wp-log.php

<?php
if ( !function_exists( 'wp_log' ) ) {

    /**
     * A file based logging utility.
     * 
     * Made for WordPress, but can be used anywhere with a single change.
     * 
     * @author Tareq Hasan <tareq@wedevs.com>
     * 
     * @param string $type type of the log
     * @param string $message log message
     * @param mixed $var any variable to log
     */
    function wp_log( $type = '', $message = '', $var = null ) {

        if ( $var !== null ) {
            if ( is_array( $var ) ) {
                //replace new line with space, double space with single space
                $message .= str_replace( array("\n", '  '), array('', ' '), var_export( $var, true ) );
            } elseif ( is_object( $var ) ) {
                //prettyfy json
                $message .= str_replace( array('":', ',', '"'), array(' => ', ', ', ''), json_encode( $var, true ) );
            } elseif ( is_bool( $var ) ) {
                $message .= $var ? 'TRUE' : 'FALSE';
            } else {
                $message .= $var;
            }
        }

        $log_message = sprintf( "[%s][%s] %s\n", date( 'd.m.Y h:i:s' ), $type, $message );
        error_log( $log_message, 3, WP_CONTENT_DIR . '/my-debug.log' );
    }

}