Adaptation Rules from TypeScript to ArkTS (3)

ArkTS Constraints on TypeScript Features Use class Instead of Types with Call Signatures Rule: arkts-no-call-signatures Severity: Error Description: ArkTS does not support call signatures in object types. Instead of using a type with a call signature, define a class with an invoke method. TypeScript Example: type DescribableFunction = { description: string; (someArg: string): string; // call signature }; function doSomething(fn: DescribableFunction): void { console.log(fn.description + " returned " + fn("")); } ArkTS Example: class DescribableFunction { description: string; constructor() { this.description = "desc"; } public invoke(someArg: string): string { return someArg; } } function doSomething(fn: DescribableFunction): void { console.log(fn.description + " returned " + fn.invoke("")); } doSomething(new DescribableFunction()); Use class Instead of Types with Construct Signatures Rule: arkts-no-ctor-signatures-type Severity: Error Description: ArkTS does not support construct signatures in object types. Instead of using a type with a construct signature, define a class. TypeScript Example: class SomeObject {} type SomeConstructor = { new (s: string): SomeObject; }; function fn(ctor: SomeConstructor) { return new ctor("hello"); } ArkTS Example: class SomeObject { public f: string; constructor(s: string) { this.f = s; } } function fn(s: string): SomeObject { return new SomeObject(s); } Only One Static Block Allowed Rule: arkts-no-multiple-static-blocks Severity: Error Description: ArkTS does not allow multiple static blocks in a class. Merge multiple static blocks into a single one. TypeScript Example: class C { static s: string; static { C.s = "aa"; } static { C.s = C.s + "bb"; } } ArkTS Example: class C { static s: string; static { C.s = "aa"; C.s = C.s + "bb"; } } No Support for Index Signatures Rule: arkts-no-indexed-signatures Severity: Error Description: ArkTS does not support index signatures. Use arrays instead. TypeScript Example: interface StringArray { [index: number]: string; } function getStringArray(): StringArray { return ["a", "b", "c"]; } const myArray: StringArray = getStringArray(); const secondItem = myArray[1]; ArkTS Example: class X { public f: string[] = []; } const myArray: X = new X(); myArray.f.push("a", "b", "c"); const secondItem = myArray.f[1]; Use Inheritance Instead of Intersection Types Rule: arkts-no-intersection-types Severity: Error Description: ArkTS does not support intersection types. Use inheritance instead. TypeScript Example: interface Identity { id: number; name: string; } interface Contact { email: string; phoneNumber: string; } type Employee = Identity & Contact; ArkTS Example: interface Identity { id: number; name: string; } interface Contact { email: string; phoneNumber: string; } interface Employee extends Identity, Contact {} No Support for this Type Rule: arkts-no-typing-with-this Severity: Error Description: ArkTS does not support the this type. Use explicit concrete types instead. TypeScript Example: interface ListItem { getHead(): this; } class C { n: number = 0; m(c: this) { // ... } } ArkTS Example: interface ListItem { getHead(): ListItem; } class C { n: number = 0; m(c: C) { // ... } }

Jun 12, 2025 - 17:10

Adaptation Rules from TypeScript to ArkTS (3)

ArkTS Constraints on TypeScript Features

Use class Instead of Types with Call Signatures

Rule: arkts-no-call-signatures
Severity: Error
Description: ArkTS does not support call signatures in object types. Instead of using a type with a call signature, define a class with an invoke method.
TypeScript Example:

type DescribableFunction = {
  description: string;
  (someArg: string): string; // call signature
};

function doSomething(fn: DescribableFunction): void {
  console.log(fn.description + " returned " + fn(""));
}

ArkTS Example:

class DescribableFunction {
  description: string;

  constructor() {
    this.description = "desc";
  }

  public invoke(someArg: string): string {
    return someArg;
  }
}

function doSomething(fn: DescribableFunction): void {
  console.log(fn.description + " returned " + fn.invoke(""));
}

doSomething(new DescribableFunction());

Use class Instead of Types with Construct Signatures

Rule: arkts-no-ctor-signatures-type
Severity: Error
Description: ArkTS does not support construct signatures in object types. Instead of using a type with a construct signature, define a class.
TypeScript Example:

class SomeObject {}

type SomeConstructor = {
  new (s: string): SomeObject;
};

function fn(ctor: SomeConstructor) {
  return new ctor("hello");
}

ArkTS Example:

class SomeObject {
  public f: string;

  constructor(s: string) {
    this.f = s;
  }
}

function fn(s: string): SomeObject {
  return new SomeObject(s);
}

Only One Static Block Allowed

Rule: arkts-no-multiple-static-blocks
Severity: Error
Description: ArkTS does not allow multiple static blocks in a class. Merge multiple static blocks into a single one.
TypeScript Example:

class C {
  static s: string;

  static {
    C.s = "aa";
  }

  static {
    C.s = C.s + "bb";
  }
}

ArkTS Example:

class C {
  static s: string;

  static {
    C.s = "aa";
    C.s = C.s + "bb";
  }
}

No Support for Index Signatures

Rule: arkts-no-indexed-signatures
Severity: Error
Description: ArkTS does not support index signatures. Use arrays instead.
TypeScript Example:

interface StringArray {
  [index: number]: string;
}

function getStringArray(): StringArray {
  return ["a", "b", "c"];
}

const myArray: StringArray = getStringArray();
const secondItem = myArray[1];

ArkTS Example:

class X {
  public f: string[] = [];
}

const myArray: X = new X();
myArray.f.push("a", "b", "c");
const secondItem = myArray.f[1];

Use Inheritance Instead of Intersection Types

Rule: arkts-no-intersection-types
Severity: Error
Description: ArkTS does not support intersection types. Use inheritance instead.
TypeScript Example:

interface Identity {
  id: number;
  name: string;
}

interface Contact {
  email: string;
  phoneNumber: string;
}

type Employee = Identity & Contact;

ArkTS Example:

interface Identity {
  id: number;
  name: string;
}

interface Contact {
  email: string;
  phoneNumber: string;
}

interface Employee extends Identity, Contact {}

No Support for this Type

Rule: arkts-no-typing-with-this
Severity: Error
Description: ArkTS does not support the this type. Use explicit concrete types instead.
TypeScript Example:

interface ListItem {
  getHead(): this;
}

class C {
  n: number = 0;

  m(c: this) {
    // ...
  }
}

ArkTS Example:

interface ListItem {
getHead(): ListItem;
}

class C {
n: number = 0;

m(c: C) {
// ...
}
}