[Starson17]

Originally Posted by chaley

@rollercoaster: I am considering implementing some version of saved searches,

Excellent, I think it's needed improvement.

so I have been thinking about the question.

Always a god idea before starting to code

1. It is my impression that someone is working on 'real' multiple libraries, so I hesitate to introduce searches onto the libraries line.

I don't like real multiple libraries. Calibre already has support for multiple libraries via 3 methods - command line, Wizard and Preferences. I don't see that anything anyone else will write would interfere with your save search code.

2. A saved search can match books that do not have the special tag, making the use of the tag unreliable. It doesn't seem reasonable either to force a user to ensure that the special tag is attached to every matched book or to automatically add the tag to the result set every time the search is executed.

I agree. The idea of adding a special tag to mark search results is problematical. It will also interfere with ereaders that use tags for collections. I'd drop that idea and stick to the idea of storing search parameters, not search results. You can always run the saved search to get the results on whatever library you want, without the need for a special tag. If you want the special tag, just run the saved search, select "e" to edit the bulk metadata and add the desired special tag.

3. Saved searches will by nature produce overlapping virtual libraries, making it difficult to know which tags must be added during import. This issue would add more unreliability to the implementation.

Agreed - see above.

4. One must be careful with confusing the semantics of library vs search. Libraries have one set of behaviors, searches another. For example, what does it mean to delete a book in a virtual library? Is it deleted from the file system? Is it deleted from the saved search (how?). What happens if the search involves formats and a format is deleted while looking at some other search: how does one know if a tag should be deleted? Can one import from one virtual library to another, and if so, what does it really mean?

Stick to saving search parameters, not results. Then these issues disappear.

My current thought is that saved searches should work like playlists, with the hope that their behavior will be less mysterious.

This goes back to saving results, not search parameters. Is result saving required? Searches are really fast.