Gabriel,
[I understand that this is not about R development, but it seemed that this was a question about R internals that would be better answered on the R-devel list.] Thanks for your answer. Yes, this is what the person who answered on SO said as well. But my question is about terminology really. Why is the internal storage type called object type, which clashes with my understanding of an object being an instance of a class, and hence should share the same name? This is a purely technical notion, which should have nothing to do with the physical reality of C storage and types. Thanks. On Wednesday, December 25, 2013 3:02 AM, Gabriel Becker <gmbec...@ucdavis.edu> wrote: Fg, > >This is not really an r-devel question. It is more appropriate for r-help as >far as I know. Please ask questions like it there in the future. > >Anyway, my understanding is that the type of an object has to do with how it >is stored internally, whereas the class has to do with how it is dispatched >on. For example, in the S3 system , it is entirely reasonable to do the >following: > > >> x = 1:10 >> class(x) = "myspecialint" >> x > [1] 1 2 3 4 5 6 7 8 9 10 >attr(,"class") >[1] "myspecialint" >> print.myspecialint = function(x, ...) print(mean(x)) >> print(x) >[1] 5.5 >> typeof(x) >[1] "integer" > >As you can see, changing the "class" of x did not change how it was stored >internally. > > >Another canonical example is the matrix class. Matrices in R are stored as >vectors of the relevant type, with additional attributes indicating their >dimension. So while there is a matrix class, there is no matrix type. > > >> x = matrix(1:10, nrow=2) >> x > [,1] [,2] [,3] [,4] [,5] >[1,] 1 3 5 7 9 >[2,] 2 4 6 8 10 >> typeof(x) >[1] "integer" > > >HTH, >~G > > > > >On Tue, Dec 24, 2013 at 12:26 PM, Fg Nu <fgn...@yahoo.com> wrote: > > >> >> >>I came across the distinction between the name of an object and the name of >>the class that it belongs to in an oblique way again today, which made me >>question my acceptance that it would be natural for them to differ. >> >>I asked a question on SO here: >>http://stackoverflow.com/questions/20762559/why-is-the-name-of-an-object-type-different-from-the-name-of-the-class-it-belong >> >>I wonder if anyone on the R-Devel list has a better explanation for why the >>class name of an object and the object type name of an object should differ? >> >>Happy holidays, >> >>fg >> >>______________________________________________ >>R-devel@r-project.org mailing list >>https://stat.ethz.ch/mailman/listinfo/r-devel >> > > >-- >Gabriel Becker >Graduate Student >Statistics Department >University of California, Davis > > > [[alternative HTML version deleted]]
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