Lua to Tex : content and variable content different?

Question

Here is something bizarre ! (I mean I don't understand). I enter a content, let's say "Something" in the (global) variable context. In line 2 of the following code, as one may anticipate, we have the same printout for the content of context and for the literal Something. However, in line 3, the content of context and the literal Something are recognized different !

\luaexec{context="Something"}
§§\luaexec{tex.print(context)}§§Something§§\\
\ifthenelse{\equal{\luaexec{tex.print(context)}}{Something}}{egal}{different}

Is there a problem of catcode, that makes the two look identical when they are different ? should I prefer luadirect, directlua, etc. instead ?

In fact, I tried with \luadirect instead of \luaexec, and it seems working, sometimes (not very stable, as sometimes, in other contexts, it doesn't work).

\luaexec{context="Something"}
§§\luaexec{tex.print(context)}§§Something§§\\
\ifthenelse{\equal{\luadirect{tex.print(context)}}{Something}}{egal}{different}

How shall I assure that the content of the variable context is recognized exactly as the literal content ?

Answer 1

The \equal test for \ifthenelse fully expands its arguments (with \protected@edef); so, for instance,

\ifthenelse{\equal{\textbf}{\expandafter\protect\csname textbf \endcsname}}{a}{b}

returns a, because the token lists resulting from these ones, after \protected@edef is applied, are the same.

On the other hand, \luaexec doesn't fully expand to a string, as mentioned in footnote 2 in the manual for luacode.

If I try

\documentclass{article}
\usepackage{ifthen,luacode}

\begin{document}

\luaexec{context="Something"}
\makeatletter\protected@edef\test{\luaexec{tex.print(context)}}
\show\test

\end{document}

I get

> \test=macro:
->\begingroup \escapechar 92 \newlinechar 10 \edef \protect \\{\\}\edef \protect \nobreakspace  {}{~}\let \%=%\let \#=#\endgroup Something.

and it's quite clear this is not the same as Something.

On the other hand, \luadirect is fully expandable and, if I change the second instance of \luaexec in the above code, I get

> \test=macro:
->Something.