Re: [gdome]reference counts and freeDoc

[Paolo Casarini <casarini CS UniBO IT>]

On Thu, 14 Jun 2001, Tobias Peters wrote:

> Do all functions returning a Gdome... object increase that object's
> reference count?
Yes, all function return always a fresh/new reference and you become the
owner of this reference. When you become the "owner" of a reference, you
have to unref it when it is no longer used.

> So after
> 
> GdomeElement* el = gdome_doc_documentElement(doc, exc);
> el = gdome_doc_documentElement(doc, exc); 
> 
> the element node pointed to by el has reference count 2 ?
Yes.

> Does gdome_doc_unref do the same thing as gdome_di_freeDoc when its
> reference count reaches zero?
no, gdome_doc_unref work only on the reference counting of the
GdomeDocument object. gdome_di_freeDoc work on the internal
rappresentation of a document:
A document can be in memory also if there's no reference to it: to free a
DOM you have to call the gdome_di_freeDoc (it free the libxml2 tree
structure);

You have not to save a GdomeDocument reference till the end of your work
because you can get a reference to a GdomeDocument with the
gdome_xx_ownerDocument method on any node of document.

> What happens when some nodes in this document are still being referenced?
This is a problem not yet resolved. Daniel should implement, in a few
month, in libxml2 a callback to signal when it frees a node. With this I
can set to NULL the GdomeNode internal pointer to the xmlNode and if a
Gdome2 user try to access to an not valid refrence I can raise a
GDOME_NULL_POINTER_ERR.  

To answer to your last question, you can call only methods
that works with the reference counting on it like gdome_xx_unref,
gdome_xx_ref on it.

To understand better the memory management of Gdome2 you can read the
article I wrote with Luca Padovani (you can find it on the Gdome2
site: http://www.cs.unibo.it/~casarini/gdome2/ in the documentation
section). The article version you can find on web is an old version
and something has changed in Gdome2. I hope I can publish the new version
soon.


Bye
    Paolo
--
Paolo Casarini - casarini cs unibo it