On Nov 10, 2007 1:27 PM, Simon Urbanek <[EMAIL PROTECTED]> wrote: > > > On Nov 10, 2007, at 1:05 PM, Duncan Murdoch wrote: > > > On 10/11/2007 1:00 PM, Duncan Temple Lang wrote: > >> -----BEGIN PGP SIGNED MESSAGE----- > >> Hash: SHA1 > >> > >> > >> > >> Duncan Murdoch wrote: > >>> Prof Brian Ripley wrote: > >>>> Please don't use 'assert' in R packages. If called, this means > >>>> that an > >>>> error in your code aborts the whole R process, including your > >>>> user's work. > >>>> I see several R packages doing this, and one of them called > >>>> 'assert' on me > >>>> earlier in the week. > >>>> > >>> I partly disagree about this. If assert() is triggered, it clearly > >>> indicates a bug in the package. If it just generated an R error, > >>> most > >>> users would ignore it, and not report it to the package maintainer. > >>> > >>> It may well be that when an assertion fails, none of the subsequent > >>> calculations are reliable, in which case returning control to the > >>> user > >>> could result in data corruption. That's worse than losing a > >>> session, > >>> because at least when you lose a session, you know it. > >>> > >>> Could we write our own implementation of assert() that displays an R > >>> error and unloads the package? I think I could do something like > >>> that > >>> in Windows by calling FreeLibrary to unload the DLL, but I'd > >>> prefer a > >>> cross-platform solution. > >> > >> I am not sure why you think we need to discard the DLL. > > > > The package author has asserted that it is no longer safe to run. > > They are shutting down R, and Brian finds that too extreme. > > > > Me too. A package should never intentionally close the R session. If > it does, it is a very severe design bug in the package (IMHO). > Anything you use assert for can be gracefully handled (as opposed to > let's say a segfault), so there is no excuse for killing the whole > process at all (deliberately wiping all user's work is rude to put it > mildly).
Oh, I normally try to wipe the harddrive too when I'm at it ;) /H > Even if it might be unsafe to run anything, I'd still want > to attempt to save my data. > > Cheers, > Simon > > > > >> What if we want to access variables and routines merely to find out > >> the resulting state after the assert(). > >> And it is not clear whether you mean any "subsequent calculations" > >> or any "subsequent calculations using code within this DLL" > >> might be unreliable. > > > > How could I know why a package author decided a shutdown is > > needed? It > > depends on the author. > > > >> > >> But regardless of that and the assumption that users will ignore this > >> error, why would you want to call FreeLibrary? Since R has induced > >> the > >> DLL to be loaded either directly or indirectly, R holds a handle > >> to the > >> DLL. If you don't use R's cross-platform facilities for releasing the > >> DLL (either at the R or C-level), you will corrupt the session, > >> specifically in the list of assumed-live DLLs. > > > > As I said, I'd prefer a cross-platform solution. > > > > Duncan Murdoch > >> > >> D. > >> > >> > >>>> We provide 'error': please do use it to return control to the > >>>> user when > >>>> your code misbehaves. > >>>> > >>>> Similarly 'exit' and 'abort' should never be used in R packages. > >>>> > >>>> > >>>> Sometimes it is not under your control: I sometimes see an rgl > >>>> failure at > >>>> > >>>> R: indirect_vertex_array.c:659: emit_DrawArrays_old: Assertion > >>>> `elements_per_request >= count' failed. > >>>> > >>>> that is coming from the Mesa GL libraries. > >>>> > >>> I'd say that's a bug, either in Mesa GL or in rgl. If you can > >>> make it > >>> reproducible, I'll try to track it down. > >>> > >>> Duncan Murdoch > >>> > >>> ______________________________________________ > >>> R-devel@r-project.org mailing list > >>> https://stat.ethz.ch/mailman/listinfo/r-devel > >> -----BEGIN PGP SIGNATURE----- > >> Version: GnuPG v1.4.7 (Darwin) > >> Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org > >> > >> iD8DBQFHNfHA9p/Jzwa2QP4RAo2BAJkB5QaFLOW5fcR6QE9JSXpIWAcEUwCggMYK > >> 2WBnl5jDgTUayU5wk8hnQj4= > >> =91by > >> -----END PGP SIGNATURE----- > > > > ______________________________________________ > > R-devel@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-devel > > > > > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
