Can we hide forum discussions and documents from a client or contractor?

Can we hide forum discussions and documents from a client or contractor?

This seems simple, so I hope it's integrated. If you have a project with agency, contractor and clients on there, you'd think you could have discussions with just the agency, or agency and contractor, or agency and client or all. Is there a way to do this? 

Similarly with documents, where do you choose who can view it?

Hopefully it's simple and I'm missing it. I know Basecamp has been using similar functionality for years and a lot of people love it.