WP: Debugging

wp-config.php

define( 'WP_DEBUG',         true );
define( 'WP_DEBUG_LOG',     true );
define( 'WP_DEBUG_DISPLAY', true );
define( 'SAVEQUERIES',      true );
define( 'SCRIPT_DEBUG',     true );
//define( 'DISABLE_WP_CRON',  true );
define( 'CONCATENATE_SCRIPTS', false );

// Write to the log file.
error_log( var_export( $foo, true ) );

// Prints debug info.
function out( $what ) {
	$bt = debug_backtrace();
	echo '<br><br>' . $bt[0]['file'] . '[' . $bt[0]['line'] . ']: <br><pre>' . print_r( $what, true ) . '</pre><br>';
}