CODEWITHSUNDEEP
rexception
Artie Ladie
Artie Ladie

Reputation: 521

R Function Doesn't Throw Error As Expected

At end of question is script (plus on github). The GitHub repo is here and can be installed with

install.packages("devtools")
devtools::install_github("ArtieLadie/RanglaPunjab")

MergePalette(name,name2) takes two names. If person only passes one name, I want the following to execute and then exit the function,

Enter 2 valid palettes. Run ListPalette() for list of palettes.

Unfortunately, when I execute MergePalette("Teej"), I get

Error in MergePalette("Teej") : argument "name2" is missing, with no default

How to fix this

MergePalette <- function(name,name2){

  pal <-  RanglaPunjab(name)

  if (is.null(name2)){
    stop("Enter 2 valid palettes. Run ListPalette() for list of palettes.")
 }
  pal2 <-  RanglaPunjab(name2)

  new_pal <-unique(c(pal,pal2))

  new_pal
}

Upvotes: 0

Views: 259

Answers (1)

r2evans
r2evans

Reputation: 160447

Two methods:

  1. Preferred: Check for missingness:

    MergePalette <- function(name,name2){
  if (missing(name2)) { stop(...) }

  2. Define a default value of NULL in the formals, and the function works:

    MergePalette <- function(name,name2=NULL){
  if (is.null(name2)) { stop(...) }

    If the user (accidentally) provides an argument to name2 that is itself NULL, the error message will be confusing. As @Moody_Mudskipper noted, by setting the default to NULL, you are implicitly telling the user that this argument is optional and/or that NULL is okay. With that, I suggest that this option is not appropriate for this question/use.

Upvotes: 2

Related Questions