Re: [Boost-users] true typedef (true_typedef) implemented in boost?

Subject: Re: [Boost-users] true typedef (true_typedef) implemented in boost?
From: Stefan Strasser (strasser_at_[hidden])
Date: 2010-07-17 11:54:41

Zitat von Robert Ramey <ramey_at_[hidden]>:

> Stefan Strasser wrote:
>> Zitat von Ryan Gallagher <ryan.gallagher_at_[hidden]>:
>>
>>> alfC <alfredo.correa <at> gmail.com> writes:
>>>
>>>> I stumbled upon the concept of true typedef, or strong typedef in
>>>> opposition to usual typedef which are weak.
>>> [snip]
>>>> I was wondering if this is already implemented in some corner of
>>>> Boost, or as a detail implementation.
>>>
>>> There's a detail impl in serialization, I believe.
>>> Search for BOOST_STRONG_TYPEDEF
>>
>> there is more interesting stuff in Boost.Seriailzation that could be
>> part of boost in general.
>>  - especially seriailzation::singleton, because it requires linking
>> to the serialization library even though you don't serialize anything.
>
> Hmmm - the whole purpose of boost::serialization::singleton was to be
> header only and require no linking against any other library.  Did
> I get this wrong?

I just remember that I got linking errors related to singletons when  
using them in (Boost.)Intro. but I'll doublecheck, maybe I'm using  
something else from Boost.Seriailzation that caused these.

>
>>  - ptr_serialization_support in
>> http://www.boost.org/doc/libs/1_41_0/boost/serialization/export.hpp
>> which forces instantiation of a function.
>
>> this apparently cannot be
>> implemented platform independently, so Boost.Config might be the right
>> library for it?
>
> These are related to boost::serialization::extended_type_info which extends
> the standard type_info facility in accordance with the needs of boost
> serialization.  This results (sort of as a side effect) support for runtime
> plugin - sort of like a poor man's C++ COM.

I'm not sure if we're talking about the same thing here as I don't see  
the connection. I meant mostly this code:

template <class Archive, class Serializable>
struct ptr_serialization_support
{
# if defined(BOOST_MSVC) || defined(__SUNPRO_CC)
     virtual BOOST_DLLEXPORT void instantiate() BOOST_USED;
# elif defined(__BORLANDC__)
     static BOOST_DLLEXPORT void instantiate() BOOST_USED;
     enum { x = sizeof(instantiate(),3) };
# else
     static BOOST_DLLEXPORT void instantiate() BOOST_USED;
     typedef instantiate_function<
         &ptr_serialization_support::instantiate
     > x;
# endif
};

which forces instantiations in order to register serializers as part  
of static initialization.
AFAIK there is no way in C++ or boost to initialize data on startup  
that is not specifically referred to (like in a static variable), but  
only modifies static data. like you do in Boost.Serialization to  
create the serializer maps.