[Openmcl-devel] Three questions

Kevin Reid kpreid at mac.com
Sat Feb 9 05:02:25 PST 2008

On Feb 8, 2008, at 19:54, Ron Garret wrote:
> Yes, but windows are a notable exception because one often wishes to
> retain pointers to them (so you can draw in them for example) but they
> can (and in the normal course of events often do) become deallocated
> asynchronously as a result of a user's actions, to wit, clicking on
> the "close" button.

Perhaps I have my facts wrong, as I haven't done any Cocoa  
programming in a long time (and have never used OpenMCL's bridge),  
but as far as I know, NSWindow is not *that much* of an exception to  
Cocoa reference counting rules.

That is, if you have a reference to the NSWindow, you should -retain  
it, and it will then not ever be deallocated out from under you. (Of  
course, you would then -release it in a finalizer on your Lisp  

(Disregard the above if OpenMCL automatically retains/releases  
foreign-pointers to ObjC objects.)

It sounds like setReleasedWhenClosed:YES might create an exception,  
but in that case -- turn that option off! Or make sure you don't  
"use" the first incrementing-of-reference-count that corresponds to - 
alloc (that is, that unit is "owned" by the internal release-when- 
closed mechanism), and retain it yourself separately.

Kevin Reid                            <http://homepage.mac.com/kpreid/>

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