Re: [NTG-context] About xstring and ConTeXt

7 Jul 2020


      Yep, now it finally works. Certainly it requires a few more lines. I was
going to rewrite some TikZ code which was too dependent on LaTeX and
xstring was the last stone on the shoe. Thank you a lot, Phelype and
Wolfgang (I didn't know about push/popmacro either and now it's in my to-do
readings).

Jairo :D

El mar., 7 de jul. de 2020 a la(s) 16:31, Phelype Oleinik (
phe.h.o1@gmail.com) escribió:
...
On Tue, Jul 7, 2020 at 6:21 PM Jairo A. del Rio 
wrote:
...
Thank, Wolfgang! Both methods work, but both fail with the following
example:
...
\pushmacro\unexpanded
\let\unexpanded\normalunexpanded
\input xstring
\popmacro\unexpanded
\starttext
\StrGobbleLeft{bcdef}{4}
\stoptext
The log says:
tex error > tex error on line 6 in file ./tests.tex: ! This can't happen
(prefixed command)
...
<argument> \unexpanded {
f}
\xs_execfirst #1#2->#1
However, some others work.
As I said, the internals of `xstring` still use \unexpanded which, after
you do \popmacro\unexpanded, will mean e-TeX's \protected, rather than
\unexpanded, which are quite different.  To be on the safe side, you'd
need to wrap every `xstring` command in
    \pushmacro\unexpanded
    \let\unexpanded\normalunexpanded
    <xstring stuff>
    \popmacro\unexpanded
to make sure that \unexpanded means what `xstring` expects.
The *proper* way to make `xstring` work in ConTeXt would be something
like Circuitikz does:
    \ifcsname normalunexpanded\endcsname
      \let\pgfcircutil@unexpanded\normalunexpanded
    \else
      \let\pgfcircutil@unexpanded\unexpanded
    \fi
then use \pgfcircutil@unexpanded in the code, which will always have the
same meaning.  That, of course, requires an update to `xstring`.
Phelype
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