Utilizing typescript to isolate specific functionality from a class without extending it

Question

Utilizing typescript to isolate specific functionality from a class without extending it

Imagine a scenario where I have a class with different areas of functionality:

export class TreeTable extends someOtherClass {
    constructor(){
       super.constructor();
    }
   //========= area 1 of functionality ====
   itemRightClick(){this.contextMenu();}
   contextMenu(){
     // open file or folder context menu
   }
   fileContextMenu(){}
   folderContextMenu(){}

   //========= area 2 of functionality ====
   loadData(){}
   subScribeStuff(){}
   unsusbscribeStuff(){}

   //======== area 3 SomeOtherClasses functionality
   someOtherClassMethod_1(){
   this.someOtherClassMethod();
   super.someOtherClassMethodTwo();
  }
}

If I decide to separate and extract abstract area-1 into an external class.

class ContextMenu {
   constructor(){}
    //========= area 1 of functionality ====
   itemRightClick(){this.contextMenu();}
   contextMenu(){
     // open file or folder context menu
   }
   fileContextMenu(){}
   folderContextMenu(){}
}
export class TreeTable extends someOtherClass {

    constructor(){
       super.constructor();
    }
   //======== AREA 1
   // DECORATE THIS CLASS WITH class ContextMenu AND ADD ITS METHODS
   //========= area 2 of functionality ====
   loadData(){}
   subScribeStuff(){}
   unsusbscribeStuff(){}

   //======== area 3 SomeOtherClasses functionality
   someOtherClassMethod_1(){
   this.someOtherClassMethod();
   super.someOtherClassMethodTwo();
  }
}

It appears to be a straightforward task that can be achieved without using inheritance, but rather through decoration. It seems that decorators (@) are not suitable for this purpose.

typescript

Answer 1

Answer №1

One thing to keep in mind is that JavaScript, unlike traditional OOP languages, does not support abstract classes.

With your current class hierarchy, it can be challenging to selectively choose members from one class and transfer them to another without extending the entire class X.

To align with OOP and SOLID principles, you may need to reconsider how you model your objects. Your class seems to have multiple responsibilities such as data loading, subscribing/unsubscribing, and context menu operations. These functionalities could be separated into their own class definitions or abstracted through TypeScript interfaces.

When focusing on different areas of functionality (1-3), here are some options:

1. Separate each area of functionality into individual classes:

class Area1 {
  ...
}

class Area2 {
  ...
}

class Area3 {
  ...
}

You can then incorporate instances of Area1, Area2, or Area3 within TreeTable or create a type hierarchy.

2. Utilize TypeScript interfaces for defining class members:

interface IArea1 {
  ...
}

interface IArea2 {
  ...
}

interface IArea3 {
  ...
}

You can implement multiple interfaces to structure your concrete types accordingly:

class TreeTable extends someOtherClass implements IArea1, IArea3 {
  // implement members for IArea1
  // implement members for IArea2
}

3. Consider using regular JavaScript objects instead of OOP:

const area1 = {
  // functions
}

const area2 = {
  // other functions
}

const area3 = {
  // additional functions
}

const treeTable = {
  ...area1,
  ...area3
}

Even when using regular objects, abstract interfaces can still be beneficial:

interface ITreeTable extends IArea1, IArea3 {
  // specific functionality
}

const treeTable: ITreeTable = {
  // interface members
};

Answer 2

One thing to keep in mind is that JavaScript, unlike traditional OOP languages, does not support abstract classes.

With your current class hierarchy, it can be challenging to selectively choose members from one class and transfer them to another without extending the entire class X.

To align with OOP and SOLID principles, you may need to reconsider how you model your objects. Your class seems to have multiple responsibilities such as data loading, subscribing/unsubscribing, and context menu operations. These functionalities could be separated into their own class definitions or abstracted through TypeScript interfaces.

When focusing on different areas of functionality (1-3), here are some options:

1. Separate each area of functionality into individual classes:

class Area1 {
  ...
}

class Area2 {
  ...
}

class Area3 {
  ...
}

You can then incorporate instances of Area1, Area2, or Area3 within TreeTable or create a type hierarchy.

2. Utilize TypeScript interfaces for defining class members:

interface IArea1 {
  ...
}

interface IArea2 {
  ...
}

interface IArea3 {
  ...
}

You can implement multiple interfaces to structure your concrete types accordingly:

class TreeTable extends someOtherClass implements IArea1, IArea3 {
  // implement members for IArea1
  // implement members for IArea2
}

3. Consider using regular JavaScript objects instead of OOP:

const area1 = {
  // functions
}

const area2 = {
  // other functions
}

const area3 = {
  // additional functions
}

const treeTable = {
  ...area1,
  ...area3
}

Even when using regular objects, abstract interfaces can still be beneficial:

interface ITreeTable extends IArea1, IArea3 {
  // specific functionality
}

const treeTable: ITreeTable = {
  // interface members
};

Utilizing typescript to isolate specific functionality from a class without extending it

Answer №1

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