Microsoft Specific
A _com_ptr_t object encapsulates a COM interface pointer and is called a “smart” pointer. This template class manages resource allocation and deallocation, via function calls to the IUnknown member functions: QueryInterface, AddRef, and Release.
A smart pointer is usually referenced by the typedef definition provided by the _COM_SMARTPTR_TYPEDEF macro. This macro takes an interface name and the IID, and declares a specialization of _com_ptr_t with the name of the interface plus a suffix of Ptr. For example,
_COM_SMARTPTR_TYPEDEF(IMyInterface, __uuidof(IMyInterface));declares the _com_ptr_t specialization IMyInterfacePtr.
A set of function templates, not members of this template class, support comparisons with a smart pointer on the right-hand side of the comparison operator.
#include <comdef.h>
Compiler COM Support Class Overview
Construction
| _com_ptr_t | Constructs a _com_ptr_t object. |
Low-level Operations
| AddRef | Calls the AddRef member function of IUnknown on the encapsulated interface pointer. |
| Attach | Encapsulates a raw interface pointer of this smart pointer’s type. |
| CreateInstance | Creates a new instance of an object given a CLSID or ProgID. |
| Detach | Extracts and returns the encapsulated interface pointer. |
| GetActiveObject | Attaches to an existing instance of an object given a CLSID or ProgID. |
| GetInterfacePtr | Returns the encapsulated interface pointer. |
| QueryInterface | Calls the QueryInterface member function of IUnknown on the encapsulated interface pointer. |
| Release | Calls the Release member function of IUnknown on the encapsulated interface pointer. |
Operators
| operator = | Assigns a new value to an existing _com_ptr_t object. |
| operators ==, !=, <, >, <=, >= | Compare the smart pointer object to another smart pointer, raw interface pointer, or NULL. |
| Extractors | Extract the encapsulated COM interface pointer. |
END Microsoft Specific