From: tharrison <tom.harrison.jr@...>
Date: 2008-01-22T01:25:12+09:00
Subject: Builder fragment wrapped by template (Ruby blocks question)?

I am calling an API that wants XML.  There are several different
methods (submit, status, fetch) that all expect the same XML block,
surrounding the specific method.  I would like to be able to declare
the Builder inside a method and pass a unique Builder chunk as a block
to be yielded from within.

This is one example: the first five lines and the last two are always
the same

  def self.build_fetch_request(thing_to_fetch_id)
    xml_out = ''
    xml = Builder::XmlMarkup.new(:target => xml_out, :indent =>
2, :level => 2)
    xml.instruct!
    xml.myapi {
      xml.apikey('super-duper-secret')
      xml.fetch {
        xml.thing(thing_to_fetch_id)
      }
    }
    xml_out
  end

So it seems like I should be able to do something like

  def self.build_request_template
    xml_out = ''
    xml = Builder::XmlMarkup.new(:target => xml_out, :indent =>
2, :level => 2)
    xml.instruct!
    xml.myapi {
      xml.apikey('super-duper-secret')
      yield           # execute my specific code here
    }
    xml_out
  end

and call it like

   def self.build_fetch_request(thing_to_fetch_id)
      self.build_request do
        xml.fetch {
          xml.thing(thing_to_fetch_id)
        }
      end
   end

But of course my block variable, "xml" (a Builder instance) is not in
scope.  I could do this easily the old Java (or C, C++ whatever) way.
But I suspect Ruby has some clever, elegant way.

What brilliant Ruby expert can show me the clever, elegant way to do
this?

Thanks a bunch,

Tom