`is_a()` vs `is_subclass_of()`

_PHP is_a() vs is_subclass_of().md

PHP is_a() vs is_subclass_of()

<?php

class A {}

class B extends A {}

interface I {}

trait T {}

class C extends B implements I {
    use T;
}

Operation	is_a()	is_subclass_of()	instanceof
A of A	✅	❌	✅
A of B	❌	❌	❌
A of I	❌	❌	❌
A of T	❌	❌	❌
A of C	❌	❌	❌
B of A	✅	✅	✅
B of B	✅	❌	✅
B of I	❌	❌	❌
B of T	❌	❌	❌
B of C	❌	❌	❌
I of A	❌	❌	❌
I of B	❌	❌	❌
I of I	✅	❌	❌
I of T	❌	❌	❌
I of C	❌	❌	❌
T of A	❌	❌	❌
T of B	❌	❌	❌
T of I	❌	❌	❌
T of T	✅	❌	❌
T of C	❌	❌	❌
C of A	✅	✅	✅
C of B	✅	✅	✅
C of I	✅	✅	✅
C of T	❌	❌	❌
C of C	✅	❌	✅

composer.json

{
    "require": {
        "symfony/console": "^7.3"
    }
}

index.php

<?php
<<<CONFIG
packages:
    - "symfony/console: ^4.1"
CONFIG;

use Symfony\Component\Console\Helper\Table;
use Symfony\Component\Console\Helper\TableStyle;
use Symfony\Component\Console\Output\ConsoleOutput;


require __DIR__.'/vendor/autoload.php';

class A
{
}

class B extends A
{
}

interface I
{
}

trait T {
}

class C extends B implements I {
    use T;
}

$classes = [
    'A',
    'B',
    'I',
    'T',
    'C',
];

$rows = [];

foreach ($classes as $class1) {
    foreach ($classes as $class2) {
        $rows[] = [
            $class1.' of '.$class2,
            is_a($class1, $class2, true) ? '<fg=green>true</>' : '<fg=red>false</>',
            is_subclass_of($class1, $class2, true) ? '<fg=green>true</>' : '<fg=red>false</>',
            class_exists($class1) && (new $class1()) instanceof $class2 ? '<fg=green>true</>' : '<fg=red>false</>',
        ];
    }
}

$table = new Table(new ConsoleOutput());

$table->setHeaders(['Operation', 'is_a()', 'is_subclass_of()', 'instanceof']);
$table->setRows($rows);

$table->render();