Re: Is Apple's singleton sample code correct?
Re: Is Apple's singleton sample code correct?
- Subject: Re: Is Apple's singleton sample code correct?
- From: mmalcolm crawford <email@hidden>
- Date: Sat, 26 Nov 2005 09:58:04 -0800
On Nov 26, 2005, at 7:21 AM, David Gimeno Gost wrote:
<http://developer.apple.com/cgi-bin/search.pl?
q=singleton&site=default_collection>
I already did that search before starting this discussion and I
haven't found anything there stating that a singleton should never
be deallocated.
The reference states that the instance cannot be released, so this is
a natural corollary.
Actually, I would consider it a bug if I found it because there is
nothing in the singleton design pattern requiring it to never be
destroyed and there are indeed reasons why you may want to actually
be allowed to destroy it when appropriate.
and
On Nov 26, 2005, at 7:53 AM, David Gimeno Gost wrote:
But I don't want to prevent the singleton from being deallocated.
[...]
That the particular adaptation of the singleton pattern made in the
Cocoa frameworks does not allow for their singletons to be
deallocated does not change what I'm saying in any way. You may
have all the variations of the pattern that you see fit your
particular needs. But they are variations, they are not part of the
pattern as it is widely known.
This appears to be the fundamental problem. You seem to want the
pattern to work in a particular way. It doesn't. It's been working
the way it has in Cocoa since before the Design Patterns book was
published (see, for example, <http://www.channelu.com/NeXT/NeXTStep/
3.3/nd/GeneralRef/02_ApplicationKit/Classes/NXColorPanel.htmld/
index.html> or, with a different implementation, <http://
www.channelu.com/NeXT/NeXTStep/3.3/nd/GeneralRef/02_ApplicationKit/
Classes/FontManager.htmld/index.html> -- the (c) date is given as
1995, but the implementation preceded that by a couple of years), and
is well-known within this community. The simple fact of the matter
is that you're not going to change this, nor is it going to be
recognised as a bug...
mmalc
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