23 July 2022 (in calibre 6.2.1):
- Performance improvement of the switch() function
The switch function now does "shortcutting". It evaluates the comparison expressions in turn. If the comparison succeeds then the result expression for that comparison is evaluated and returned. No other result expressions are evaluated. This provides a performance improvement of at least 50%. It can be much higher if the switch() has many compare/result pairs and they are organized in decreasing probability order.
Behavior change: because most of the result expressions and some of the compare expressions are not evaluated, expressions with side effects that formerly were evaluated might not be. You can no longer expect side effects to work. For example, you shouldn't use expressions that contain assignments in a switch().
- Add a tooltip in the column icon advanced rule editor explaining that an advanced rule can return a compound icon by separating the individual icons (file names) with a ':' (colon).