hi, just a few sidenotes on recent development regarding the XiMpLe package (which was written as a toolkit for the rkwarddev package, originally).
in the develop branch, the package now has some new features to make scripting
and maintaining XML trees more straightforward.
the new function gen_tag_functions() generates wrapper functions around
XMLNode() by tag name. functions go to .GlobalEnv by default, but you can also
have them in an attached environment instead, e.g.
attach(list(), name="XiMpLe_wrappers")
gen_tag_functions(
tags=c("a", "div"),
envir=as.environment("XiMpLe_wrappers")
)
this creates the functions a_() and div_() which are wrappers for XMLNode("a")
and XMLNode("div"), respectively. also, node attributes can now generally be
given as named arguments with the dots parameter, i.e. these all produce the
same result:
# old syntax
XMLNode("a", "click here", attrs=list(href="foo.html"))
# now also valid syntax
XMLNode("a", "click here", href="foo.html")
# new wrapper function
a_("click here", href="foo.html")
to make this usable, i renamed the first argument of XMLNode(), which defines
the XML node name. until now, the argument was called "name", which is also a
commonly used attribute name, so you'd still have to use the old attrs list to
circumvent collisions. it is now called "tag_name" and i hope this doesn't
break anything, as the first argument is often used without explicitly writing
it's name out...
another new feature is the "as_script" parameter in pasteXML(). instead of
showing the object as XML code, pasteXML(..., as_script=TRUE) returns script
code that is using the wrapper functions:
my_node <- div_(
a_("click here", href="foo.html")
)
cat(pasteXML(my_node))
# <div>
# <a href="foo.html">
# click here
# </a>
# </div>
cat(pasteXML(my_node, as_script=TRUE))
# div_(
# a_(href="foo.html",
# "click here"
# )
# )
turning existing XML documents into R scripts should therefore be much easier
now.
i've also tried to make the XML parser not freak out when it encounters empty
attributes (i.e., only the attribute name without a value, as common in
HTML5). that needs more testing. the current workaround is to add a value
(same as attribute name), as there's still no way to generate empty attributes
yet.
viele grüße :: m.eik
--
dipl. psych. meik michalke
institut f"ur experimentelle psychologie
abt. f"ur diagnostik und differentielle psychologie
heinrich-heine-universit"at d-40204 d"usseldorf
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