CComObject

CComObject is a template class found in Microsoft's Active Template Library (ATL) that provides a concrete implementation of a COM object. It is designed to be instantiated by ATL's aggregation mechanisms, specifically through the CComCoClass template. When you derive a class from CComObject, you are essentially creating a COM server that can be instantiated and managed by the COM runtime.

The primary purpose of CComObject is to handle the complexities of COM object creation and management, such as reference counting and interface querying. It typically works in conjunction with other ATL classes like CComObjectRootEx, which manages the object's lifetime and aggregation state, and CComCoClass, which provides the factory mechanism for creating instances of the CComObject-derived class.

When a COM client requests an interface from an object created using CComObject, the CComObjectRootEx base class intercepts the `QueryInterface` call. It then uses the information provided by the CComCoClass to determine which interfaces the object supports and returns the appropriate interface pointer. Similarly, `AddRef` and `Release` calls are handled by the reference counting mechanism within CComObjectRootEx, ensuring the object is properly deallocated when no longer in use.

In essence, CComObject simplifies the process of writing COM components by abstracting away much of the low-level COM boilerplate code. Developers can focus on implementing their COM interfaces and business logic, relying on CComObject and its associated ATL classes to manage the underlying COM infrastructure.