Hi

Does anyone know if it's possible to somehow use the Qt 4 threading API to return a custom QFuture? My scenario is this: I have a GUI that displays a couple of lists of strings, but the code that generates the lists involves multiple hard-drive reads, some processing, etc., so the GUI tends to lag a bit during list generation.

The only custom feature that I've been able to find is QtConcurrent::run(), which just wraps a normal return type in a single-item QFuture. I'd like to be able to return the items of the list as they are generated, but I can't seem to find any documentation on doing so (Google, this forum, Qt 4 docs).

Thanks,
Syd

I've never used QFuture (guess I need to upgrade from 4.3.5...) In the past the way I have tackled your problem (if I understand it correctly) is by running a thread for the computation and then emit'ing a signal periodically. You need to connect the signal you will emit to a method that in your case will update the GUI list before starting the computation.

This should work from within a QFuture object

I tried that, but the types I was passing around weren't QObjects or integral types, so short of wrapping them in special classes, that didn't work. However, I was looking at the Qt source, and the undocumented QFutureInterface class gives me all the functionality I was looking for. Not sure how good of an idea it is to be using such a class, and I haven't tested it yet, but it looks like it should work beatifully. Unfortunately, I'm left to figure out it's behaviour on my own.