I am struggling to defuse my ... arguments in one context in particular and I cannot understand why.

I can make a function like this and defuse ... appropriately:

library(dplyr)
library(tidyr)

fill_na <- function(.x,...){

  dotArgs <- rlang::dots_list(...,.named=TRUE,.homonyms="last")
  tidyr::replace_na(.x,dotArgs)  

}

df <- tibble::tribble(
  ~colA, ~colB,
  "a",   1,
  "b",   2,
  "c",   NA,
  NA,    4
)

> fill_na(df,colA="c",colB=2)
# A tibble: 4 × 2
  colA   colB
  <chr> <dbl>
1 a         1
2 b         2
3 c         2
4 c         4

Great, but if I make this function

myFun <- function(inside_of,from_what, ... ,.metadata_defaults=list("Gender"="Undefined","Age"=35),.by_maxFormantHz=TRUE,.recompute=FALSE,.package="superassp"){

    dotArgs <- rlang::dots_list(...,.named=TRUE,.homonyms="last")
    return(1)

}

I get this result:

> myFun(inside_of=ae,from_what=forest,fs=fm, fbw=bw)
Error in rlang::dots_list(..., .named = TRUE, .homonyms = "last") : 
  object 'fm' not found

How come the arguments are not defused here, but were in the first example?

CodePudding user response：

The dots aren’t defused in either of your functions. Per the docs, dots_list() “evaluate[s] all arguments contained in ... and return[s] them as a list” (emphasis added). You just don’t notice it in your fill_na() function because you’re not passing it an undefined variable, so the lack of defusing doesn’t cause any problems.

If you want to defuse the dots, use enquos().

myFun <- function(inside_of,
                  from_what,
                  ...,
                  .metadata_defaults = list("Gender" = "Undefined", "Age" = 35),
                  .by_maxFormantHz = TRUE,
                  .recompute = FALSE,
                  .package = "superassp") {
    dotArgs <- rlang::enquos(...)
    return(1)
}

myFun(inside_of = ae, from_what = forest, fs = fm, fbw = bw)
# 1

You can then use !!!dotArgs inside dots_list() when you’re ready to evaluate.