MinIoC is a single-file, minimal C# IoC container. While there are several great IoC solutions available which are much more powerful and flexible, MinIoC aims to enable lightweight/small-footprint projects with a simple implementation. It is distributed as a single .cs file which can be included and compiled in other projects.

var container = new Container();

container.Register<IFoo>(typeof(Foo));
container.Register<IBar>(() => new Bar());
container.Register<IBaz>(typeof(Baz)).AsSingleton();

/* ... */

var baz = container.Resolve<IBaz>();

The example above calls the generic Register<T>(Type) and Register<T>(Func<T>) methods. The first one binds the generic parameter type to an actual type, the second binds the generic parameter type to a factory function. Calling Resolve<T>() creates an instance of the registered type.

For a type binding, the container uses the actual type's first constructor. All arguments need to also be resolvable by the container.

The container implements IServiceProvider, exposing an object GetService(Type type) method and two non-generic registration methods: Register(Type @interface, Func<object> factory) and Register(Type @interface, Type implementation).

Generic extension methods are provided both for registration (Register<T>(Type), Register<T>(Func<T>), Register<T>()) and resolution (T Resolve<T>()).

By default, each call to Resolve<T>() creates a new instance. Two other object lifetimes are supported: singleton and per-scope.

A singleton is created by calling AsSingleton() after registration:

container.Register<IFoo>(typeof(Foo)).AsSingleton();

var instance1 = container.Resolve<IFoo>();
var instance2 = container.Resolve<IFoo>();

Assert.AreEqual(instance1, instance2);

Scopes allow finer-grained lifetime control, where all types registered as per-scope are unique within a given scope. This allows singleton-like behavior within a scope but multiple object instances can be created across scopes. Scopes are created by calling CreateScope() on a contianer instance and they also implement IServiceProvider, exposing an object GetService(Type type) method (and a Resolve<T>() extension method):

container.Register<IFoo>(typeof(Foo)).PerScope();
  
var instance1 = container.Resolve<IFoo>();
var instance2 = container.Resolve<IFoo>();

// Container is itself a scope
Assert.AreEqual(instance1, instance2);

using (var scope = container.CreateScope())
{
    var instance3 = scope.Resolve<IFoo>();
    var instance4 = scope.Resolve<IFoo>();

    // Instances should be equal inside a scope
    Assert.AreEqual(instance3, instance4);
    
    // Instances should not be equal across scopes
    Assert.AreNotEqual(instance1, instance3);
}

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