Bash script in Ruby DATA section

bash.rb

#!/usr/bin/env ruby -w
function, list, f = {}, [], nil

def function.method_missing(meth, *args, &block)
  return self[meth.to_s] if has_key? meth.to_s
  raise NoMethodError
end

class Function
  @@global = String.new

  def self.header(line)
    @@global << line.lstrip 
  end

  def initialize(name)
    @local = String.new
  end

  def to_s
    @@global + @local
  end

  def exec
    %x| #{to_s} |
  end

  def <<(line)
    @local << line.lstrip
  end
end

DATA.each do |line|
  case line
    when /\Afunction (\w+)/ then function[$1] = f = Function.new $1 
    else if f.is_a?(Function) then f << (line =~ /\A}/ ? '' : line)
      else Function.header line
    end
  end
end

puts function.hello.exec
puts function.bye.exec

__END__
#!/bin/bash
GREETING='Hello World'

function hello() {
  echo "${GREETING}"
}

function bye() {
  echo 'Bye Bye'
}