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### 7.6 CORBA and other Interfaces

COM is not the only architecture where interfaces are used. CORBA knows interfaces, UNO (the OpenOffice API) uses interfaces, and Java as well. These languages do not know the IUnknown interface used as the basis of all interfaces in COM. It would therefore be a bad idea if an interface automatically descended from IUnknown if no parent interface was specified. Therefore, a directive {$INTERFACES} was introduced in Free Pascal: it specifies what the parent interface is of an interface, declared without parent. More information about this directive can be found in the Programmer’s Guide.

Note that COM interfaces are by default reference counted, because they descend from IUnknown.

Corba interfaces are identified by a simple string so they are assignment compatible with strings and not with TGUID. The compiler does not do any automatic reference counting for the CORBA interfaces, so the programmer is responsible for any reference bookkeeping.

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