The "Chain of Responsibility" is a design pattern in software development that belongs to the category of behavioral patterns. It allows the encapsulation of requests, commands, or actions and enables multiple objects to have the opportunity to handle a request sequentially until an object in the chain takes responsibility for processing it.
The pattern is often used to achieve loose coupling between the sender and receiver of a request. Instead of the sender of a request knowing exactly which object will handle the request, the request is passed through a chain of objects until a suitable object capable of processing the request is found.
Here is a simplified description of the pattern:
There is an abstract class or interface that defines the common interface for all objects in the chain. It usually contains a method that handles the request and a reference to the next object in the chain.
Concrete implementations of this abstract class or interface form the individual links of the chain. Each link decides whether it can handle the request or pass it to the next link in the chain.
The links are connected in a sequential chain, with each link pointing to the next one.
When a request arrives, it is sent to the first link in the chain. The first link decides whether it can handle the request or not. If yes, the request is processed, and the process is complete. If not, the request is passed to the next link in the chain, and this process continues until the request is processed or the chain ends.
The Chain of Responsibility pattern is particularly useful when there are multiple objects that can handle a request in different steps or in different ways. It provides a flexible and extensible structure where you can easily add new links or change the order without modifying the sender's code.
This pattern is used in many areas of software development, including GUI event handling, middleware frameworks, error handling, and more.
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