FlowChart, FlowDecision, FlowSwitch inheritance RRS feed

  • Question

  • Why it's not possible to extend the flowchart model? It would be nice in some scenarios to have the opportunity to subclass these classes to make our flow control activities. I know that the designer experience would be difficult, but is it planed to unseal these classes?
    Karol Deland, Québec
    Friday, October 23, 2009 10:08 PM


  • Hi Karol,

    Currently there are no plans in WF 4 to make these types inheritable (actually, all activities in the framework are sealed). The approach that we recommend is using composition (activities can be freely composed) and when that is not enough write your own custom activities. The general model that WF has taken is one that favors composition over inheritance.

    That said, the story for writing custom activities have been dramatically simplified in .NET 4. There are no special steps involved in writing a custom composite activity (in WF 4 is just an activity like any other else). We are providing the activity authors the same tools that we use for writing the out of the box activities (we are not using any special or internal feature in Sequence or Flowchart).

    Leon Welicki,
    Program Manager, Connected Framework Team

    Saturday, October 24, 2009 12:04 AM