Topic: Sort List retrieved from vl-file-systime

[Lee Mac]

I realise that, however, if the foo predicate function does return T, what does vl-sort do in turn? Perhaps I am missing something on this one 

[MP]

I realise that, however, if the foo predicate function does return T, what does vl-sort do in turn?

Ahhh, gotchu. Once might conclude that it swaps the items but I doubt that is the case as it would imply a bubble sort, the worst performing sort of all sort algorithms. My guess is that vl-sort uses the predicate's results to index the items then performs a merge or quick sort, but heh, it's just a guess.

[Lee Mac]

I know what you mean about the bubble sort, I had to manually write one out for one of my maths modules... tedious indeed. But thanks for the insight. I just wondered to its operation as I wouldn't know how to structure the predicate function depending on how the vl-sort dealt with the returns from the predicate function.

[MP]

I wouldn't know how to structure the predicate function depending on how the vl-sort dealt with the returns from the predicate function.

You're clear on it now? All you need do is ensure it (the predicate function) returns non nil in the event that item 1 is less than item 2 (assuming normal ascending sort). What establishes "less than" vl-sort cares not; kinda the beauty of it.

[Lee Mac]

Gotcha Thanks - non-nil for the sorting order that you want to achieve.