値のセット時に任意のフィルタを行うアクセサクラス

filterable_accessor.php

<?php
namespace Acme;

$int_filter = function($value) {
    if (!preg_match('/\A(?:0|[1-9][0-9]*)\z/', (string)$value)) {
        throw new \InvalidArgumentException('invalid unsigned integer.');
    }
    return (int)$value;
};

$length_checker = function($value, $min = null, $max = null) {
    $length = mb_strlen($value);
    if (isset($min) && $length < $min) {
        throw new \InvalidArgumentException(
            sprintf('character length must not less than %s.', $min));
    }
    if (isset($max) && $length > $max) {
        throw new \InvalidArgumentException(
            sprintf('character length must not greater than %s.', $max));
    }
    return $value;
};

$sanitizer = function($value) {
    return preg_replace('/[\x00-\x08\x0B\x0C\x0E-\x1F\x7F]+/S', '', $value);
};

$normalize_newline = function($value) {
    return str_replace("\r", "\n", str_replace("\r\n", "\n", $value));
};

$user = FilterableAccessor::instance(array(
    'number' => function($value) use ($int_filter) {
        return $int_filter($value);
    },
    'name' => function($value) use ($length_checker, $sanitizer) {
        return $length_checker(
            $sanitizer($value), 1, 10);
    },
    'comment' => function($value) use ($length_checker, $sanitizer, $normalize_newline) {
        return $length_checker(
            $normalize_newline(
                $sanitizer($value), null, 50));
    },
));

// プロパティ形式
$user->number = '1';
$user->name = 'Tanaka';
echo '<pre>';
var_dump($user->number); // int(1)
var_dump($user->name); // string(6) "Tanaka"
echo '</pre>';

// メソッド形式
$user->number('2')->name('Suzuki');
echo '<pre>';
var_dump($user->number()); // int(2)
var_dump($user->name()); // string(6) "Suzuki"
echo '</pre>';

// フィルタで制御コードをサニタイズ（←言うな）
$user->name("Holy\x00\x00\x00"); // NULL byte
echo '<pre>';
var_dump($user->name()); // string(4) "Holy"
echo '</pre>';

// フィルタで改行コードを正規化
$user->comment("Hoge\r\nFuga\r\nPiyo\r\n"); // CR+LF newline
echo '<pre>';
var_dump($user->comment()); // string(15) "Hoge\nFuga\nPiyo\n"
echo '</pre>';


// 未定義プロパティへのアクセス
echo '<pre>';
try {
    $user->age = '30';
} catch (\InvalidArgumentException $e) {
    echo $e->getMessage(); //  The property "age" does not exists.
}
echo '</pre>';

// フィルタでチェック
echo '<pre>';
try {
    $user->number = '-1';
} catch (\InvalidArgumentException $e) {
    echo $e->getMessage(); //  The property "number" is not valid : invalid unsigned integer.
}
echo '</pre>';

// フィルタでチェック
echo '<pre>';
try {
    $user->name('VeryVeryLongName');
} catch (\InvalidArgumentException $e) {
    echo $e->getMessage(); //  The property "name" is not valid : character length must not greater than 10.
}
echo '</pre>';

FilterableAccessor.php

<?php
namespace Acme;

class FilterableAccessor
{
    private $attributes;
    private $filters;

    public function __construct(array $params = array())
    {
        $this->init($params);
    }

    public static function instance(array $params = array())
    {
        return new static($params);
    }

    public function init(array $params = array())
    {
        $this->attributes = array();
        $this->filters = array();
        if (!empty($params)) {
            foreach ($params as $name => $filter) {
                if (!is_callable($filter)) {
                    throw new \InvalidArgumentException(
                        sprintf('The property "%s" filter is not callable.', $name));
                }
                $this->filters[$name] = $filter;
                $this->attributes[$name] = null;
            }
        }
        return $this;
    }

    public function __get($name)
    {
        return $this->get_attribute($name);
    }

    public function __set($name, $value)
    {
        return $this->set_attribute($name, $value);
    }

    public function __call($name, array $args)
    {
        switch (count($args)) {
        case 0:
            return $this->get_attribute($name);
        case 1:
            return $this->set_attribute($name, $args[0]);
        }
        throw new \BadMethodCallException(
            sprintf('Invalid method "%s"' , $name));
    }

    private function set_attribute($name, $value)
    {
        if (!array_key_exists($name, $this->attributes)) {
            throw new \InvalidArgumentException(
                sprintf('The property "%s" does not exists.', $name));
        }
        if (isset($this->filters[$name])) {
            $message = null;
            $valid = true;
            try {
                $value = call_user_func($this->filters[$name], $value);
            } catch (\Exception $e) {
                $message = $e->getMessage();
                $valid = false;
            }
            if (!$valid) {
                throw new \InvalidArgumentException(
                    sprintf('The property "%s" is not valid%s', $name,
                        (isset($message)) ? " : {$message}" : '.'));
            }
        }
        $this->attributes[$name] = $value;
        return $this;
    }

    private function get_attribute($name)
    {
        if (!array_key_exists($name, $this->attributes)) {
            throw new \InvalidArgumentException(
                sprintf('The property "%s" does not exists.', $name));
        }
        return $this->attributes[$name];
    }

}