On Fri, Sep 11, 2015 at 11:06:08AM +0100, Joseph Wright wrote:
>On 11/09/2015 10:46, Alexander Grahn wrote:
>> 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?
>This is by-design. Comma lists can't contain empty items, commas, etc.:
>sequences can. The reason is comma lists are 'close' to the user level,
>and there stray empty entries are normally best ignored.
This is very unfortunate, because I want to be able to correctly process
user input of comma sparated items which /may/ contain empty items.
With \@for from LaTeX2e I can easily process such input properly:
\documentclass{article}
\begin{document}
\makeatletter
\@for\listitem:=,,foo,bar,\do{
\typeout{item:\listitem}
}
\makeatother
\end{document}
Now I am looking for an L3 equivalent of \@for.
Alexander
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