Database Ownership of Objects

An object that is implicitly owned by the database rather than another database object is called a root object. The database contains ten root objects: the nine symbol tables and the named object dictionary. All filing operations begin by filing out the root objects of the database. See Object Filing.

With the exception of root objects, every object in the database must have an owner, and a given object can have only one owner. The database is a tree created by this hierarchy of owned objects. The following call adds an object to the database and assigns an ID to it, but the object does not yet have an owner:

db->addAcDbObject(...);

Usually, you will add the object to its owner using a member function that simultaneously adds it to the database, such as the AcDbBlockTableRecord::appendAcDbEntity() function, which performs both tasks at once.

AutoCAD ownership connections are as follows:

• Only block table records can own entities. All objects of classes derived (directly or indirectly) from AcDbEntity must be owned by AcDbBlockTableRecord
• Each symbol table owns a particular type of symbol table record.
• An AcDbDictionary object can own any AcDbObject object.
• Any AcDbObject object can have an extension dictionary; an object owns its extension dictionary.

In addition, applications can set up their own ownership connections.