hasArg
Check for Argument Names

### Description

Checks the current call for an argument corresponding to name. The name can be one of the formal arguments or a named component of .... The behavior on ... distinguishes this function from !missing(name).

### Usage

    hasArg(name)

### Arguments

name | an argument to the function in which the call to hasArg occurs. This can also be a string constant specifying an argument name.

Value
returns a logical value.

- If the specified argument is a formal argument to the function where hasArg appears, and if the current call supplies this argument, hasArg returns TRUE.
- If ... is an argument and the current call contains this argument name as a named argument, hasArg returns TRUE.

See Also
missing, names, match.call, args, match.arg.
Examples

    ftest <- function(x1, ...) c(hasArg(x1), hasArg(y2))
    ftest(1)      ## [1]  TRUE, FALSE
    ftest(1, 2)   ## [1]  TRUE, FALSE
    ftest(y2=2)   ## [1] FALSE,  TRUE
    ftest(y=2)    ## [1] FALSE, FALSE (no partial matching on ... args)
    ftest(y2=2, x=1) ## [1] TRUE, TRUE
    ## 'x' actual argument partial matches to x1 before hasArg is called

Package methods version 6.1.5-18
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