using System;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using System.Windows;
using System.Windows.Input;

namespace WpfApp006
{
  public class MainWindowVM : INotifyPropertyChanged
  {

    public ICommand CreateNewTextBoxCommand
    {
      get => new HelperCommand((state) =>
      {
        Num = DateTime.Now.ToLongTimeString();
        RaisePropertyChanged(nameof(Num));
      });
    }

    public string Num { get; set; }

    public event PropertyChangedEventHandler PropertyChanged;
    private void RaisePropertyChanged([CallerMemberName] string propName = "") =>
      PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propName));

  }

  public class HelperCommand : ICommand
  {
    private readonly Action<object> _execute;
    private readonly Predicate<object> _canExecute;
    public HelperCommand(Action<object> execute) : this(execute, canExecute: null) { }
    public HelperCommand(Action<object> execute, Predicate<object> canExecute)
    {
      if (execute == null) throw new ArgumentNullException("execute");
      this._execute = execute;
      this._canExecute = canExecute;
    }
    public event EventHandler CanExecuteChanged;
    public bool CanExecute(object parameter) => this._canExecute == null ? true : this._canExecute(parameter);
    public void Execute(object parameter) => this._execute(parameter);
    public void RaiseCanExecuteChanged() => this.CanExecuteChanged?.Invoke(this, EventArgs.Empty);
  }
}