Fair enough. Then maybe we can come up with a different solution to the problem I want to solve.
I wanted this function primarily so that I could capture the date that an item was added to a playlist. Here is why.
I have a watchlist playlist that I add movies to that I want to watch. For example, I am scrolling through my movies and see a movie I have been meaning to watch, but I am not in the mood for at the moment, I add it to my watchlist playlist. I then have a smartlist that uses that watchlist and filters it by number of plays, if the number of plays is zero, display the movie, if it's greater than zero, hide it. This works pretty great except that if I want to re-watch a movie then the number of plays is not zero and it won't display.
This old thread has details of my current setup if the above isn't sufficient.
One solution I came up with was the timestamp idea. I wanted to use timestamp to capture the date a movie was added to a playlist so that I could compare that date against the date that a movie was last played, if the date added to playlist was later than last played then it would appear on my watchlist.
Maybe an alternative solution would be a function that could be used in an after playback expression that removes an item from a playlist. Or a new date/time function such as:
timestamp()
The timestamp() function returns a floating-point value representing the current system date and time. Very similar to the now() function except that the value is static.
Example
if(isequal(FilePlaylists(), Watchlist,
, formatdate(timestamp(), date),)
I am open to any kind of solution.