Re: ARC and C++ structures
On 15 Sep 2021, at 17:39, Matt Jacobson mailto:mhjacob...@me.com>> wrote: On Sep 15, 2021, at 11:21 AM, Tor Arne Vestbø mailto:tor.arne.ves...@qt.io>> wrote: On 14 Sep 2021, at 16:33, Matt Jacobson via Cocoa-dev mailto:cocoa-dev@lists.apple.com>> wrote: By default, when an NSWindow is `-close`d (which can only happen once in its lifetime), Interesting. If the NSWindow is retained elsewhere, can it not be ordered in again? Appreciate any details you can provide :) I was wrong about this detail. The window can definitely be ordered in again, and any subsequent `-close` does *not* issue a `-release`, even if the window `isReleasedWhenClosed`. (How confusing.) Thanks for the clarification! Cheers, Tor Arne ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: ARC and C++ structures
> On Sep 15, 2021, at 11:21 AM, Tor Arne Vestbø wrote: > > >> On 14 Sep 2021, at 16:33, Matt Jacobson via Cocoa-dev >> mailto:cocoa-dev@lists.apple.com>> wrote: >> >> By default, when an NSWindow is `-close`d (which can only happen once in its >> lifetime), > > Interesting. If the NSWindow is retained elsewhere, can it not be ordered in > again? Appreciate any details you can provide :) I was wrong about this detail. The window can definitely be ordered in again, and any subsequent `-close` does *not* issue a `-release`, even if the window `isReleasedWhenClosed`. (How confusing.) So ignore the parenthetical part, but do `setReleasedWhenClosed:NO` your windows. Matt ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: ARC and C++ structures
On 14 Sep 2021, at 16:33, Matt Jacobson via Cocoa-dev mailto:cocoa-dev@lists.apple.com>> wrote: By default, when an NSWindow is `-close`d (which can only happen once in its lifetime), Interesting. If the NSWindow is retained elsewhere, can it not be ordered in again? Appreciate any details you can provide :) Cheers, Tor Arne ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: ARC and C++ structures
Thanks. That did it. Interestingly, not only did the Applie Migration
tool not flag a potential problem, but the docs on NSWindow and
releaseWhenClosed don't even hint of it.
> Hi Tom,
>
> > On Sep 14, 2021, at 9:53 AM, Tom Doan via Cocoa-dev
> > wrote:
> >
> > I have a multiple platform application (Windows, Mac, GTK) that is
> > primarily organized using C++ with Objective-C used for the
> > Mac-specific interface. I recently switched to use ARC (as we are
> > using Scintilla which recently switched to ARC). However, I am
> > getting a zombied release of an NSWindow instance. So far as I can
> > tell, the memory handling of this seemed to be fine pre-ARC.
> > Unfortunately, because it's an NSWindow, the Instruments output for
> > it has 100's of toolbox calls, so it's very hard to tell where the
> > extra release is. What should I be looking for?
> >
> > Just to describe this, there's an EWindow C++ structure which has
> > the NSWindow * as a member (under Mac OS; it's an HWND under Windows
> > and Widget under GTK). It's after the delete of the EWindow that
> > things go south. I'm assuming that ARC is putting in a release, but
> > I haven't really seen any good description of how ARC interacts with
> > C++. A release there seems fine---the question is where is the
> > earlier (apparently erroneous) release.
>
> ARC will insert code at the end of your C++ destructor to release any
> strong id members.
>
> One possible wrinkle is the default release-when-close behavior of
> NSWindow. By default, when an NSWindow is `-close`d (which can only
> happen once in its lifetime), AppKit sends it a `-release`. The idea
> is that this release balances the initial `+alloc`.
>
> However, this is somewhat incompatible with ARC, which doesn´t know
> about this special behavior and will attempt to insert its own release
> to balance the alloc.
>
> Here is an example of a program that works perfectly fine under MRR
> but crashes under ARC:
>
> #import
>
> NSWindow *window;
>
> int main(void) {
> @autoreleasepool {
> window = [[NSWindow alloc]
> initWithContentRect:NSMakeRect(0., 0., 100.,
> 100.) styleMask:NSWindowStyleMaskTitled
> backing:NSBackingStoreBuffered defer:NO];
> [window makeKeyAndOrderFront:nil]; [window
> close]; window = nil;
> }
> }
>
> You can disable this behavior by changing the `releasedWhenClosed`
> property of the window to `NO`:
>
> [window setReleasedWhenClosed:NO];
>
> Matt
>
---
2717 Harrison St
Evanston, IL 60201
USA
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Re: ARC and C++ structures
Hi Tom,
> On Sep 14, 2021, at 9:53 AM, Tom Doan via Cocoa-dev
> wrote:
>
> I have a multiple platform application (Windows, Mac, GTK) that is
> primarily organized using C++ with Objective-C used for the
> Mac-specific interface. I recently switched to use ARC (as we are
> using Scintilla which recently switched to ARC). However, I am
> getting a zombied release of an NSWindow instance. So far as I
> can tell, the memory handling of this seemed to be fine pre-ARC.
> Unfortunately, because it's an NSWindow, the Instruments output
> for it has 100's of toolbox calls, so it's very hard to tell where the
> extra release is. What should I be looking for?
>
> Just to describe this, there's an EWindow C++ structure which has
> the NSWindow * as a member (under Mac OS; it's an HWND under
> Windows and Widget under GTK). It's after the delete of the
> EWindow that things go south. I'm assuming that ARC is putting in a
> release, but I haven't really seen any good description of how ARC
> interacts with C++. A release there seems fine---the question is
> where is the earlier (apparently erroneous) release.
ARC will insert code at the end of your C++ destructor to release any strong id
members.
One possible wrinkle is the default release-when-close behavior of NSWindow.
By default, when an NSWindow is `-close`d (which can only happen once in its
lifetime), AppKit sends it a `-release`. The idea is that this release
balances the initial `+alloc`.
However, this is somewhat incompatible with ARC, which doesn’t know about this
special behavior and will attempt to insert its own release to balance the
alloc.
Here is an example of a program that works perfectly fine under MRR but crashes
under ARC:
#import
NSWindow *window;
int main(void) {
@autoreleasepool {
window = [[NSWindow alloc]
initWithContentRect:NSMakeRect(0., 0., 100., 100.)
styleMask:NSWindowStyleMaskTitled backing:NSBackingStoreBuffered defer:NO];
[window makeKeyAndOrderFront:nil];
[window close];
window = nil;
}
}
You can disable this behavior by changing the `releasedWhenClosed` property of
the window to `NO`:
[window setReleasedWhenClosed:NO];
Matt
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ARC and C++ structures
I have a multiple platform application (Windows, Mac, GTK) that is primarily organized using C++ with Objective-C used for the Mac-specific interface. I recently switched to use ARC (as we are using Scintilla which recently switched to ARC). However, I am getting a zombied release of an NSWindow instance. So far as I can tell, the memory handling of this seemed to be fine pre-ARC. Unfortunately, because it's an NSWindow, the Instruments output for it has 100's of toolbox calls, so it's very hard to tell where the extra release is. What should I be looking for? Just to describe this, there's an EWindow C++ structure which has the NSWindow * as a member (under Mac OS; it's an HWND under Windows and Widget under GTK). It's after the delete of the EWindow that things go south. I'm assuming that ARC is putting in a release, but I haven't really seen any good description of how ARC interacts with C++. A release there seems fine---the question is where is the earlier (apparently erroneous) release. Tom Doan Estima --- 2717 Harrison St Evanston, IL 60201 USA ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
