module Tins::ThreadGlobal

def instance_thread_global(name, value = nil)

variable.
_name_. If the value _value_ is given, it is used to initialize the
Define a thread global variable for the current instance with name 
def instance_thread_global(name, value = nil)
  sc = class << self
    extend Tins::ThreadGlobal
    self
  end
  sc.thread_global name, value
  self
end

def thread_global(name, default_value = nil, &default)

value _value_ is given, it is used to initialize the variable.
Define a thread global variable named _name_ in this module/class. If the 
def thread_global(name, default_value = nil, &default)
  is_a?(Module) or raise TypeError, "receiver has to be a Module"
  default_value && default and raise ArgumentError,
    "require either default_falue or default block"
  if default_value
    default = -> * { default_value }
  end
  name = name.to_s
  var_name = "@__#{name}_#{__id__.abs}__"
  lock = Mutex.new
  modul = self
  define_method(name) do
    lock.synchronize {
      if default && !modul.instance_variable_defined?(var_name)
        modul.instance_variable_set var_name, default.call
      end
      modul.instance_variable_get var_name
    }
  end
  define_method(name + "=") do |value|
    lock.synchronize { modul.instance_variable_set var_name, value }
  end
  self
end