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

[michael josenhans]

Charles Duffy wrote:
> On Mon, 2003-12-22 at 17:16, michael josenhans wrote:
>
> > Any good XML patch should take the DTD into account when merging.
>
>
> Much of the argument here is that knowing that the new document
> validates is insufficient to know that the new document is semantically
> valid (ie. that when loaded into the app which created the two documents
> from which it was created, said app will represent a document that is in
> fact The Right Thing).

If there is an DTD. The application must be able to eat any valid DTD.
Especially, if there are open formats like OpenOffice, where not 
everthing is under control of one implemetation, this in not an 
disadvantage.

> Consider the case where an app loading a merged document presumes that
> each style element will have a distinct "name" value, but where each
> branch added a different style element with the same name;

This is the same problem like archs file tagging. Just lets the 
application put a unique tag to the node. Either a running number 
containing the branch name or use a random number.

If the attched tage to the node is identical, it was a change otherwise 
a new node.

> a DTD cannot
> validate that this did not occur, 

> and so may produce a document which
> validates against the DTD but still crashes the app which created the
> document.

If the application is buggy, it must be fixed. I can not see why we 
should respect tools that creast when someone changes anything in a 
libary that is used by the output filter.

> > What you need here for XML files is:
> >
> > xml-md5sum
>
>
> Better approach: Normalize the trees, then use a regular plain-vanille
> md5sum.

fast & easy. cool.

Execept that we likely need a specical normalization reatment for 
unorderd nodes. These likely need to be come sorted alpahabetiaclly 
before  applying the checksum.

Michael