Question

I’ve been unable to find any info on this, which seems like it could be the only way to solve a past unanswered question of mine on SO. However, I think this should really be a separate question now.

I am wondering if there is a way to dynamically redefine an ICommand-derived class’s CanExecute method. I’m still new to .NET and perhaps this is really obvious, but I haven’t been able to figure it out. Has anyone here done this sort of thing before? If I could get this working, it would be very useful for my particular problem. Basically, I want to be able to loop over a List of ICommands and force all of their CanExecute methods to return true by replacing their implementation with a different one.

From searching for things like “.NET code replacement”, I found this article, but I was hoping that there’s a slightly simpler approach. However, if I have to, I’ll do it.

Answer 1

Have your ICommand derived class call a delegate to determine if CanExecute can be done, this way you can expose a setter for the delegate and change it at runtime

As a simple example:

public class MyCommand : ICommand
{
  private Func<object, bool> _canExecuteMethod;

  public void SetCanExecuteMethod(Func<object, bool> canExecuteMethod)
  {
    //check delegate not null if need be
    _canExecuteMethod = canExecuteMethod;
  }

  public bool CanExecute(object parameter)
  {
    //check for null delegate - maybe return false if it's null....
    return _canExecuteMethod(parameter);
  }

  //....other codefor ICommand

}

You could also utilize just Func<bool> for the delegate if you don’t need the extra data to make the decision. Also the delegate can be exposed elsewhere if required and just called from the ICommand class