[luatex] callbacks in luatex 0.89

Hans Hagen pragma at wxs.nl
Thu Feb 11 10:47:29 CET 2016

On 2/10/2016 11:43 PM, David Carlisle wrote:
> Comparing the list of callbacks in luatex 0.89 to those in 0.80 the
> changes seem to be

> - append_to_vlist_filter

that one was missing indeed

> - hpack_quality

part of the interceptors (overful rule stuff)

> - process_rule

handy in case one implements user rules

> - show_warning_message

just one of interceptors (we normalized all warnings/errors but there is 
still some work todo)

> Gone

> - pdf_stream_filter_callback

that one never did anything and was a left-over from an experiment

> - token_filter

There is no replacement for the callback. The new token scanner permits 
defining new functionality that needs some kind of parsing (like picking 
up a dimension or count) and acting on that but picking up and feeding 
back into the input stream of pure tokens has been removed.

we might add a token.print function (if so it will be around version 
0.95) in which case one can use token.get_tok in an endless loop to pick 
up tokens and print them back but (as with the callback) it will be very 

> the first three new ones are documented in the manual but not
> show_warning_message
> the two that have gone are not documented anywhere as a change that I can find.

because the first one never was there (there is some more undocumented 
stuff in there, which might become formal when we release 0.90 in which 
case it will be documented - the next tugboat might have some more info 
about that)

> This came up as a user query about some old code of Taco's on
> stackexchange using token_filter
> http://tex.stackexchange.com/a/21691/1090
> What is the intended replacement for token_filter?

none, the new scanner is intended for implementing interfaces (and maybe 
introspection) but not for manipulating the input stream


                                           Hans Hagen | PRAGMA ADE
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