PropertyChanged?.Invoke(...) 调用 在单步执行 Set 语句时再次调用 setter

Question

我有一个实现 INotifyPropertyChanged 的​​简单基类。该代码有效。但是，当我单步执行 Set 语句时，当 Set 语句调用 SetProperty() 时，我注意到 PropertyChanged?.Invoke(...) 调用再次调用 setter。

因此，子类中的 setter 代码看起来像：

private string someProperty ;
public string SomeProperty { get => someProperty ;
set {
    // Do some tests on value to make sure it's valid
    SetProperty(ref someProperty, value);
    // Now do some other stuff once that is set
}

当我单步执行它时，调用堆栈显示：

• SomeProperty.Set( valuetype value); ????怎么又来了？？？？ --- 5
• 外部代码 --- 4
• OnPropertyChanged(string propertyName ) --- 3
• SetProperty(field, value) --- 2
• SomeProperty.Set( valuetype value) ---- 初始设置执行

代码片段：

public abstract class ViewModelBase : INotifyPropertyChanged
{        
    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        Dev.Tools.Assert(propertyName != null, "propertyName can't be null.... ");
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    // This is used to support change tracking.  But 
    //   the problem happens even when TrackChangedFields is false.
    // The EqualityComparer prevents this from being recursive.
    public virtual bool SetProperty<T>(ref T field, T newValue, [CallerMemberName] string propertyName = null)
    {
        if (!EqualityComparer<T>.Default.Equals(field, newValue))
        {
            field = newValue;
            OnPropertyChanged(propertyName);

            if (TrackChangedFields && !IgnoreFieldList.Contains(propertyName))
            {
                ChangedFieldList.Add(new ChangedRecordDetail(propertyName, field, newValue, ViewModelName));
            }
            return true;
        }
        return false;
    }

知道为什么PropertyChanged?.Invoke() 调用导致集合再次触发？

同样，这段代码运行良好。我只是不明白为什么会发生第二次对 setter 的调用，也不明白该怎么做才能只调用一次 setter。