class Sinatra::Base

def invoke

Run the block with 'throw :halt' support and apply result to the response. 
def invoke
  res = catch(:halt) { yield }
  res = [res] if Integer === res or String === res
  if Array === res and Integer === res.first
    res = res.dup
    status(res.shift)
    body(res.pop)
    headers(*res)
  elsif res.respond_to? :each
    body res
  end
  nil # avoid double setting the same response tuple twice
end