Simple classes for identifying an XML document containing R code
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 source to read the
code into R and also used in link{xmlSource} to read just parts of it.
XMLCodeFile represents the file by its name;
XMLCodeDoc parses the contents of the file when the R object is created.
Therefore, an XMLCodeDoc is a snapshot of the contents at a moment in time
while an XMLCodeFile object re-reads the file each time and so reflects
any "asynchronous" changes.
One can create these objects using coercion methods, e.g
as("file/name", "XMLCodeFile")
or as("file/name", "XMLCodeDoc").
One can also use xmlCodeFile.
.Data:Object of class "character"
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.
signature(from = "XMLCodeFile", to = "XMLCodeDoc"):
parse the XML document from the "file" and treat the result as a
XMLCodeDoc object.
signature(file = "XMLCodeFile"): read and evaluate all the
R code in the XML document. For more control, use xmlSource.
Duncan Temple Lang
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)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.