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

From: james.jones_at_[hidden]
Date: 2006-12-12 10:58:19

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.

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