Re: [Boost-users] Boost.Utility/Singleton Problem when using with dynamic libraries

Hello, Unfortunately I still need help with these problems please. Is there anybody who could explain me how to use the Boost.Utilty/Singleton with dlls? The test examples of the singleton didn't clearify for me, how I can do this. Best regards Niklas

Hello, I want to use the Boost.Utility/Singleton together with dll's. I use the Visual Studio 2005 and Windows XP. I have three dynamic libraries. In library A the Singleton is implemented and library B and C access to the Singleton. The dynamic libraries B and C

are compiled with the clr compiler Option. The Problem is, that the Singleton will be twice instantiated when library A and B access to the singleton.

The singleton declaration looks like the following code: //Singleton.h class Singleton : public boost::singleton { public: CPP_API Singleton (boost::restricted); … BOOST_SINGLETON_PLACEMENT_DECLARATION … } CPP_API is a definition of the dll export.

#if defined( _WIN32 ) && defined( _MSC_VER ) # if defined SINGLETON_EXPORTS # define CPP_API __declspec( dllexport ) # else # define CPP_API __declspec( dllimport ) # pragma warning( disable : 4251 ) // 'identifier' : class 'type' needs to have dll-interface to be used by clients of class 'type2'

# endif #endif

In the Project properties of library B and C in "additional linkage input" I included the import library of the dll A.

Another problem is, that the application crashes when I close the application. The crash happens in C.dll!_CRT_INIT(void * hDllHandle=0x0f8b0000, unsigned long dwReason=0, void * lpreserved=0x00000001) line 420 -> _free_crt ( onexitbegin ) ; And also : B.dll!_CRT_INIT(void * hDllHandle=0x0f8b0000, unsigned long dwReason=0, void * lpreserved=0x00000001) line 420 -> _free_crt ( onexitbegin ) ; If I don't use the singleton, the application will not crash.

Another Problem is, that I can not compile the following code:

class DataPoolManagerImpl : public boost::mutexed_singleton {

Then I will get the following error message:

boost\utility\mutexed_singleton.hpp(212) : error C2248: "boost::mutexed_singleton::instance_proxy": cannot access private class, which is declared in boost::mutexed_singleton

with [ Derived=DataPoolManagerImpl, DisposalSlot=2 ] \boost\utility\mutexed_singleton.hpp(41): see declaration of 'boost::mutexed_singleton::instance_proxy'

with [ Derived=DataPoolManagerImpl, DisposalSlot=2 ] \boost\utility\mutexed_singleton.hpp(211): During compiling the class template of the static data member "const boost::mutexed_singleton::instance_proxy boost::mutexed_singleton::instance".

with [ Derived=DataPoolManagerImpl, DisposalSlot=2, SubsystemTag=datapoollib_tag ] \datapoolmanager.h(43): see reference of instantiation of compiled class template "boost::mutexed_singleton".

with [ DataPoolManagerImpl, DisposalSlot=2, datapoollib_tag ] \boost\utility\mutexed_singleton.hpp(212) : error C2440: Initialization': 'boost::mutexed_singleton::instance_proxy' could not converted in 'boost::mutexed_singleton::instance_proxy'

with [ Derived=DataPoolManagerImpl, DisposalSlot=2 ]

With : class DataPoolManagerImpl : public boost::singleton There are no compiler errors.

Could you tell me how I can solve these problems please? Thank you for your help in advance and best regards Niklas

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