Chain of responsibility Design Pattern

the chain of responsibility pattern creates a chain of receiver objects for a request. This pattern decouples sender and receiver of a request based on type of request. This pattern comes under behavioral patterns.

In this pattern, normally each receiver contains reference to another receiver. If one object cannot handle the request then it passes the same to the next receiver and so on.

We have to create a simple chain for checking dictionary value and returning valid dictionary in final chain.

Problem

The code of the checks, which had already looked like a mess, became more and more bloated as you added each new feature. Changing one check sometimes affected the others. Worst of all, when you tried to reuse the checks to protect other components of the system, you had to duplicate some of the code since those components required some of the checks, but not all of them.

The system became very hard to comprehend and expensive to maintain. You struggled with the code for a while, until one day you decided to refactor the whole thing.(link)

The bigger the code grew, the messier it became.

Solution

Like many other behavioral design patterns, the Chain of Responsibility relies on transforming particular behaviors into stand-alone objects called handlers. In our case, each check should be extracted to its own class with a single method that performs the check. The request, along with its data, is passed to this method as an argument.

The pattern suggests that you link these handlers into a chain. Each linked handler has a field for storing a reference to the next handler in the chain. In addition to processing a request, handlers pass the request further along the chain. The request travels along the chain until all handlers have had a chance to process it.

Here’s the best part: a handler can decide not to pass the request further down the chain and effectively stop any further processing.

In our example with ordering systems, a handler performs the processing and then decides whether to pass the request further down the chain. Assuming the request contains the right data, all the handlers can execute their primary behavior, whether it’s authentication checks or caching.

Chain of Responsibility design pattern

Implementation

In the first step we create a request handler for connect class together in chain . from this link you can clone source.

Handler Source in c#

In the second step we can create chain . in this sample i create 3 chain and send a dictionary in parameter . in the first chain we choice only numeric value .(link)

Numeric Handler

the second chain Limited value between x and y .

Limited value handler

the second chain is Power Value chain .

Power Numeric value handler

in the init of program we can call chain like below steps .

Main program