title: call generic function without params
body: <pre><code>protocol IDataSource:AnyObject{
      typealias DS;
      typealias U;
      func dataSource(ds:DS, index:Int?);
      func dataSource(ds:DS, data:[U]);
  }
  
  class DataSource&lt;T:AnyObject&gt;{
  
      var map = [NSManagedObjectID:T]();
      var data = [T]();
      var ctrls:NSHashTable = NSHashTable.weakObjectsHashTable();
      func find(value:T)-&gt;Int?;
      var selected:T?;
  
      func setNeedsUpdate&lt;Bar:IDataSource where Bar.U==T,Bar.DS==DSGen&gt;(){
          for ctrl in self.ctrls.allObjects {
              let client = ctrl as! Bar;
              client.dataSource(self, data:self.data);
          }
      }
      func foo(){
          // error
          setNeedsUpdate()    
      }
  }
  </code></pre>
  
  <p>How I can call method setNeedsUpdate()?
  compiler error " Cannot invoke 'setNeedsUpdate' with no arguments"</p>