How to pass some (but not all) further arguments with “…”

Question

One of my in-progress functions calls grep() with value = TRUE hard-coded. I\'d like to pass all of the further arguments except <

Answer 1

You can combine Curry with do.call:

require(functional)
f <- function(pattern, x, ...)
{
  dots <- list(...)
  dots <- dots[!grepl('value', names(dots))]
  do.call(Curry(grep, pattern=pattern, x=x, value=TRUE), dots)
}

Curry provides the known arguments, and dots supplies everything other than "value" in ....

Answer 2

One way is to just make value a named parameter but ignore the input - that way it will never be a part of the dots to begin with.

f <- function(pattern, x, value = "hahaThisGetsIgnored", ...){
   grep(pattern, x, value = TRUE, ...)
}

You can also use the idea in the answer @MatthewLundberg gave but by doing the argument manipulation without Curry so you don't need the functional package

f <- function(pattern, x, ...){
  dots <- list(...)
  # Remove value from the dots list if it is there
  dots$value <- NULL
  args <- c(list(pattern = pattern, x = x, value = TRUE), dots)
  do.call(grep, args)
}