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In this article, the editor introduces in detail "what is the composition of web iterator pattern", the content is detailed, the steps are clear, and the details are handled properly. I hope that this article "what part of web iterator pattern is made up of?" can help you solve your doubts.

Applicability

Provides a unified method for accessing aggregate objects of different components.

Support for different forms of traversal in a unified way.

To sum up, the iterator pattern can be used to achieve different kinds of traversal of different kinds of objects in one way.

structure

Participant

Iterator (abstract iterator class)

Abstract iterators define the interfaces needed to get and traverse elements. The interface defined in the class diagram is just an example. In practical applications, there are other options. For example, you can let the next method return child elements in addition to moving the current location, thus omitting the IsDone interface.

ConcreteIterator (representational iterator class)

-the concrete iterator implements the iterator interface. When implementing the iterator interface, you may need to access the data of the aggregate class directly or indirectly through other iterators that access the aggregate class.

Aggregate (aggregate class)

-aggregation defines the interface that creates the corresponding iterator object. The use of this interface is equivalent to the factory method pattern. In other words, this aggregate class should have other functions as well.

ConcreteAggregate (figurative aggregation class)

-A concrete aggregate class implements the interface for creating the corresponding iterator, which returns a concrete instance of ConcreteIterator.

In many cases, this inheritance relationship occurs between abstract aggregate classes and concrete aggregation classes, not because of the need for this abstraction to generate iterator actions, but because of the functional requirements of the two classes themselves. Generating iterators is only a requirement for software development, not an essential feature of a class. There are also many situations where this inheritance relationship is not needed at all.

Collaboration

ConcreteIterator takes the current child elements in the aggregation and is able to find subsequent objects to traverse.

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