Question

是否可以在CollectionChanged事件中获取项目的Instance？

例如：

public class Foo
{
    public string Name { get; set; }
    public ObservableCollection<Bar> Bars { get; set; }

    public Foo()
    {
        Bars += HelperFoo.Bars_CollectionChanged;
    }
}

public class Bar
{
    public string Name { get; set; }
}

public static class HelperFoo
{
    public static voic Bars_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        //sender is the collection Foo.Bars
        //can I get the Instance of Foo?
    }
}

（我不介意使用反射）

如果这不可能有办法获得初始化其他对象的对象实例吗？

例如：

public class Foo
{
    public string Name { get; set; }

    public Foo()
    {
        var bar = new Bar(); //yes I know, I could write new Bar(this) and provide an overload for this
    }
}

public class Bar
{
    public string Name { get; set; }

    public Bar()
    {
        //Get the Foo, since the constructor is called within Foo, is this possible?
        //without providing an overload that takes an object, and just change it to `(new Bar(this))`
    }
}

Answer 1

你的代码看起来很奇怪。

如果您的HelperFoo课程需要对Foo执行某些操作，请将其Foo传递给它，并让它自己订阅Bar个事件。

如果HelperFoo不了解Bars的任何内容，请在Foo上公开一个事件并订阅该事件。当Foo更改时，您可以在Bars内提出事件。

阅读Law Of Demeter。

Answer 2

我同意@Gaz但是如果你真的想要做你所描述的，那么在你的HelperFoo类中添加一个Dictionary。然后在你的Foo类中添加它作为创建者，如下所示。

public static class HelperFoo
{
    private static Dictionary<ObservableCollection<Bar>, object> lookupCreators = new Dictionary<ObservableCollection<Bar>, object>();

    public static void AddBarsCreator(ObservableCollection<Bar> bars, object creator)
    {
        lookupCreators.Add(bars, creator);
    }

    public static void Bars_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        ObservableCollection<Bar> bars = (ObservableCollection<Bar>)sender;
        if (lookupCreators.ContainsKey(bars))
        {

        }
    }
}

public class Foo
{
    public ObservableCollection<Bar> Bars { get; set; }

    public Foo()
    {
        Bars = new ObservableCollection<Bar>();
        HelperFoo.AddBarsCreator(Bars, this);
        Bars.CollectionChanged += HelperFoo.Bars_CollectionChanged;
    }
}

CollectionChanged获取持有该集合的对象的实例

2 个答案: