function __construct(?string ...$args){
        echo "Running " . __METHOD__ ,
            " args: " . implode(", ", $args) . PHP_EOL;
    }
}

#[Attribute(Attribute::TARGET_ALL)]
class Baz {
    function __construct(
        private string $parameter
    ){
        echo "Running " . __METHOD__ ,
            " arg: " . $this->parameter . PHP_EOL;
    }
}

#[Foo]                                      // [0]
#[Bar]                                      // [1]
#[Bar("Banana")]                            // [2]
#[Bar("Banana", "Apple", "Lemon", "Grape")] // [3]
#[Baz("The Only One")]                      // [4]
class Qux
{
}

// Getting class attribute with ReflectionClass
$ref    =   new ReflectionClass(Qux::class);
$attrs  =   $ref->getAttributes(); // Array of attributes

$attrs[0]->newInstance(); // "Running Foo::__construct"
$attrs[1]->newInstance(); // "Running Bar::__construct args: "
$attrs[2]->newInstance(); // "Running Bar::__construct args: Banana"
$attrs[3]->newInstance(); // "Running Bar::__construct args: Banana, Apple, Lemon, Grape"
$attrs[4]->newInstance(); // "Running Baz::__construct arg: The Only One"