radada wrote:
Hi there again
For some reasons, which would be too long to describe, I want to subclass
the DOMDocument class into a XMLDocument class.
In other words, XMLDocument inherits from DOMDocument.
DOMDocument is an abstract base class, so you will need to implement
every pure virtual function in your derived class. Perhaps it would be
better to derive your class from DOMDocumentImpl, but that could be
tricky, because DOMDocumentImpl was probably not designed to be a base
class.
Here's the tricky question : since the DMODocument uses a factory to be
create (createDocument method from DOMImplementationRegistry), how can I
build an XMLDocument.
Do you know if this works :
XMLDocument:: XMLDocument()
{
DOMImplementation *impl =
DOMImplementationRegistry::getDOMImplementation(XMLString::transcode("LS"));
this = (XMLDocument*) impl->createDocument();
}
It is illegal to assign to the "this" pointer, and the compiler will
emit an error if your code does this. I'm surprised your compiler didn't.
Even if you were allowed to assign to the this pointer, the cast is
illegal. Casting a pointer doesn't change the type of the object being
pointed to.
If not, what solutions can I have other than creating a class that does not
inherits from DOMDocument and simply have a DOMDocument variable?
I can think of several ways to do this:
1. Create your own implementation registry and use it instead.
2. Modify the Xerces-C source code to create an instance of your type
instead of DOMDocumentImpl.
I would caution you to be very careful when doing this, because you need
to ensure your implementation is 100% compliant with the existing
implementation.
Dave
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