On 13/08/2009, at 6:10 AM, J.Fine wrote:

> Instead of writing, say,
>    \def\centerline #1{\hbox to\hsize{#1}}
> I'd like to be able to write something like
>    \def\centerline #text{\hbox to\hsize{#text}}
>
> This is an example of named parameters in macro definitions.

For the record, I agree that this would be a nice way to write  
arguments in TeX. But has writing #1, ##1, ####1 instead really ever  
stood in the way of writing TeX macros? I feel that from the document- 
level point of view, it's much more important to *input* the arguments  
as named parameters; it doesn't seem that important to me how we refer  
to arguments within a macro.

\centerline{width=\hsize,text=...}

This is where keyval-style processing has the upper hand to rigid  
macro arguments, and I think (despite the power of xparse) that we'll  
see much more gain from a standard and powerful keyval model than from  
a powerful way to define macros with complex argument types.

* * *

As far as the limitations of TeX are concerned for LaTeX3, I believe  
that
    (a) much of the limitations of LaTeX2e simply stem from lack of  
standardisation
    (b) regardless of the fact that LuaTeX seems destined to be the  
next standard engine, even without Lua many packages could be  
simplified by adopting the expl3 programming 'language'
    (c) any problems/limitations with TeX now can be solved/overcome  
with Lua later

To ignore Lua in favour of a less-well integrated scripting language,  
at this stage, doesn't seem productive to me.

Will