From: Dick Davies <rasputnik@...>
Date: 2004-04-24T19:39:09+09:00
Subject: Re: Problem assigning an Array object to an Array-subclass object

* Kristof Bastiaensen <kristof@vleeuwen.org> [0404 10:04]:
> On Fri, 23 Apr 2004 11:15:16 -0400, Richard Lionheart wrote:
> 
> > notes =<<NOTES
> >     I didn't like to_s' output for an Array of strings.
> >     Array#to_s simply concatenated them
> >     or inserted a comma separator.
> >     So I wrote my own.
> > 
> > class MyArrayType < Array
> >     def to_s
> >         print "Starting MyArrayType#to_s"
> >         s = ""
> >         s.each { |x| s += "; " if s.length>0; s += x.to_s }
> >         s
> >     end
> > end
> > 
> > myA1 = MyArrayType.new
> > myA1 = %w[x1, y1]
> > puts myA1.to_s  # x1,y1 .... expected x1; x2 .... MyArrayType#to_s not
> > invoked
> > 
> 
> Hi,
> if all you want to do is change the to_s method, why not
> just add it to Array?
> 
> class Array
>   def my_to_s
>     join("; ")
>   end
> end
> 
> a = %w[x1 y1]
> puts a.my_to_s

Trouble is some other Array using method may expect tho old behaviour,
but you can do this on a per instance basis:

0rasputin@lb:rasputin$ ruby instancedef.rb 
before override: a = foobarack, b = eenymeenymineymo
after override: a = foo:bar:ack, b = eenymeenymineymo
0rasputin@lb:rasputin$ cat instancedef.rb 
a = []
b = []

a = %w( foo bar ack)
b = %w(eeny meeny miney mo)

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

def a.to_s
  self.join(':')
end

puts "after override: a = #{a.to_s}, b = #{b.to_s}"
0rasputin@lb:rasputin$ 

-- 
Is it possible that software is not like anything else, that it is
meant to be discarded: that the whole point is to always see it as a
soap bubble?
Rasputin :: Jack of All Trades - Master of Nuns