inherit types from base class

[Zain-ul-din]

Suggestion

🔍 Search Terms

inheriting base types into child class without importing them manually

⭐ Suggestion

In TypeScript v4.9.4, if we extend a class from another file, we also need to import the corresponding types in order to access the base types. I propose that TypeScript should include a feature called "type inheritance" that allows us to access the base types without having to import them.

📃 Motivating Example

Here is some examples using V4.9.4

   // pkg.ts
   export default abstract class Base {
       public get (req: Request, res: Response): Promise<void> {}
   }

  
   /// client side
  
   import Base from '@pkg'
   import { Request, Response } from '@pkg'
   
   class Child extends Base {
       public get (req: Request, res: Response ): Promise<void> {}  
   }
   

Here are some issues with this code:-

• It is unnecessary to import the types Request and Response in the child class if the base class has already been imported. This adds unnecessary code and complexity.

• There is no code intelligence in the child class to show which methods are defined in the base class, making it harder to understand and work with the code.

I think this is not a good idea to import types if we have already imported the class Base and also there is no code intelligence in the child class for which method to override or which already defines inside the base class.

💻 Use Cases

The proposed feature, "type inheritance," would allow for the following syntax in TypeScript:

   // pkg.ts
   export default abstract class Base {
       public get (req: Request, res: Response): Promise<void> {}
   }

  
   /// client side
  
   import Base from '@pkg'
   
   class Child extends Base {
       public get (req: inherit, res: inherit): inherit {}  
   }
   

Expected behavior:-

• With this syntax, the compiler would recognize the types from the base class and provide code intelligence to show which methods
  are defined in the base class. It would also throw an error if the method is not available in the base class.

[fatcerberus]

Duplicate of the more comprehensive proposal #36165

[Zain-ul-din]

@fatcerberus do you have any plan to add this feature in upcoming versions?

[fatcerberus]

I’m not a TypeScript developer but maybe if you’re good Santa will bring you a new feature or two… probably not this one though

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.

[Zain-ul-din]

@RyanCavanaugh when we'll see this fix in typescript?