Re: [Boost-users] how to work with shared pointers to avoid clumsiness

Subject: Re: [Boost-users] how to work with shared pointers to avoid clumsiness
From: Jon Biggar (jon_at_[hidden])
Date: 2008-12-03 09:25:22

Roman Shmelev wrote:
> Hi,
> 
> I've tried to read boost docs and some forums but still cannot
> understand how to make things simple and right.
> 
> 1) I have an object that is dynamically allocated and I want it to
> delete itself (so I understood I need to use shared_ptr)
> 2) The object must be deleted not after the last shared_pointer to it
> will be destroyed, because some external functions will call it later
> one more time. And then it must be destroyed.
> 3) Of course, that external functions cannot accept shared_ptrs.
> 4) So, I need my object to know when all shared_ptrs to it are
> destroyed. Then it sets some flag (I_CAN_DESTROY_MYSELF_SOON) and when
> some external code (that holds simple pointer to this object) will
> call its function, then it will destroy itself.
> 
> How to solve this in an elegant way?
> I'm currently do not use shared_ptr, but my implementation is cumbersome.
> 
> Maybe I need one more shared_ptr inside the object.. I don't know.

You could use a custom deleter function that, instead of deleting the 
object, calls a method that sets the "I_CAN_DESTROY_MYSELF_SOON" flag.

Of course you're risking memory leaks if the expected function call 
never occurs.

-- 
Jon Biggar
jon_at_[hidden]
jon_at_[hidden]
jonbiggar_at_[hidden]