On 17/02/2010 14:59, Joseph Wright wrote:
> On 17/02/2010 14:38, Philipp Stephani wrote:
>> through the input processor, things like spaces and comments are
>> inevitably lost. I thought of something like this:
>
> We had quite a bit of discussion before about verbatim input and xparse.
> At the time the general agreement seemed to be that you can't reliably
> tackle all verbatim items with a generic function. So we decided that it
> was best to stick to code that will work reliably and accept that some
> items (a small percentage of all functions) will need handling "by hand".

I should add that the issue was *if* you could include verbatim input 
using \NewDocumentCommand (as the last argument). The problem is not so 
much getting things right for one argument but dealing with the various 
cases:
  - Several arguments with only the last optional
  - Verbatim w.r.t. only some characters (some can be handled with 
\scantokens, some cannot)
  - Dealing entirely properly with nested functions (and making sure 
that the limitations are clear).
-- 
Joseph Wright