How to throw exceptions in a PHP class' __toString method

to-string.php

<?php
class MyClass {

	public function __toString() {
		try {
			return $this->render();
		} catch(Exception $e) {
			// the __toString method isn't allowed to throw exceptions
			// so we turn them into an error instead
			trigger_error($e->getMessage() . "\n" . $e->getTraceAsString(), E_USER_ERROR);
			return '';
		}
	}

	private function render() {
		throw new Exception('Uh oh!');
	}

or define a ToStringException class that triggers an error on construction, this exception can then be thrown
directly from within __toString

<?php
declare(strict_types=1);

class ToStringException extends Exception
{
    public function __construct(string $message = "", int $code = 0, Throwable $previous = null)
    {
        trigger_error($message, E_USER_ERROR);
    }
}