RE: Temporary notes in Emacs buffers?

[Drew Adams]

This broaches the question of what is being annotated,
the file as a container (e.g. inode) or its contents

 

If we're still talking about bookmarks, then either one can be the target. To 
get to the content you first get to the container. But there's no requirement 
that you target any of the content. A bookmark can act in any way you like on a 
file, as container, without having anything to do with the content. A 
bookmark's handler is just a function.

What happens when one moves the file?
What happens when one copies the file?
What if after the copy one deletes the original?

My sense is that this thread is most concerned with use
case number 1.

An approach not yet mentioned is including some form of
UUID as a file local variable.  In such a setting notes
indirect through a persistent UUID-to-path map.  A file
handler recognizes relevant operations on UUID annotated
and updates the map.  This might also include updating
the new copy's UUID to preserve uniqueness.

If Emacs gives you a way to get to a file by an UUID that doesn't change when 
you move the file, then you could use that in a bookmark. That might, indeed, 
be a good answer. I don't know that Emacs provides such a way (how?). (You can 
get the inode of a file, but can you find a file, given its inode?)