[Openmcl-devel] initforms in objc classes ?
R. Matthew Emerson
rme at clozure.com
Fri Feb 1 13:46:26 PST 2008
On Jan 31, 2008, at 8:38 AM, Didier Verna wrote:
> Gary Byers <gb at clozure.com> wrote:
>> (If we -do- have examples that use initforms on foreign slots, we
>> should fix the examples or change how this case is handled.)
> I was actually led to think it was possible because of this (from
> (defclass apropos-window-controller (ns:ns-window-controller)
> ((apropos-array :foreign-type :id :initform +null-ptr+
> :reader apropos-array
> Of course, the actual initform value seemed to me somewhat redundant
> with what I read from the doc (the site seems to be back online) and
> from your replay (+null-ptr+ *is* what you call "binary 0" right ?).
Er, well, in my lame defense, I think that the :initform is left over
from when I was trying to have the apropos-array slot be a lisp
array. When I changed it to an Objective-C array (so I could bind it
to an NSArrayController), I left in the :initform slot option. Note
that I cleverly changed the NIL to +null-ptr+, though. Good thing I
was paying attention. :-/
Sorry for the bad example.
On a somewhat unrelated note, taking a look at that apropos-window
code makes me remember wondering if @property-style slot options might
be an interesting feature.
In Objective-C 2.0, it's my understanding that you can say something
@property(retain) NSArray *aproposArray;
in the @interface section, and then in the @implementation section, say
and the compiler will provide accessor methods for aproposArray for
you, implementing the appropriate retain/release code in the setter
I thought it might be cool if there were some rational way to get CLOS
automatically generate reader/writer methods that would do the right
thing wrt retain and release. I didn't do much of anything more than
play around briefly before deciding that I would actually have to
think hard about it, so I went on to easier things.
Anyway, the upshot is that I wanted to point out that using CLOS's
automatically defined setter methods for slots containing Objective-C
objects is likely to cause leaks.
Hence the setf method for the apropos-array slot that I defined by
hand (instead of using the :accessor slot option) that does the retain/
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