What is the Work<> class for in Orchard CMS?

Question

Plain and simple, what is the use case of the Orchard.Environment.Work<> class defined in Orchard\Environment\WorkContextModule.cs?

It can be found in several places like

private readonly Work<IContainerService> _containerService;

public Shapes(Work<IContainerService> containerService) {
  _containerService = containerService;
...

Is it for delayed resolution of IContainerService?

Answer 1

The Work class is for lazy loading dependency injection. The dependency is not resolved when instantiating the class, but only when calling the Value property:

private readonly IMyService _myService;
private readonly IMyOtherService _myOtherService;
public MyClass(Work<IMyService> myService, IMyOtherService myOtherService) {
    // Just assign the Work class to the backing property
    // The dependency won't be resolved until '_myService.Value' is called
    _myService = myService;
    // The IMyOtherService is resolved and assigned to the _myOtherService property
    _myOtherService = myOtherService;
}

Now only when _myService.Value is called, the IMyService gets resolved by the Dependency resolver, which gives you the working of a lazy loading dependency injection.