Re: Automagic instantiation of singletons?
Re: Automagic instantiation of singletons?
- Subject: Re: Automagic instantiation of singletons?
- From: Christian Brunschen <email@hidden>
- Date: Fri, 18 Nov 2005 13:26:46 +0000
On 18 Nov 2005, at 12:47, Jonathan del Strother wrote:
Is there any way to persuade a singleton object to create itself?
I have a few singleton objects that need to exist throughout the
lifetime of the application, and am currently instantiating them in
my application controller's applicationDidFinishLaunching: method.
It would be nice if I didn't have to explicitly do this. My
initial thought was that you could do it through the singletons' +
(void)initialize method - but of course, this isn't called at
application startup - it's only called the first time you try and
access the object, so it still needs to be manually set up.
Any other suggestions? I suspect it's not actually possible, but
thought I'd throw it out to the obj-c gurus and see what they have
to say...
The usual way is to have a class method through which you access the
singleton, and in that class method you lazily create and initialize
the singleton - something liek the following (typed into email, not
compiled, so will have bugs):
<quote source="MySingleton.h">
@interface MySingleton : NSObject {
}
+ sharedInstance;
@end
</quote>
<quote source="MySingleton.m">
#import <MySingleton.h>
@implementation MySingleton
static MySingleton *sharedInstance = nil;
+ sharedInstance {
if (sharedInstance == nil) {
sharedInstance = [[MySingleton alloc] init];
}
return sharedInstance;
}
</quote>
Best wishes,
Jon
// Christian Brunschen
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