Refactoring Pantheon_Sessions::initialize_session_override() using do{...}while(false);

0.readme.md

Example use of do {...} while(false)

See this gist for background.

This example comes from my work here when looking for a solution for this issue related to this WordPress plugin.

I recognized I could make it clearer using the do {...} while(false) pattern so I wanted to document here.

Note:

1. The lack of nested if statements in the "Better" version compared with the "Changed" version.
2. The lack of complex if condition in the "Better" version compared with the "AlternateChanged" version.

---

However I am not going to submit my "better" version as a patch because most people don't appreciate how this pattern can help so I will be choosing my battles on the PR.

Note that I think that function could be further refactored but my only goal was to stop the PHP error "PHP Warning: session_set_save_handler(): Cannot change save handler when headers already sent" from showing up in the PHP error log when running a WP-CLI command on Pantheon, and any futher refactoring could potential have unintended consequences such as this one.

1.OriginalInitializeSessionOverride.php

class Pantheon_Sessions {
	/**
	 * Override the default sessions implementation with our own
	 *
	 * Largely adopted from Drupal 7's implementation
	 */
	private function initialize_session_override() {

		require_once dirname( __FILE__ ) . '/inc/class-session.php';
		require_once dirname( __FILE__ ) . '/inc/class-session-handler.php';
		$session_handler = new Pantheon_Sessions\Session_Handler;
		if ( PHP_SESSION_ACTIVE !== session_status() ) {
			session_set_save_handler( $session_handler, false );
		}
		// Close the session before $wpdb destructs itself.
		add_action( 'shutdown', 'session_write_close', 999, 0 );
	}
}

2.ChangedInitializeSessionOverride.php

class Pantheon_Sessions {
	/**
	 * Override the default sessions implementation with our own
	 *
	 * Largely adopted from Drupal 7's implementation
	 */
	private function initialize_session_override() {

		require_once dirname( __FILE__ ) . '/inc/class-session.php';
		require_once dirname( __FILE__ ) . '/inc/class-session-handler.php';
		$session_handler = new Pantheon_Sessions\Session_Handler;
		if ( PHP_SESSION_ACTIVE !== session_status() ) {
			if ( ! defined( 'WP_CLI' ) || ! WP_CLI ) {
				session_set_save_handler( $session_handler, false );
			}
		}
		// Close the session before $wpdb destructs itself.
		add_action( 'shutdown', 'session_write_close', 999, 0 );
	}
}

3.AlternateChangedInitializeSessionOverride.php

	/**
	 * Override the default sessions implementation with our own
	 *
	 * Largely adopted from Drupal 7's implementation
	 */
	private function initialize_session_override() {

		require_once dirname( __FILE__ ) . '/inc/class-session.php';
		require_once dirname( __FILE__ ) . '/inc/class-session-handler.php';
		$session_handler = new Pantheon_Sessions\Session_Handler;
		if ( PHP_SESSION_ACTIVE !== session_status() && ( ! defined( 'WP_CLI' ) || ! WP_CLI ) ) {
			session_set_save_handler( $session_handler, false );
		}
		// Close the session before $wpdb destructs itself.
		add_action( 'shutdown', 'session_write_close', 999, 0 );
	}

4.BetterInitializeSessionOverride.php

class Pantheon_Sessions {
	/**
	 * Override the default sessions implementation with our own
	 *
	 * Largely adopted from Drupal 7's implementation
	 */
	private function initialize_session_override() {

		do {

			require_once dirname( __FILE__ ) . '/inc/class-session.php';
			require_once dirname( __FILE__ ) . '/inc/class-session-handler.php';
			$session_handler = new Pantheon_Sessions\Session_Handler;

			if ( PHP_SESSION_ACTIVE === session_status() ) {
				break;
			}

			if ( defined( 'WP_CLI' ) && WP_CLI ) {
				break;
			}

			session_set_save_handler( $session_handler, false );

		} while (false);

		// Close the session before $wpdb destructs itself.
		add_action( 'shutdown', 'session_write_close', 999, 0 );

	}

}