| hasArg {methods} | R Documentation |
Look for an Argument in the Call
Description
Returns TRUE if name corresponds to an argument in the
call, either a formal argument to the function, or a component of
..., and FALSE otherwise.
Usage
hasArg(name)
Arguments
name |
The unquoted name of a potential argument. |
Details
The expression hasArg(x), for example, is similar to
!missing(x), with two exceptions. First, hasArg will look for
an argument named x in the call if x is not a formal
argument to the calling function, but ... is. Second,
hasArg never generates an error if given a name as an argument,
whereas missing(x) generates an error if x is not a
formal argument.
Value
Always TRUE or FALSE as described above.
See Also
missing
Examples
ftest <- function(x1, ...) c(hasArg(x1), hasArg(y2))
ftest(1) ## c(TRUE, FALSE)
ftest(1, 2) ## c(TRUE, FALSE)
ftest(y2=2) ## c(FALSE, TRUE)
ftest(y=2) ## c(FALSE, FALSE) (no partial matching)
ftest(y2 = 2, x=1) ## c(TRUE, TRUE) partial match x1