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 Sender: Mailing list for the LaTeX3 project <[log in to unmask]> Date: Fri, 12 Sep 2008 12:29:51 +0100 Reply-To: Mailing list for the LaTeX3 project <[log in to unmask]> Subject: Re: \tlp_put ... MIME-Version: 1.0 Content-Transfer-Encoding: 7bit In-Reply-To: <[log in to unmask]> Content-Type: text/plain; charset=ISO-8859-1 From: Joseph Wright <[log in to unmask]> Parts/Attachments: text/plain (49 lines) Frank Mittelbach wrote: > > some history, perhaps Morten can say more because I think he did some of the > updates ... > > very early definition: > > \def_long_new:Npn \tlp_put_right:Nn #1#2{\tlp_set:No #1{#1#2}} > > current documentation says > > % A word of warning is appropriate here: Token list pointers are > % implemented as macros and as such currently inherit some of the > % peculiarities of how \TeX\ handles "#"s in the argument of > % macros. In particular, the following actions are legal > % \begin{verbatim} > % \tlp_set:Nn \l_tmpa_tlp{##1} > % \tlp_put_right:Nn \l_tmpa_tlp{##2} > % \tlp_set:No \l_tmpb_tlp{\l_tmpa_tlp ##3} > % \end{verbatim} > % |x| type expansions where macros being expanded contain |#|s do not > % work and will not work until there is an |\expanded| primitive in > % the engine. If you want them to work you must double |#|s another > % level. > % > > > from which I infer that the > > \tlp_set:Nn \l_exp_tlp{#2} > > was actually added to raise the error when setting / adding to the tlp and not > during some later expansion deep down. Okay, seems sensible. > However, we could do better now I guess given that we assume for expl3 that > eTeX is the underlying engine nowadays > > > however the problem will be to ensure that the single # will work in all > circumstances ie all usages of tlps and I'm not sure that wil be possible As I say, I've altered what I was trying to do to follow this advice. So the problem is solved for me, at least. I will be more careful about this from now on (I suppose I should be anyway). -- Joseph Wright