private function save_meta_data( $slug, $data ) {

		$prev = get_post_meta( $this->post->ID, $slug, true );

		if ( null === $data && $prev ) {
			delete_post_meta( $this->post->ID, $slug );
		} elseif ( $data !== $prev ) {
			update_post_meta( $this->post->ID, $slug, $data );
		}

	}
private function save_meta_data( $slug, $data ) {

		$prev = get_post_meta( $this->post->ID, $slug, true );

		if ( null === $data && $prev ) {
			delete_post_meta( $this->post->ID, $slug );
		} elseif ( $data !== $prev ) {
			update_post_meta( $this->post->ID, $slug, $data );
		}

	}
private function save_meta_data ( $ slug , $ data ) { $ prev = get_post_meta ( $ this -> post -> ID , $ slug , true ) ; if ( null === $ data && $ prev ) { delete_post_meta ( $ this -> post -> ID , $ slug ) ; } elseif ( $ data !== $ prev ) { update_post_meta ( $ this -> post -> ID , $ slug , $ data ) ; } }
Save the meta data for the post

@since  1.0.0
@access private

@param string $slug slug of the meta_key
@param mixed  $data Data to be saved
Save the meta data for the post