DelegateCommand.cs

public class DelegateCommand<T> : ICommand
    {
        private readonly Predicate<T> _canExecute;

        private readonly Action<T> _execute;

        public DelegateCommand(Action<T> execute) : this(execute, x => true)
        { }

        public DelegateCommand(Action<T> execute, Predicate<T> canExecute)
        {
            _execute = execute ?? throw new ArgumentNullException(nameof(execute));
            _canExecute = canExecute ?? throw new ArgumentNullException(nameof(canExecute));
        }

        public event EventHandler CanExecuteChanged;

        public bool CanExecute(object parameter) => _canExecute((T)parameter);

        public void Execute(object parameter) => _execute((T)parameter);

        public void RaiseCanExecuteChanged() => CanExecuteChanged?.Invoke(this, EventArgs.Empty);
    }

    public class DelegateCommand : DelegateCommand<object>
    {
        public DelegateCommand(Action execute) : this(execute, () => true)
        { }

        public DelegateCommand(Action execute, Func<bool> canExecute)
            : base(x => execute(), x => canExecute()) { }
    }