I'm reading the ng-book on angular 2 revision 47 page 250 and there is the following passage:
When we put the class itself into the list of providers like this:
providers: [ MyService ]That is telling Angular that we want to provide a singleton instance of MyService whenever MyService is injected. Because this pattern is so common, the class by itself is shorthand notation for the following, equivalent configuration:
providers: [ { provide: MyComponent, useClass: MyComponent } ]
Is it a typo and what is meant should be:
providers: [
{ provide: MyService, useClass: MyService }
]
It's typo, since you can't use components as Providers, here's the official docs
The Provider class and provide object literal We wrote the providers array like this:
providers: [Logger]This is actually a shorthand expression for a provider registration using a provider object literal with two properties:
[{ provide: Logger, useClass: Logger }]The first is the token that serves as the key for both locating a dependency value and registering the provider.
The second is a provider definition object, which we can think of as a recipe for creating the dependency value. There are many ways to create dependency values ... and many ways to write a recipe