Code Generation with Ruby

I just watched some parts of a Google Tech Talk Video about code generation. It was a videotaped presentation by Jack Harrington, the author of "Code Generation in Action" to some of the developers at Google. I didn't find most of the presentation to be that interesting, but there was one snippet of Ruby code that I liked. It looked something like this:

require 'erb'

File.open('./test.txt', 'w+') do |f|
  name='Darcy'
  erb = ERB.new(File.new('template').read)
  f.write(erb.result(binding))
end

My template file was a single line that contained this: "Hello <%=name%>". I think you can probably figure out what the result would look like ;-)

The real example he used in his presentation was slightly more elaborate in that he had a source of data, an XML file, and he used REXML (a great XML library in Ruby) to read the source to generate a SQL file.

I'm not a big advocate of code generation but if you find yourself in the unenviable position of needing to do it then this is a great place to sprinkle in a little Ruby magic.