Re: [Boost-users] serializable any

From: Robert Ramey (ramey_at_[hidden])
Date: 2008-08-09 18:38:36

troy d. straszheim wrote:
> Robert Ramey wrote:
>> troy d. straszheim wrote:
>>>> Hey,
>>>>
>>>> Here's an autoregistering serializable any, I think it qualifies as
>>>> hacky
>>>> and suboptimal.  Of course the typeid(T).name() strings aren't
>>>> portable,
>>
>> if you use serialization/extended_type_info, instead of
>> typeid(T)name() you can use the strings used by BOOST_CLASS_EXPORT
>> which are portable.
>
> Hm, I don't quite follow...
>
>   BOOST_CLASS_EXPORT(T)
>
> just associates "T" with typename T.  Maybe one could cobble together
> something like
>
>   BOOST_ANY_EXPORT(U)
>
> which would expand to something like
>
>   BOOST_CLASS_EXPORT_GUID(boost::any::holder<U>, "boost_any_holder_"
> BOOST_PP_STRINGIZE(U))

Something like that

> But one of the OP's requirements was that a list of instantiations of
> anys not be necessary.  Do we want to toss that requirement
> in favor of moving closer to something that could actually go into the
> library... or what am I missing?

Hmm - I don't think you're missing anything.  You're right, if you use
typeid() you don't have to "predeclare" anything - but it can't be used to
create portable archives.  That's the whole justification for creating
BOOST_CLASS_EXPORT...

Basically, either one has to do one of the following:

a) except the fact that in some sense one has to "declare" any<U> as being 
"exportable"
b) eliminated the heretofore enforced requirement that archives be portable.

So far we've done a) - hence shared_ptr serialization has a macro (whose 
name
I forget) to handle a situation.  Leveraging on this concept - and 
diminishing
the proliferation of special cases would argue for something similer in 
other special
cases - like boost::any

Robert Ramey

PS:what does OP stand for?