On Thu, 2003-06-26 at 16:04, Stefan Seefeld wrote:
I don't really understand why we need three different classes to manage documents. In particular I don't understand why you provide a 'document_ptr' that is a wrapper around document_ref.
The document_ref and document_ptr would only be used when a non owning reference or pointer is required. Even then you could use dom::document * and dom::document & instead in most cases.
One big difference between a reference and a pointer is that a reference must contain a valid non null value.
ok, but are these types really needed ?
My current proposal only provides dom::document_ptr, and I use implicit refcounting on the underlying document tree. It seems to work quite fine. I provide a bool operator () that tells me whether the document_ptr is referring to a document or not.
dom::document_ref doc1; // Error dom::document_ref doc2( 0 ); // Error dom::document_ptr doc3; // Ok dom::document_ptr doc4( 0 ); // Ok
This means you do not have to check references for null values. A pointer can be useful if you wish to be able to delay initialisation or if an value is optional.
void some_function( document_ref doc ); // You must pass a doc void some_function( document_ptr doc ); // You could pass 0
ok, I can see that as useful.
And I don't use a 'document' class, as that is managed implicitely by my dom::document_ptr:
dom::document_ptr document; // create new document; dom::document_ptr doc(document); // create second reference to it dom::document_ptr doc2 = document.clone(); // clone it, i.e. make deep copy
This is not consistent with the standard library or C++ in general. It will seem strange that the pointer class 1) Does not require dereferencing
would you say the same if the class name was spelled 'document_ref' instead ?
2) Contains a valid and non null value after default construction
right, see my followup post to that mail.
3) Has a constructor such as document_ptr( "config.xml" ) 4) Has member functions such as write_to_file
The alternative would allow both...
boost::shared_ptr< dom::document > doc( new dom::document() ); boost::shared_ptr< dom::document > doc1( doc ); dom::document doc2( *doc1 );
and if the 'doc1' reference was non-owning...
dom::document doc(); // Create new doc dom::document & doc1( doc ); // Second reference dom::document doc2( doc1 ); // Deep copy
right, but given such an approach, what would nodes return in their 'parent()' method ?
Regards, Stefan
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