layout, title, folder, permalink, categories, tags
| layout | title | folder | permalink | categories | tags | |||
|---|---|---|---|---|---|---|---|---|
| pattern | Singleton | singleton | /patterns/singleton/ | Creational |
|
Intent
Ensure a class only has one instance, and provide a global point of access to it.
Applicability
Use the Singleton pattern when
- there must be exactly one instance of a class, and it must be accessible to clients from a well-known access point
- when the sole instance should be extensible by subclassing, and clients should be able to use an extended instance without modifying their code
Typical Use Case
- the logging class
- managing a connection to a database
- file manager