CSharp随笔-癫疯之作

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if (e.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Add)
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{
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    string ipString = string.Join("，", e.NewItems.Cast<IWebSocketConnection>().Select(x => x.ConnectionInfo.ClientIpAddress));
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    WeakReferenceMessenger.Default.Send<DisplayAlertMessage>(new("有新用户连接", ipString));
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}
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else if (e.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Remove)
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{
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    string ipString = string.Join("，", e.OldItems.Cast<IWebSocketConnection>().Select(x => x.ConnectionInfo.ClientIpAddress));
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    WeakReferenceMessenger.Default.Send<DisplayAlertMessage>(new("有用户断开连接", ipString));
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}
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else
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{
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    throw new InvalidOperationException("不支持此类操作");
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}

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WeakReferenceMessenger.Default.Send<DisplayAlertMessage>(((Func<(string, System.Collections.IList), (string, string)>)(t => (t.Item1, string.Join("，", t.Item2.Cast<IWebSocketConnection>().Select(x => x.ConnectionInfo.ClientIpAddress)))))(e.Action switch
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{
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    System.Collections.Specialized.NotifyCollectionChangedAction.Add => ("有新用户连接", e.NewItems),
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    System.Collections.Specialized.NotifyCollectionChangedAction.Remove => ("有用户断开连接", e.OldItems),
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    _ => throw new InvalidOperationException("不支持此类操作")
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}).ToDisplayAlertMessage());
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internal static class ValueTupleExtensions // C#不能把Tuple展开成多个参数 :(
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{
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    public static DisplayAlertMessage ToDisplayAlertMessage(this ValueTuple<string, string> tuple)
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    {
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        return new DisplayAlertMessage(tuple.Item1, tuple.Item2);
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    }
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}