Re: singleton pattern in cocoa
Re: singleton pattern in cocoa
- Subject: Re: singleton pattern in cocoa
- From: Christopher J Kemsley <email@hidden>
- Date: Mon, 14 Sep 2009 09:43:53 -0700
About the only thing that I'd recommend is that the "static" be inside
the +sharedSingleton method so that you aren't able to take the cheap-
way-out and call that variable directly in other class methods before
it's created.
For the rest of it: it seems to follow Apple's patterns - for
instance, [NSNotificationCenter defaultCenter] and [NSStatusBar
systemStatusBar] and [UIAccelerometer sharedAccelerometer] and
sharedAddressBook... etc
A lot of things use the sharedMyClass, but a lot (though fewer) of
things also use their own name.
That method of singletons is pretty common though.
On 10 Sep 2009, at 1:07 PM, Manuel Grau wrote:
Hi all,
As I come from java world, I was trying to implement the singleton
pattern, very usual in java. After searching in internet I found
this code from wikipedia:
@interface MySingleton : NSObject
{
}
+ (MySingleton *)sharedSingleton;
@end
@implementation MySingleton
static MySingleton *sharedSingleton;
+ (MySingleton *)sharedSingleton
{
@synchronized(self)
{
if (!sharedSingleton)
[[MySingleton alloc] init];
return sharedSingleton;
}
}
+(id)alloc
{
@synchronized(self)
{
NSAssert(sharedSingleton == nil, @"Attempted to allocate a second
instance of a singleton.");
sharedSingleton = [super alloc];
return sharedSingleton;
}
}
@end
What do you think about this implementation? I'm newbie with cocoa
and I'm not sure.
Thanks.
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