On 16/02/2011 16:04, Bruno Le Floch wrote:
>> If it's as good as it seems then it allows all sorts of expandable things,
>> such as optional argument parsing and expandable nested mapping.
> 
> We had a short discussion with Joseph about optional argument parsing.
> The obvious constraint is that the last argument must be mandatory, so
> we can just look for its opening delimiter. Then it is in principle
> possible, but argument specifications like {oom} become quite tricky,
> since #{ has to be used when grabbing each of these arguments. I
> haven't looked at the implementation of xparse in detail, though.

In this discussion I did say that whether fully-expandable arguments
should be limited to 'om'-like cases was an open question. If it's more
sensible over all then I'm happy with this: that part of xparse is very
much 'experimental'.

> I've put the code for \fullyexpand online for those interested, as
> well as a very primitive macro expander. (
> http://users.aims.ac.za/~bruno/LaTeX/ULcase/ )

Another thing to read after work :-)
-- 
Joseph Wright