I have this base class:

export class ActVsBudget {
  constructor(
    public budget?: number,
    public actual?: number,
    public monthDiff?: number,
    public cumBudget?: number,
    public cumActual?: number,
    public cumDiff?: number
  ) {}
}

And this extended class:

export class CostOverview extends ActVsBudget {
  constructor(
    public plant?: Plant,
    public plantArea?: PlantArea,
    public costCenter?: CostCenter,
    public costAccType?: CostAccountingType,
    public year?: number,
    public month?: number
  ) {
    super();
  }
}

Now, I want a function, which takes a parameter (an array) of any class, which extends the above base class.

With this function signature I can pass the above CostOverview class as a parameter because of the inheritance:

calculateSums(data: ActVsBudget[])

But then what if I need access to any other property of the child class. I can't have acces these properties with this signature.

I tried something like this:

calculateSums(data: <T extends ActVsBudget>[])

But ts complains, that I need some brackets before the [.

What would be the right function signature?

Thanks.

CodePudding user response：

You have you generic definition wrong: :

calculateSums<T extends ActVsBudget>(data: T[]) {
 ...
}

Documentation

CodePudding user response：

First, you should know that you can not define a type like this:

calculateSums(data: <T extends ActVsBudget>[])

Instead, you should use and define your type before parentheses like:

caculateSums<TYPE extends ActVsBudget>(data: TYPE[]);

When you want to use it you should do something like using other properties of the new inherited class. SomeClass in example

class SomeClass extends ActVsBudget {}

const similarData = [new SomeClass(), new SomeClass()];

calculateSums<SomeClass>(similarData);