rubyx/lib/parfait/layout.rb

# An Object is really a hash like structure. It is dynamic and
# you want to store values by name (instance variable names).
#
# One could (like mri), store the names in each object, but that is wasteful
# Instead we store only the values, and access them by index.
# The Layout allows the mapping of names to index.

# The Layout of an object describes the memory layout of the object
# The Layout is a simple list of the names of instance variables.
#
# As every object has a Layout to describe it, the name "layout" is the
# first name in the list for every Layout.

# But as we want every Object to have a class, the Layout carries that class.
# So the layout of layout has an entry "object_class"

# In other words, the Layout is a list of names that describe
# the values stored in an actual object.
# The object is an List of values of length n and
# the Layout is an List of names of length n
# Together they turn the object into a hash like structure

module Parfait
  class Layout < List

    # set the names of the instance variables in one go
    # used while booting the classes. At runtime the list would grow dynamically
    def set_names list
      self.set_length list.length
      index = 0
      while index < list.length do
        list.set(index , array.get(index))
      end
    end

    # beat the recursion! fixed known offset for class object in the layout
    def get_object_class()
      return internal_object_get(CLASS_INDEX)
    end
  end
end