From: Yossef Mendelssohn <ymendel@...>
Date: 2008-05-06T00:14:33+09:00
Subject: Re: Hash question



On May 5, 8:42 am, "Robert Klemme" <shortcut...@googlemail.com> wrote:
> 2008/5/5 Axel Etzold <AEtz...@gmx.de>:
>
>
>
> > Hi ---
> >  -------- Original-Nachricht --------
> >  > Datum: Mon, 5 May 2008 22:10:31 +0900
> >  > Von: Damjan Rems <d_r...@yahoo.com>
> >  > An: ruby-t...@ruby-lang.org
> >  > Betreff: Hash question
>
> >  >  I would like to return only part of hash as hash object.
>
> >  >  Example:
> >  >   h = { "a" => 100, "b" => 200, "c" => 300 }
> >  >   result = h.somemethod('a','c')
> >  >   # should result in { "a" => 100, "c" => 200}
>
> >  > Is this already build in Hash object or should I start and code it.
>
> >  > by
> >  > TheR
> >  > --
> >  > Posted viahttp://www.ruby-forum.com/.
>
> >  you can use Hash#select or Hash#delete or Hash#delete_if for tasks like
> >  this.
> >  See some examples in the documentation for Hash:
>
> >  http://www.ruby-doc.org/core/classes/Hash.html#M002898
>
> Unfortunately these return Array instead of Hash.
>
> Kind regards
>
> robert
>
> --
> use.inject do |as, often| as.you_can - without end

Fortunately, this bone-headed behavior will be fixed in 1.9.  Until
then, you can do what many others do and use Hash#reject with negative
logic.

In other words, instead of

    { "a" => 100, "b" => 200, "c" => 300 }.select { |k, v|  %w[a
c].include?(k) }

use

    { "a" => 100, "b" => 200, "c" => 300 }.reject { |k, v|  !%w[a
c].include?(k) }

Yes, I like this about as much as you'd think.

--
-yossef