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

Hang on, why do you want this to work?

Your childAction is something that accepts a CancelCommand and does something with it.

But upperAction could be invoked on any IDomainCommand, not just a CancelCommand. Supposing the above compiled; what should then happen when I do

upperAction(new EditCommand());

where class EditCommand : IDomainCommand ?

If you attempt an assignment the other way round:

        var upperAction = new Action(idc => { });
        Action childAction = upperAction;

it works and you don't even need a cast. Any Action counts as an Action.