Define a function with argument checking

`def` is the main utility of this package. It allows users to define functions that perform argument checking when called.

def(.f, ...)

Arguments

.f	Function
...	Named arguments for the function

Value

A function that will check its arguments when called

Examples

# Check argument type
succ <- def(x = "numeric", {
  x + 1
})

succ(1) # => 2
#> [1] 2
succ('a') # => error
#> Error in succ("a"): Errors were found when checking validity of arguments:
#>   x ->  Is a: numeric


# Check if argument is in a set of possible values
f1 <- def(x = list(TRUE, FALSE, NA, NULL), {
  x && !x
})

# Check any condition on an argument
f2 <- def(x = (~ . > 0 && . < 10), {
  x + 1
})

# Chain multiple checks
f3 <- def(x = "character" %&% (~ length(grep("hi", .)) > 0), {
  paste(x, "world!")
})

# Set default values
f4 <- def(x = "numeric" %=% 0, {
  rep(TRUE, x)
})