[lltx] luatexbase.is_in_callback

[Arno Trautmann]

Patrick Gundlach wrote:
> Am 21.07.2011 um 14:11 schrieb Arno Trautmann:
>> I'd like to use the post_linebreak_filter to manipulate the node list, but only if a macro appears in that given paragraph.
>
> Can you use attributes there? Then you can test whether certain attributes are in a paragraph and apply your code.

Yes, and I do in fact. But I'm not sure how this solves my problem here? 
Maybe I'll be more precise on what I want to do:
I've written a function randomcolor that inserts a color whatsit before 
(push) and after (pull) every glyph in a paragraph, using the 
post_linebreak_filter. Now I want to provide a command 
\textrandomcolor{} that does the same, but only with the text in the 
argument. For this, I use the same function as above, but set an 
attribute at the beginning of the argument and unset it at the end, and 
in the function, I test for this attribute. Fine.
However, in a paragraph that does /not/ contain any \textrandomcolor, I 
don't want the function to loop through all nodes. Let's say, for 
performance reasons …

But maybe I just don't understand your answer, sorry …

cheers
Arno