Re: [Gretl-devel] strange bug (due to bundles?)

On Sat, 11 May 2013, Allin Cottrell wrote: > On Fri, 10 May 2013, Sven Schreiber wrote: > >> I think I found a bug in gretl that is quite subtle. The attached script >> demonstrates the bug -- or actually in its current form it demonstrates how >> to work around the bug. [...] > > Thanks, Sven. Actually, not so terribly subtle. What's broken is the idiom > > bundle.member -= decrement > bundle.member += increment > > and the moment I saw that I thought "Uh oh, that's not going to work, is it?" > If you replace it with > > bundle.member = bundle.member - decrement > bundle.member = bundle.member + decrement > > it should work fine. > > Obviously, however, we need to either (a) make the idiom you cited work right > or (b, last resort) disallow it with an error message -- and not just > silently mess up. For the present, plan (b) is implemented in CVS: you get an error message if you try "modified assignment" (such as "+=") to a bundle member. We can revisit this, but it'll be quite complicated to implement plan (a).