From: daz <dooby@...10.karoo.co.uk>
Date: 2003-06-12T01:53:30+09:00
Subject: Re: [RCR] join block


"Joel VanderWerf" <vjoel@PATH.Berkeley.EDU> wrote:

> [...] It's just that if someone said "Now join takes a block",
>  this is what I would guess it would do:
>
>    class Array
>      alias old_join join
>
>      def join(str=nil)
>        if block_given?
>          raise if str # can't think what else to do
[..]

One option would be to pass the sepString into the block.
No, wait!  Don't run away.

Wholly inspired by your idea:-
(using Enumerable#inject - in later Rubys)

#####
class Array
  alias :join_orig :join

  def join(*args)
    if block_given?
      ret_ = ''
      inject(false) do |x, y|
        ret_ << (x==false ? nil : yield(x, y, args)).to_s << y.to_s
        y
      end
      ret_
    else
      join_orig(args[0] || $,)
    end
  end
end

puts([0,1,2,3].join)
svsep = $, ; $, = '....+....'; puts([0,1,2,3].join); $, = svsep
puts([0,1,2,3].join(" still works "))
puts
puts('{' << [1,2,3,"a","b",5,"c"].join(',', '} {') {|x, y, z|
    (x.class == y.class) ? z[0] : z[1] }   << '}')
puts('{' << [1,2,3,"a","b",5,"c"].join           do |x, y|
    (x.class == y.class) ? ',' : '} {' end << '}')
puts

# "Joel's Jewel" (as he might prefer it :<D)
puts([1,2,3,4,4,3,7,7,1].join('==', '>', '<') {|x,y,z| " #{ z[x<=>y] } "})
# [(v2.0 beta : DfB)   - "I knew that 'spaceship' was there for a reason"]

#####

#-> 0123
#-> 0....+....1....+....2....+....3
#-> 0 still works 1 still works 2 still works 3
#->
#-> {1,2,3} {a,b} {5} {c}
#-> {1,2,3} {a,b} {5} {c}
#->
#-> 1 < 2 < 3 < 4 == 4 > 3 < 7 == 7 > 1

If it comes to a vote on this, I would like to nominate JVW as my proxy.
Had he not mentioned pairs, this thread might have closed after a
manageable number of comments :-)


daz
(- Retiring with no hint of an opinion.  I'm working on a separate
RCR concerning '_with_index' which I'm hoping will give a whole lot
of support to the '*_w_i' crew - pres. BlackD. who IMHO has been
treated scathingly on this matter <cough>.  It'll require max. input
from all quarters so that if YM says YAGNI, we can say YWFWA :!)