CSF.Extensions.DependencyInjection 1.0.0

Dependency Injection extensions

This package adds capabilities to Microsoft.Extensions.DependencyInjection. At present, the only functionality it adds is optional Lazy resolvers for registered services.

Lazy resolvers

Lazy resolvers are a convenience for services which do not always need to be resolved, particularly those which have a performance cost to resolve. By resolving a Lazy<T> for the service, instead of just T, if the service is never used (IE: Lazy<T>.Value is never accessed) then the service is never fully resolved.

When ExtendedServiceProviderOptions.AddLazyResolver is true (see below) then before building the service provider, every service descriptor in the service collection is duplicated by an equivalent service descriptor for a lazy service of the same kind.

• Existing service descriptors that are already for Lazy<T> will not be used to generate lazy resolvers
• If there is already a matching service descriptor for Lazy<T> then a new one will not be generated
• Service lifetime scope is respected in the generation of lazy resolvers
  • EG: If a service descriptor is scoped, then the generated lazy service will also be scoped
• Keyed services are respected in the generation of lazy resolvers
  • EG: If a service descriptor has a key, then the generated lazy service will have that same key

Usage

To automatically add lazy resolvers for all of your registered services, use an implementation of ExtendedServiceProviderOptions instead of ServiceProviderOptions. Set the property AddLazyResolvers to true and pass this object to the BuildServiceProvider extension method.