[R-pkg-devel] S3 method, useMethod and <-, using Roxygen

Daniel Lüdecke d.luedecke at uke.de
Fri Oct 23 10:30:56 CEST 2015

I don't exactly know how to name my problem, so I try to describe it.

In my package (sjmisc), I have a function to set label attributes to 

set_labels <- function(x, labels, ...) {

Usage would be:
x <- set_labels(x, c("lo", "high"))

No I wanted to also add functionality to directly change a value:
set_labels(x) <- c("lo", "high")

So I added this to my package source:

#' @rdname set_labels
#' @export
`set_labels<-` <- function(x, force.labels = FALSE, force.values = TRUE, 
value) {

#' @rdname set_labels
#' @export
`set_labels<-.default` <- function(x, force.labels = FALSE, force.values 
= TRUE, value) {
   x <- set_labels(x, values, force.labels, force.values)

However, running the check gives following note and warnings:

* checking R code for possible problems ... NOTE
set_labels<-.default: no visible binding for global variable 'values'
* checking Rd files ... OK
* checking Rd metadata ... OK
* checking Rd line widths ... OK
* checking Rd cross-references ... OK
* checking for missing documentation entries ... OK
* checking for code/documentation mismatches ... WARNING
Functions or methods with usage in documentation object 'set_labels' but 
not in code:

* checking Rd \usage sections ... WARNING
Objects in \usage without \alias in documentation object 'set_labels':

Bad \usage lines found in documentation object 'set_labels':
     <- value

Functions with \usage entries need to have the appropriate \alias
entries, and all their arguments documented.
The \usage entries must correspond to syntactically valid R code.
See chapter 'Writing R documentation files' in the 'Writing R
Extensions' manual.

I don't know what to do here. Any help is appreciated!

Thanks in advance


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