xmlSource <-
  #
  # We could also do things this way
  #  source(textConnection(saveXML(xsltApplyStyleSheet("cityTemperatures.xml", "~/Projects/org/omegahat/XML/Literate/segment.xsl"))))
  #
  #
function(url, ..., envir =globalenv(),
          handlers = list(code = code, example = code, "function" = code,
                           startElement = function(x) NULL),
          ids = character(),
          omit = character(),
          ask = FALSE, 
          fatal = TRUE, verbose = FALSE)
{
  library(XML)

  evalNode = 
   function(node) {
                      #XXX check all ancestors. Ideally exclude them in the XPath query
                     if(xmlName(xmlParent(node)) == "ignore")
                       return(FALSE)
     
                     tmp = xmlGetAttr(node, "id", NA)
                     if(is.na(tmp) && length(ids) > 0 && !("" %in% ids))
                       return()
                     
                     if(!is.na(tmp)) {
                       if(length(omit) > 0 && tmp %in% omit) {
                         if(verbose)
                           warning("skipping id ", tmp)
                         return()
                       } else if(length(ids) > 0 && !(tmp %in% ids)) {
                         if(verbose)
                           warning("ignoring id ", tmp)
                         return()
                       }
                     }

                     tmp = xmlGetAttr(node, "ignore", NA, converter = as.logical)
                     if(!is.na(tmp) && tmp)
                       return()
                     txt = xmlValue(node)
                     if(verbose)
                       cat("*************\nEvaluating node\n", txt, "\n")
                     cmd = parse(text = txt)
                     eval(cmd, globalenv())
   }  

  doc = xmlTreeParse(url, ..., useInternal = TRUE)
#  on.exit(free(doc))

  if(ask) {
     v = getNodeSet(doc, "//r:function|//r:init|//r:code", c("r", "r" = "http://www.r-project.org"))
     funs = sapply(v, xmlName) == "function"
     if(any(funs)) {

     }
  }
  
  v = getNodeSet(doc, "//r:function", c("r", "r" = "http://www.r-project.org"))
  ans = sapply(v, evalNode)
 
  v = getNodeSet(doc, "//r:init[not(@eval='false')]|//r:code[not(@eval='false')]", c("r", "r" = "http://www.r-project.org"))
  ans = sapply(v, evalNode)

  
  invisible(ans)
}