# How to break the 9-argument limit

If you think about it, you will realise that Knuth’s command definition syntax:

\def\blah#1#2 ... #9{}

is intrinsically limited to just 9 arguments. There’s no direct way round this: how would you express a 10th argument? — and ensure that the syntax didn’t gobble some other valid usage?

If you really must have more than 9 arguments, the way to go is:

\def\blah#1#2 ... #9{%
\def\ArgI{{#1}}%
\def\ArgII{{#2}}%
...
\def\ArgIX{{#9}}%
\BlahRelay
}
\def\BlahRelay#1#2#3{%
% arguments 1-9 are now in
%   \ArgI-\ArgIX
% arguments 10-12 are in
%   #1-#3
%
}

This technique is easily extendible by concert pianists of the TeX keyboard, but is really hard to recommend.


\flowerinstance{species=Primula veris,
family=Primulaceae,
location=Coldham's Common,
locationtype=Common grazing land,
date=1995/04/24,
numplants=50,
soiltype=alkaline
}

The merit of such verbosity is that it is self-explanatory: the typist doesn’t have to remember that argument twelve is soiltype, and so on: the commands may be copied from field notes quickly and accurately.
keyval.sty
Distributed as part of graphics

* faq-mac-prog.tex (q-keyval): tweak words about getoptk