March 2006 - Boost - lists.boost.org

[optional] swap initialized with uninitialized
by Vaclav Vesely 10 Mar '06

10 Mar '06

Hi, When two optionals are swaped and only one is initialized, then wrapped value in the uninitialized optional is constructed and that in initialized one is destroyed. It's maybe not necessary. It should be sufficient and more effective to swap optional_base's member (m_initialized and m_storage). Is there any reason for this implementation? Regards, Vaclav

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[assign] ptr_map_inserter
by Vladimir Prus 10 Mar '06

10 Mar '06

Hi, the above test fails on a large number of compilers, with what looks like a legitimate compile error. For example, see: http://tinyurl.com/j3tg5 Can somebody look into this? Thanks, Volodya

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[serialization] nvp.hpp include order problem
by Kim Barrett 10 Mar '06

10 Mar '06

In boost 1.33.1, using gcc 3.3.5 (SuSE9.3 on x86 if it matters) I've run into an include order problem with the serialization library. It seems that including <boost/serialization/nvp.hpp> before including <boost/archive/polymorphic_iarchive.hpp> (or oarchive) doesn't work. In a translation unit that does this and includes an invocation of serialization, I get an error of the form: .../iserializer.hpp: In constructor `...iserializer<Archive, T>::iserializer() [with ARchive = polymorphic_archive, T = my_type]': ... lots of intermediate instantiations ... error: incomplete type boost::serialization::extended_type_info_null<my_type> cannot be used to name a scope If nvp.hpp is included later (or not explicitly included at all, since I see that polymorphic_iarchive.hpp includes it at the end of its include block), all is well. A little more poking at it by hoisting out the nested includes from nvp.hpp directly into my source file found that including polymorphic_[io]archive.hpp before type_info_implementation.hpp makes the problem go away too. nvp -> level -> traits -> type_info_implementation I know Robert has fixed a bunch of include order issues, and I think I recall that some of those fixes were post-1.33.1. Is this a known one? Or is a reproducible test case needed? Or is this a real include order dependency that one simply must avoid?

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Pre-Built Libraries for gcc/Windows?
by David Greene 10 Mar '06

10 Mar '06

Does anyone have a set of pre-built Boost libraries that can be installed on a Windows system for use with gcc 3.2.1? Thanks. -Dave

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[statechart] - templated states do not compile (transit not defined)
by Oliver.Kowalke＠infineon.com 10 Mar '06

10 Mar '06

Hello, the code below doesn't compile (gcc-3.4.6 on Linux). 'transit in scope not defined' Any glue? Regards, Oliver #include <iostream> #include <stdexcept> #include <boost/mpl/list.hpp> #include <boost/statechart/custom_reaction.hpp> #include <boost/statechart/exception_translator.hpp> #include <boost/statechart/simple_state.hpp> #include <boost/statechart/state_machine.hpp> #include <boost/statechart/transition.hpp> namespace mpl = boost::mpl; namespace sc = boost::statechart; struct EvX : sc::event< EvX > {}; struct EvY : sc::event< EvY > {}; template< typename S > struct X; template< typename S > struct sm : public sc::state_machine< sm< S >, X< S >, std::allocator< void >, sc::exception_translator<> > { void unconsumed_event( const sc::event_base & ) { throw std::runtime_error( "unknown event!" ); } }; template< typename S > struct Z : public sc::simple_state< Z< S >, sm< S > > {}; template< typename S > struct Y; template< typename S > struct X : public sc::simple_state< X< S >, sm< S > > { typedef mpl::list< sc::transition< EvY, Y< S > >, sc::custom_reaction< sc::exception_thrown > > reactions; sc::result react( sc::exception_thrown const&) { try { throw; } catch ( std::exception const& e) { return transit< Z< S > >(); } <<=== error catch ( ... ) { return forward_event(); } } }; template< typename S > struct Y : public sc::simple_state< Y< S >, sm< S > > {}; int main() { try { sm< int > fsm; fsm.initiate(); fsm.process_event( EvY() ); fsm.process_event( EvX() ); return 0; } catch ( std::runtime_error const& e) { std::cerr << e.what() << std::endl; } catch (...) { std::cerr << "unhandled exception" << std::endl; } return -1; }

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[preprocessor] BOOST_PP_CAT fails for VC6.5 and VC7.1
by Peder Holt 09 Mar '06

09 Mar '06

BOOST_PP_CAT involving __LINE__ fails for VC < 8.0 #include <boost/preprocessor/cat.hpp> void test() { int i=1; int BOOST_PP_CAT(i,__LINE__)=1; } with the following error message: d:\SourceCode\finally\test.cpp(5) : error C2374: 'i' : redefinition; multiple initialization d:\SourceCode\finally\test.cpp(4) : see declaration of 'i' d:\SourceCode\finally\test.cpp(5) : error C2143: syntax error : missing ';' before '=' d:\SourceCode\finally\test.cpp(5) : error C2143: syntax error : missing ';' before '=' Preprocessing the code using /P /EP first, yields valid code that compiles without problems. Regards, Peder

