\name{edit}
\alias{edit}
\alias{edit.default}
\alias{vi}
\alias{emacs}
\alias{pico}
\alias{xemacs}
\alias{xedit}
\title{Invoke a Text Editor}
\description{
  Invoke a text editor on an \R object.
}
\usage{
\method{edit}{default}(name = NULL, file = "", title = NULL,
     editor = getOption("editor"), \dots)

vi(name = NULL, file = "")
emacs(name = NULL, file = "")
pico(name = NULL, file = "")
xemacs(name = NULL, file = "")
xedit(name = NULL, file = "")
}
\arguments{
  \item{name}{a named object that you want to edit. If name is missing
    then the file specified by \code{file} is opened for editing.}
  \item{file}{a string naming the file to write the edited version to.}
  \item{title}{a display name for the object being edited.}
  \item{editor}{a string naming the text editor you want to use.  On
    Unix the default is set from the environment variables \env{EDITOR}
    or \env{VISUAL} if either is set, otherwise \code{vi} is used.  On
    Windows it defaults to \code{notepad}.}
  \item{\dots}{further arguments to be passed to or from methods.}
}
\details{
  \code{edit} invokes the text editor specified by \code{editor} with
  the object \code{name} to be edited.  It is a generic function,
  currently with a default method and one for data frames and matrices.

  \code{data.entry} can be used to edit data, and is used by \code{edit}
  to edit matrices and data frames on systems for which
  \code{data.entry} is available.

  It is important to realize that \code{edit} does not change the object
  called \code{name}. Instead, a copy of name is made and it is that copy
  which is changed. Should you want the changes to apply to the object
  \code{name} you must assign the result of \code{edit} to
  \code{name}. (Try \code{\link{fix}} if you want to make permanent
  changes to an object.)
  
  In the form \code{edit(name)},
  \code{edit} deparses \code{name} into a temporary file and invokes the
  editor \code{editor} on this file. Quitting from the editor causes
  \code{file} to be parsed and that value returned.
  Should an error occur in parsing, possibly due to incorrect syntax, no
  value is returned. Calling \code{edit()}, with no arguments, will
  result in the temporary file being reopened for further editing.
  
  Currently only the internal editor in Windows makes use of the 
  \code{title} option; it displays the given name in the window 
  header.
}
\seealso{
  \code{\link{edit.data.frame}},
  \code{\link{data.entry}},
  \code{\link{fix}}.
}
\note{
  The functions \code{vi}, \code{emacs}, \code{pico}, \code{xemacs},
  \code{xedit} rely on the corresponding editor being available and
  being on the path. This is system-dependent.
}
\examples{
\dontrun{
# use xedit on the function mean and assign the changes
mean <- edit(mean, editor = "xedit")

# use vi on mean and write the result to file mean.out
vi(mean, file = "mean.out")
}
}
\keyword{utilities}