Set & get Ruby global variables using Fiddle

global_variable.rb

require 'fiddle'
require 'fiddle/import'

module GlobalVariable
  extend Fiddle::Importer
  dlload Fiddle::Handle::DEFAULT

  extern 'void rb_gv_set(const char*, unsigned long)'
  extern 'unsigned long rb_gv_get(const char*)'
end

module Kernel
  def set_global_variable(name, value) = GlobalVariable.rb_gv_set(name.to_s, Fiddle.dlwrap(value))
  def get_global_variable(name) = Fiddle.dlunwrap GlobalVariable.rb_gv_get name.to_s
end

set_global_variable(:$samp, 1_337)
get_global_variable(:$samp)