test-logger.rb

module Test
  class Log
    attr_accessor :gc, :name
    def initialize(name, gc=nil)
      @name = name
      @gc = gc || {}
    end

    def log(data)
      puts data.merge(:name => @name).inspect
    end
  end

  def self.init(gc=nil)
    @logger = Log.new("init", gc=gc)
    @logger.freeze
  end

  def self.logger
    @logger ||= Log.new("logger")
  end

  def self.log(data)
    log_data = @logger.gc.merge(data)
    @logger.log(log_data)
  end
end

Test.init(gc={:gc => "test"})
Test.log(:tl => "test log")
begin
  Test.logger.gc = {:gc => "THAWED"}
rescue RuntimeError, TypeError => e
  Test.log(:e => e.class, :e_message => e.message)
end
Test.log(:tl => "test log")

~ : ruby -v
ruby 1.9.3p484 (2013-11-22 revision 43786) [x86_64-darwin13.0.0]
~ : ruby tmp/test-logger.rb
{:gc=>"test", :tl=>"test log", :name=>"init"}
{:gc=>"test", :e=>RuntimeError, :e_message=>"can't modify frozen Test::Log", :name=>"init"}
{:gc=>"test", :tl=>"test log", :name=>"init"}
~ : rbenv local 2.1.0
~ : ruby -v
ruby 2.1.0p0 (2013-12-25 revision 44422) [x86_64-darwin13.0]
~ : ruby tmp/test-logger.rb
{:gc=>"test", :tl=>"test log", :name=>"init"}
{:gc=>"test", :e=>RuntimeError, :e_message=>"can't modify frozen Test::Log", :name=>"init"}
{:gc=>"test", :tl=>"test log", :name=>"init"}
~ : rbenv local 1.8.7
~ : ruby -v
ruby 1.8.7 (2012-02-08 patchlevel 358) [i686-darwin13.0.0]
~ : ruby tmp/test-logger.rb
{:tl=>"test log", :gc=>"test", :name=>"init"}
{:e=>TypeError, :gc=>"test", :e_message=>"can't modify frozen object", :name=>"init"}
{:tl=>"test log", :gc=>"test", :name=>"init"}