Re: Is this the Right way TO release COM interface ?
Hi Sachin,
My concern is avoiding Memory leaks or dangling interfaces. So i hace
implemented RAII ( resource acquisition is Initialisation ) kind of
technique
in most of functions. to give you equivalent example it goes like ...
void func( IMAPIfolder* f)
{
IMAPIfolder * folder = f;
IMAPITable *contents = NULL;
folder->GetContentsTable(&contents);
// This class will be responsible to release the content interface in
//its destructor
CSmartFolderContent fcontent(contents);
You can use
CComPtr<IMAPITable> spContents;
folder->GetContentsTable(&spContents);
instead. The CComPtr template class is designed for this
try
{
// some processing
// call another function
}
// not all exception will be catched so i cant release content here
Why are you not catching all possible exceptions?
Are the caught higher in the call stack?
catch(my_exception e)
You should catch exceptions by reference to avoid the
creation of temporary objects:
catch(my_exception& e)
is there any harm for assigning and releasing COM interfaces like this ?
except double releasing i think there is no harm in this type of strategy
..
CComPtr has the advantage that you only have one variable to access the
interface pointer, compared to your two variables contents and fontents.
And CComPtr implement assignment and copy operators to properly
call AddRef and Release as needed.
The only weakness is the & operator, when used to assign a new interface
pointer to the smart pointer. You have to clear the smart pointer before
reusing its & operator.
CComPtr<IMAPITable> spTable;
folder->GetContentsTable(&spTable);
// wrong:
folder->GetContentsTable(&spTable); // the second & call will leak
// correct:
spTable = NULL; // this releases the interface pointer
folder->GetContentsTable(&spTable); // before overriding it
--
SvenC