magic/xml

Photo from Commons by Fabian Köster, GFDL.

The promised library for XML-oriented programming with Ruby got implemented :-) Most of the examples from my last post work. One cool technique I discovered during the coding is "duplicate and modify". It makes very pretty functional-style programming possible:

a = XML.new(:foo, {:a => "1"}, "Hello")
b = a.dup{ @name = :bar }
c = a.dup{ self[:a] = "2" }
d = a.dup{ self << ", world!" }

Basically the optional block given to dup is instance_evaled in context of the new object. I think this is general and cool enough that we can probably find a few uses for it in the standard library. Everything works Ruby way, so we can do things like:

include XHTML
a  = A.new({:href => "http://www.google.com/"}, "Google")
a[:href] = "http://earth.google.com/"
a << " Earth"

The library does not know how to parse XML (wow). It can only generate it, and output formatting is done by simply printing it. I'll take a look at XML-parsers later. It should be trivial to connect one. DTDs, XML namespaces, explicit entities (< > and the usual stuff gets auto-escaped, so don't worry) get a big meh. If they can be supported without making the common case more complicated, then I'm all for it. If not - you can always use some other library. Download is here. Unit tests and the blog are the only documentation for now.