CamelBones

On Tue, Nov 2, 2010 at 1:39 PM, Matt Sergeant <matt@...> wrote:
> Just a simple question - when do I need to retain()/release() things in
> CamelBones? I assume it's not done automagically?

It's semi-automatic. When an Objective-C object is passed to Perl, a
Perl object "wrapper" is created and a -retain is sent to the ObjC
object. When the "wrapper" object is destroyed by Perl (which happens
according to Perl's normal scoping & reference counting rules), its
destructor sends the corresponding -release to the object it wraps.

Unfortunately, CamelBones has no knowledge of Objective-C's ownership
rules. That is, while it does establish and then relinquish the
explicit ownership claim that it uses to keep a native object alive
for as long as its wrapper exists, the bridge *doesn't* attempt to
address the implicit ownership on objects created with +alloc or a
method containing the word "copy." Thus, objects created using such
methods must still need to be sent a -(auto)release message. The
easiest way to handle that is to do so immediately upon using such a
method to create an object:

  my $foo = Foo->alloc()->init()->release();
  my $bar = $foo->mutableCopy()->autorelease();

This use of -(auto)release doesn't destroy these objects immediately,
because the $foo and $bar "wrapper" objects have *also* sent them a
-retain message, and *that* ownership claim won't be balanced until
$foo and $bar are destroyed according to normal Perl scoping and
reference rules. The -(auto)release in the above is solely to balance
the implicit "retain" that was sent by the +alloc and -mutableCopy
methods.

sherm--

-- 
Cocoa programming in Perl:
http://camelbones.sourceforge.net

On Tue, Nov 2, 2010 at 4:48 PM, Sherm Pendley <sherm.pendley@...> wrote:
> On Tue, Nov 2, 2010 at 1:39 PM, Matt Sergeant <matt@...> wrote:
>> Just a simple question - when do I need to retain()/release() things in
>> CamelBones? I assume it's not done automagically?
>
> It's semi-automatic. When an Objective-C object is passed to Perl, a
> Perl object "wrapper" is created and a -retain is sent to the ObjC
> object. When the "wrapper" object is destroyed by Perl (which happens
> according to Perl's normal scoping & reference counting rules), its
> destructor sends the corresponding -release to the object it wraps.

Okay, that's the intent at least... reviewing the relevant code, it
appears that isn't actually happening. :-(

sherm--

-- 
Cocoa programming in Perl:
http://camelbones.sourceforge.net

On Tue, 2 Nov 2010, Sherm Pendley wrote:

> On Tue, Nov 2, 2010 at 1:39 PM, Matt Sergeant <matt@...> wrote:
>> Just a simple question - when do I need to retain()/release() things in
>> CamelBones? I assume it's not done automagically?
>
> It's semi-automatic. When an Objective-C object is passed to Perl, a
> Perl object "wrapper" is created and a -retain is sent to the ObjC
> object. When the "wrapper" object is destroyed by Perl (which happens
> according to Perl's normal scoping & reference counting rules), its
> destructor sends the corresponding -release to the object it wraps.

OK, so it's fair to say that my current use of retain/release in 
DVDSpanner is superfluous?

Matt.

Sherm Pendley wrote:
> On Tue, Nov 2, 2010 at 4:48 PM, Sherm Pendley<sherm.pendley@...>  wrote:
>    
>> On Tue, Nov 2, 2010 at 1:39 PM, Matt Sergeant<matt@...>  wrote:
>>      
>>> Just a simple question - when do I need to retain()/release() things in
>>> CamelBones? I assume it's not done automagically?
>>>        
>> It's semi-automatic. When an Objective-C object is passed to Perl, a
>> Perl object "wrapper" is created and a -retain is sent to the ObjC
>> object. When the "wrapper" object is destroyed by Perl (which happens
>> according to Perl's normal scoping&  reference counting rules), its
>> destructor sends the corresponding -release to the object it wraps.
>>      
>
> Okay, that's the intent at least... reviewing the relevant code, it
> appears that isn't actually happening. :-(
>    

Can you expand on that?


Matt.

On Wed, Nov 3, 2010 at 8:52 AM, Matt Sergeant <matt@...> wrote:
> Sherm Pendley wrote:
>
> On Tue, Nov 2, 2010 at 4:48 PM, Sherm Pendley <sherm.pendley@...>
> wrote:
>
>
> On Tue, Nov 2, 2010 at 1:39 PM, Matt Sergeant <matt@...> wrote:
>
>
> Just a simple question - when do I need to retain()/release() things in
> CamelBones? I assume it's not done automagically?
>
>
> It's semi-automatic. When an Objective-C object is passed to Perl, a
> Perl object "wrapper" is created and a -retain is sent to the ObjC
> object. When the "wrapper" object is destroyed by Perl (which happens
> according to Perl's normal scoping & reference counting rules), its
> destructor sends the corresponding -release to the object it wraps.
>
>
> Okay, that's the intent at least... reviewing the relevant code, it
> appears that isn't actually happening. :-(
>
>
> Can you expand on that?

I haven't looked at that code in a couple of years, but a quick review
of it doesn't turn up any of the relevant -retain or -release calls,
nor is there a DESTROY() method in the relevant Perl code. I know what
*should* be happening, but it doesn't look like the code actually got
done. I suspect it's something I intended to do, but didn't finish due
to my meltdown/burnout. :-(

On the other hand, I've been rewriting some parts of ShuX - the
browser panel, so that it shows the contents of the PAR kits, among
other things - and haven't been getting any hard crashes that would
indicate over-released objects. That's the good news. Opening and
closing a bunch of modules with it *does* increase memory use, though,
so there are certainly memory leaks.

sherm--

-- 
Cocoa programming in Perl:
http://camelbones.sourceforge.net