Re: [Boost-users] shared_ptr with custom free function

From: Ovanes Markarian (om_boost_at_[hidden])
Date: 2006-12-12 11:54:23

In addition,
You could specify a custom deleter, which is supported by the shared_ptr. 

In your case it can be something like:

struct Deleter
{
        void operator ()(blob* pblob)
        {
                free_blob(pblob);
        }
};

shared_ptr<blob>   blob_ptr(create_blob(), Deleter());

Good Luck,
Ovanes

-----Original Message-----
From: james.jones_at_[hidden] [mailto:james.jones_at_[hidden]]

Sent: Tuesday, December 12, 2006 4:58 PM
To: boost-users_at_[hidden]
Subject: Re: [Boost-users] shared_ptr with custom free function

From: "Phil Endecott" <spam_from_boost_users_at_[hidden]>
> I have a C library that returns pointers to structs, and has special 
> free functions that I must call to finalise and free these structs. Is 
> there any way that I can create a shared_ptr that will call this 
> special library free function when the last copy is destroyed? I was 
> hoping that there would be some way of achieving this by overloading 
> operator delete, but it seems not. Any ideas?

I would think one solution would be simply to wrap your C struct in a C++
class with a constructor and a destructor, then use shared_ptr on the C++
struct. Example:

C:

struct blob { ... };

blob * create_blob ();
void free_blob(blob *);

C++:

class foo
{
public:
        foo() : data(create_blob())	{}
        ~foo() { free_blob(data); }
private:
        blob * data;
};

Now use shared_ptr< foo > as you usually would. This also gives you the
flexibility NOT to use shared_ptr if you choose.

-
James Jones             Administrative Data Mgmt.
Webmaster               375 Raritan Center Pkwy, Suite A
Data Architect          Edison, NJ 08837
_______________________________________________
Boost-users mailing list
Boost-users_at_[hidden]
http://lists.boost.org/mailman/listinfo.cgi/boost-users