Reposting from a week ago to see if there is an answer?

Hi There:
Trying to use variable with saveboxes and getting unexpected result. Why won't the variable show when I use the savebox?

thanks!
John

Class File (excerpt):
\let\@foo\relax
\def\foo#1{\def\@foo{#1}}
\newcommand{\showfoo}{\@foo}
\newsavebox{\testbox}
\sbox{\testbox} { Testbox goes \showfoo}

Tex File (excerpt):
\begin{document}
\foo{foo}
Test box test: \usebox{\testbox}

Show foo test: \showfoo
\end{document}

Output:
Test box test: Testbox goes
Show foo test: foo

Am 10.09.22 um 23:45 schrieb johnl...@gmail.com:
> Reposting from a week ago to see if there is an answer?
>
> Hi There:
> Trying to use variable with saveboxes and getting unexpected result. Why won't the variable show when I use the savebox?

The box is rendered when you define it, which is in the preamble in your
example. After that, when the box as rendered is used as is. There's no
box-creating macro code left which could be interpreted with current values.

At the moment when the box is created, \@foo is \relax, so there's
nothing \showfoo would show.

HTH,
Julius

PS: If you create a full minimal example it's easier for others to play
with your code and find the problem. Something like:

\documentclass{article}
\makeatletter
> \let\@foo\relax
> \def\foo#1{\def\@foo{#1}}
> \newcommand{\showfoo}{\@foo}
> \newsavebox{\testbox}
> \sbox{\testbox} { Testbox goes \showfoo}
>
% Tex File (excerpt):
> \begin{document}
> \foo{foo}
> Test box test: \usebox{\testbox}
>
> Show foo test: \showfoo
> \end{document}
>
> Output:
> Test box test: Testbox goes
> Show foo test: foo