[luatex] Changing catcodes in \directlua

[Manuel Pégourié-Gonnard]

Le 06/07/2010 08:34, Paul Isambert a écrit :
> \directlua{tex.print("a\noexpand\alpha b")}
> [...] But what surprises me is the space 
> before the ``b''. Where does it come from? I'd think ``\alpha'' when it 
> was still a command would have gobbled it...?
> 
The space is first gobbled, then another space is generated when TeX converts
the unexpanded '\alpha' token to a string of characters. If you don't want any
space, you can use \string\alpha.

This is exactly the same as \write and other TeX82 primitives. Try

\write20{|\noexpand\alpha|\string\alpha|}

and look at the terminal (or log).

Manuel.