setup

# File lib/set.rb, line 567
    def setup   # :nodoc:
      @@setup and return

      module_eval {
        # a hack to shut up warning
        alias old_init initialize
      }
      begin
        require 'rbtree'

        module_eval           def initialize(*args)            @hash = RBTree.new            super          end          def add(o)            o.respond_to?(:<=>) or raise ArgumentError, "value must respond to <=>"            super          end          alias << add, __FILE__, __LINE__+1
      rescue LoadError
        module_eval           def initialize(*args)            @keys = nil            super          end          def clear            @keys = nil            super          end          def replace(enum)            @keys = nil            super          end          def add(o)            o.respond_to?(:<=>) or raise ArgumentError, "value must respond to <=>"            @keys = nil            super          end          alias << add          def delete(o)            @keys = nil            @hash.delete(o)            self          end          def delete_if            block_given? or return enum_for(__method__)            n = @hash.size            super            @keys = nil if @hash.size != n            self          end          def keep_if            block_given? or return enum_for(__method__)            n = @hash.size            super            @keys = nil if @hash.size != n            self          end          def merge(enum)            @keys = nil            super          end          def each(&block)            block or return enum_for(__method__)            to_a.each(&block)            self          end          def to_a            (@keys = @hash.keys).sort! unless @keys            @keys          end, __FILE__, __LINE__+1
      end
      module_eval {
        # a hack to shut up warning
        remove_method :old_init
      }

      @@setup = true
    end