tp_binding_of_caller.rb

module B
  extend self

  @enabled = false

  def enable!
    return if @enabled

    clear
    @enabled = true
    @trace = TracePoint.new(:call, :c_call, :return, :c_return) do |tp|
      handle(tp)
    end
    @trace.enable
  end

  def binding_of_caller(n)
    offset = 2
    @bindings[-(n + offset)]
  end

  def disable!
    return unless @enabled

    clear
    @enabled = false
    @trace.disable
  end

  private def clear
    @bindings = []
  end

  private def handle(tp)
    case tp.event
    when :call, :c_call
      @bindings.push tp.binding
    when :return, :c_return
      @bindings.pop
    else
      raise "[bug] unknown event: #{tp.event}"
    end
  end
end

B.enable!

def a
  var = 10
  b
  puts var
end

def b
  c
end

def c
  B.binding_of_caller(2).eval('var = :hello')
end

a() # hello

B.disable!