MulleObjCSingleton.md

MulleObjCSingleton

Protocol for implementing singleton objects in mulle-objc. Provides thread-safe singleton initialization and access.

Required Methods

Instance Access

• +sharedInstance - Get singleton instance

Initialization

• +initializeSingleton - Initialize singleton instance

Helper Functions

• MulleObjCInstanceIsaSingleton - Check if instance is singleton
• MulleObjCClassIsaSingleton - Check if class is singleton

Usage Example

@interface MySingleton : NSObject <MulleObjCSingleton>
@end

@implementation MySingleton

+ (instancetype) sharedInstance
{
   return( MulleObjCSingletonCreate( self));
}

+ (void) initializeSingleton
{
   // Initialize singleton state here
}

@end

// Usage
id instance = [MySingleton sharedInstance];

Important Notes

1. Thread Safety

   • Thread-safe initialization
   • Safe instance access
   • Handle concurrent calls
   • Consider TAO rules

2. Initialization

   • One-time setup
   • Handle dependencies
   • Clean up properly
   • Check state

3. Best Practices

   • Lazy initialization
   • Handle errors
   • Document usage
   • Test thoroughly

4. Performance

   • Cache instance
   • Minimize locks
   • Consider inlining
   • Handle contention

Note: This protocol provides thread-safe singleton implementation. The singleton instance is created lazily on first access and guaranteed to be initialized only once.