From ripley at stats.ox.ac.uk  Sun Jul 20 09:22:10 2008
From: ripley at stats.ox.ac.uk (Prof Brian Ripley)
Date: Sun, 20 Jul 2008 08:22:10 +0100 (BST)
Subject: [Rd] multiple names to assign
In-Reply-To: <4879CD49.2080406@pburns.seanet.com>
References: <4879CD49.2080406@pburns.seanet.com>
Message-ID: <alpine.LFD.1.10.0807200807530.11304@gannet.stats.ox.ac.uk>

Warning does seem sensible (and there is already a test for length > 0), 
so I've added one.

Generally R has followed the Unix philosophy of not chatting and trying to 
make sense of the user's inputs (although it has multiple authors, and 
some advocate more of what others see as nannying).  We do see enough 
'what does this error message mean' about *warnings* on R-help to see the 
downside.

On Sun, 13 Jul 2008, Patrick Burns wrote:

> 'assign' does not give a warning if 'x' has length
> greater than 1 -- it just uses the first element:
>
> assign(c('a1', 'a2'), 1:2)
>
> One way of thinking about this is that people using 'assign' get what 
> they deserve.

Or possibly intend, although as the help page incorrectly suggested that 
a quoted character string was needed, they would have had to have read 
the source code to know what should happen.

> The other is that it is used seldom enough that adding a warning isn't 
> going to slow things down appreciably.
>
> Patrick Burns
> patrick at burns-stat.com
> +44 (0)20 8525 0696
> http://www.burns-stat.com
> (home of S Poetry and "A Guide for the Unwilling S User")

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595



[Rd] multiple names to assign
Prof Brian Ripley