Question

可以看到的是，链表支持如，整形、句柄、指针、字符串的存储，而在存储中，对于每一个节点的类型设置“restype”必须与存储的数据类型（mds_u_val联合下的数据类型）对应，如此实例中的设置扩展数据代码段：

	 resbuf* pExDataRb = nullptr;
	 std::vector <resbuf*> vBuf;
	 resbuf* pLastNode = nullptr;
	 auto CreateNewXData = [&]() {

		 pLastNode = pExDataRb = acutBuildList(AcDb::kDxfRegAppName, sTemp, 0);

		 m_mRealNum.GetWindowTextW(sTemp);
		 if (sTemp.GetLength())
		 {
			 auto pBuf = acutBuildList(AcDb::kDxfXdReal, _wtof(sTemp), 0);
			 pLastNode->rbnext = pBuf;
			 pLastNode = pLastNode->rbnext;
			 vBuf.push_back(pBuf);
		 }
		 m_mShortNum.GetWindowTextW(sTemp);
		 if (sTemp.GetLength())
		 {
			 auto pBuf = acutBuildList(AcDb::kDxfXdInteger16, _wtoi(sTemp), 0);
			 pLastNode->rbnext = pBuf;
			 pLastNode = pLastNode->rbnext;
			 vBuf.push_back(pBuf);
		 }
		 m_mLongNum.GetWindowTextW(sTemp);
		 if (sTemp.GetLength())
		 {
			 auto pBuf = acutBuildList(AcDb::kDxfXdInteger32, _wtoi(sTemp), 0);
			 pLastNode->rbnext = pBuf;
			 pLastNode = pLastNode->rbnext;
			 vBuf.push_back(pBuf);
		 }
		 m_mString.GetWindowTextW(sTemp);
		 if (sTemp.GetLength())
		 {
			 auto pBuf = acutBuildList(AcDb::kDxfXdAsciiString, sTemp, 0);
			 pLastNode->rbnext = pBuf;
			 pLastNode = pLastNode->rbnext;
			 vBuf.push_back(pBuf);
		 }

		 CString sTempY, sTempZ;
		 {
			 m_m3dVectorX.GetWindowTextW(sTemp);
			 if (!sTemp.GetLength())
				 return;
			 m_m3dVectorY.GetWindowTextW(sTempY);
			 if (!sTempY.GetLength())
				 return;
			 m_m3dVectorZ.GetWindowTextW(sTempZ);
			 if (!sTempZ.GetLength())
				 return;
			 mds_real vVec[] = { _wtof(sTemp),_wtof(sTempY),_wtof(sTempZ) };
			 auto pBuf = acutBuildList(AcDb::kDxfXdXCoord, vVec, 0);
			 pLastNode->rbnext = pBuf;
			 pLastNode = pLastNode->rbnext;
			 vBuf.push_back(pBuf);
		 }
	 };

上述代码段中，我们再次使用到了acutBuildList宏，在构造选择集的介绍文章中我们已对该宏进行了介绍，再次不再赘述。而在构造扩展数据时，大致的结构如下：