From: E S <eero.saynatkari@...>
Date: 2005-02-08T07:19:41+09:00
Subject: Re: iteration the ruby way

> L�hett�j�: "Robert Klemme" <bob.news@gmx.net>
> Aihe: Re: iteration the ruby way
> 
> 
> "David A. Black" <dblack@wobblini.net> schrieb im Newsbeitrag 
> news:Pine.LNX.4.61.0502061257450.13178@wobblini...
> Hi --
> 
> On Mon, 7 Feb 2005, E S wrote:
> 
> >> "Robert Klemme" <bob.news@gmx.net>
> >> Aihe: Re: iteration the ruby way
> >>
> >>
> >> "E S" <eero.saynatkari@kolumbus.fi> schrieb im Newsbeitrag
> >> news:20050206143902.PIMQ15813.fep31-app.kolumbus.fi@mta.imail.kolumbus.fi...
> >>>> L�hett�j�: Kaspar Schiess <eule@space.ch>
> >>>> Aihe: Re: iteration the ruby way
> >>>> (In response to 
> >>>> news:1107566961.943586.81760@g14g2000cwa.googlegroups.com
> >>> by William James)
> >>>>> Shouldn't that be
> >>>>>
> >>>>> ary[0...-1].each {|e| do_something(e) }
> >>>>> do_something_else(ary.last)
> >>>>>
> >>>>> or
> >>>>>
> >>>>> ary[0..-2].each {|e| do_something(e) }
> >>>>> do_something_else(ary.last)
> >>>>>
> >>>>> ?
> >>>>
> >>>> I would prefer this solution for its clarity of expression.
> >>>
> >>> Me too :) I just think the #inject won on the neat-o factor,
> >>> particularly since it seemed adequate for the OP.
> >>
> >> Partly yes and partly no: apart from the cute factor, there is a real
> >> advantage of the inject solutions show: they work for *all* Enumerables
> >> while the array indexing works only for arrays.  So #inject is more 
> >> general.
> >> Also, Array#[] creates a new array instance along the way which is a bit
> >> inefficient.  But I do agree that the indexing might be more readable.
> >
> > I think assuming an Array is valid in the described scenario (which
> > is the last element in a Hash, after all?)
> 
> > If you goal was to create a string representation of the hash, with
> > some kind of marker between each key/value pair -- but not after the
> > last one -- then the last-ness of the last element would be important
> > in the sense that you'd treat it differently (whatever it was, and
> > whether or not it remained the same from one run to another).
> 
> Note though that you might as well treat the *first* element specially. 
> IMHO that's usually easier even with #each:
> 
> first = true
> enum.each do |e|
>   if first
>     first = false
>   else
>     print " -- "
>   end
>   print e
> end
> print "\n"

class Array
  alias :head :first
  def tail
    self[1..-1]
  end  
end

? :)
 
> Kind regards
> 
>     robert

E