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[interprocess] placement new allocator for vector
by Brent Arias 09 Apr '09

09 Apr '09

I'd like to have a user type that contains a vector and yet is still binary serializable, *AND* that can be used entirely inside or outside of shared memory. My idea is to give the vector a placement new allocator, it goes like this: class MyBinarySerialType { struct SomeItem { char first[10]; char second[10]; }; SomeItem m_Items[16]; //The placement new allocator points with an offset_ptr<SomeItem> //to the location &m_Items[0] boost::interprocess::vector<SomeItem, /*placement new allocator*/> m_vItems; public: MyBinarySerialType(const /*placement new allocator*/ &alloc); } I'd like to know if interprocess allocators can already do this for me (via template params, etc) or if I need to write my own allocator. If this is done correctly, I think it means I can "new" MyBinarySerialType from the regular heap and it will work entirely outside of shared memory. Likewise if I use segment.construct<MyBinarySerialType>()(...), then the whole thing should be created inside of shared memory. Either way, the vector will allocate strictly to a piece of memory inside the size of the class. Brent Arias

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[date_time] Time duration parsing
by Konstantin Litvinenko 09 Apr '09

09 Apr '09

Hi All! I have a string "14:34" and want to parse it into boost::posix_time::time_duration. How can I do that?

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[serialization] Export question
by Tom Aylesworth 09 Apr '09

09 Apr '09

I just want to make sure that I understand the use of the Serialization library's EXPORT macros. On the "Serializable Concepts" page of the documentation, it states: -- The macro BOOST_CLASS_EXPORT_GUID associates a string literal with a class. ... This permits each class to be in a separate header file along with its string identifier. -- However, on the "Special Considerations" page, I find: -- Note that the implementation of this functionality requires that the BOOST_CLASS_EXPORT macro appear after and the inclusion of any archive class headers for which code is to be instantiated. ... Note that including BOOST_CLASS_EXPORT in the "a.hpp" header itself as one would do with other serialization traits will make it difficult or impossible to follow the rule above regarding inclusion of archive headers before BOOST_CLASS_EXPORT is invoked. This is different than other serialization traits which would normally be included in same file as the class declaration. -- The associated example shows the EXPORT macro following the #include of the header defining the class to be exported. I would certainly much rather have the EXPORT macros appear in the header with the class that defines them. I take it that means I have to guarantee that the file actually responsible for operating on an archive includes my headers with the class definitions and EXPORT macros *after* including the appropriate archive headers (e.g., "boost/archive/xml_oarchive.hpp"). Is that correct? Are there any other gotchas I should be aware of if I place the EXPORT macros in the headers with the classes to be exported? Thanks, Thomas Aylesworth Senior Software Engineer Reality Mobile

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boost build interface
by Igor 09 Apr '09

09 Apr '09

I have a suggestion: Why not make a simple dialog window with several check buttons and few radio buttons where you will choose what kind of library you want to build(static/dynamic, release/debug), one edit line in which you enter the location where you want your libraries to be built, and one push button that will execute the build process? It would make the building process of the boost libraries 100 times easier.

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[interprocess] named mutex clean up
by Chard 09 Apr '09

09 Apr '09

Does calling named_mutex::remove() have consistent cross-platform behaviour? The reason I ask is that I am trying to use a named mutex for an "I'm the only process" check. That is, the process takes a shared lock on the named mutex (at start up), then, at points within the program, it attempts to get an exclusive lock in order to perform the check/actions. When finished, the mutex is returned to a shared lock. The problem is, if a process dies in some unforeseen manner - and does not get to call named_mutex::remove() - the named_mutex is left orphaned in the system (in a shared lock) such that other processes can never get an exclusive lock. On the Windows platform, I've found I can call named_mutex::remove() at start up, which seems to clean up the named_mutex if it is orphaned, or just do nothing if another, active, process has a lock - exactly the behaviour I require. However, is this platform independent, and a suitable technique?

