[luatex] multiple callbacks

Hans Hagen pragma at wxs.nl
Sun Jan 4 18:27:05 CET 2009

Elie Roux wrote:
> Elie Roux a écrit :
>> I took Hans' example and modified it so that it compiles. I come up 
>> with a minor Lua problem (see the last comment), and a strange 
>> problems : it seems that callbacks are called two times... If someone 
>> better than me in Lua can take a look...
> Update : a simple
> callback.register("hpack_filter",function(head,...)
>    texio.write_nl("I am a callback")
>    return head, true
> end,1)

no ,1 needed here; this is the luatex register function not the 

> writes two times "I am a callback", which is not the case for

it depends on the packing of boxes, and there can be much packing going 
on (like for instance in the page builder), so even a simple


might give you one for 'test', one for the pagenumber, etc etc

> callback.register("post_linebreak_filter",function(h, groupcode, glyphes)
>    texio.write_nl("I am a callback")
>    return true
> end,1)
> that writes it only once, is it normal?

depends on the number of paragraphs


                                           Hans Hagen | PRAGMA ADE
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