From: warren ferguson <warren_e_ferguson@...>
Date: 2010-08-08T07:39:27+09:00
Subject: question about sub-class of array

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I don't understand why thsi isn't working. I wanted to introduce a subclass=
 of the Array class called Bitvector. A bit vector is an array of 0s and 1s=
=2C ordered from lsb at index 0 to msb at the highest index=2C so
"10011" as a string would be [1=2C1=2C0=2C0=2C1] as an Bitvector. Here's wh=
at I tried:
=20
class Bitvector < Array
  def initialize(*)
    @a =3D super
  end
  def to_s
    # convert Bitvector=2C ordered lsb to msb=2C
    # to string of 0s and 1s=2C ordered msb to lsb
    @a.map{|i| i.to_s(2)}.reverse.join
  end
end
class String
  def to_bv
    # convert bit string of 0s and 1s=2C ordered msb to lsb=2C
    # to Bitvector=2C ordered lsb to msb
    Bitvector.new(self.reverse.split(//)).map{|k| k.to_i(2)}
  end
end
# ----------------------------
v =3D "10011".to_bv
puts "v.class =3D #{v .class}"
puts "v =3D #{v}"
puts "--"
 =20
v =3D Bitvector.new([0=2C1])
puts "v.class =3D #{v .class}"
puts "v =3D #{v}"
=20
The output from this program is
=20
v.class =3D Array
v =3D [1=2C 1=2C 0=2C 0=2C 1]
--
v.class =3D Bitvector
v =3D 10

What I don't understand is why the first part reports v is of class Array=
=2C instead of class Bitvector.
=20
Thanks=2C Warren 		 	   		  =

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