\name{writeWIxml}
\alias{writeWIxml}
\alias{readWIxml}
\title{Functions to read and write widgetInvoke XML files}
\description{
  These functions are used to serialize object of class \code{wFun} to
  and from XML files.  
}
\usage{
writeWIxml(wFun, file = paste(funName(wFun), "xml", sep = "."))
readWIxml(file)
}

\arguments{
  \item{wFun}{An object of class \code{\link{wFun}} to serialize.}
  \item{file}{The filename to use for reading or writing.}
}
\details{
  The class \code{\link{wFun}} is used to create the user interface in
  the \code{\link{widgetInvoke}} function.  These \code{\link{wFun}}
  objects must be precreated for any given function, and then stored in
  XML format in the \code{inst/wFun} directory of the appropriate
  package, and are then read in with \code{readWIxml} when the user
  calls \code{\link{widgetInvoke}} for that function.

  The XML format used first defines the primary tag of \code{wFun},
  which indicates the start of a \code{wFun} definition.  There are two
  main sub-fields in the \code{wFun} block: \code{funName} and
  \code{funArgList}.  The former simply contains a string indicating the
  name of this function.  The \code{funArgList} block itself contains a
  series of smaller blocks, each representing an argument to the
  function.

  Within the \code{funArgList} are a series of \code{funArg} blocks.
  Within each \code{funArg} are six tags.  The first is \code{argName},
  detailing the argument's name.  The second is \code{argDefault}, which
  if not empty is the default value of the argument.  Next is
  \code{argType}, which describes the type of the argument
  (e.g. character, numeric, logical, or ANY for an untyped argument).
  The \code{argLocation} field specifies which tab this argument appears
  on in the \code{\link{widgetInvoke}} notebook, and
  \code{argWidgetType} describes the type of widget to use in displaying
  this argument.  Finally, the \code{argRequired} field is a logical
  value specifying if this argument is required to be filled in by the
  user (or a default) before evaluation of the function.

  As an example, the following is an example for the function
  \code{\link{apropos}}:
  \preformatted{
    <?xml version="1.0"?>
    <wFun xmlns:bt="http://www.bioconductor.org/WINVOKE">
        <funName>apropos</funName>
        <funArgList>
                <funArg>
                        <argName>what</argName>
                        <argDefault></argDefault>
                        <argType>ANY</argType>
                        <argLocation>main</argLocation>
                        <argWidgetType>TypeIn</argWidgetType>
                        <argRequired>FALSE</argRequired>
                </funArg>
                <funArg>
                        <argName>where</argName>
                        <argDefault>FALSE</argDefault>
                        <argType>logical</argType>
                        <argLocation>main</argLocation>
                        <argWidgetType>Radio</argWidgetType>
                        <argRequired>FALSE</argRequired>
                </funArg>
                <funArg>
                        <argName>mode</argName>
                        <argDefault>"any"</argDefault>
                        <argType>character</argType>
                        <argLocation>main</argLocation>
                        <argWidgetType>TypeIn</argWidgetType>
                        <argRequired>FALSE</argRequired>
                </funArg>
        </funArgList>
    </wFun>
  }  
}
\value{
The \code{readWIxml} will return an object of class \code{\link{wFun}}
representing the data stored in the specified XML file.
  
The \code{writeWIxml} function has no return value.
}
\author{Jeff Gentry}
\seealso{\code{\link{createWF}}, \code{\link{widgetInvoke}}}
\examples{
   z <- readWIxml(system.file("wFun-example", "apropos.xml",
                  package="widgetInvoke"))
   writeWIxml(z, file=tempfile())
}
\keyword{utilities}