Class: Singleton

• Inheritance
• Description
• Class protocol
  • accessing
  • initialization
  • instance creation

Inheritance:

   Object
   |
   +--Singleton
      |
      +--Dolphin::DeafObject

Package:

stx:libbasic2

Category:

System-Support

Version:

rev: 1.7 date: 2019/04/03 06:37:30

user: stefan

file: Singleton.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Author:

Stefan Vogel (stefan@zwerg)

Description:

Subclasses of Singleton have only a single instance.
The instance creation methods ensure that there is only one instance.

Singletons that would have inherited from Object could inherit from
Singleton. For Singletons that do not inherit from Object, 
you have to copy the Singleton's code to your class.


[class instance variables:]
    theOnlyInstance     Object          The only instance of this class

[class variables:]
    Lock                RecursionLock   A global lock to protect agains races during instance creation

Class protocol:

 singletonLock

can be used by other classes that are not subclasses of Singleton

 theOnlyInstance

 initialize

(comment from inherited method)
called only once - initialize signals

 basicNew

allocate a singleton in a thread-safe way.
Do lazy locking here

 basicNew: anInteger

allocate a singleton in a thread-safe way.
Do lazy locking here

 new

allocate a singleton in a thread-safe way.
Do lazy locking here

 new: count

allocate a singleton in a thread-safe way.
Do lazy locking here

 releaseInstance

release the singleton's instance.
Use only for debugging!