Now for the experiment: I'd like to know how people use this function. Is it useful on its own? Is it only used as building block in more complex expressions and should be be replaced/accompanied by higher-level functions? Please post your comments here! If there are a lot of responses I will split them to a separate thread, so it might be helpful to put discussions about $days_ago and other things in separate posts.
That's it for now. Thank you for your attention!
I added this to my text display, here is how I set it up
$if(%last_played%,
$ifequal($days_ago(%first_played%),0
,This is the first time this track has played
,This track has been played %play_count% times and the last time was $days_ago(%last_played%) days ago)
,This is the first time this track has played)
EDIT - I just started using foo_playback_custom and have it update at the end of the song and this works perfectly for me.