custom sort functions pollute cache

[natask]

the first call to org-ql-select with a custom sort function works correctly. however subsequent calls return missing list of results. It also affects calls that hit the cache.

This happens because (sort) modifies the list. the cache becomes polluted. future calls query the same list from the cache. but because the list is malformed, subsequent applications of the sort function return malformed resulted.

fix by replacing (sort) with (-sort), which copies the list before sorting.

[alphapapa]

Thanks for reporting. I don't have time to verify this at the moment, but, assuming your analysis is correct, what you propose may not be the best solution, because it would impose a performance penalty, especially with large numbers of results.

[natask]

I neglected to mention that org ql's default sort functions are implemented using (-sort).

org-ql/org-ql.el

Line 1893 in 208e103

(-sort (sorter pred) items)))

Although I share your reservations, aside from solving the bug, the performance is within org ql's current implementation.

[alphapapa]

You're right, of course.

I've verified the bug. I don't quite understand how it's happening, because AFAICT sort is being called on a copy of the results produced by -flatten-n, but destructive functions can be tricky like that (maybe those Clojure folks are onto something...).

Thanks for your patience. I'll apply this in the next bug-fix release.