type AnyClass = { new(...args: any[]): any }

/**

/** * Simple User class with scopes

/** * Simple User class with scopes */

class User {

id: string

scope: Set<string>

constructor(id: string, scopes: string[]) {

this.id = id

this.scope = new Set(scopes)

}

}

/**

/** * A decorator which limits other class definitions to use the scope

/** * A decorator which limits other class definitions to use the scope */

function limitScope(...scopes: string[]) {

return function<T extends AnyClass>(target: T): T {

// Create a synthetic superclass

return class extends target {

constructor(...args: any[]) {

super(...args)

// Search constructor arguments for a User object

const user = args.find((arg) => (arg instanceof User))

if (user) {

// Check scopes and throw error

if (! scopes.every((scope) => user.scope.has(scope))) {

throw new Error('User does not have scope')

}

}

else if (scopes.length > 0)

throw new Error('No User provided to validate scopes')

}

} as T

}

}

@limitScope('admin')

class Refund {

constructor(createdBy: User) {

console.log('Creating a refund')

}

}

const admin = new User('admin_user_id', ['admin'])

const customer = new User('customer_id', ['user'])

const refund = new Refund(admin)

Adding initialization to the constructor