>Both are dispatched ONLY through the type of arguments.
Not quite. The dispatch may be by type but C++ identifies the arguments by position, while S4 applies R's dispatch rules and respect the names, if present. Regarding your example from a previous email: > ...You can write the previous function prototypes simply as > > int larger(int x, int y); > char larger(char first, char second); You can do this in C++ only because C++ doesn't care what you call the parameters. I don't know why you would want to do this (in C++ or R), it seems such a bad style even if possible. In R you can define methods with different arguments, e.g. by declaring your function with a signature like: larger <- function(x, y, first, second) but then to use argument 'first' you need to use it something like 'larger(first = whatever, ...)'. Georgi Boshnakov -----Original Message----- From: R-package-devel [mailto:r-package-devel-boun...@r-project.org] On Behalf Of Linus Chen Sent: 18 May 2019 10:28 To: Dario Strbenac Cc: r-package-devel@r-project.org Subject: Re: [R-pkg-devel] Function Overloading of S4 Methods Dear Dario, I think differently, I think my examples show the resemblance between the way of "dispatching" for S4 generic and that for C++ overloaded function. Both are dispatched ONLY through the type of arguments. Again following your original example: int larger(int x, int y); char larger(char first, char second); char larger(char x, char y){ # This will work! if y>x y else x; } x = 'a' ; b='b'; larger(x,y); # this will still call the second function. The declaration "char largerChar(char first, char second);" does not make any constraint on the name of argument... Hope this helps. Best, Lei Chen On Sat, May 18, 2019 at 10:00 AM Dario Strbenac <dstr7...@uni.sydney.edu.au> wrote: > > Good day, > > Your conclusion seems to be different to the details you discussed. Don't you > intend to conclude that it's not possible with an S4 generic to define > methods with different argument names which is different to a language such > as C++? > > -------------------------------------- > Dario Strbenac > University of Sydney > Camperdown NSW 2050 > Australia > ______________________________________________ > R-package-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-package-devel ______________________________________________ R-package-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-package-devel ______________________________________________ R-package-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-package-devel
