[Dev-luatex] attributes

Hans Hagen pragma at wxs.nl
Sun May 27 14:08:00 CEST 2007

Chris Rowley wrote:
> Taco wrote --
>> When replying, please edit your Subject line so it is more specific
>> Hans and I are working on a new feature we call "attributes".
> Sounds like the idea we talked about in ... somewhere ...??
dunno, the name attribute is rather generic -)
> So is this an arbitrary dictionary (list of name, value pairs?
no, currently just an array of numbers attached to each node, the index 
in the attribute

attr 1, value 10
attr 5, value 32

so, when attr 5 deals with color, teh value 10 can represent a specific 
color; eventually this will result in a pdfliteral or special to be 
inserted but that's up to the user (macro writer); such insertion can 
take place for instance at shipout time by manipulating the final node 
list (then typeset content)
>> An attribute is an item that becomes attached to the actual nodes
>> that are to be typeset.
> But what is a `node to be typeset'?  Or is this deliberately vague?
the node lists at each stage ... after boxing, before line breaking, 
what enters the output routine (linebreaking done then);
> Anything in an hlist or vlist?  Or only character(/glyph??) nodes?
anything ... glyphs, glue, penalty, whatsits, h/vlists ...

luatex only provides generic mechanisms are provided, (i.e. opens up the 
engine and adds a few features that we think that should be there); one 
can use attributes to implement for instance color, but the actual 
implementation is up to the macro package writer (ok, i will probably 
provide some generic code, but even then, the interfaces on top of that 
may differ)


                                          Hans Hagen | PRAGMA ADE
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