Typescript Class inference

Question

Does anyone know how to get the current class in an abstract-generic-class | how to reference the current class like a type "CurrentClass" and not just the abstract class?

reason: i'm writing a small library, that should "infer" the current class without doing "as CurrentClass"

abstract class Super {
  public static create(args: keyof CurrentClass) {}
}

class CurrentClass extends Super {}

// to prevent
CurrentClass.create({} as CurrentClass);

i searched everywhere, but couldnt find an answer to this, so is it even possible in typescript?

this question would solve it, but not for static functions

Update: it seems that this is the issue i was looking for

Titian Cernicova-Dragomir · Accepted Answer · 2019-09-21 06:15:25Z

1

The usual workaround is to add a type parameter to infer the target from the call:

abstract class Super {
  s = ""
  public static create<T>(this:new (...a: any[]) => T, args: keyof T) {}
}

class CurrentClass extends Super {
  c = ""
}

// to prevent
CurrentClass.create("c"); // ok
CurrentClass.create("s"); // ok

play

answered Sep 21, 2019 at 6:15

Titian Cernicova-Dragomir

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6 Comments

hasezoey Over a year ago

but this workaround wouldnt give me the keys(/type infomation) from the abstract Super class, right?

Titian Cernicova-Dragomir Over a year ago

@hasezoey sure it would, that comes from inheritance .. in the example I added keys from both Super and CurentClass. If you don't want keys from Super you can use Exclude

hasezoey Over a year ago

i meant like in the create function i wouldnt have the types of super, because i cant see an "extends" or assignment there

Titian Cernicova-Dragomir Over a year ago

@hasezoey There are multiple variations of the solution depending on your needs.You could do create<T extends Super> if you need access to instance members of super. You will not have access to the statics of Super although if we complicate the type a bit more you can gain access to them. Let me know if you have a concrete issue you are having trouble with.

hasezoey Over a year ago

this is my current implementation & what i wanted to have

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