Module 13 - Advanced DI


ng-new	Angular 14 - 16 new features

Angular 14 comes with a new |dirty trick" - the inject function
This function allows to inject dependencies into a function (not just constructors)

import { inject } from '@angular/code';

function myFunc() {
    const service = inject(MyService);
}

There is only one cavet... this function can only run in "injection context".
Injection context is a fancy term. It means, that while the inject function is executed, there has to be an injector present in a very specific global variable that the function will access.
What is means - effectively - is that we can only use the inject function in:
- The constructor of an angular object (Component, Directive, Pipe, Service)
- One of the functions that angular calls: Guard, Resolver, Effect, Interceptor
- A function that we specifically call in the correct context
We can use the runInInjectionContext function to execute a function in the context of an injector.
We have seen how to create our own injectors, and how to inject the component injector into the component.

Angular 16 allows us to inject the DestroyRef instance into our component.
We can use it to apply logic during destruction, without implementing the OnDestroy interface.
We saw that there are some new functions that take advantage of that, for example the takeUntilDestroyed rxjs operator.
Again - the only cavet is that these functions must be called in injection context.
Currently, when you call a function, there is no way to tell if it (or one of the inner function it calls) are supposed to run in context. So this feature is quire problematic...

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