Re: [Boost-users] revisiting casting a boost::shared_ptr to void*

Subject: Re: [Boost-users] revisiting casting a boost::shared_ptr to void*
From: Michael Powell (mwpowellhtx_at_[hidden])
Date: 2014-07-29 22:01:51

On Tue, Jul 29, 2014 at 11:30 AM, Michael Powell <mwpowellhtx_at_[hidden]> wrote:
> On Tue, Jul 29, 2014 at 11:25 AM, Chris Cleeland
> <chris.cleeland_at_[hidden]> wrote:
>>
>>
>>
>> On Tue, Jul 29, 2014 at 11:02 AM, Michael Powell <mwpowellhtx_at_[hidden]>
>> wrote:
>>>
>>> Along the lines what Edward suggested, if the "origin" of the pointer
>>> is your thread, then somehow you need to make sure that memory lives
>>> beyond the lifetime of the external, in this case C, API, context and
>>> all, etc, etc. No room for debate in that topic; it is what it is,
>>> deal with it in a responsible manner.
>
> The C API is not managing the life time of the instance allocated to
> the shared_ptr. When the shared_ptr<> falls out of scope, all bets are
> off. Plain and simple.

Not to beat a dead horse. But here's an apt analogy: I could be wrong,
but you are dividing by zero and not expecting a div by zero exception
(or worse) to occur.

>> Yes, I agree that I'm responsible.  If I didn't know or think that, then I
>> wouldn't have asked the question in the first place.
>>
>> I'm not debating whether or not I *should* be responsible--I'm asking a
>> question related to best-practices for fulfilling that responsibility in the
>> absence of the ability to use a shared pointer and its concomitant semantics
>> everywhere the pointer is held. While I appreciate your response and
>> Edward's response, neither answers the question asked.
>>
>> Thanks to Dominique for sharing a technique.  I hadn't thought of using a
>> heap-allocated shared pointer instance as the proxy.  I had thought of
>> stashing another shared pointer instance in the C++ object that manages the
>> callback registration itself, but wasn't sure if that lifecycle would
>> coincide exactly.  The heap is probably the better of the two since it
>> dissociates all lifecycles.
>>
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