Process the ... arguments of a function.

dotsNames returns the names of the ... arguments, or a character vector of empty strings if they are unnamed (without evaluating ...).

subDots returns the ... arguments as a list of expressions.

dp1Dots returns the ... arguments as a character vector of deparsed expressions.

checkDots errors or warns about extraneous arguments in the ... of its caller.

Usage

dotsNames(...)

subDots(...)

dp1Dots(..., collapse = " ", width.cutoff = 500L)

checkDots(..., error = TRUE, which.call = -1, allowed = character(0))

Arguments

...

"the dots", as passed from the caller.

collapse

a string, passed to paste.

width.cutoff

integer in [20, 500] determining the cutoff (in bytes) at which line-breaking is tried.

error

a logical value indicating whether to throw an error (TRUE) or a warning (FALSE) for extraneous arguments.

which.call

passed to sys.call. A caller may use -2 if the message should mention its caller.

allowed

character vector of named elements in ... which are "allowed" and hence do not cause an error or warning.

Value

For dotsNames, a character vector of the names of the ... arguments.

For subDots, a list of expressions.

For dp1Dots, a character vector of deparsed expressions.

For checkDots, NULL (invisibly), called for its side effects.

Details

dotsNames is an implementation of allNames for ... arguments.

subDots is a simple wrapper for as.list(substitute(...())).

dp1Dots applies deparse1 to each element of subDots(...).

checkDots is a variation of chkDots for use in functions that want to error in case of extraneous arguments, not just warn. checkDots also shows whether extraneous arguments are named or unnamed, and if unnamed, the message will show the deparsed expressions of the unnamed arguments. See examples.

See also

..., chkDots, stop, warning, substitute, deparse1.

Examples

f <- function(...) dotsNames(...)
f(1, 2, mean(1:10))
#> [1] "" "" ""
f(a = 1, b = 2, mean(1:10))
#> [1] "a" "b" "" 

f <- function(...) subDots(...)
f(a = 1, b = 2, mean(1:10))
#> $a
#> [1] 1
#> 
#> $b
#> [1] 2
#> 
#> [[3]]
#> mean(1:10)
#> 

f <- function(...) dp1Dots(...)
f(a = 1, b = 2, mean(1:10))
#>            a            b              
#>          "1"          "2" "mean(1:10)" 

f <- function(x, ...) checkDots(..., allowed = "b")
f(1, b = 1)
try(f(1, a = 1, b = 2, mean(1:10)))
#> Error : In f(1, a = 1, b = 2, mean(1:10)) :
#>  extra named argument ‘a’ is not allowed.
#>  extra unnamed argument ‘mean(1:10)’ is not allowed.