On 17 Jun 2014, at 14:07, Hironori KITAGAWA <[email protected]> wrote:
> Hello,
>
> When I processed the following source (test1.tex) by LuaTeX rev 5021,
> I got "assertion failed" error:
>
> ----
> %#!luatex
> \directlua{
> callback.register('vpack_filter',
> function(h)
> tex.set('vbadness', 2000)
> return h
> end
> )
> }
>
> \vbox{}
> \bye
> ----
> $ luatex test1
> This is LuaTeX, Version beta-0.79.1 (TeX Live 2014/dev) (rev 5021)
> restricted \write18 enabled.
> (./test1.texluatex: ../../../source/texk/web2c/luatexdir/tex/texnodes.w:1022:
> free_error: Assertion `p> my_prealloc' failed.
> ----
>
> Is it dangerous to assign internal parameters of TeX
> in a callback, as in test1.tex above?
The crash was a bug, and that was easily fixed (already committed to the luatex
repo). However,
what assignments there do, is probably not what you want: it is functionally
equivalent to:
\vbox{}
\vbadness2000
(to put it another way: any tex.set() inside the filter are acted upon *after*
the closing brace of the box.
Best wishes,
Taco
