Thanks for the report. The issue is that one cannot set special attributes like names, dim, dimnames, etc on S4 objects. I was aready working on this and will have a fix soon.
> a2 <- new("A2") > dim(a2) <- c(2, 3) Error in dim(a2) <- c(2, 3) : invalid first argument On Mon, Jun 5, 2017 at 6:08 PM, Hervé Pagès <hpa...@fredhutch.org> wrote: > Hi, > > It's nice to be able to define S4 classes with slots that correspond > to standard attributes: > > setClass("A1", slots=c(names="character")) > setClass("A2", slots=c(dim="integer")) > setClass("A3", slots=c(dimnames="list")) > > By doing this, one gets a few methods for free: > > a1 <- new("A1", names=letters[1:3]) > names(a1) # "a" "b" "c" > a2 <- new("A2", dim=4:3) > nrow(a2) # 4 > a3 <- new("A3", dimnames=list(NULL, letters[1:3])) > colnames(a3) # "a" "b" "c" > > However, when it comes to subclassing, some of these slots cause > problems. I can extend A1: > > setClass("B1", contains="A1") > > but trying to extend A2 or A3 produces an error (with a non-informative > message in the 1st case and a somewhat obscure one in the 2nd): > > setClass("B2", contains="A2") > # Error in attr(prototype, slotName) <- attr(pri, slotName) : > # invalid first argument > > setClass("B3", contains="A3") > # Error in attr(prototype, slotName) <- attr(pri, slotName) : > # 'dimnames' applied to non-array > > So it seems that the presence of a "dim" or "dimnames" slot prevents a > class from being extended. Is this expected? I couldn't find anything > in TFM about this. Sorry if I missed it. > > Thanks, > H. > > -- > Hervé Pagès > > Program in Computational Biology > Division of Public Health Sciences > Fred Hutchinson Cancer Research Center > 1100 Fairview Ave. N, M1-B514 > P.O. Box 19024 > Seattle, WA 98109-1024 > > E-mail: hpa...@fredhutch.org > Phone: (206) 667-5791 > Fax: (206) 667-1319 > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel