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Message-ID:  <4D2600D3.7060400@morningstar2.co.uk>
Date:         Thu, 6 Jan 2011 17:50:11 +0000
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From: Joseph Wright <joseph.wright@MORNINGSTAR2.CO.UK>
Subject: Re: variable opt arg delimiters [was: Defining a ...]
To: LATEX-L@listserv.uni-heidelberg.de
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Status: R

On 06/01/2011 17:37, Paul Thompson wrote:
> The optional argument thing could be better handled by using named arguments.
> So, for \parbox, which has optional and mandatory arguments, we currently have
>
>
> \parbox[pos][height][inner-pos]{width}{text}
>
> This is mindlessly confusing in many cases.  Why not have
>
> \parbox{pos=t,height=something,innerpos=t,width=something}{text}
>
>
> The use of named arguments is vastly superior to positional arguments,
> especially when optional arguments can be specified.

Not directly relevant to the discussion about how one defines optional 
arguments, but very true in any case. I hope you'll allow one optional 
argument as 'reasonable', as this often makes sense:

   \foo[<optional-keyval-list>]{<mandatory-argument>}

At this stage, user-level syntax for LaTeX3 is undecided but I suspect 
that there is likely to be a greater use of key--value stuff where 
appropriate.

> Don't even get me started on \newcommand.

\NewDocumentCommand has only mandatory arguments :-)
-- 
Joseph Wright