key-of<T>型

配列

code:php

/**

* @param key-of<array{a:1,b:2}> $a1

* @param value-of<array{a:1,b:2}> $a2

function f($a1, $a2): void

{

PHPStan\dumpType($a1); // Dumped type: 'a'|'b'

PHPStan\dumpType($a2); // Dumped type: 1|2

}

サンプルコード

code:php

<?php declare(strict_types = 1);

class Prog

{

const LANGS = [

'cpp' => 'C++',

'js' => 'JavaScript',

'php' => 'PHP',

'py' => 'Python',

'rb' => 'Ruby',

];

/**

* @param value-of<self::LANGS> $name

public function __construct(private string $name) {}

/**

* @param key-of<self::LANGS> $extension

public static function byExt(string $extension): self

{

return new self(self::LANGS$extension);

}

public function __toString()

{

return $this->name;

}

$o1 = new Prog('C');

$o2 = Prog::byExt('cxx');