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

missing

Aliases
  • hasArg
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 # }
Documentation reproduced from package methods, version 3.5.2, License: Part of R 3.5.2

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