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Message-ID:  <4D6250F1.2020806@morningstar2.co.uk>
Date:         Mon, 21 Feb 2011 11:48:01 +0000
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From: Joseph Wright <joseph.wright@MORNINGSTAR2.CO.UK>
Subject: Re: Fully expandable "x" argument (was "expandable \uppercase...")
To: LATEX-L@listserv.uni-heidelberg.de
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Status: R

On 21/02/2011 11:20, Bruno Le Floch wrote:
>> (I haven't looked into doing it non-expandably, which would be more robust.)
> 
> My claim is that expandable is just as robust as non-expandable if
> - we have access to the full argument (i.e. no peeking ahead)
> - there is no token of catcode 1 other than a true "{"
> - there is no token of catcode 10 and character code other than 32 (space).

I suspect condition (2) is  killer. While assuming "{" is catcode 1 is
fine for LaTeX-like input, what happens if you're using LaTeX3 with some
other input syntax (for example XML)?
-- 
Joseph Wright