1\name{as.function.formula} 2\alias{as.function.formula} 3\title{ Make a one-line function from a formula. } 4\description{ 5 Create a function from a formula. 6} 7\usage{ 8\method{as.function}{formula}(x, ...) 9} 10\arguments{ 11 \item{x}{ Formula with no left side. } 12 \item{\dots}{ Currently not used. } 13} 14\value{ 15 A function is returned whose formal arguments are the 16 variables in the left hand side, whose body 17 is the expression on the right side of the formula and whose 18 environment is the environment of the formula. If there is 19 no left hand side the free variables on the right, in the 20 order encountered are used as the arguments. \code{letters}, 21 \code{LETTERS} and \code{pi} are ignored and not used as arguments. 22 If there is no left hand side and 23 any of \code{..1}, \code{..2}, ..., \code{..9} are found 24 as free variables then they are not used as arguments but \code{...} 25 is used as a trailing argument instead. 26 If there is no left hand side and \code{`&`} is found as a free variable 27 then that variable is used as the first argument and \code{...} is added 28 as the last argument. 29 If the left hand side is \code{0} then the function is created as 30 a zero argument function. 31} 32\note{\code{->}, \code{->>}, \code{=}, \code{<-}, \code{<<-} and \code{?} 33all have lower operator precdence than \code{~} so function bodies that 34contain them typically must be surrounded with \code{{...}}.} 35\seealso{ \code{\link[base]{Syntax}}.} 36\examples{ 37old.options <- options(keep.source = FALSE) 38as.function(~ as.numeric(x) + as.numeric(y)) 39as.function(x + y ~ as.numeric(x) + as.numeric(y)) # same 40as.function(~ ..1 + ..2) 41# the replacement function in gsubfn uses as.function.formula to 42# interpret formulas as functions. Here we insert ! after each digit. 43gsubfn("[0-9]", ~ paste0(`&`, "!"), "ab4cd5") 44\dontrun{ 45# example where function body must be surrounded with {...} 46# due to use of <<-. See warning section above. 47assign("mywarn", NULL, .GlobalEnv) 48fn$tryCatch( warning("a warning"), 49 warning = w ~ { mywarn <<- conditionMessage(w)}) 50print(mywarn) 51} 52options(old.options) 53} 54\keyword{ character } 55