LaTeX3 "V" expansion in braces

Question

How do I set the value of a variable such that its content is the value from another variable surrounded in curly braces?

For example, if \l_tmpa_tl is \alpha, how should I control expansion so that \l_tmpb_tl is {\alpha}?

What if I want \l_tmpb_tl to be {{\alpha}}?

You might find this useful: https://tex.stackexchange.com/q/572885/86 — Andrew Stacey, Aug 28 '22 at 08:39
Similar question →expl3 - LaTeX3 - Expand nested argument - TeX - LaTeX Stack Exchange — user202729, Nov 25 '22 at 10:17

score 5 · Accepted Answer · answered Aug 28 '22 at 02:31

5

Using \exp_not:V seems to do what you're looking for, although there may be a more elegant way.

Running this:

\nonstopmode
\ExplSyntaxOn
\tl_new:N \somemacro
\tl_set:Nn \somemacro { some~content }
\tl_set:Nn \l_tmpa_tl { \somemacro }
\tl_set:Nx \l_tmpb_tl {{{ \exp_not:V \l_tmpa_tl }}}
\ShowCommand \l_tmpa_tl
\ShowCommand \l_tmpb_tl
\ExplSyntaxOff
\csname @@end\endcsname

gives this output:

> \l_tmpa_tl=macro:
->\somemacro .
<argument> \l_tmpa_tl
l.10 \ShowCommand \l_tmpa_tl
> \l_tmpb_tl=macro:
->{{\somemacro }}.
<argument> \l_tmpb_tl
l.11 \ShowCommand \l_tmpb_tl

answered Aug 28 '22 at 02:31

Max Chernoff

4,667

Thank you so much for the answer! I am not aware of the existence of \exp_not:V. It is so difficult to not miss something in the LaTeX3 documentation! – Alan Xiang Aug 28 '22 at 03:59
1

I think this is the most elegant solution :) – Skillmon Aug 28 '22 at 20:17

LaTeX3 "V" expansion in braces

1 Answers1