@hazae41/box

Box

Rust-like Box for TypeScript

npm i @hazae41/box

Node Package 📦

Features

Current features

• 100% TypeScript and ESM
• No external dependencies
• Similar to Rust
• Can hold data
• Unit-tested
• Uses Result from @hazae41/result

Usage

The Box<T extends Disposable> will:

• hold a disposable object T
• only dispose the object if it still owns it
• no longer own it if the box is moved

import { Box } from "@hazae41/box"

class D {
  [Symbol.dispose]() { 
    console.log("it should only happen once")
  }
}

/**
 * At the end of this block, D will only be disposed once
 */
{
  using box = new Box(new D())
  using box2 = box.move()
}

Rules

1. You can't pass a disposable object without wrapping it in a Box
2. You can't hold a disposable object without wrapping it in a Box
3. You can't hold a Box without owning it and disposing it after
4. You can't return a Box without unwrapping it

This means the typical object holding a Box looks like this

import { Box } from "@hazae41/box"

class MyWrapper<T extends Disposable> {

  private constructor(
    /**
     * Rule 2. hold as box
     **/
    readonly box: Box<T>
  ) {}

  [Symbol.dispose]() {
    /**
     * Rule 3. dispose any box you hold
     **/
    this.box[Symbol.dispose]()
  }

  static create<T extends Disposable>(box: Box<T>) {
    /**
     * Rule 3. own any box you want to hold
     **/
    return new MyWrapper(box.move())
  }

  use() {
    /**
     * Rule 1. only pass as box
     **/
    something(this.box)
  }

  export(): T {
    /**
     * Rule 4. unwrap on return
     **/
    return this.box.unwrap()
  }

}