ConfigTemplate class

config_template.rb

require 'yaml'
require 'erb'

class Struct
  def get_binding
    binding
  end
end

class ConfigTemplate
  def initialize(configfile, environment)
    conf = YAML.load_file configfile
    raise "No such environment: #{environment}" if not conf.has_key? environment
    env = conf[environment]
    if conf.has_key? 'default'
      env = conf['default'].merge env
    end
    env['environment_name'] = environment
    @binding = make_binding env
  end
    
  def convert_file(infile, outfile)
    e = ERB.new File.open(infile).read
    File.open(outfile, 'w') { |f| 
      f.write e.result(@binding)
    }
  end

  def get(name)
    eval name.to_s, @binding
  end

  def method_missing(name, *args, &block)
    get name
  end

  private
  def make_binding(env)
    klass = Struct.new *env.keys.map { |k| k.intern }
    k = klass.new *env.values
    # support up to 5 levels of embedding
    5.times { k = klass.new *env.values.map { |v| ERB.new(v.to_s).result(k.get_binding) } }
    k.get_binding
  end
end