[R] passing a modified argument to an S3 method

Sat Apr 20 19:29:43 CEST 2024

> On Apr 19, 2024, at 1:36 PM, CRAN.r via R-help <r-help using r-project.org> wrote:
> 
> Is there a way to pass a modified argument from an S3 generic to a method?  Here's a non-working example that I want to return "abcd".
> 

grep-ing the source code is often a good way to answer a question like this.

Particularly, with NextMethod there seem to be plenty of instances in which the original arguments are modified before a call to a method.

One such is `t.data.frame` and there seem to be other methods for "data.frame" objects that modify the objects before calling NextMethod.

HTH,

Chuck

>  test <- function(x, y = NULL){
>    y <- "abcd"
>    UseMethod("test")
>  }
>  test.default <- function(x, y = NULL) y
>  test(x = 3)
> 
> Is that possible? I've looked around a lot, but can't find any examples or discussion.
> 
> Jay
> 
> From nobody Sat Apr 20 10:07:59 2024
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> Subject: passing a modified argument to an S3 method
> Date: Fri, 19 Apr 2024 20:36:22 +0000
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> 
> Is there a way to pass a modified argument from an S3 generic to a method?  Here's a non-working example that I want to return "abcd".
> 
>  test <- function(x, y = NULL){
>    y <- "abcd"
>    UseMethod("test")
>  }
>  test.default <- function(x, y = NULL) y
>  test(x = 3)
> 
> Is that possible? I've looked around a lot, but can't find any examples or discussion.
> 
> Jay
> 