Assemblyscript: Is it possible to call a static function on generic type <T>?

Created on 15 Mar 2019  ·  3Comments  ·  Source: AssemblyScript/assemblyscript

Example:

class Temp {
  static decode(buf: Uint8Array): Temp {
    return new Temp(); 
  }
}

function decode<T>(buf: Uint8Array): T {
  return T.decode(buf);
}

let a = decode<Temp>(new Uint8Array());
question
Source
picture evgenykuzyakov

Most helpful comment

No, this also not possible in typescript.
But you could do something like this:

class Base {
  static decode<T>(buf: Uint8Array): T {
    return instantiate<T>(); // `instantiate` is AssemblyScript's builtin
  }
}

class Temp extends Base {
}

let a = Base.decode<Temp>(new Uint8Array(1));
picture MaxGraey on 15 Mar 2019
👍2

All 3 comments

No, this also not possible in typescript.
But you could do something like this:

class Base {
  static decode<T>(buf: Uint8Array): T {
    return instantiate<T>(); // `instantiate` is AssemblyScript's builtin
  }
}

class Temp extends Base {
}

let a = Base.decode<Temp>(new Uint8Array(1));
MaxGraey picture MaxGraey on 15 Mar 2019
👍2

If you know the output is a reference, you can use the changetype macro like this.

changetype<T>(changetype<usize>(T.decode(buf)));

You will be responsible for making sure the output of the decode function matches the definition of the T data type.

This is not safe, and you would need to know what you are doing.

jtenner picture jtenner on 15 Mar 2019

Thanks

evgenykuzyakov picture evgenykuzyakov on 15 Mar 2019
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