public function enable() {

        global $wp_filesystem;

        $plugin = $GLOBALS[ 'redisObjectCache' ];

        if ( $plugin->object_cache_dropin_exists() ) {

            if ( $plugin->validate_object_cache_dropin() ) {
                WP_CLI::line( __( 'Redis object cache already enabled.', 'redis-cache' ) );
            } else {
                WP_CLI::error( __('An unknown object cache drop-in was found. To use Redis run: wp redis update-dropin.', 'redis-cache') );
            }

        } else {

            WP_Filesystem();

            if ( $wp_filesystem->copy( WP_PLUGIN_DIR . '/redis-cache/includes/object-cache.php', WP_CONTENT_DIR . '/object-cache.php', true ) ) {
                WP_CLI::success( __( 'Object cache enabled.', 'redis-cache' ) );
            } else {
                WP_CLI::error( __( 'Object cache could not be enabled.', 'redis-cache' ) );
            }

        }

    }