Ruby Hoists Variables!

ruby_hoist.rb

class Foo
  def awesome(x)
    y = 50
    x + y
  end
end

set_trace_func proc { |event, file, line, id, binding, classname|

  # output the binding at the start of any call to Foo#awesome

  if id == :awesome and event == "call"
    puts binding.eval("local_variables").inspect
  end
}

Foo.new.awesome(100)

# if you run this the output will be:
# [:x, :y]

# so Ruby effectively hoists variables