On 02.09.2005 10:24:12 Finn Bock wrote:
> [Luca]
> 
> > Speaking of extensions, I'd like to resurrect the layout extensions 
> 
> That isn't exactly use of the term "extension" which I'm using and which 
> I think Jeremias is using in the ExtensionPoints wiki. Your extensions 
> are additional useful features, when I talk about extensions it is the 
> ability to dynamicly load additional behaviour without modifying FOP 
> sources.

Well, extension is such a generic term, like plug-in (<ot>and yet the
concept was patentable</ot>). Anyway, I don't think that Luca's
extensions differ so much from the extensions I documented in the Wiki.

> If your features could be implemeted as dynamicly loaded code, the 
> result would be a lean FOP with incredible power ...

No quite related to this thread, but just to let you know: I'm currently
working on the generic extension mechanism that, for example, renderers
will be able to use. I realized it would probably not be much more work
to implement it generically than to hard-code the PostScript extensions
into FOP.

> > that 
> > were part of the code used to start the Knuth branch, but I want to be 
> > sure I'm allowed to do it.
> 
> .. and you wouldn't have to ask. :-)
> 
> OTOH, I'm not entirely sure how to design and implement such a system 
> that dynamicly loads code into the layout system.

Neither am I in this case. At the very least it would involve
subclassing certain LMs and dynamically registering them for the layout
engine. But that would probably be the least of problems, since the
new behaviour goes right into the breaking algorithm.

> > The set of extensions (a couple of new properties, and some new value 
> > for an existing one) 
> 
> New properties are fine, new values to existing properties are bad, I 
> think. It basicly makes the fo file into a FOP file, since no other 
> processer can handle the 'illegal' values. It would be better to define 
> fox:display-align="fill" which when specified will override the value of 
> display-align.

Good point.

<snip/>


Jeremias Maerki

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