Acad::ErrorStatus
upgradeOpen();
If the object is currently open AcDb::kForRead with only one reader, then this function upgrades the object to open AcDb::kForWrite. In the process of changing to open for write, the object is closed, thus triggering any pertinent notification. Returns Acad::eOk if successful. If the object has more than one reader, then the open status is not changed and Adesk::eHadMultipleReaders is returned. If the object is already open AcDb::kForWrite, then Acad::eWasOpenForWrite is returned. If the object is currently sending notification, then the open status is not changed and Acad::eWasNotifying is returned.
Note A call of this function does not need to be matched with a call to downgradeOpen(), since a call to close() or cancel() will sufficiently cleanup the entity抯 open state.
注意这个函数中的说明 If the object has more than one reader, then the open status is not changed and Adesk::eHadMultipleReaders is returned |