Question

我不确定如何说出这个问题，所以希望以下细节可以帮助您了解这里究竟发生了什么。这是我以前从未遇到的事情，它在代码风格上的独特性对我来说是相当奇怪的。

我下载了SSH.NET的源代码，并尝试将组件的源代码合并为整体项目的一部分，但是有许多块，例如以下块：

        public static int Read(Socket socket, byte[] buffer, int offset, int size, TimeSpan timeout)
        {
#if FEATURE_SOCKET_SYNC
            var totalBytesRead = 0;
            var totalBytesToRead = size;

            socket.ReceiveTimeout = (int) timeout.TotalMilliseconds;

            do
            {
                try
                {
                    var bytesRead = socket.Receive(buffer, offset + totalBytesRead, totalBytesToRead - totalBytesRead, SocketFlags.None);
                    if (bytesRead == 0)
                        return 0;

                    totalBytesRead += bytesRead;
                }
                catch (SocketException ex)
                {
                    if (IsErrorResumable(ex.SocketErrorCode))
                    {
                        ThreadAbstraction.Sleep(30);
                        continue;
                    }

                    if (ex.SocketErrorCode == SocketError.TimedOut)
                        throw new SshOperationTimeoutException(string.Format(CultureInfo.InvariantCulture,
                            "Socket read operation has timed out after {0:F0} milliseconds.", timeout.TotalMilliseconds));

                    throw;
                }
            }
            while (totalBytesRead < totalBytesToRead);

            return totalBytesRead;
#elif FEATURE_SOCKET_EAP
            var receiveCompleted = new ManualResetEvent(false);
            var sendReceiveToken = new BlockingSendReceiveToken(socket, buffer, offset, size, receiveCompleted);

            var args = new SocketAsyncEventArgs
            {
                UserToken = sendReceiveToken,
                RemoteEndPoint = socket.RemoteEndPoint
            };
            args.Completed += ReceiveCompleted;
            args.SetBuffer(buffer, offset, size);

            try
            {
                if (socket.ReceiveAsync(args))
                {
                    if (!receiveCompleted.WaitOne(timeout))
                        throw new SshOperationTimeoutException(string.Format(CultureInfo.InvariantCulture,
                            "Socket read operation has timed out after {0:F0} milliseconds.", timeout.TotalMilliseconds));
                }

                if (args.SocketError != SocketError.Success)
                        throw new SocketException((int) args.SocketError);

                return sendReceiveToken.TotalBytesTransferred;
            }
            finally
            {
                // initialize token to avoid the waithandle getting used after it's disposed
                args.UserToken = null;
                args.Dispose();
                receiveCompleted.Dispose();
            }
#else
#error Receiving data from a Socket is not implemented.
#endif
        }

在尝试构建时，编译器会卡在#error Receiving data from a Socket is not implemented.行并抛出异常CS1029，我可以忽略它，但我更关注的是为什么所有这些条件都失败了满足（例如：#elif FEATURE_SOCKET_EAP），我能做些什么呢？

此外，由于故障转移到Error CS0161 'SocketAbstraction.Read(Socket, byte[], int, int, TimeSpan)': not all code paths return a value段导致编译器使用内联消息抛出异常（例如：#else抛出CS1029），我得到#else <foo>以<foo>作为描述的异常，并且还阻止方法中的返回值

我可以做些什么来纠正这些类型的问题，以及为什么有人会以这种方式使用内联编译器失败问题？

Answer 1

您必须为其中一个指定的条件编译符号配置IDE。

如果您使用的是Visual Studio：

打开项目属性
转到标签＆＃34;构建＆＃34;
输入其中一个值＆＃34; FEATURE_SOCKET_EAP＆＃34;或＆＃34; FEATURE_SOCKET_SYNC＆＃34;进入字段＆＃34;条件编译符号＆＃34;。

另见：https://csharp.2000things.com/tag/conditional-compilation/

编译器`#error` inline条件是未定义的变量在编译时抛出错误。我怎样才能解决这个问题？

1 个答案: