# File lib/ruote/svc/treechecker.rb, line 38
    def initialize(context)

      return if context['use_ruby_treechecker'] == false

      checker = Rufus::TreeChecker.new do

        exclude_fvccall :abort, :exit, :exit!
        exclude_fvccall :system, :fork, :syscall, :trap, :require, :load
        exclude_fvccall :at_exit

        #exclude_call_to :class
        exclude_fvcall :private, :public, :protected

        #exclude_raise             # no raise or throw

        exclude_eval              # no eval, module_eval or instance_eval
        exclude_backquotes        # no `rm -fR the/kitchen/sink`
        exclude_alias             # no alias or aliast_method
        exclude_global_vars       # $vars are off limits
        exclude_module_tinkering  # no module opening

        exclude_rebinding Kernel # no 'k = Kernel'

        exclude_access_to(
          IO, File, FileUtils, Process, Signal, Thread, ThreadGroup)

        #exclude_class_tinkering :except => Ruote::ProcessDefinition
          #
          # excludes defining/opening any class except
          # Ruote::ProcessDefinition

        exclude_call_to :instance_variable_get, :instance_variable_set
      end

      stricter_checker = checker.clone
      stricter_checker.add_rules do
        exclude_def    # no method definition
        exclude_raise  # no raise or throw
      end

      # the checker used when reading process definitions

      @def_checker = stricter_checker.clone # and not dup
      @def_checker.freeze

      ## the checker used when dealing with conditionals
      #
      #@con_checker = checker.clone # and not dup
      #@con_checker.add_rules do
      #  exclude_raise # no raise or throw
      #  at_root do
      #    exclude_head [ :block ] # preventing 'a < b; do_sthing_evil()'
      #    exclude_head [ :lasgn ] # preventing 'a = 3'
      #  end
      #end
      #@con_checker.freeze
        #
        # lib/ruote/exp/condition.rb doesn't use this treechecker
        # kept (commented out) for 'documentation'

      # the checker used when dealing with code in $(ruby:xxx}

      @dol_checker = stricter_checker.clone # and not dup
      @dol_checker.freeze

      # the checker used when dealing with BlockParticipant code

      @blo_checker = checker.clone # and not dup
      @blo_checker.add_rules do
        exclude_def    # no method definition
      end
      @blo_checker.freeze

      # the checker used for CodeParticipant

      @cod_checker = checker.clone # and not dup
      @cod_checker.freeze

      freeze
        # preventing further modifications
    end