打字稿通用接口函数

Question

I have a little problem with my generic interface function. I guess I watched too long on the same point... can someone please show me what Iam doing wrong?

Interface:

export interface Compareable<T>
{
    equals(compareable:T):boolean;
}

function:

function isInCompareableArray<T>(compareable:Compareable<T>, arr:Array<Compareable<T>>) : boolean
{
  for(let i of arr)
  {
    if (compareable.equals(i)) return true;
  }

  return false;
}

call:

let dateRef:DateRef //DateRef implements Compareable<DateRef>
let arr:Array<DateRef>

isInCompareableArray<DateRef>(dateRef, arr);

Error:

ERROR in function ... if (compareable.equals(i)) return true; 
...: Argument of type 'Compareable<T>' is not assignable to parameter of type 'T'.

Iam bit lost here. Can you help?

Answer 1

It should be:

function isInCompareableArray<T>(compareable: Compareable<T>, arr: Array<T>): boolean {
    for (let i of arr) {
        if (compareable.equals(i)) return true;
    }

    return false;
}

Where the array is of type Array<T> (or simply T[] ) instead of Array<Compareable<T>> .

Answer 2

Oh my... shame on me :) I lost the scope.

This works:

function:

export function isInCompareableArray<T>(compareable:Compareable<T>, arr:Array<T>) : boolean ...