Prism.Autofac.Mutable.Wpf

This library provides Autofac support for Prism. Support for Autofac in Prism has been removed in Prism WPF 7.0 due to Autofac's ContainerBuilder.Update being marked as obsolete.

The library supports both .NET Core 3.0 and .NET Framework 4.5.

How it works

While ContainerBuilder.Update is obsolete, Autofac allows you to dynamically add an IRegistrationSource to an existing container. Adding new IRegistrationSources is handled by a wrapper interface, IMutableContainer.

public interface IMutableContainer : IContainer
{
    void RegisterTypes(Action<ContainerBuilder> builder);
}

Internally, the method RegisterTypes creates a new container with all the new registrations, and adds itself as an ExternalRegistrySource to the existing container. IMutableContainer is registered as IContainer.

The AutofacRegionNavigationContentLoader and AutofacServiceLocatorAdapter are based completely on the classes by the same name in Prism.Autofac, although they take an ILifetimeScope instead of an IContainer as input.

Loading modules

A custom IModuleInitializer (AutofacModuleInitializer) is registered to resolve modules. For each module, it calls IMutableContainer's RegisterTypes.

mutableContainer.RegisterTypes(builder =>
{
    var registry = new AutofacContainerRegistry(builder);
    moduleInstance.RegisterTypes(registry);
    registry.FinalizeRegistry();
});

The AutofacContainerRegistry is an IContainerRegistry, which is what IModule expects.

How to use it

Your application should inherit from the abstract class PrismApplication, which in turn inherits from PrismApplicationBase.

Module registration

Your modules will receive an IContainerRegistry to use when registering types. This follows the new IoC concept for Prism.

Limitations

The interface IContainerExtension gets registered by PrismApplicationBase. If you resolve this interface and try to register new types after the initial container has been built, a AutofacContainerRegistryFinalizedException is thrown. The correct way to do it (outside of a module) is to resolve IMutableContainer and use the RegisterTypes method.
Calling IsRegistered will return false while building the container. Registrations are not available until the ContainerBuilder has been built. Modules can check IsRegistered for all types registered from PrismApplication, and for types registered by already initialized modules.

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