Simple debug trace to wp-content/debug.log

log.php

/**
 * Simple debug trace to wp-content/debug.log
 *
 * @usage _log( $var );
 */
if ( ! function_exists( '_log' ) ) {
	function _log() {

		$args = func_get_args();

		// loop
		foreach ( $args as $arg ) {

			$arg = _log_check_value( $arg );

			// Print each item separately
			if ( true == WP_DEBUG ) {

				error_log( $arg );

			} else {

				ob_start();
				echo '[' . date( 'd-M-Y h:i:s T' ) . '] ' . $arg . '\r\n';
				file_put_contents( ABSPATH . 'wp-content/debug.log', ob_get_contents(), FILE_APPEND );
				ob_end_clean();

			}

		}

	}

	function _log_check_value( $arg ) {

		if ( is_array( $arg ) || is_object( $arg ) ) {
			$arg = print_r( $arg, true );
		} elseif ( is_bool( $arg ) ) {
			$arg = ( $arg ? 'true' : 'false' ) . ' (bool)';
		}

		return $arg;
	}
}