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\name{XMLCodeFile-class}
%\Rdversion{1.1}
\docType{class}
\alias{XMLCodeFile-class}
\alias{XMLCodeDoc-class}
\alias{xmlCodeFile}
\alias{[[,XMLCodeFile-method}
%\alias{[[,XMLCodeFile,ANY,ANY-method}
\alias{[[,XMLCodeFile,ANY-method}
\alias{coerce,XMLCodeFile,XMLCodeDoc-method}
\alias{coerce,character,XMLCodeDoc-method}
\alias{coerce,character,XMLCodeFile-method}
\alias{source,XMLCodeFile-method}
\title{Simple classes for identifying an XML document containing R code}
\description{
These two classes allow the user to identify an XML document or file
as containing R code (amongst other content). Objects of either of these
classes can then be passed to \code{\link{source}} to read the
code into R and also used in \code{link{xmlSource}} to read just parts of it.
\code{XMLCodeFile} represents the file by its name;
\code{XMLCodeDoc} parses the contents of the file when the R object is created.
Therefore, an \code{XMLCodeDoc} is a snapshot of the contents at a moment in time
while an \code{XMLCodeFile} object re-reads the file each time and so reflects
any "asynchronous" changes.
}
\section{Objects from the Class}{
One can create these objects using coercion methods, e.g
\code{as("file/name", "XMLCodeFile")}
or \code{as("file/name", "XMLCodeDoc")}.
One can also use \code{xmlCodeFile}.
}
\section{Slots}{
\describe{
\item{\code{.Data}:}{Object of class \code{"character"}}
}
}
\section{Extends}{
Class \code{"\linkS4class{character}"}, from data part.
Class \code{"\linkS4class{vector}"}, by class "character", distance 2.
%Class \code{"\linkS4class{data.frameRowLabels}"}, by class "character", distance 2.
%Class \code{"\linkS4class{EnumerationValue}"}, by class "character", distance 2.
%Class \code{"\linkS4class{NodeIndex}"}, by class "character", distance 2.
%Class \code{"\linkS4class{RAnonymousFunctionOrCode}"}, by class "character", distance 2.
}
\section{Methods}{
\describe{
\item{[[}{\code{signature(x = "XMLCodeFile", i = "ANY", j = "ANY")}:
this method allows one to retrieve/access an individual R code element
in the XML document. This is typically done by specifying the value of the XML element's
"id" attribute.
}
\item{coerce}{\code{signature(from = "XMLCodeFile", to = "XMLCodeDoc")}:
parse the XML document from the "file" and treat the result as a
\code{XMLCodeDoc} object.
}
\item{source}{\code{signature(file = "XMLCodeFile")}: read and evaluate all the
R code in the XML document. For more control, use \code{\link{xmlSource}}.}
}
}
\author{Duncan Temple Lang}
\seealso{
\code{\link{xmlSource}}
}
\examples{
src = system.file("exampleData", "Rsource.xml", package = "XML")
# mark the string as an XML file containing R code
k = xmlCodeFile(src)
# read and parse the code, but don't evaluate it.
code = xmlSource(k, eval = FALSE)
# read and evaluate the code in a special environment.
e = new.env()
ans = xmlSource(k, envir = e)
ls(e)
}
\keyword{classes}
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