Covariance and Contravariance for Action Delegates

Question

I\'m stuck, why isn\'t this working:

  var childAction = new Action(blabla);
  Action upperAction = (Action

        

Answer 1

Your forgetting how these delegates are being used

var childAction = new Action(blabla);
Action upperAction = (Action) childAction;

means that upperAction will at some point in the future be called, passing some form of an IDomainCommand object. You are giving it an function which can only handle CancelCommand objects. But there are (probably) other classes which implement IDomainCommand, and upperAction could potenially be called with any of them.