From: E S <eero.saynatkari@...>
Date: 2005-02-05T07:57:27+09:00
Subject: Re: iteration the ruby way

> L�hett�j�: E S <eero.saynatkari@kolumbus.fi>
> Aihe: Re: iteration the ruby way
> 
> > L�hett�j�: Navindra Umanee <navindra@cs.mcgill.ca>
> > Aihe: Re: iteration the ruby way
> > 
> > John Wilger <johnwilger@gmail.com> wrote:
> > > > I have a question about The Ruby Way.  Pickaxe gives the following
> > > > example for using iterators in Ruby:
> > > > 
> > > > a = [ "a", "b", "c" ]
> > > > a.each {|x| print x, " -- " }
> > > > 
> > > > This outputs:
> > > > 
> > > > a -- b -- c --
> > > > 
> > > > But what if I want to print "a -- b -- c"?  What's the proper Ruby way
> > > > of doing that?
> > > 
> > > a = ["a","b","c"]
> > > puts a.join(' - ')
> > 
> > I guess I over-simplified.  I really want to do computations based on
> > each element and compute my output.  However, it's slightly different
> > for the last element.  I would like to detect the last element in the
> > iteration.
> > 
> > For example:
> > 
> >      bottom_items.each{ |item|
> >         do_something_with(item[0], item[1], item[2])
> > 	if_not_last_item_do_this    
> >      }
> 
> Since you're not doing the same thing on all elements, these should
> be conceptually correct. 
> 
>   ary = ary[0..-1].each {|el| do_something el }
>   do_something_else!(ary.last)

Bah, mail client snipped that... should have been

  ary[0..-1].each {|e| do_something(e) }
  do_something_else(ary.last)
  
  # Or

  ary[0..-1].map! {|e| do_something(e)  }
  do_something_else!(ary.last) 

Depending on the context.

>   ary.each_index {|i| do_smth(ary[i]) unless i == ary.size - 1} 
> 
> > Thanks,
> > Navin.

E