[Dev-luatex] Very simple sample?

[Taco Hoekwater]

Javier Bezos wrote:
> Hello,
> 
> I'm trying to use \directlua, but until now all
> may attempts failed. I begun with:
> 
> \documentclass{book}
> \begin{document}
> \directlua0{tex.print("\uppercase{hello}");}
> \end{document}
> 
> and then wrapped \directlua with every combination
> possible of \texscantokens, \luaescapestring,
> \scantokens and so on, but nothing seems to work
> (no errors, but I get "uppercase" printed, perhaps
> with dashes and quotes, and of course "hello" still
> in lower case).
> 
> Please, could you provide an example showing what
> I should do. Are \directlua and tex.print the right
> commands to use?

Yes, but tex interprets commands inside the \directlua
argument and on top of that lua interprets \ in strings,
so you need a way to get two backslashes in the tex.print
argument

This is the simplest solution:

   \let\\\relax
   \directlua0{tex.print("\\uppercase{hello}");}

But you may need something else in LaTeX, where \\
has built-in semantics.

Best, Taco