Decorator that binds class methods compatible with TypeScript 5.0

bound.ts

function bound<This extends object, Args extends any[], Return>(
  target: (this: This, ...args: Args) => Return,
  context: ClassMethodDecoratorContext<This, (this: This, ...args: Args) => Return>
) {
  const methodName = String(context.name);

  if (context.private) {
    throw new Error(`${bound.name} cannot decorate private properties like ${methodName}.`);
  }

  context.addInitializer(function () {
    Object.assign(this, { [methodName]: target.bind(this)})
  });
}

Example:

class Rolodex<const T> {
  index: number;
  length: number;

  constructor(private sequence: NonEmptyArray<T>) {
    this.sequence = sequence;
    this.index = 0;
    this.length = sequence.length;
  }

  @bound
  next(): T {
    return this.sequence[++this.index % this.length]!;
  }
}

const { next } = new Rolodex([10, 20, 30]);

console.log(next()) // without the decorator, it would throw "Cannot read properties of undefined (reading 'sequence')"

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