From: Robert Klemme <bob.news@...>
Date: 2003-02-03T22:13:54+09:00
Subject: Re: Local variables & blocks


<ichimal@fenix.ne.jp> schrieb im Newsbeitrag
news:20030203205757.22039@kana.fenix.ne.jp...
> Hi,
>
> In message "Re: Local variables & blocks"
>     on 03/02/03, matz writes:
>
> >|  I think, it should be a first-class special value like
#<non-initialized>.
> > Hmm, "nil" is a special value for uninitialized slot.
>
>   If #<non-initialized> were newly established, what value can I get from
> following code?
>
> if #<non-initialized> then
>     foo = true
> else
>     foo = nil
> end
>
>   I say again, double meaning may be harmful.

There's no double meaning. As matz pointed out, this is exactly what nil is
for. I don't see any advantage in creating another distinction between nil
and #<non-initialized> - IMHO this is artifical. If you really needed the
distinction (which I guess is rare), you could introduce a additional
boolean flag for this.

def blocktest(*args)
  args.each do |arg|
    initialized = true
    foo = (foo or arg)
  end

  p "not initialized" unless initialized
end

Note: 'and' operation does not make much sense for aggregation here without
initialization since 'nil and <anything>' always yields 'nil'.

Second Note: I guess, you forgot the braces since 'and' has lower
precedence than '='. Your original code would have been grouped like this:
(foo = foo) and arg, which would always leave foo as nil.

Regards

    robert