what's the difference between the patterns Strategy, Visitor and Template Method?

Question

I\'m in a class where we just learned about these design patterns. However I couldn\'t see any difference between them. They sound just like the same, creating concrete classes

Answer 1

Commonalities:

1. Strategy, Template method and Visitor : All three patterns are categorized as behavioural patterns.

Differences:

1. Template method uses Inheritance and Strategy uses composition
2. The Template method implemented by the base class should not be overridden. In this way, the structure of the algorithm is controlled by the super class, and the details are implemented in the sub classes
3. Strategy encapsulates the algorithm behind an interface, which provide us ability to change the algorithm at run time
4. Visitor pattern is used to perform an operation on a group of similar kind of Objects. With the help of visitor pattern, we can move the operational logic from the objects to another class
5. If there is a change in implementation of Operation, we have to just change Visitor class instead of touching all other objects.

Have a look at Template method , Strategy and Visitor and Sourcemaking articles for better understanding.

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