Re: [xml] redicting parts of trees

[Daniel Veillard <veillard redhat com>]

On Mon, Jun 27, 2005 at 10:44:44AM -0400, Rob Richards wrote:
> Kasimier Buchcik wrote:
> 
> >
> >The context has just an initial "void * _private" field, to be able to
> >extend it. Adding fields to it, at the end, won't break ABI
> >compatibility.
> > 
> >
> How do you not break compatibility? For example, A new field is added, 
> which if not NULL would cause the execution of some function while 
> inside the adopt node function. If someone where to create a context 
> structure, without using some initialization function, then a crash most 
> likely would occur as the field is not initialized to NULL.

  If you have code compiled against libxml2-2.6.21 but using libxnl2-2.6.20 
you have no hard garantee. The ABI garantees are only forward, never backward.
The structure won't shrink. Adding allocation/deallocation functions can
limit risks.

Daniel

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