The Singleton Pattern
The Singleton pattern provides a global means to access a unique object while ensuring the extensibility of that object. Figure 6-8 shows the class diagram.
Figure 6-8. Singleton pattern class diagram
This pattern has the following parts:
- Concrete singleton
- Singleton interface
- Abstract Factory Method pattern
- Abstract product
- Concrete product
- Abstract creator
- Concrete creator
- Client
The pattern's benefits are as follows:
- Grants global access to an object
- Maintains access to its unique instance
- Reduces the need for multiple global variables
- Permits subclasses
It also has this drawback:
- Requires configuration
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