Re: Is this the Right way TO release COM interface ?

From:

=?Utf-8?B?U2FjaGlu?= <Sachin@discussions.microsoft.com>

Newsgroups:

microsoft.public.vc.language

Date:

Tue, 21 Apr 2009 04:51:01 -0700

Message-ID:

<06E39516-0C26-4A0C-B755-A212FB5C4C55@microsoft.com>

what will happen if i assign a CComPtr to a naked Interface pointer

TestMe()
{
IFolder* naked;
CComPtr<IFolder*> sFolder;

// say i acquire it by some mean
::GetFolder (&sFolder);

naked = sFolder;

}

will there be only one object created for Folder interface ?

Is there any leak ?
I assume that smart pointer class object sFolder will release
automatically when function returns.

"Sachin" wrote:

that was very Good Suggestion.. Thanks A lot..

few answers to your queries

1. > // 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?

-> There could be few unhanded exception ( C RunTime exception ) which wont
be caught in our custom handlers ..

2. I hope the CComPtr will release the resource when the immediate enclosing
bracket goes out of scope irrespective of how it unwinds ( function returns
or exception time stack unwinding because the earlier solution i used was
full proof for this condition)

      void func()
      {

          {
                CComPtr<IMAPITable> spContents;
          }// here spContents will be released

        }

or do i have to explicitely set it to NULL ?
spContent = NULL;

3. may be linked with above point when you say
"The only weakness is the & operato" Does that mean

// WRONG ?
for ( int i = 0; i<10; i++)
{
     CComPtr<IMAPITable> spTable;
     folder->GetContentsTable(&spTable);
}

// RIGHT
CComPtr<IMAPITable> spTable;
for ( int i = 0; i<10; i++)
{
   spTable = NULL;
     folder->GetContentsTable(&spTable);
}

// WRONG
CComPtr<IMAPITable> spTable;
for ( int i = 0; i<10; i++)
{
     folder->GetContentsTable(&spTable);
}