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% File src/library/methods/man/hasArg.Rd
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% File src/library/methods/man/hasArg.Rd
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% Part of the R package, http://www.R-project.org
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% Part of the R package, http://www.R-project.org
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% Copyright 1995-2007 R Core Team
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% Copyright 1995-2013 R Core Team
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% Distributed under GPL 2 or later
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% Distributed under GPL 2 or later
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\name{hasArg}
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\name{hasArg}
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\alias{hasArg}
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\alias{hasArg}
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\title{Look for an Argument in the Call}
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\title{Look for an Argument in the Call}
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}
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}
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\usage{
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\usage{
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hasArg(name)
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hasArg(name)
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}
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}
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\arguments{
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\arguments{
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  \item{name}{The unquoted name of a potential argument.}
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  \item{name}{The name of a potential argument, as an unquoted name or
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    character string.}
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}
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}
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\details{
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\details{
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  The expression \code{hasArg(x)}, for example, is similar to
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  The expression \code{hasArg(x)}, for example, is similar to
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  \code{!missing(x)}, with two exceptions.  First,  \code{hasArg} will look for
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  \code{!missing(x)}, with two exceptions.  First,  \code{hasArg} will look for
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  an argument named \code{x} in the call if \code{x} is not a formal
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  an argument named \code{x} in the call if \code{x} is not a formal
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  Always \code{TRUE} or \code{FALSE} as described above.
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  Always \code{TRUE} or \code{FALSE} as described above.
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}
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}
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\seealso{ \code{\link{missing}} }
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\seealso{ \code{\link{missing}} }
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\examples{
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\examples{
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ftest <- function(x1, ...) c(hasArg(x1), hasArg(y2))
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ftest <- function(x1, ...) c(hasArg(x1), hasArg("y2"))
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ftest(1) ## c(TRUE, FALSE)
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ftest(1) ## c(TRUE, FALSE)
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ftest(1, 2)  ## c(TRUE, FALSE)
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ftest(1, 2)  ## c(TRUE, FALSE)
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ftest(y2=2)   ## c(FALSE, TRUE)
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ftest(y2 = 2)   ## c(FALSE, TRUE)
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ftest(y=2)    ## c(FALSE, FALSE) (no partial matching)
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ftest(y = 2)    ## c(FALSE, FALSE) (no partial matching)
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ftest(y2 = 2, x=1)  ## c(TRUE, TRUE) partial match x1
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ftest(y2 = 2, x = 1)  ## c(TRUE, TRUE) partial match x1
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 - 
 
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}
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}
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\keyword{ programming }
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\keyword{ programming }