# Scrutor [](https://ci.appveyor.com/project/khellang/scrutor) [](https://www.nuget.org/packages/Scrutor) > Scrutor - I search or examine thoroughly; I probe, investigate or scrutinize > From scrūta, as the original sense of the verb was to search through trash. - https://en.wiktionary.org/wiki/scrutor Scrutor is a library that provides assembly scanning and decoration extensions for Microsoft.Extensions.DependencyInjection, a popular dependency injection framework for .NET. The library adds two extension methods to `IServiceCollection`: `Scan` and `Decorate`. `Scan` is the entry point to set up your assembly scanning, while `Decorate` is used to decorate already registered services. ### Installation To install the Scrutor NuGet Package, use the following commands: #### Package Manager Console ``` Install-Package Scrutor ``` #### .NET Core CLI ``` dotnet add package Scrutor ``` ### Usage #### Scanning ```csharp var collection = new ServiceCollection(); collection.Scan(scan => scan // We start out with all types in the assembly of ITransientService .FromAssemblyOf() // AddClasses starts out with all public, non-abstract types in this assembly. // These types are then filtered by the delegate passed to the method. // In this case, we filter out only the classes that are assignable to ITransientService. .AddClasses(classes => classes.AssignableTo<ITransientService>()) // We then specify what type we want to register these classes as. // In this case, we want to register the types as all of its implemented interfaces. // So if a type implements 3 interfaces; A, B, C, wed end up with three separate registrations. .AsImplementedInterfaces() // And lastly, we specify the lifetime of these registrations. .WithTransientLifetime() // Here we start again, with a new full set of classes from the assembly above. // This time, filtering out only the classes assignable to IScopedService. .AddClasses(classes => classes.AssignableTo<IScopedService>()) // Now, we just want to register these types as a single interface, IScopedService. .As<IScopedService>() // And again, just specify the lifetime. .WithScopedLifetime() // Generic interfaces are also supported too, e.g. public interface IOpenGeneric .AddClasses(classes => classes.AssignableTo(typeof(IOpenGeneric<>))) .AsImplementedInterfaces() // And you scan generics with multiple type parameters too // e.g. public interface IQueryHandler .AddClasses(classes => classes.AssignableTo(typeof(IQueryHandler<,>))) .AsImplementedInterfaces()); ``` #### Decoration ```csharp var collection = new ServiceCollection(); // First, add our service to the collection. collection.AddSingleton<IDecoratedService, Decorated>(); // Then, decorate Decorated with the Decorator type. collection.Decorate<IDecoratedService, Decorator>(); // Finally, decorate Decorator with the OtherDecorator type. // As you can see, OtherDecorator requires a separate service, IService. We can get that from the provider argument. collection.Decorate<IDecoratedService>((inner, provider) => new OtherDecorator(inner, provider.GetRequiredService<IService>())); var serviceProvider = collection.BuildServiceProvider(); ```
