title: Using a Function Argument as a Dynamic Variable
body: <p>Is there any way to make this work without resorting to calling the subscript directly?</p>
  <pre><code>@dynamicMemberLookup
  final class Fuzzy {
      private var backing: [String: String] = [:]
      subscript(dynamicMember key: String) -&gt; String? {
          get {
              return backing[key]
          }
          set {
              backing[key] = newValue
          }
      }
  }
  
  let fuzz = Fuzzy()
  
  func worksFine() {
      fuzz.hello = &quot;hi :)&quot;
      print(fuzz.hello!)
  }
  
  // *** HERE WOULD LIKE TO PASS ARG DYNAMICALLY
  func canThisWork(with arg: String) {
      print(fuzz\.arg)
  }
  </code></pre>