For those interested, It appears the reason was because of a compiler error I hit, and didn't ask about, or really worry how to resolve it. :-/ Function declaration: typedef boost::function < VSSP ( std::string, EncodingEnum) > CreateTypeFunc; bool ElementBase::disconnectCreateTypeSignal(const CreateTypeFunc& slot) { LOG4CXX_DEBUG(logger_, "disconnectCreateTypeSignal in"); bool retValue = false; createTypeSignal_.disconnect(slot); <snip!> } Error: (apologies for the length) c:\Program Files\boost\boost_1_35_0\boost\signals\signal_template.hpp(242) : error C2666: 'boost::operator`=='' : 4 over loads have similar conversions; c:\Program Files\boost\boost_1_35_0\boost\function\function_base.hpp(669): could be 'boo st::enable_if_c<B,T>::type boost::operator ==<boost::signal2<R,T1,T2,Combiner,Group,GroupCompare,SlotFunction>::slo t_fun ction_type>(Functor,const boost::function_base &) with [B=true,T=bool,R=boost::detail::function_traits_helper<boost::add _pointer<boost::shared_ptr<model::VariantStorage> (std::string,model::EncodingEnum::EncodingEnum)>::type>::result_type,T 1=boost::detail::function_traits_helper<boost::add_pointer<boost::shared _ptr<model::VariantStorage> (std::string,model:: EncodingEnum::EncodingEnum)>::type>::arg1_type,T2=boost::detail::functio n_traits_helper<boost::add_pointer<boost::shared _ptr<model::VariantStorage> (std::string,model::EncodingEnum::EncodingEnum)>::type>::arg2_type,Combi ner=boost::last_valu e<boost::detail::function_traits_helper<boost::add_pointer<boost::shared _ptr<model::VariantStorage> (std::string,model:: EncodingEnum::EncodingEnum)>::type>::result_type>,Group=int,GroupCompare =std::less<int>,SlotFunction=boost::function<mod el::VariantStorageSharedPtr (std::string,model::EncodingEnum::EncodingEnum)>,Functor=boost::signal2< boost::detail::funct ion_traits_helper<boost::add_pointer<boost::shared_ptr<model::VariantSto rage> (std::string,model::EncodingEnum::Encoding Enum)>::type>::result_type,boost::detail::function_traits_helper<boost:: add_pointer<boost::shared_ptr<model::VariantStor age> (std::string,model::EncodingEnum::EncodingEnum)>::type>::arg1_type,boost ::detail::function_traits_helper<boost::add _pointer<boost::shared_ptr<model::VariantStorage> (std::string,model::EncodingEnum::EncodingEnum)>::type>::arg2_type,boo st::last_value<boost::detail::function_traits_helper<boost::add_pointer< boost::shared_ptr<model::VariantStorage> (std::s tring,model::EncodingEnum::EncodingEnum)>::type>::result_type>,int,std:: less<int>,boost::function<model::VariantStorageS haredPtr (std::string,model::EncodingEnum::EncodingEnum)>>::slot_function_type]'; c:\Program Files\boost\boost_1_35_0\bo ost\function\function_base.hpp(660): or 'boost::enable_if_c<B,T>::type boost::operator ==<Function>(const boost::f unction_base &,Functor) with [B=true,T=bool,Function=model::ElementBase::CreateTypeFunc,Functor=model ::ElementBase::Crea teTypeFunc]'; c:\Program Files\boost\boost_1_35_0\boost\function\function_template.hpp(832): or 'void boost::opera tor ==<R,T0,T1,Allocator>(const boost::function2<R,T0,T1,Allocator> &,const boost::function2<R,T0,T1,Allocator> &) with [R=model::VariantStorageSharedPtr,T0=std::string,T1=model::EncodingEnum: :EncodingEnum,Allocator=std::allocator<void>]'; or 'built-in C++ operator==(boost::function2<R,T0,T1,Allocator>::safe_bool with [R=model::VariantStorageSharedPtr, T0=std::string,T1=model::EncodingEnum::EncodingEnum,Allocator=std::alloc ator<void>], boost::function2<R,T0,T1,Allocator> ::safe_bool with [R=model::VariantStorageSharedPtr,T0=std::string,T1=model::EncodingEnum: :EncodingEnum,Allocator=std::al locator<void>])'; while trying to match the argument list '(boost::signal2<R,T1,T2,Combiner,Group,GroupCompare,SlotFunct ion>::slot_function_type with [R=boost::detail::function_traits_helper<boost::add_pointer<boost::share d_ptr<model::Varia ntStorage> (std::string,model::EncodingEnum::EncodingEnum)>::type>::result_type,T1= boost::detail::function_traits_helper <boost::add_pointer<boost::shared_ptr<model::VariantStorage> (std::string,model::EncodingEnum::EncodingEnum)>::type>::ar g1_type,T2=boost::detail::function_traits_helper<boost::add_pointer<boos t::shared_ptr<model::VariantStorage> (std::strin g,model::EncodingEnum::EncodingEnum)>::type>::arg2_type,Combiner=boost:: last_value<boost::detail::function_traits_helper <boost::add_pointer<boost::shared_ptr<model::VariantStorage> (std::string,model::EncodingEnum::EncodingEnum)>::type>::re sult_type>,Group=int,GroupCompare=std::less<int>,SlotFunction=boost::fun ction<model::VariantStorageSharedPtr (std::strin g,model::EncodingEnum::EncodingEnum)>], const model::ElementBase::CreateTypeFunc)'; c:\Program Files\boost\boost_1_35_0\ boost\signals\signal_template.hpp(224) : see reference to function template instantiation 'void boost::signal2<R,T1,T2,C ombiner,Group,GroupCompare,SlotFunction>::do_disconnect<T>(const Function &,boost::mpl::bool_<C_>) with [R=boost::detail ::function_traits_helper<boost::add_pointer<boost::shared_ptr<model::Var iantStorage> (std::string,model::EncodingEnum::E ncodingEnum)>::type>::result_type,T1=boost::detail::function_traits_help er<boost::add_pointer<boost::shared_ptr<model::V ariantStorage> (std::string,model::EncodingEnum::EncodingEnum)>::type>::arg1_type,T2=bo ost::detail::function_traits_help er<boost::add_pointer<boost::shared_ptr<model::VariantStorage> (std::string,model::EncodingEnum::EncodingEnum)>::type>:: arg2_type,Combiner=boost::last_value<boost::detail::function_traits_help er<boost::add_pointer<boost::shared_ptr<model::V ariantStorage> (std::string,model::EncodingEnum::EncodingEnum)>::type>::result_type>,Gr oup=int,GroupCompare=std::less<in t>,SlotFunction=boost::function<model::VariantStorageSharedPtr (std::string,model::EncodingEnum::EncodingEnum)>,T=model: :ElementBase::CreateTypeFunc,Function=model::ElementBase::CreateTypeFunc ,C_=false]' being compiled; c:\Documents and Set tings\td26134\Desktop\trunk1\src\model\ElementBase.cpp(440) : see reference to function template instantiation 'void boo st::signal2<R,T1,T2,Combiner,Group,GroupCompare,SlotFunction>::disconnec t<model::ElementBase::CreateTypeFunc>(const T &) with [R=boost::detail::function_traits_helper<boost::add_pointer<boost::share d_ptr<model::VariantStorage> (std::string, model::EncodingEnum::EncodingEnum)>::type>::result_type,T1=boost::detail ::function_traits_helper<boost::add_pointer<boos t::shared_ptr<model::VariantStorage> (std::string,model::EncodingEnum::EncodingEnum)>::type>::arg1_type,T2=bo ost::detail ::function_traits_helper<boost::add_pointer<boost::shared_ptr<model::Var iantStorage> (std::string,model::EncodingEnum::E ncodingEnum)>::type>::arg2_type,Combiner=boost::last_value<boost::detail ::function_traits_helper<boost::add_pointer<boos t::shared_ptr<model::VariantStorage> (std::string,model::EncodingEnum::EncodingEnum)>::type>::result_type>,Gr oup=int,Gro upCompare=std::less<int>,SlotFunction=boost::function<model::VariantStor ageSharedPtr (std::string,model::EncodingEnum::E ncodingEnum)>,T=model::ElementBase::CreateTypeFunc]' being compiled scons: *** [build_dir\Windows\src-model\ElementBase.obj] Error 2