binding_merge.rb

class Proc
  def merge_binding!(other_binding)
    other_binding.eval("local_variables").each do |var|
      var_id = other_binding.eval(var.to_s).object_id
      binding.eval("#{var} = ObjectSpace._id2ref(#{var_id})")
    end
  end
end

x = 3
some_proc = proc { puts x }

some_proc.call
puts x

def foo(block)
  x = 10
  block.merge_binding! binding
end

foo some_proc
some_proc.call # Outputs 10!

puts x # 10 too