[Gnu-arch-users] Re: File-tpye plug-in architecture for Arch?

[Tom Lord]

    > From: michael josenhans <address@hidden>

    > I would expect any diff tool should to complain, if it is used for 
    > diffing between 2 XML files, which reference different DTDs.

In fact, some explicitly don't.  But anyway, the question concerns the
output of the patch tools -- not whatever input the diff tool refuses
to process.


    > xml-patch
    > ---------
    > When applying patches, xml-patch tools shall use the DTD in order to 
    > generate a valid XML-document.

That would be a requirement, yes.   Necessary but not sufficient to
the task.

Another issue here is that while OpenOffice promises to reasonably
handle those files which conform to the various DTDs which it, itself,
might have generated -- it does not promise to reasonably handle all
files that conform to those DTDs.  Just as the DTDs are a subset of
XML-in-general, the documents reasonably handled by OpenOffice is a
subset (not a priori an improper or proper subset) of those XML docs
that pass the DTDs.

I understand that that is a subtle point and that we most likely have
a language barrier between us -- but do you see what I am saying?


    > Example: [...]
    > 
    > If the DTD would indicate the colorlist could either be empty or contain 
    > one 'color-item' child, patch should complain about a merge conflict and 
    > ask the user to resolve.

You're just restating the problem, not solving it.  How is the user to
resolve this conflict, especially in the specific case of OpenOffice
documents?  By editting the raw XML?  By editting the source documents
in anticipation of how they will be handled by the diff/patch
algorithms?


    > Summary:

    > Any good XML patch should take the DTD into account when
    > merging. If it does not, you will be required to do more manual
    > merging effort than needed.

Again, you're just restating, not solving the problem.

The DTD doesn't contain enough information for the patch tool to
generate output which includes conflict markers.

Therefore, the patch tool must sometimes say "I can't produce any
useful output whatsoever" from the perspective of the tools who's DTDs
we are trying to generate.   What the hell is supposed to happen then?

-t