The generic function com-object-query-interface
is called by the built-in implementation of query-interface
for the class standard-i-unknown. The built-in primary method specializing on standard-i-unknown
handles the i-unknown
interface and all the interfaces specified by the define-com-implementation
form for the class of object.
In most cases, there is no need to specialize this generic function for user-defined classes.
LispWorks COM/Automation User Guide and Reference Manual - 23 Mar 2017