c# - 当属性在 C# 中只有 getter 时如何创建属性更改事件

Question

假设我有这个类(这实际上是为了演示目的):

class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string IdNumber { get; set; }

    // CheckPopulationRegistry() checks against the database if a person
    // these exact properties (FirstName, LastName, IdNumber etc.) exists.
    public bool IsRealPerson => CheckPopulationRegistry(this);
}

我想在 IsRealPerson 更改时收到通知。

通常，我会实现 INotifyPropertyChanged 接口(interface)，但之后我需要 create an OnIsRealPersonChanged() method, and call it from the setter ，我没有。

想法？

Answer 1

你需要这样的东西:

public class Person : INotifyPropertyChanged
{
    private string firstName;
    private string lastName;

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

    private bool CheckPopulationRegistry(Person p)
    {
        // TODO:
        return false;
    }

    public string FirstName
    {
        get { return firstName; }
        set
        {
            if (firstName != value)
            {
                firstName = value;
                OnPropertyChanged();
                OnPropertyChanged(nameof(IsRealPerson));
            }
        }
    }

    public string LastName
    {
        get { return lastName; }
        set
        {
            if (lastName != value)
            {
                lastName = value;
                OnPropertyChanged();
                OnPropertyChanged(nameof(IsRealPerson));
            }
        }
    }

    // IdNumber is omitted

    public bool IsRealPerson => CheckPopulationRegistry(this);

    public event PropertyChangedEventHandler PropertyChanged;

}