Can I cast a contextExtension parameter?

[aSapien]

Hi @vilic,

Is it possible to cast a ContextExtension parameter?

Example:

1. Defined a Class with a cast() function that takes Slack user_id and resolves a user email:

   export class SlackUserResolved implements StringCastable<SlackUserResolved> {
   constructor(public email: string){}
   
   async cast(id: string, context: CastingContext<SlackUserResolved>): Promise<SlackUserResolved> {
   const { email } = await getSlackUserProfile(id) as any;
   return new SlackUserResolved(email);
   }
   }

2. Defined a command that expects a SlackResolvedUserCommandContext (defined below)

   
   @command({
   description: 'This command is listing stuff',
   })
   export default class extends Command {
   @metadata
   execute(context: SlackResolvedUserCommandContext) {
   return listStuffForUser(context.profile);
   }
   }

**Now, here's where I'm having trouble:**

How do I get the user to be resolved before command invocation?
I can't `await` inside the constructor. What do I do? 

2. Defined a `SlackResolvedUserCommandContext` class extending `SlackCommandContext` that I would like to have the user email resolved:
```javascript
export class SlackResolvedUserCommandContext extends SlackCommandContext {
  public profile: SlackUserResolved;
  constructor(options: ContextOptions, contextExt: SlackCommandContext) {
    super(options, contextExt);
  }
}

Appreciate the assistance, Sapien

[vilicvane]

@aSapien Hi, currently it's not possible to have context resolved asynchronously. I guess you have to use work around like let email = await context.getEmail(); for this purpose.

[aSapien]

Got it. Thanks, @vilic!

btw, I would like to offer my greatest gratitude for developing this lib. I think this may be the only CLI node library that isn't tightly coupled to a process and/or stdio.

Chapeau 🎩

[vilicvane]

@aSapien Thanks, it's really nice to know that you enjoy this idea!