[luatex] multiple callbacks

Hans Hagen pragma at wxs.nl
Sun Jan 4 17:19:21 CET 2009

Arthur Reutenauer wrote:
>> Keep in mind that not all callbacks have the same i/o characteristics.
>   I was aware of that, but did not know the details of each callback.
> I've been playing mostly with define_font.
>> For example, 'process_input_buffer' has:
>>   function(<string> buffer)
>>     return <string> adjusted_buffer
>>   end
>   Therefore, the responsibility of calling the appropriate interface
> could maybe be left to the macro writer who calls the callback, not the
> author of the macro package?

well, one can create a caller for each type of callback, and many are 

>> Btw, callback.add() could just return false when it detects a
>> conflict with an already existing function, and true otherwise.
>> Then the caller could decide how to handle the error.
>   Sure, that would also be a possibility.

one can never catch alle errors; for instance a style could mess up the 
node list which can make luatex crash; one just has to assume that the 
writer does a decent job

                                           Hans Hagen | PRAGMA ADE
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