Its not a policy that including serialization trigger autolinking. If it currently does, it contravenes my intention. When I last looked at this I wasn't convinced this was actually happening. I took precautions to avoid this and felt it was addressed. Your detailed investigation motivates me to look again and more carefully. It is also helpful for showing me where to look. I'll do this. Thanks for sheding light on this. I've been a little bogged down in this area as now the auto-linking of DLLS on vc6 and vc7 stopped working. I'm not sure why this is. Its only a problem on with these compilers. I'm still bogged down on this. Robert Ramey P.S. The local macro IMPORT is to trigger the autolinking for DLL import library. I'm sort of suspicious of this as I made a change here to address a problem when compiling from the VC IDE. RR Joaquín Mª López Muñoz wrote:
Allow me to repost a digest of my last two messages about the issue of autolinking in Boost.Serialization. If the final decision is to *not* adhere to my proposed policy, I'd be grateful to know asap, so that I can hack my way in my own source code. Thank you,
Joaquín M López Muñoz Telefónica, Investigación y Desarrollo
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I humbly request that you reconsider your design so that the following guarantee is honored:
* (A) Any code including *only* boost/serialization/*.hpp headers won't trigger autolinking of Boost.Serialization.
The following is a rationale for this policy: a 3rd party library that provides *intrusive* serialization capabilities will most likely need to include some of boost/serialization/*.hpp. If those headers trigger autolinking, the user will face the annoying fact that Boost.Serialization is autolinked even if she didn't explicitly try to use serialization at all. Granted, if the serialization capabilities of the 3rd party library are not taking advantge of, autolinking will ultimately have no effect on the final binary, but the point is that the user will be forced nonetheless to have the Boost.Serialization lib built and available. This is most unfortunate in the case the 3rd party library is a header-only lib, since the user may very well be using it without having built anything from Boost. This is exactly what's happening now with Boost.MultiIndex.
Autolinking is triggered by the (implicit) inclusion of boost/serialization/config.hpp. This header is in turn included by void_cast.hpp and extended_type_info.hpp, and if you pull out from this thread it turns out virtually any boost/serialization/*.hpp header will trigger autolinking. To honor (A), you just have to remove the inclusion of boost/serialization/config.hpp by the aforementioned void_cast.hpp and extended_type_info.hpp. From what I can see, the inclusion is done so as to bring in the definition of BOOST_SERIALIZATION_DECL, so in principle having this macro defined in a separate header would suffice.
If (A) is honored, autolinking will be triggered only when including boost/archive/*.hpp headers, which IMHO is just fine, since these are a sure sign that the user (not the 3rd party library) is explicitly requesting serialization capabilities and will welcome the autolinking stuff.
I have inspected the source code and looks like autolinking is triggered in three points:
boost/serialization/config.hpp boost/archive/detail/auto_link_archive.hpp boost/archive/detail/auto_link_warchive.hpp
So, it seems like my proposal boils down to removing autolinking from the first header. As a proof of concept, I've done so (see attached modified source); with this changes in place, my local tests seem to indicate that: * Autolinking does not kick in if including only boost/serialization/*.hpp headers. * Autolinking still works if including any of boost/archive/*.hpp. boost/serialization/config.hpp has a local macro named IMPORT whose semantics escapes me, so I might be missing something.
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