[Behavioral 4] Iterator design pattern with code example in TypeScript скачать в хорошем качестве

[Behavioral 4] Iterator design pattern with code example in TypeScript

What is the Iterator Design Pattern? The Iterator Design Pattern is used to provide a way to access elements of a collection (like arrays, lists, or other data structures) sequentially without exposing the underlying structure. It allows you to traverse a collection, one item at a time, without needing to know how the collection is implemented (e.g., whether it’s an array, a list, or something else). This pattern is useful when you need to loop over a collection, especially when you want to abstract the iteration logic from the actual collection class. You can use this pattern in situations where you have collections or aggregates (like arrays, sets, or custom collections) and you want to: • Hide the complexity of the collection’s traversal. • Provide a consistent way to iterate over different types of collections. • Allow multiple iterators to traverse a collection independently. Code link to try - https://jsfiddle.net/Dorogonov/ef3w21... CodeExplanation: In this code, we use the Iterator Design Pattern to traverse a collection of numbers. 1. Iterator Interface: This defines three methods (current(), next(), and hasNext()) that any concrete iterator (such as NumberIterator) must implement. These methods help access the current item, move to the next item, and check if there are more items left to traverse. 2. NumberIterator Class: This is the concrete implementation of the Iterator interface for numbers. It manages the position of the current element in the collection and provides the logic to get the current item, move to the next one, and check if there are more items left in the collection. 3. Aggregate Interface: This interface defines a method createIterator() which must be implemented by any class that wants to allow iteration. It acts as a factory for creating an iterator for the collection. 4. NumberCollection Class: This class represents a collection of numbers. It implements the Aggrigate interface and has methods to add numbers to the collection and create an iterator (createIterator()) to traverse the collection using the NumberIterator class. 5. Usage: A NumberCollection is created, items (numbers) are added to the collection, and an iterator is created. The iterator is then used to traverse and print all the numbers in the collection.