Re: std::auto_ptr with malloc

From:

"Greg Herlihy" <greghe@pacbell.net>

Newsgroups:

comp.lang.c++.moderated

Date:

15 Dec 2006 08:26:12 -0500

Message-ID:

<1166092789.852769.160550@80g2000cwy.googlegroups.com>

Ivan Novick wrote:

Hi,

Is it correct to assume that std::auto_ptr will call delete and not
free, and that if memory is allocated with malloc that using the
std::auto_ptr class is not safe?

If this is the case, then does anyone know of a way to make this class
use free instead of delete and or is there another class that is
already in use that can will do free instead of malloc?

There is another class that can be used to free malloc'ed blocks. In
fact, it's looks like this:

     struct StMalloc
     {
         StMalloc(void *p = NULL)
             : p_( p)
         {
         }

         void * get() const { return p_; }

         ~StMalloc()
         {
             if ( p_ != NULL)
                 free( p_);
         }

     private:
         void operator=(void *) const;
              StMalloc(const StMalloc& );

         void * p_;
     };

StMalloc is not as widely known as std::auto_ptr, but then give it
time, it is only a few minutes old. :-) I guess my point is that -
unlike shared pointers which are tricky to implement - all stack-based
resource manager classes follow the same basic pattern. So if you can't
find an existing class that you like, write one yourself, or use mine
(just be sure to test it first if you do).

Greg

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