Function to check names of input to a function

check_args.R

# This function can be called inside of other functions to check
# if the names of the input match the names of the arguments
check_args <- function(call_match) {
	call_names <- as.character(call_match)
	arg_names <- names(as.list(call_match))
	stopifnot(
		"Names of input must match names of arguments" = isTRUE(all.equal(call_names[-1], arg_names[-1]))
	)
}

# For example, define a "strict sum" function
strict_sum <- function(a, b, c) {
	# check that the input names match the arguments
	check_args(match.call())
	# if they do, calculate the sum
	sum(c(a, b, c))
}

# Try it out
a <- 1
b <- 2
c <- 3

# This works, because the names of the input (the input objects themselves)
# match the names of the function arguments 
strict_sum(a,b,c)

# But these will fail
strict_sum(a,b,3)
strict_sum(b,a,c) # etc...