Question

I am doing the following tutorial, to learn about the MVVM pattern in WPF. There’s something I don’t understand about the following seemingly partly given implementation of ICommand interface.

In the code below the _canExecute variable is used as a method and a variable. I was thinking it’s some event of some kind, but ICommand already has an event to be implemented and it’s not _canExecute.

So can someone help me as to what _canExecute is supposed to be?

  1: #region ICommand Members
  2: 
  3: public bool CanExecute(object parameter) {
  4:     return _canExecute == null ? true : _canExecute(parameter);
  5: }
  6: 
  7: public event EventHandler CanExecuteChanged {
  8:     add { CommandManager.RequerySuggested += value; }
  9:     remove { CommandManager.RequerySuggested -= value; }
 10: }
 11: 
 12: public void Execute(object parameter) {
 13:     _execute(parameter);
 14: }
 15: 
 16: #endregion

Answer 1

_canExecute would be a Predicate<object>, whereas _execute would be an Action<object>.

See my delegate command blog post for another example.