From: Mark Sparshatt <msparshatt@...>
Date: 2004-04-29T04:05:20+09:00
Subject: Re: Last minute details

Richard Lionheart wrote:

>Hi Dick,
>
>I think I'm on top of the subtleties involved with my question:
>
>1.  I dropped the initial assignments to a and b,  because no matter what
>they refer to (empty array,  string, whatever),  they'll be assigned new
>references by the subsequent assignments.  I confirmed this by adding a puts
>
>2.  I initially dropped the "my_" prefix to to_s,  since it looked more
>elegant (to me,  at least).  But when testing,  I found now way to undo that
>change to Array so that unexpected results would probably obtain in extended
>use of my revised approach.
>
>  
>
if you want to save the old version of to_s you can use the alias method

class Array     # Override to_s
   alias old_to_s to_s
   def to_s
        join("; ")
   end
 end

then you can access the old to_s behaviour by using the old_to_s method. 
Or if you want to change to_s back to it's default behaviour you can use

class Array
    alias to_s old_to_s
end

i.e.

a = %w( foo bar ack)
puts "After assignment \"a = %w( foo bar ack)\",   a.class.to_s =
#{a.class.to_s}"
b = %w(eeny meeny miney mo)
puts "Before override:  a = #{a.to_s},  b = #{b.to_s}"

class Array     # Override to_s
  alias old_to_s to_s
  def to_s
        join("; ")
  end
end

puts "After override:   a = #{a.to_s}, b = #{b.to_s}"

class Array
  alias to_s old_to_s
end

puts "After re-override:  a = #{a.to_s}, b = #{b.to_s}"

results=<<RESULTS
After assignment "a = %w( foo bar ack)",   a.class.to_s =
Array
Before override:  a = foobarack,  b = eenymeenymineymo
After override:   a = foo; bar; ack, b = eeny; meeny; miney; mo
After re-override:  a = foobarack, b = eenymeenymineymo
RESULTS

--
Mark Sparshatt