Re: GtkImageView

[muppet <scott asofyet org>]

On Jan 6, 2008, at 1:59 PM, Jeffrey Ratcliffe wrote:

> On 05/01/2008, Emmanuele Bassi <ebassi gmail com> wrote:
> > try with:
> >
> >  GdkRectangle_copy *
> >
> > instead of GtkRectangle_ornull *.
>
> That works, thanks for the help.
>
> Why didn't it work before?

Memory lifetime.

The object returned to perl was pointing at the spot on the C stack  
where the rect lived.  After the xsub returned, this no longer  
contained a rectangle, and just gave you randomly-changing garbage.  I  
didn't crash because you didn't try to write to it, and the address  
was still inside the valid address space of the process.

The _copy typemap variant instead creates a copy of the object, so the  
reference returned to perl points to its own heap copy of the rectangle.

If you're morbidly curious, see the "Wrapping Boxed Types" section of  
the Binding HowTo:
http://gtk2-perl.sourceforge.net/doc/binding_howto.pod.html#wrapping%20boxed%20types


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