From: Eric Hodel <drbrain@...7.net>
Date: 2005-01-20T03:45:04+09:00
Subject: Re: is defined? fast?

--Apple-Mail-16--995960007
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset=US-ASCII; format=flowed

On 19 Jan 2005, at 09:46, Robert Klemme wrote:

>
> "Eric Hodel" <drbrain@segment7.net> schrieb im Newsbeitrag
> news:12DE17DB-69B1-11D9-AFB0-000D93436DA0@segment7.net...
>
> Looks like the simple var check is better performance wise.  
> Personally I
> never felt the need for defined? - only during my initial Ruby stages,
> when I carried some Perl thinking with me; but never after I got rid of
> that. :-)

module M
   def functionality
     do_stuff if @x
   end
end

class C
   include M
end

C.new.functionality

With ruby -w, this will give an 'uninitialized instance variable' 
warning.  M#functionality needs to be written this way to get rid of 
the warning:

module M
   def functionality
     @x = default unless defined? @x
     do_stuff if @x
   end
end

> Ah, and btw, you don't need the "true if ".  Not that it matters
> performance wise since you applied it everywhere - but I prefer to 
> reduce
> redundancy... :-)

I feel it is necessary.  You're benchmarking the case of:

statement if defined? something

vs.

statement if $global

I like being specific.

-- 
Eric Hodel - drbrain@segment7.net - http://segment7.net
FEC2 57F1 D465 EB15 5D6E  7C11 332A 551C 796C 9F04

--Apple-Mail-16--995960007
content-type: application/pgp-signature; x-mac-type=70674453;
	name=PGP.sig
content-description: This is a digitally signed message part
content-disposition: inline; filename=PGP.sig
content-transfer-encoding: 7bit

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.4 (Darwin)

iD8DBQFB7qqDMypVHHlsnwQRAqHsAJ9Xy4dnzr95vk71Yl+IHgsxLTjdMgCfTn5h
N3CZl9ogw+NkmFLLn73FIU0=
=ZtyN
-----END PGP SIGNATURE-----

--Apple-Mail-16--995960007--