From: "Ara.T.Howard" <ahoward@...>
Date: 2004-02-17T00:34:55+09:00
Subject: Re: Hash#values_at

On Mon, 16 Feb 2004, Yukihiro Matsumoto wrote:

> Date: Mon, 16 Feb 2004 15:33:59 +0900
> From: Yukihiro Matsumoto <matz@ruby-lang.org>
> Newsgroups: comp.lang.ruby
> Subject: Re: Hash#values_at
> 
> Hi,
> 
> In message "Hash#values_at"
>     on 04/02/16, "Ara.T.Howard" <Ara.T.Howard@noaa.gov> writes:
> |
> |what is the rational behind this?
> |
> |  ({}.values_at :a).empty? #=> false
> |
> |i would expect
> |
> |  ({}.values_at :a) #=> nil
> |
> |or
> |
> |  ({}.values_at :a) #=> []
> |
> |but not the actual
> |
> |  ({}.values_at :a) #=> [nil]
> |
> |there must be some reason for this, but i cannot see why returning an 'array
> |full of nothing' is preferable to returning an 'emtpy array'...  is there some
> |way of thinking about this that will make it seem less suprising?
> 
>  def values_at(*args)
>    args.collect do |i|
>      self[i]
>    end
>  end
> 
> 							matz.

ah.  also

  irb(main):001:0> {:k=>:v}.values_at
  => []

thanks.

-a
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