From gregor.gorjanc at bfro.uni-lj.si  Sat Sep  2 22:02:10 2006
From: gregor.gorjanc at bfro.uni-lj.si (Gregor Gorjanc)
Date: Sat, 02 Sep 2006 22:02:10 +0200
Subject: [Rd] [<-.POSIXlt changes order of attributes (PR#9197)
In-Reply-To: <Pine.LNX.4.64.0609011416490.11719@gannet.stats.ox.ac.uk>
References: <20060901115839.3758019A05@slim.kubism.ku.dk>
	<Pine.LNX.4.64.0609011416490.11719@gannet.stats.ox.ac.uk>
Message-ID: <44F9E342.9050900@bfro.uni-lj.si>

Hello,

Prof Brian Ripley wrote:
> Please point us to the documentation that says attributes are ordered.
> E.g. R-lang.texi says
> 
>   All objects except @code{NULL} can have one or more attributes attached
>   to them.  Attributes are stored as a list where all elements are named.
> 
> (although in fact they are stored in a pairlist).
> 
> I know of tens of functions that change the order of attributes, and 
> did look at teaching identical() that they are not ordered.  But 
> since they are stored as a pairlist, it would be quite expensive.

I agree that there is no need for attributes to be always in the same
order as this is tedious to achieve as you noted above, but identical()
seems to care about this.

> (Given that attributes seem to be growing in use, another internal storage 
> mechanism is becoming more appropriate.)

Which internal storage mechanism are you talking about here?

> BTW, all.equal() does not assume attributes are ordered.

-- 
Lep pozdrav / With regards,
    Gregor Gorjanc

----------------------------------------------------------------------
University of Ljubljana     PhD student
Biotechnical Faculty
Zootechnical Department     URI: http://www.bfro.uni-lj.si/MR/ggorjan
Groblje 3                   mail: gregor.gorjanc <at> bfro.uni-lj.si

SI-1230 Domzale             tel: +386 (0)1 72 17 861
Slovenia, Europe            fax: +386 (0)1 72 17 888

----------------------------------------------------------------------
"One must learn by doing the thing; for though you think you know it,
 you have no certainty until you try." Sophocles ~ 450 B.C.




[Rd] [<-.POSIXlt changes order of attributes (PR#9197)
Gregor Gorjanc