call arbitrary chained methods on wrapper class

Question

I'm creating a wrapper class for an API because my application will need to call it with different credentials at different times. I started off passing the wrapper a method and arguments and then doing (basically) this when calling it

call
  set_credentials
  TheAPI::Thing.send(method, args)
ensure
  reset_credentials_to_default
end

HOWEVER, I realized that a challenge here is if I need to chain methods; this way I can only call one at a time; so for example I wouldn't be able to to TheAPI::Thing.find(id).delete. (At least, not without re-calling the credentials setter, which is undesirable since I have to fetch a token).

Is there a way using ruby to collect the methods/args being chained onto an object? Or would I simply have to pass in some ugly ordered set of things?

EDIT: Surely activerecord's query builder does something like this, collecting the chained methods before returning, and then after they're all collected, ensuring that as a final step the query is built, called, and returned?

Answer 1

the way to do this is to define a proxy object and to pass that around instead of the actual thing.

In the object itself, hold a reference to the Thing and override method_missing: http://ruby-doc.org/core-2.1.0/BasicObject.html#method-i-method_missing

In the method missing do the thing you are doing today. In a nutshell this is what ActiveRecord is doing.

As far as chaining things, I don't believe it would be a problem as methods that can be chained usually return references to self. When you call the 2nd method in the chain, you actually have done the work for the first one and have an object that has the 2nd method in the chain. The only trick you need to pay attention to is that you want to return a reference to the proxy class that encapsulates the thing instead of the actual return of the thing if you want the chaining to succeed.

Give it a shot and ping me if you run into trouble and I can spin up a fully working example.