From: Harry Spier <harryspier@...>
Date: 2010-09-12T10:34:42+09:00
Subject: Converting from one class to another in Ruby

Dear list members,

I have an application with a class Binary_matrix < Array (which is just
a two dimensional array filled with zeroes and ones).  I also have other
classes which have to_Binary_matrix methods to convert objects of their
class to Binary_matrix objects.

The Ruby code I came up with to do the conversions is as follows.

class A
  def to_Binary_matrix(from_initialize_method = false)
     ...some logic to convert class A object to binary_matrix_format
     if from_initialize_method
        return an_A_type_object_in_binary_matrix_format
    else
        return
Binary_matrix.new(an_A_type_object_in_binary_matrix_format)
    end
  end
end


class B
  def to_Binary_matrix(from_initialize_method = false)
     ...some logic to convert class B object to binary_matrix_format
     if from_initialize_method
        return a_B_type_object_in_binary_matrix_format
    else
        return
Binary_matrix.new(a_B_type_object_in_binary_matrix_format)
    end
  end
end

class Binary_matrix < Array
   def initialize arg
      self.replace arg.to_Binary_matrix(true)
   end
end

This allows me to do:

a = A.new
an_A_as_a_Binary_matrix_object = a.to_Binary_matrix
b_as_a_Binary_matrix_object = Binary_matrix.new(b)

It works but it seems a little clunky to me.  Is their a more Rubyish or
elegent way of doing this.  In particular is it possible to get rid of
the flag I use (from_initialize_method) to keep me from getting into an
infinite loop as I go between the .to_Binary_matrix methods and the
initialize method in Binary_matrix

Thanks in advance,
Harry
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