So I did open a new subject and move the discussion to R-devel now. >>>>> "MM" == Martin Maechler <[EMAIL PROTECTED]> >>>>> on Mon, 24 Jul 2006 11:46:05 +0200 writes:
>>>>> "Gabor" == Gabor Grothendieck <[EMAIL PROTECTED]> >>>>> on Sun, 23 Jul 2006 09:02:35 -0400 writes: Gabor> Looking at the diff.POSIXt code we see the problem is Gabor> that it takes the length of the input using length Gabor> which is wrong since in the case of POSIXlt the Gabor> length is always 9 (or maybe length should be defined Gabor> differently for POSIXlt?). MM> Though I agree with Spencer that a user may expect MM> length() to behave differently, but I don't think this MM> would be a good idea. Yes, length() is generic, but its MM> help() emphasizes that for lists, length() should be the MM> number of list elements. Of course anyone one *can* MM> define length() methods that behave differently for MM> his/her classes, but then one would also want to make MM> sure that e.g. x[length(x)] or 'x[length(x)] <- value' MM> works and -- in a case of simple S3 class built on a MM> list, would work differently than if x was a the simple list. Hmm, after thinking a bit more, and particularly after seeing all the other methods we already have working for "POSIXlt", I'm much less sure if (re)definining length(<POSIXlt>) would be such a bad idea. Indeed, "[", and "[<-" and "[[" already work with an implicit length of 'length_of_series' and not length 9, and so does str(). So it seems to me, there is more reasonable momentum *for* a length.POSIXlt() method than I first considered. Still not sure what the wisest decision would be, and I am asking for more opinions or arguments pro / con. Since Brian Ripley has done the most work on the POSIX[cl]?t classes, we should also wait on his opinion. Martin MM> In my view, I would only consider redefing length() for MM> "non-basic" S4 classes, i.e. those with slots, where no MM> confusion is possible, since these objects are MM> definitely not simple vectors nor lists (aka "generic" MM> vectors). ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel