[Rd] Possible bug in `class<-` when a class-specific '[[.' method is defined

[Michael Lawrence]

I'm unable to reproduce this with R 3.6.1. Which version are you
using? Is this a fresh session?

On Mon, Jul 15, 2019 at 3:25 AM Ghiggi Gionata <gionata.ghiggi using epfl.ch> wrote:
>
> Hi all !
>
> I noticed a strange behaviour of the function `class<-` when a class-specific '[[.' method is defined.
>
> Here below a reproducible example :
>
>
> #-------------------------------------------------------------------.
>
> counttt <- 0
>
> `[[.MYCLASS` = function(x, ...) {
>   counttt <<- counttt + 1
>   # browser()
>   x = NextMethod()
>   return(x)
> }
>
> df <- as.data.frame(matrix(1:20, nrow=5))
> class(df) <- c("MYCLASS","data.frame")
> counttt
>
> # The same occurs when using structure(, class=) or attr(,"class")<-
> df <- as.data.frame(matrix(1:20, nrow=5))
> df <- structure(df, class=c("MYCLASS","data.frame"))
> attr(df, "class") <- c("MYCLASS","data.frame")
>
> #-------------------------------------------------------------------.
>
> Why in this example `class<-` is calling  `[[.MYCLASS` 9 times ?
>
> Is there a way to avoid `class<-` to call `[[.MYCLASS` ?
>
>
> Thank you in advance for your help and suggestions.
>
> Gionata
>
>
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-devel using r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel



-- 
Michael Lawrence
Scientist, Bioinformatics and Computational Biology
Genentech, A Member of the Roche Group
Office +1 (650) 225-7760
michafla using gene.com

Join Genentech on LinkedIn | Twitter | Facebook | Instagram | YouTube