PHP名前付き引数を配列から展開してみる

ctor_named_args.php

<?php

interface Instantiatable
{
}

class Instantiator
{
    /**
     * @template T
     * @param class-string<T> $class_name
     * @param Parameter[] $params
     * @return T
     */
    public function instantiate(string $class_name, array $params): object
    {
        if (!is_a($class_name, Instantiatable::class, true)) {
            throw new \InvalidArgumentException("$class_name does not implement Instantiatable");
        }
        
        return new $class_name(...array_reduce($params, function ($kwargs, $param) {
            $kwargs[$param->getName()] = $param->getValue();

            return $kwargs;
        }, []));
    }
}

class Parameter
{
    public function __construct(
        private readonly string $name,
        private readonly string $type,
        private readonly string $value,
    ) {
    }

    public function getName(): string
    {
        return $this->name;
    }

    public function getValue(): mixed
    {
        return match ($this->type) {
            'string' => $this->value,
            'int' => intval($this->value),
            'float' => floatval($this->value),
            'bool' => boolval($this->value),
            default => throw new \UnexpectedValueException("Unexpected type: {$this->type}"),
        };
    }
}

class Hoge implements Instantiatable
{
    public function __construct(private readonly int $a, private readonly int $b)
    {
    }

    public function __toString(): string
    {
        return "a={$this->a}, b={$this->b}";
    }
}

$paramSets = [
    [
        new Parameter(name: 'a', type: 'int', value: '100'),
        new Parameter(name: 'b', type: 'int', value: '200'),
    ],
    [
        new Parameter(name: 'b', type: 'int', value: '2'),
        new Parameter(name: 'a', type: 'int', value: '3'),
    ],
];

$instantiator = new Instantiator();

foreach ($paramSets as $params) {
    $hoge = $instantiator->instantiate(Hoge::class, $params);
    echo $hoge, "\n";
}

__halt_compiler();
This will outputs:
$ php ctor_named_args.php
a=100, b=200
a=3, b=2