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[finally] early draft available
by Alexander Nasonov 09 Mar '06

09 Mar '06

First version of BoostCandidate.Finally is available. There is only one header file so I didn't put the library to boost vault. I can do this upon request. Header file boost/finally.hpp: http://tinyurl.com/fwy6q Examples: libs/finally/example/hello.cpp: http://tinyurl.com/errx4 libs/finally/example/finally.cpp: http://tinyurl.com/jc692 Documentation in qbk format: http://tinyurl.com/h655f Alternatively, you can browse CVS tree online: http://cvs.sourceforge.net/viewcvs.py/cpp-experiment/finally/ In short, BoostCandidate.Finally is a (better, in my opinion) replacement both for try-finally block and for ScopeGuard. It can be used when RAII approach is not quite applicable. Typical example is VectorInserter class in ScopeGuard article by Andrei Alexandrescu and Petru Marginean ( http://tinyurl.com/26vzp ). Below is a comparison with ScopeGuard approach (typeof registration is omitted for brevity). // code snipset copied from ScopeGuard article: void User::AddFriend(User& newFriend) { friends_.push_back(&newFriend); ScopeGuard guard = MakeObjGuard( friends_, &UserCont::pop_back); pDB_->AddFriend(GetName(), newFriend.GetName()); guard.Dismiss(); } // First form of BoostCandidate.Finally void User::AddFriend(User& newFriend) { friends_.push_back(&newFriend); bool dismiss = false; BOOST_FINALLY_BEGIN( (friends_)(dismiss) ) { if(!dismiss) friends_.pop_back(); } BOOST_FINALLY_END; pDB_->AddFriend(GetName(), newFriend.GetName()); dismiss = true; } // Second form of BoostCandidate.Finally void User::AddFriend(User& newFriend) { friends_.push_back(&newFriend); boost::scope_guard guard; BOOST_FINALLY_BEGIN( (guard)(friends_) ) { friends_.pop_back(); } BOOST_FINALLY_END(guard); pDB_->AddFriend(GetName(), newFriend.GetName()); guard.dismiss(); } Waiting for comments and suggestions ... -- Alexander Nasonov alnsn <@> yandex <.> ru

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[filesystem] Could you only use printable ASCII characters in source file?
by gchen 09 Mar '06

09 Mar '06

While compiling the file path.hpp, VC8, the following line: // ?Copyright Beman Dawes 2002-2005 could generate a warning C4819 (The file contains a character that cannot be represented in the current code page), if Windows is using not English code page. The reason is the ASCII of '?' in above line is 0xA9. My question is, could you use printable characters (Codes 33 to 126) in source file? IMHO, it would be better if you change the line to: // (C)Copyright Beman Dawes 2002-2005 Thanks gchen

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[rerere-post] codewarrior 9.5/9.4 help badly needed for ptr_container
by Thorsten Ottosen 09 Mar '06

09 Mar '06

Hi Guys, There is some really wierd error that makes even newer codewarrior choke: http://tinyurl.com/eo6ry I suspect this is easy to fix fom somebody with the compiler. Would somebody please have a look? Thanks -Thorsten

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[iterator] Borland 2006 patch
by AlisdairM 09 Mar '06

09 Mar '06

Borland Compiler has a problem with typename keyword followed by a double-colon, trivial patch follows: cvs diff -u -wb -- boost\detail\iterator.hpp (in directory E:\sourceforge\devel\boost\) Index: boost/detail/iterator.hpp =================================================================== RCS file: /cvsroot/boost/boost/boost/detail/iterator.hpp,v retrieving revision 1.33 diff -u -w -b -r1.33 iterator.hpp --- boost/detail/iterator.hpp 3 Sep 2004 15:41:08 -0000 1.33 +++ boost/detail/iterator.hpp 27 Jan 2006 22:30:08 -0000 @@ -477,7 +477,11 @@ distance(Iterator first, Iterator last) { typedef typename iterator_traits<Iterator>::difference_type diff_t; +#if BOOST_WORKAROUND( __BORLANDC__, BOOST_TESTED_AT(0x581)) + typedef typename boost::detail::iterator_traits<Iterator>::iterator_category iterator_category; +#else typedef typename ::boost::detail::iterator_traits<Iterator>::iterator_category iterator_category; +#endif return iterator_traits_::distance_select<Iterator,diff_t>::execute( first, last, (iterator_category*)0); OK to apply? -- AlisdairM

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