InstanceProducer Class

Simple Injector

Produces instances for a given registration. Instances of this type are generally created by the container when calling one of the Register overloads. Instances can be retrieved by calling GetCurrentRegistrations() or GetRegistration(Type, bool).

Inheritance Hierarchy

SystemObject
SimpleInjectorInstanceProducer
SimpleInjectorInstanceProducerTService

Namespace: SimpleInjector
Assembly: SimpleInjector (in SimpleInjector.dll) Version: 5.3.0

Syntax

ASP.NET

Copy

public class InstanceProducer

Public Class InstanceProducer

The InstanceProducer type exposes the following members.

Constructors

	Name	Description
	InstanceProducer	Initializes a new instance of the InstanceProducer class.

Top

Properties

	Name	Description
	ImplementationType	Gets the originally registered implementation type. Note that the actual type, returned by GetInstance, will be different from ImplementationType when decorators or interceptors are applied. This property will always return the originally registered implementation type. In case the implementation type is unknown, which happens for instance when registering FuncTResult delegates, the service type is returned.
	Lifestyle	Gets the Lifestyle for this registration. The returned lifestyle can differ from the lifestyle that is used during the registration. This can happen for instance when the registration is changed by an ExpressionBuilt registration or gets decorated.
	Registration	Gets the Registration instance for this instance. Please note that, when decorators are applied, this instance is replaces and will become the registration for the outermost decorator.
	ServiceType	Gets the service type for which this producer produces instances.

Top

Methods

	Name	Description
	BuildExpression	Builds an expression that expresses the intent to get an instance by the current producer. A call to this method locks the container. New registrations can't be made after a call to this method.
	FromExpression	Creates a new InstanceProducer based on the given serviceType and expression where the expression will be used as-is; no interception (using ExpressionBuilt) such as decorators will be applied.
	GetInstance	Produces an instance.
	GetRelationships	Gets the collection of relationships for this instance that the container knows about. This includes relationships between the registered type and its dependencies and relationships between applied decorators and their dependencies. Note that types that are not newed up by the container and properties that are injected inside a custom delegate that is registered using the RegisterInitializer method are unknown to the container and are not returned from this method. Also note that this method will return an empty collection when called before the registered type is requested from the container (or before Verify is called).
	VisualizeObjectGraph	Builds a string representation of the object graph with the current instance as root of the graph.
	VisualizeObjectGraph(VisualizationOptions)	Builds a string representation of the object graph with the current instance as root of the graph.

Top

Remarks

The Register method overloads create InstanceProducer instances internally, but InstanceProducers can be created manually to implement special scenarios. An InstanceProducer wraps Registration instance. The Registration builds an Expression that describes the intend to create the instance according to a certain lifestyle. The InstanceProducer on the other hand transforms this Expression to a delegate and allows the actual instance to be created. A Registration itself can't create any instance. The InsanceProducer allows intercepting created instances by hooking onto the Container.ExpressionBuilt event. The RegisterDecorator methods for instance work by hooking onto the ExpressionBuilt event and allow wrapping the returned instance with a decorator.

Examples

The following example shows the creation of two different InstanceProducer instances that wrap the same Registration instance. Since the Registration is created using the Singleton lifestyle, both producers will return the same instance. The InstanceProducer for the

Copy

Interface1

however, will wrap that instance in a (transient)

Copy

Interface1Decorator

Copy

var container = new Container();

// ServiceImpl implements both Interface1 and Interface2.
var registration = Lifestyle.Singleton.CreateRegistration<ServiceImpl, ServiceImpl>(container);

var producer1 = new InstanceProducer(typeof(Interface1), registration);
var producer2 = new InstanceProducer(typeof(Interface2), registration);

container.RegisterDecorator(typeof(Interface1), typeof(Interface1Decorator));

var instance1 = (Interface1)producer1.GetInstance();
var instance2 = (Interface2)producer2.GetInstance();

Assert.IsInstanceOfType(instance1, typeof(Interface1Decorator));
Assert.IsInstanceOfType(instance2, typeof(ServiceImpl));

Assert.AreSame(((Interface1Decorator)instance1).DecoratedInstance, instance2);

Reference

SimpleInjector Namespace