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Message-ID:  <20150911094655.GA29867@hzdr.de>
Date:         Fri, 11 Sep 2015 11:46:55 +0200
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From: Alexander Grahn <A.Grahn@HZDR.DE>
Subject: non-intuitive behaviour of clist with empty items
To: LATEX-L@LISTSERV.UNI-HEIDELBERG.DE
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Envelope-To: <rainer.schoepf@GMX.NET>
Status: R

Good afternoon,

consider the following example:

  \documentclass{article}
  \usepackage{expl3}
  
  \begin{document}
    \ExplSyntaxOn
      \clist_set:Nn\l_tmpa_clist{,,foo,bar,}
      \typeout{\clist_count:N\l_tmpa_clist}    %expected:  5,    I get 2.
      \typeout{\clist_item:Nn\l_tmpa_clist{3}} %expected: `foo`, I get `'.
      \typeout{\clist_item:Nn\l_tmpa_clist{4}} %expected: `bar`, I get `'.
    \ExplSyntaxOff
  \end{document}

Why does \clist_set:Nn ignore empty items when initialising a clist
variable from a token list? Is this intended behaviour? Is there a
work-around?

Kind regards
Alexander