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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