Question

如何将Task.Factory.FromAsync工厂用于通过“out”参数返回多个值的end方法？

begin方法有这个签名：

public virtual System.IAsyncResult BeginGetCaseStatus(int CaseOID, int ClientOID, System.AsyncCallback @__Callback, object @__UserData)

结束方法是：

public virtual void EndGetCaseStatus(System.IAsyncResult @__AsyncResult, out DTGenericCode[] BasicStatus, out DTGenericCode[] ARStatus)

我可以使用一些方法：

public Task<?> GetCaseStatusAsync(int CaseOID, int ClientOID)
{
    return Task.Factory.FromAsync  (BeginGetCaseStatus(CaseOID, ClientOID, null, null), EndGetCaseStatus(?, ?));
}

Answer 1

没有FromAsync重载对此有用。最好的选择可能是构建自己的包装器：

public class ResultStatus
{
     public ResultStatus(DTGenericCode[] basicStatus, DTGenericCode[] arStatus)
     {
         this.BasicStatus = basicStatus;
         this.ARStatus = arStatus;
     }
     public DTGenericCode[] BasicStatus { get; private set; }
     public DTGenericCode[] ARStatus { get; private set; }
}

public Task<ResultStatus> GetCaseStatusAsync(int CaseOID, int ClientOID)
{
     var tcs = new TaskCompletionSource<ResultStatus>();
     theClass.BeginGetCaseStatus(CaseOID, ClientOID, iar =>
             {
                 DTGenericCode[] bs;
                 DTGenericCode[] as;
                 theClass.EndGetCaseStatus(iar, out bs, out as);

                 tcs.SetResult(new ResultStatus(bs, as));
             }, null);

     return tcs.Task;
}

Answer 2

endMethod的{{1}}参数是委托，因此您可以使用lambda将FromAsync() - 表单转换为out方法的正常形式。类似的东西：

-End

虽然您可能希望使用自定义类型而不是private static Task<Tuple<DTGenericCode[], DTGenericCode[]>> GetCaseStatusAsync( int CaseOID, int ClientOID) { return Task.Factory.FromAsync( BeginGetCaseStatus, ar => { DTGenericCode[] basicStatus; DTGenericCode[] arStatus; EndGetCaseStatus(ar, out basicStatus, out arStatus); return Tuple.Create(basicStatus, arStatus); }, CaseOID, ClientOID, null); }。

Task.Factory.FromAsync与End方法中的“out”参数

2 个答案: