smuuf/primi

<?php

declare(strict_types=1);

namespace Smuuf\Primi\Helpers\Wrappers;

/**
 * A "wrapper" control structure emulating Python's context manager behavior.
 * This is to provide easy-to-use resource management (so you don't forget
 * anything important after doing something).
 *
 * For details about context managers in Python see:
 * https://docs.python.org/3/library/contextlib.html.
 *
 * Classes may extend this abstract wrapper class and then use it:
 *
 * ```php
 * class YayWrapper extends AbstractWrapper {
 *   public function executeBefore() {
 *     echo "yay enter";
 *   }
 *
 *   public function executeAfter() {
 *     echo "yay exit";
 *   }
 * }
 *
 * $wrapper = new YayWrapper;
 * $wrapper->wrap(function() {
 *   // 'yay enter' will be echoed first.
 *   echo "something.";
 *   // 'yay exit' will be echoed last.
 * });
 * ```
 */
abstract class AbstractWrapper {

    /**
     * @return mixed
     */
    public function wrap(callable $fn) {

        $enterRetval = $this->executeBefore();
        try {
            $retval = $fn($enterRetval);
            unset($fn);
            return $retval;
        } finally {
            $this->executeAfter();
        }

    }

    /**
     * @return mixed
     */
    abstract public function executeBefore();

    abstract public function executeAfter(): void;

}