From: Brian Candler <B.Candler@...>
Date: 2003-05-31T06:37:28+09:00
Subject: Re: Iteration - last detection

On Sat, May 31, 2003 at 03:13:16AM +0900, Anders Borch wrote:
> John Johnson wrote:
> >I may be over simplifiying, but Enumerable defines max, so couldn't you:
> >
> >a = {}
> >a["a"] = "A"
> >a["b"] = "B"
> >a["c"] = "C"
> >a.each { |key, val|
> >  print "#{key} = #{val}"
> >  if key === a.keys.max
> >    puts " and that's the last one"
> >  else
> >    puts
> >  end
> >}
> 
> that would only work if the array is sorted...

More precisely, it only works if the array (or other collection) elements
have a defined <=> method which can compare them.

irb(main):010:0> [1,5,3,2,1].max
=> 5

However that's still no good, as it involves iterating over the collection a
second time. For something like an IO object, attached to a pipe which can't
be rewound, you can't iterative over it twice.

Regards,

Brian.