strategy pattern_

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What is the Strategy Pattern?

The Strategy Pattern is a behavioral design pattern that allows you to define a family of algorithms, encapsulate each one of them, and make them interchangeable. This pattern lets the algorithm vary independently from clients that use it.

When should you use the Strategy Pattern?

You should use the Strategy Pattern when you have a set of related algorithms or behaviors, and want to be able to switch between them dynamically at runtime. It is particularly useful when you want to avoid long if-else or switch statements for selecting the desired behavior.

How does the Strategy Pattern work?

The Strategy Pattern works by defining a common interface for all the strategies, usually through an abstract class or an interface. Each strategy encapsulates a specific algorithm or behavior. The client can then select the strategy to be used at runtime. The client is unaware of the specific implementation details of each strategy, which allows for easy swapping of strategies.

What are the benefits of using the Strategy Pattern?

Using the Strategy Pattern offers several benefits:

• Code reuse: Strategies can be reused in different contexts by different clients.
• Flexibility: The ability to switch strategies at runtime provides flexibility and adaptability to changing requirements.
• Readability: The pattern promotes clean and readable code by encapsulating the algorithm or behavior in separate classes.

Can you provide an example?

Sure! Let"s take an example of a shopping cart. The behavior of calculating the total price of the cart can vary depending on different discount strategies. We can have strategies such as "NoDiscount", "PercentageDiscount", and "FixedAmountDiscount". By using the Strategy Pattern, we can easily switch between these strategies without modifying the cart code.

Conclusion

The Strategy Pattern is a powerful tool for managing and selecting different algorithms or behaviors at runtime. It promotes code reuse, flexibility, and readability. By encapsulating each algorithm or behavior in a separate strategy class, the pattern allows for easy swapping and customization. Next time you find yourself in a situation where you have multiple interchangeable options, consider using the Strategy Pattern to make your code more maintainable and extensible.

来源：亚洲公益报