Thanks, Duncan. That's helpful.
In addition, I confess I had a closing parenthesis in the wrong place.
Should be: . . . .GlobalEnv), silent = TRUE)
Cheers,
Russ
-----Original Message-----
From: Duncan Murdoch <murdoch.dun...@gmail.com>
Sent: Saturday, August 10, 2019 2:43 PM
To: Lenth, Russell V <russell-le...@uiowa.edu>; Iñaki Ucar
<iu...@fedoraproject.org>
Cc: r-package-devel@r-project.org
Subject: Re: [R-pkg-devel] [External] Re: Farming out methods to other packages
On 10/08/2019 3:27 p.m., Lenth, Russell V wrote:
> Hmmmm, I thought of an approach -- a kind of manual dispatch
> technique. My generic is
>
> recover_data <- function(object, ...) {
> rd <- try(getS3method("recover_data", class(object)[1], envir =
> .GlobalEnv, silent = TRUE))
> if (!inherits(rd, "try-error"))
> rd(object, ...)
> else
> UseMethod("recover_data")
> }
>
> and similar for emm_basis. The idea is it tries to find the method among
> globally registered ones, and if so, it uses it; otherwise, the internal one
> is used.
That's a bad test: class(object) might be a vector c("nomethod", "hasmethod").
You're only looking for recover_data.nomethod, and maybe only
recover_data.hasmethod exists.
The getS3method() function won't automatically iterate through the class,
you'll need to do that yourself, for example
S3methodOrDefault <- function(object, generic, default) {
for (c in class(object)) {
rd <- try(getS3method(generic, c, envir = .GlobalEnv, silent = TRUE))
if (!inherits(rd, "try-error"))
return(rd)
}
return(default)
}
used as
S3methodOrDefault(object, "recover_data", internal_recover_data)
Duncan Murdoch
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