[gobo-eiffel-develop] Re: Re: suggestions for gexace

[Sven E. <sve...@we...>]

Andreas Leitner <no...@sb...> schrieb am 02.10.01:
> On Fri, Sep 28, 2001 at 11:20:03PM +0200, Sven Ehrke wrote:
> > Andreas Leitner <no...@sb...> schrieb am 28.09.01:
> > > On Fri, Sep 28, 2001 at 01:26:56AM +0200, Sven Ehrke wrote:
> > > 
> > > Could you please give examples of what such a transformation should do. My first though was to generalize the tasks and add the resulting features to gexace firectly.
> > 
> > Well if you look at the produced ace files we have a cluster list
> > containing items like:
> > 
> >   kernel_misc: "${GOBO}/library/kernel/misc";
> > 
> > Instead of the ace file the produced xml file
> > could contain (among other things) the cluster list in xml form:
> > 
> >   <cluster_list>
> >     <cluster name="kernel_misc" location="${GOBO}/library/kernel/misc"/>
> >   </cluster_list>
> > 
> > Above and below there can be additional information which gexace found
> > during the xace parse process. We could also (if we find it makes sense)
> > insert some "hook" tags to make it easier for the xsl to replace
> > them with certain customizable things.
> > Actually I think the xsl's would be really small and easy to understand
> > and besides that much more flexible than hard wiring it into gexace.
> > If you look at Eric's xsl's you can see what is possible with xslt.
> > Compared to those these would be really easy I think.
> > 
> > The production of the xml file should be really easy for gexace since
> > it has all the information already.
> 
> I have yet to take a closer look at XSL. I can see a point in your request, although I also see a problem. That does not neccesarily mean the problem is in your request, it may as well reside be the current architecture of gexace:
> 
> If we add a XACE->more-specific-XACE transformation and the provide a XSL to transform the more-specific-XACE into ACE files we basically provide two mechanisms to do the same thing:
> 
> a) use gexace to do the whole job
> b) use gexace plus xsl transformations
> 
> Eiffel has a long tradition of providing only one reasonable mechanism to archive one goal. And I think this is a good tradition. Providing multiple mechanisms results in confusion on the devopers side as to what is the best way to do a thing.
> 
> This is not an argument against the xsl approach it is an argument agains having both aproaches in GOBO. If we really go for the XSL way, it should be the only one.

I agree here. But remember that with a XML document produced by gexace people could do with it whatever they
would like to. Since it is XML they can use all the tools and libraries available. Gexace at the moment is really doing
two things at once:
1) reading the xace files and gathering all the information within them.
2) produce an ace file which contains that information in another format.

Having a separate module for each of these steps would increase reusablity.
So from a purists point of view I would support the XSL approach.
The drawback is that we would have to deliver
some non Eiffel stuff as part of gobo: the xsl libraries (xalan). So far it has been an optional addon which one
could use or not. If we would go the XSL way (and only that way) it becomes a mandatory part of GOBO.
I am not sure if this is acceptable or not.

> 
> My understanding of what would be a typical task for gexace and what for XSL is still somewhat fuzzy - maybe you can help me understand the issue better (;

gexace would then just produce a single flat XML out of the individual xace files.
Producing ace files from that XML is then the job of an XSL.
But remember: producing an ace file from that XML is just a special case of application (although the most important
at the moment). But one cannot foresee what ideas people have in future and having the information in XML
would be certainly very useful then.
I can setup a small example consisting of a XML and a XSL file if I find the time this week.

- Sven


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