A ruby implementation of python's with statement

with_statement.rb

# A ruby implementation of python's with statement
# 
# not sure if this is semantically identical, it was meant as a small excercise

module WithStatement

  def with(*objs)
    raise "no block given" unless block_given?

    options = objs.unshift! if objs.last.is_a? Hash
    options = { :enter => :enter_with, :exit => :exit_with }.merge(options || {})

    entered = 0

    begin
      # Initialize all objs with the given method (default: Object#enter_with)
      objs.each { |obj| obj.send options[:enter]; entered += 1 }
      yield *objs
    ensure
      # Ensure their appropriate exit methods are called in reverse order
      # no matter if an exception was raised or not
      objs[0...entered].reverse.each { |obj| obj.send options[:exit] }
    end
  end

end