Leveraging generic type parameter as an argument

I am currently working on developing a generic function that calls another function with an any type parameter. Here is what I have attempted:

static GetInstance<T>(): T {
        return <T>injector.get(T); // get(param: any): any
    }

The issue is that this code does not compile successfully. I am encountering the error message Cannot find name 'T'.

I experimented with get(typeof T), but it seems that typeof T returns a string value of "function".

What steps can I take to resolve this problem?

To clarify, the get() method accepts types as parameters. Here is an example of how you can use it:

import { MyService } from '..'

constructor(){
    let val = this.injector.get(MyService);
}

Answer №1

Generics in TypeScript serve as a design-time tool only. They will not be compiled into JavaScript during runtime. When attempting to utilize generics, it is important to understand that they are effectively placeholders meant for static analysis.

In simpler terms, the symbol T does not have an actual presence. It is a conceptual placeholder provided for clarity. Attempting to treat it like a regular variable will result in errors, as T has no tangible value.

Therefore, when implementing the GetInstance method, ensure that the get function receives a real parameter instead of T, which has no concrete definition.

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