02 - extracting data while parsing a document.rb

O Reilly Ruby Cookbook source code

event_xml = %{
<events>
  <clean system="dev" start="01:35" end="01:55" area="build" error="1" />
  <backup system="prod" start="02:00" end="02:35" size="2300134" error="0" />
  <backup system="dev" start="02:00" end="02:01" size="0" error="2" />
  <backup system="test" start="02:00" end="02:47" size="327450" error="0" />
</events>}
#---
require 'rexml/document'
require 'rexml/streamlistener'

class ErrorListener
  include REXML::StreamListener
  def tag_start(name, attrs)
    if attrs["error"] != nil and attrs["error"] != "0"
      puts %{Event "#{name}" failed for system "#{attrs["system"]}" } +
	%{with code #{attrs["error"]}}
    end
  end
end
#---
REXML::Document.parse_stream(event_xml, ErrorListener.new)
# Event "clean" failed for system "dev" with code 1
# Event "backup" failed for system "dev" with code 2
#---