Module: Arrayclass

Defined in:
lib/arrayclass.rb

Class Method Summary collapse

Class Method Details

.new(fields) ⇒ Object 



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# File 'lib/arrayclass.rb', line 35

def self.new(fields)
  nclass = Class.new(Array)  
  nclass.class_eval('def self.inherited(sc)
                       sc.instance_variable_set("@arr_size", @arr_size)
                       sc.instance_variable_set("@ind", @ind.dup)
                       sc.instance_variable_set("@attributes", @attributes.dup)
                     end

                    ')

  nclass.class_eval('def self.size()
                       @arr_size 
                     end
                     def self.ind()
                       @ind
                     end
                    ')

  
  nclass.class_eval('def self.add_member(name)
                       i = @arr_size
                       self.class_eval("def #{name}() self[#{i}] end")
                       self.class_eval("def #{name}=(val) self[#{i}]=val end")
                       self.class_eval("@ind[:#{name}] = #{i}")
                       self.class_eval("@ind[\"#{name}\"] = #{i}")
                       self.class_eval("@attributes << :#{name}")
                       self.class_eval("@arr_size = @attributes.size")
                       $TMP_CRAZY = $VERBOSE; $VERBOSE = nil
                       $VERBOSE = $TMP_CRAZY
                    end')


  # This list is derived from ImageList in ImageMagick (and I've added some
  # applicable to this guy) (I've left zip here as it is applicable and a
  # great method)
  %w(flatten flatten! assoc join rassoc push pop <<).each do |att|
    nclass.class_eval("undef_method :#{att}")
  end
  nclass.class_eval("undef_method :transpose if Array.instance_methods(false).include?('transpose')")
  nclass.class_eval("@ind = {}")
  # array to preserve order
  nclass.class_eval("@attributes = []")
  nclass.class_eval("@arr_size = 0")
  fields.each_with_index do |field,i|
    nclass.add_member(field.to_s)
  end
  nclass.class_eval '
      def initialize(args=nil) 
        if args.is_a? Array
          super(args)
        elsif args.is_a? Hash 
          super(self.class.size)
          h = self.class.ind
          args.each do |k,v|
            self[h[k]] = v
          end
        else 
          super(self.class.size)
        end
      end'

  # list of 
  nclass.class_eval('def self.members() @attributes end')
  nclass.class_eval('def members() self.class.members end')
  nclass.class_eval("def is_a?(klass)
                       if klass == Array ; false
                       else ; super(klass)
                       end
                     end
                     alias_method :kind_of?, :is_a?")

  nclass.class_eval('def inspect
                       bits = members.map do |v| 
                         val = self.send(v)
                         val = "nil" if val.nil?
                         "#{v}=#{val.inspect}"
                       end
                       string = bits.join(", ")
                       "<(Arrayclass based) #{string}>"
                     end ')

  # NOTE that two separate objects will hash differently (even if their
  # content is the same!)
  nclass.class_eval('def hash() object_id end')
  nclass
end