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From Stefano Mazzocchi <>
Subject Re: [C2] Generator affecting future processing
Date Mon, 05 Mar 2001 23:27:25 GMT
Jason Foster wrote:
> Is it possible for a Generator to change the processing chain at runtime?

No and I'll be *strongly* against making this possible.

> When I was playing with the ScriptGenerator, I thought that it would be nice
> for the Generator to be also to do things like choose a skin using
> information from a database.

No, it's a clear programmer-oriented view of the world and will generate
concern overlap, thus increase maintenance costs over time.
> My bet is that a generator can create a new parameter, much like {1}, but
> nothing leapt to view.  Does anyone have any suggestions?

As Berin said, actions are the way to go here.
> The problem with the simple solution proposed above is that some skins might
> require more than one transformation.  Can a Generator specify
> transformations in additional to those in the sitemap? Alternatively can a
> Generator bypass a transformation?

Generators generate. Period. 

It would be like placing the software to run your computer into the
powerplant that generates the power just because it would be nice to do
so from a powerplant engineer perspective.
> I guess my question is how tightly coupled is Cocoon2 to the sitemap?


> The
> sitemap seems much more static than a complex system (say a web-based
> e-journal that includes workflow capabilities) might require.

No, I disagree, it simply forces you to think more at first on how to
componentize/design your sitemap in such a way that all requirements are

> It certainly rocks for less crazily dynamic situations.

While designing the sitemap semantics I imagined all the possible
crazily dynamic situations and I could never find one that was not
possible to write using a static sitemaps.

At ApacheCON in London we had a big discussion over 'dynamic pipelines'
and nobody was able to come up with an example that *required* this.
Jason, dynamic pipelines are what Cocoon1 is based on and almost every
Cocoon1 user knows that reactors are a bad pattern because aspects are
crosscut too much.

Only fixed pipelines enforce SoC and given that no example, so far,
required something different to be implemented, I don't think the model
is wrong.

Stefano Mazzocchi      One must still have chaos in oneself to be
                          able to give birth to a dancing star.
<>                             Friedrich Nietzsche

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