Class RelayCommand : ICommand

Question

Class RelayCommand : ICommand

{
readonly Action<object> _execute;
readonly Predicate<object> _canExecute;

public RelayCommand(Action<object> execute)
: this(execute, null)
{
}

public RelayCommand(Action<object> execute, Predicate<object> canExecute = null)
{
if (execute == null)
{
throw new ArgumentNullException("execute");
}

_execute = execute;
_canExecute = canExecute;
}

public bool CanExecute(object parameter)
{
return _canExecute == null ? true : _canExecute.Invoke(parameter);
}

public event EventHandler CanExecuteChanged
{
add
{
CommandManager.RequerySuggested += value;
}
remove
{
CommandManager.RequerySuggested -= value;
}
}

public void Execute(object parameter)
{
_execute.Invoke(parameter);
}
}