wpf,如何绑定当前日期？

<Window x:Class="YourNamespace.YourWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Your Window" Height="450" Width="800">
    <Grid>
        <TextBlock Text="{Binding CurrentDate}" />
    </Grid>
</Window>

using System;
using System.ComponentModel;
using System.Runtime.CompilerServices;

namespace YourNamespace
{
    public class YourViewModel : INotifyPropertyChanged
    {
        private DateTime _currentDate;

        public DateTime CurrentDate
        {
            get { return _currentDate; }
            set
            {
                _currentDate = value;
                OnPropertyChanged();
            }
        }

        public YourViewModel()
        {
            CurrentDate = DateTime.Now;
        }

        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

public partial class YourWindow : Window
{
    public YourWindow()
    {
        InitializeComponent();
        DataContext = new YourViewModel();
    }
}