Set custom field for one post at a time

Hi all,

I would like to know whether there is an option in WordPress to keep a custom field specific to a particular post that author decides.

Next time he will choose another post and set the same custom field for that post, means the custom field should be unset from the older post. In effect there should be only one post with that cusotm field at a time, and should be unset from all older post at the same time.

We can use a WP loop and delete_post_meta fuction in functions.php file using ‘save_post’ action to do this. But I would like to know if there is any other option in WordPress by default.

Thanks in advance.