On 11/16/2021 8:22 PM, Joey McCollum via ntg-context wrote:
As the subject of this question suggests, this is really more of a question about expansion control (a topic that is still a bit obscure to me). Suppose I have a macro \inner that expects a single argument or an assignment of parameters in brackets. For my purposes, I don't want this macro to do anything when it is typeset, so I'll just define it as empty:
``` \def\inner[#1]\empty ```
Now suppose I have another macro \outer that invokes this macro with some specific input and sets some plain text after it:
``` \def\outer{\inner[123] etc.} ```
What I'd like to do is parse the argument of \inner in \outer. I was hoping that a string search in Lua would work, but I'm not having any luck. A minimal (non)-working example is included below:
```
\def\inner[#1]\empty
\def\outer{\inner[123] etc.}
\startluacode
local userdata = userdata or {}
function userdata.parseinner(str)
local innerparams = ""
if string.find(str, "\\inner(%b[])") then
i, j = string.find(str, "\\inner(%b[])")
innerparams = string.sub(str, i+1, j-1) -- we just want the content inside the brackets
end
context(innerparams)
return
end
\stopluacode
\def\parseinner#1{\ctxlua{userdata.parseinner([==[#1]==])}}
\starttext
Testing:\blank
\parseinner{\outer}
\stoptext
```
My problem is that when I pass \outer to the \parseinner macro, it gets fully expanded, so there isn't anything left to match "\\inner%b[]". Is there a way to expand \outer when I pass it to the \parseinner macro without also expanding the \inner macro inside it? Or is there some other preferred way of doing this?
One can always abuse native tex: \starttext \def\MyOuter#1% {\beginlocalcontrol % hides the next \let\Indeed\empty \def\MyInner[##1]{\gdef\Indeed{##1}}% \setbox\scratchbox\hpack{#1}% \endlocalcontrol % but only if needed \Indeed} whatever: \MyOuter{\MyInner[oeps]}% \edef\ItWorks{\MyOuter{\MyInner[oeps]}} whatever: \meaningless\ItWorks \stoptext -- ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl -----------------------------------------------------------------