hasArg
Look for an Argument in the Call
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.
- Keywords
- programming
Usage
hasArg(name)Arguments
- name
The name of a potential argument, as an unquoted name or character string.
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
Examples
library(methods)
# NOT RUN {
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
# }
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