Handler seniorManager = new SeniorManager() Example implementation for supervisor and senior manager classes that are successors of employee and supervisor respectively can be seen below:Ĭopy Code Handler employee = new Employee() If it is true the request will be processed else it is passed to the successor of employee. The business rule for the employee is that the mobile should be of Type basic, which is implemented in the CanHandle method. The employee class accepts a mobile object and check if it can be handled by itself. If not, it will be passed to the next handler in chain by calling successor. The handle request method will check if the object in question (mobile) can be handled by the current handler. SetSuccessor method is where we form the chain between different handlers (in our case the store hierarchy of employee, supervisor and senior managers). The interface handler defines two methods SetSuccessor and HandleRequest. Public override void HandleRequest(Mobile mobile)Ĭonsole.WriteLine( " ", Public abstract void HandleRequest(Mobile mobile)
Public void SetSuccessor(Handler successor) Consider a mobile phone store where we have mobile phones of different types (basic, budget and premium). Let us implement the COR using an example. In this article I explain how we can use specification pattern to close COR code for future modification and make it flexible and reusable. Also changes to the chain cannot be done without modifying the code in all scenarios.
However the classic COR is not flexible enough to be reused as it is bound to the domain models in the implementation. It is always handy when we have a reusable workflow design to be used across different domain with in the same organization or between different organizations. In other words, the request will be passed between different receivers in sequential chain until the right receiver is met.īelow is the class diagram for the classic chain of responsibility pattern:ĬOR is a very useful pattern in scenarios such as workflow. Mediator/Observer patterns do the same job but the link between the receivers (chain) in COR makes it stand out from the others. Chain of responsibility (COR) is a pattern which helps us to avoid coupling between sender and receiver.
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