[Kde-bindings] playground/bindings/kimono

Richard Dale rdale at foton.es
Thu Feb 8 12:02:29 UTC 2007

On Thursday 08 February 2007, Phil Thompson wrote:
> On Thursday 08 February 2007 11:17 am, Richard Dale wrote:
> > SVN commit 631534 by rdale:
> >
> > * Added a strongReferenceMap to hold a mapping from a C++ pointer to
> >   a C# instance. It is used to prevent garbage collection for instances
> >   which are contained in another instance, such as a QObject with a
> >   parent, even when there are no references to the child within the C#
> >   Qyoto application code. When the parent finally deletes the child on
> >   the C++ side, the reference is removed from the Dictionary by the
> >   SmokeMarshallers.UnmapPointer() method.
> There are other places where this can happen - not just with QObject
> parent/child relationships. There are also methods where the reverse
> happens. You could look at the PyQt .sip files to see all the places where
> it needs to be considered - just grep for '/Transfer'.
Thanks for the suggestion, I've had a look and there are a lot of methods 
annotated with Transfer. In QtRuby the garbage collection works differently - 
a function is called in the mark phase of garbage collection, and in that it 
has to tranverse the children of any container instance. So it doesn't need 
to monitor every method that might change the status of the children, and 
just needs to know which are container classes and how to find the children.

So I could just pull out all the Transfer methods from PyQt, and put them into 
a table used when generating the code for the C# Qyoto sources, and add a 
suitable annotation on the method calls that could be queried at runtime to 
determine whether a strong reference should be created or removed.

-- Richard

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