Decorator Builder

CSF.DecoratorBuilder is a small library to assist developers in making use of the decorator pattern in their own .NET projects. It provides a structured, easy-to-read & boilerplate-free way to configure how services are created through dependency injection, using the decorator or chain of responsibility patterns.

TL;DR what's decorator?

The decorator pattern is characterised by multiple classes which implement the same interface. A decorator class takes a dependency upon (it wraps) an object of the same interface as it implements.

The functionality of a decorator class is typically "do whatever the wrapped object would have done, plus the functionality in this class". The decorator pattern is well-used to add functionality to (to "decorate") an existing service, without needing to edit the original class that provides the service. Thus it helps developers adhere to open/closed principle.

There is also a good writeup of decorator on the refactoring guru website.

Chain of responsibility too

The chain of responsibility pattern is structurally the same as decorator except it is characterised by different behaviour. In a chain of responsibility each class determines "can I do the work?". If the class can, then it performs whatever functional task is required and/or returns a result. If it cannot then it does nothing more than return the result from the wrapped object (which has the same interface).

This library can also support chain of responsibility interchangeably with decorator.

How this library is used

There are a few ways to use this library. Firstly you will want to choose the right NuGet package(s); this library is usable with either or both of Microsoft.DependencyInjection.Abstractions or Autofac, depending upon your dependency injection needs.

This library supports both static dependency injection logic & using the decorator builder directly, such as within your own factory classes. These two techniques may also be mixed and used together, as appropriate for the needs of your application.