On 3/12/2023 2:24 PM, Bruce Horrocks via ntg-context wrote:
I have an existing macro that I'd like to extend.
The current definition is \define[3]\mycommand{...} which I'd like to extend to
take an optional 4th parameter plus an optional setup parameter.
Thus I currently invoke it as:
\mycommand{aa}{bb}{cc}
and I'd like to be able to extend it so that any of the following can be used:
\mycommand{aa}{bb}{cc}
\mycommand{aa}{bb}{cc}{dd}
\mycommand{aa}{bb}{cc}{dd}[ee]
or
\mycommand[ee]{aa}{bb}{cc}{dd} % if this is more the ConTeXt way
where {dd} is the optional extra parameter and, if it is present, then [ee] can
also be optionally added (because it controls how {dd} is printed).
If it helps, the actual body of the macro can easily be a call to Lua so it's
fine if the function takes 5 params where 4 and 5 can be nil or empty strings.
I've trawled through syst-aux.mkiv but it only covers optional numbers of [ ]
or { } but not combinations of both (which given the vast numbers of
combinations is perhaps not surprising!). Have I missed something obvious that
would help me?
So, four optional with mandate {} plus a fallback to an optional []
\starttext
\tolerant\def\mycommand#=#=#=#=#:[#5]%
{\ifparameter#1\or(1:#1)\fi
\ifparameter#2\or(2:#2)\fi
\ifparameter#3\or(3:#3)\fi
\ifparameter#4\or(4:#4)\fi
\ifparameter#5\or[5:#5]\fi}
\startbuffer
\mycommand{aa}{bb}{cc}
\mycommand{aa}{bb}{cc}{dd}
\mycommand{aa}{bb}{cc}{dd}[ee]
\mycommand{aa}{bb}{cc}
\mycommand{aa}{bb}{cc}{dd}
\mycommand{aa}{bb}{cc}{dd}[ee]
\stopbuffer
\typebuffer
\startlines \getbuffer \stoplines
\stoptext
I'm not saying that it's the best solution, you can add \protected in
front of the \def if needed.
Hans
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Hans Hagen | PRAGMA ADE
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