Скачать или смотреть Singleton design pattern and when not to use it

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Singleton pattern as the name suggests provides a single instance of class
Theoretically it can have lots of use cases, and it is one of the most overused or abused design pattern.

Criteria for using singleton pattern:
1. Exactly one instance of class is required
2. Class will be accessed from more than one place in code

Use Cases:
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