Hi Jairo,

ConTeXt's \unexpanded is e-TeX's \protected, so the error boils down to
something like: \edef\x{\unexpanded{#}}, which works in Plain but not in
ConTeXt.

Usually packages that claim to be generic have to cope with that.
xstring would need to do (in a ConTeXt-specific loader):
    \let\xstring@unexpanded\normalunexpanded
and
    \let\xstring@unexpanded\unexpanded
in Plain and LaTeX loaders, then then use \xstring@unexpanded in the
code.  But `xstring` doesn't claim (that I found, at least) to be
compatible with ConTeXt, so it's understandable: though if it is
compatible with Plain, it wouldn't be hard to adapt to ConTeXt.

That said, you can load `xstring` if you do:
     \let\unexpanded\normalunexpanded
     \input xstring.tex
     \let\unexpanded\protected
but the internals of the package will probably be comprimised by the
misuse of (ConTeXt) \unexpanded.

Phelype

On Tue, Jul 7, 2020 at 3:40 PM Jairo A. del Rio <jairoadelrio6@gmail.com> wrote:
>
> Reading about macro bundles meant to be generic (format agnostic), some of them work in plain/LaTeX, but crash when loaded on ConTeXt. The following happens with xstring.tex
>
> tex error > tex error on line 372 in file xstring.tex: ! Illegal parameter number in definition of \xs_reserved_C
>
>
> <to be read again>
>
> 1
>
> \xs_newlines ->\unexpanded {}\xs_def \xs_arg_i {##1
>
> }
>
> \xs_newmacro_ ...name \xs_myarg }\edef \xs_reserved_C {\unexpanded \expandafter {\xs_newlines
>
> }\edef \noexpand \xs_call }\edef \xs_reserved_D {...
>
> l.372 \xs_newmacro\StrRemoveBraces{}{1}{1}
>
> {%
>
>
> <empty file>
>
>
> You meant to type ## instead of #, right? Or maybe a } was forgotten somewhere
>
> earlier, and things are all screwed up? I'm going to assume that you meant ##.
>
> I've tried changing the catcode regime, but with no effect.
>
> Don't misunderstand me. I'm aware of ConTeXt capabilities and string manipulation via Lua. My question is more like: "Why doesn't xstring.tex?"
>
> Sorry if my question is outside the scope of ConTeXt developers/maintainers. Thank you very much.
>
> Jairo :)
>
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