Online PHP editor | output for jGPb4

<?php abstract class StringObject { protected string $string; public function __toString(): string { return $this->string; } } class StringObjectException extends Exception { public readonly string $string; public function __construct(string $string, string $message = "", int $code = 0, Throwable $previous = null) { parent::__construct($message, $code, $previous); $this->string = $string; } } class CountableString extends StringObject { private int $lettersCount; public function __construct(string $string) { $this->string = $string; $this->lettersCount = mb_strlen($string); } public function countLetters(): int { return $this->lettersCount; } } class EmptyStringException extends StringObjectException {} class NotEmptyString extends StringObject { /** * @throws EmptyStringException */ public function __construct(string $string) { if ('' === $string) { throw new EmptyStringException(string: $string, message: 'Expected not empty string.'); } $this->string = $string; } } class TooLongStringException extends StringObjectException {} class LimitedLengthString extends StringObject { /** * @throws TooLongStringException */ public function __construct(CountableString $string, int $maxLength) { if ($maxLength < $string->countLetters()) { throw new TooLongStringException(string: $string, message: 'Too long string'); } $this->string = $string; } } class TenLettersStringValidator { private const MAX_LETTERS_COUNT = 10; private const ERROR_MESSAGE = 'Expected string not longer then: "%d letters" got: "%s"'; public function __invoke(string $string): ?string { $error = null; try { new LimitedLengthString(new CountableString($string), self::MAX_LETTERS_COUNT); } catch (TooLongStringException $exception) { $error = sprintf(self::ERROR_MESSAGE, self::MAX_LETTERS_COUNT, $exception->string ); } return $error; } } $validators = [new TenLettersStringValidator]; $errors = []; $string = 'Тестовая строка'; foreach ($validators as $validator) { $result = $validator($string); $result ? $errors[] = $result : null; } var_dump($errors);