Thomas Petzoldt wrote: > Patrick Burns wrote: >> One idea of program design is that users >> should be protected against themselves.
... and r coherently implements this idea :] >> >> It is my experience that users, especially >> novices, tend to over-split items rather than >> over-clump items. The fact that items are >> returned by the same function call would >> argue to me that there is a connection between >> the items. >> >> >> Patrick Burns >> patr...@burns-stat.com >> +44 (0)20 8525 0696 >> http://www.burns-stat.com >> (home of "The R Inferno" and "A Guide for the Unwilling S User") > > Hi Gabor, Patrick, Ivo and vQ, hello thomas, > > I agree with Patrick and Gabor that it is not needed. IMHO it is good > design that a function (in a mathematical sense) returns ONE object, > let it a single value, a list or an S3/S4 object. in r functions are not functions in the mathematical sense. r is not quite a functional programming language, though it's certainly closer to fp than c or fortran, say. if one were really interested in whether the feature is desired as a convenience rather than in enforcing one's own opinion, one'd ask users. it's certainly not *needed* in the sense that you can do without it -- but then there are many more features in r which are not needed (and some of them are more harmful than multiple return values would be). > This can be passed to another function as a whole or can be splitted > to its parts according to different needs. right, but that's extra work with coding and performance penalty. > If only single parts are required, than I would suggest to use > accessor functions preferably written as generics working on returned > S3 or S4 objects. I'm strongly against going back to the past S > behaviour and I wonder a little bit about this discussion. i don't know that s behaviour, it's quite possible that it was really wrong. but the fact that s had it wrong (if it did) does not mean that multiple return values are wrong per se. > I like it to have a clean workspace with only a few objects. why would letting others choose for themselves be a bad idea? that's what perl, python, ruby, or more recent languages such as scala, do -- functions can return (tuples of) multiple values which you can capture separately and/or collectively. multiple assignment is a fairly common feature in modern programming languages. it seems that this is a remote dream in r, because 'users should be protected against themselves'. vQ ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
