Attribute Macro com_class 

#[com_class]

Defines a COM class that implements one or more COM interfaces.

#[com_class(CLSID, interfaces...)]
struct S { /* ... */ }

• CLSID - A unique ID of the exposed class. The clients use the class ID to specify the class when they want to construct an object. The value must be a valid GUID, AUTO_GUID or NO_GUID.
• interfaces - Any number of interfaces that the class implements.

Associated types: struct, enum

If the CLSID is specified as NO_GUID, the class cannot be constructed by the clients. It can still be returned as a return value from other intercom methods.