[Openmcl-devel] Autorelease question

Ron Garret ron at awun.net
Tue Jun 2 13:23:51 PDT 2009

This question arises from ticket #526 (http://trac.clozure.com/ccl/ticket/526 
).  I'm moving the discussion to the list because I thought this might  
be of general interest.

I do this:

(defclass scribble-view (ns:ns-view)
   ((path :initform (#/bezierPath ns:ns-bezier-path)))
   (:metaclass ns:+ns-object))

(defun make-scribble-window ()
    (let* ((rect (ns:make-ns-rect 0 0 300 300))
	  (w (make-instance 'ns:ns-window
			    :with-content-rect rect
			    :style-mask (logior #$NSTitledWindowMask
			    :backing #$NSBackingStoreBuffered
			    :defer t))
           (v (make-instance 'scribble-view)))
      (#/setTitle: w #@"Scribble")
      (#/setContentView: w v)
      (#/center w)
      (#/orderFront: w nil)
      (print (slot-value v 'path))

(slot-value (make-scribble-window) 'path)

and the result is a bogus ObjC object.  RME says this is because:

"You are initializing the path slot in your scribble-view instance  
with an autoreleased NSBezierPath. The NSBezierPath instance will be  
released on the next trip through the event loop."

But I don't understand why this should be the case.  The NSBezierPath  
object was not allocated on the event loop thread, so why should it be  
(auto)released there?  Doesn't every thread (and hence every listener)  
have its own autorelease pool?


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