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Boost.Random - random_device error LNK2019 ()
by Valen 09 Apr '09

09 Apr '09

Hello there! Windows XP, Boost 1.38, VC++ 7.1 / Mingw 3.4.2 sample code: //----------------------------------------------------- #include <boost/random/uniform_int.hpp> #include <boost/random/variate_generator.hpp> #include <boost/nondet_random.hpp> int main() { boost::random_device m; typedef boost::uniform_int<> distribution_type; distribution_type generator2(m()); return 0; } //----------------------------------------------------- VC++ Output: error LNK2019: unresolved external symbol "public: __thiscall boost::random_device::~random_device(void)" (??1random_device@boost@@QAE@XZ) referenced in function "protected: void __thiscall CGraphDoc::OnBtnNewnode(void)" (?OnBtnNewnode@CGraphDoc@@IAEXXZ) error LNK2019: unresolved external symbol "public: unsigned int __thiscall boost::random_device::operator()(void)" (??Rrandom_device@boost@@QAEIXZ) referenced in function "protected: void __thiscall CGraphDoc::OnBtnNewnode(void)" (?OnBtnNewnode@CGraphDoc@@IAEXXZ) error LNK2019: unresolved external symbol "public: __thiscall boost::random_device::random_device(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??0random_device@boost@@QAE@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) referenced in function "protected: void __thiscall CGraphDoc::OnBtnNewnode(void)" (?OnBtnNewnode@CGraphDoc@@IAEXXZ) error LNK2001: unresolved external symbol "private: static char const * const boost::random_device::default_token" (?default_token@random_device@boost@@0QBDB) fatal error LNK1120: 4 unresolved externals MinGW gave same output I checked the sources and find no implementation of ~random_device and etc... Can anyone help please? -- View this message in context: http://www.nabble.com/Boost.Random---random_device-error-LNK2019-%28%29-tp2… Sent from the Boost - Users mailing list archive at Nabble.com.

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Passing reference to boost::bind object
by david.weber＠l-3com.com 08 Apr '09

08 Apr '09

So, we are implementing boost::signals/slots, and in several cases, we have a connect() function to allow us to hook up an arbitrary slot to the signal, without exposing the details of the signal for cleanliness issues. We would like to implement the signals::trackable interface, and have the objects which are passing in the bound slot manage their connections in this manner. However, we are passing them as boost::function objects, which (as documented) does not work properly with boost::function objects, only boost::bind objects. In all of the documentation that I've found, about assigning the results of a boost::bind call were to function objects. Is there an alternative available to not destroy the trackable functionality that we're trying to use? Thanks --dw

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help building boost for iphone
by Kenny Riddile 08 Apr '09

08 Apr '09

I'm fairly inexperienced with boost.build and I'm having an issue building boost for the iphone. My user-config.jam (I put this in the same dir as the bjam executable right?) looks like this: using darwin : 4.0.1~iphone : /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/arm-apple-darwin9-g++-4.0.1 -arch arm : <striper> : <architecture>arm <target-os>iphone <macosx-version>iphone-2.2 ; using darwin : 4.0.1~iphonesim : /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/g++ : <striper> : <architecture>x86 <target-os>iphone <macosx-version>iphonesim-2.2 ; and I'm invoking bjam like this: ./bjam debug release toolset=darwin --layout=system link=static architecture=arm target-os=iphone macosx-version=iphone-2.2 My error is that it can't find g++ becuase it isn't looking in the right place: g++-4.0: installation problem, cannot exec '/usr/bin/arm-apple-darwin9-g++-4.0.1': No such file or directory

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[graph] hash_set
by liquid 08 Apr '09

08 Apr '09

How to use hash_setS? If I define BOOST_HAS_HASH the compiler will generate "error C2977: 'stdext::hash_set' : too many template arguments". This is caused by using "BOOST_STD_EXTENSION_NAMESPACE::hash_set<Key,Eq,Hash,Alloc>" in definition of "template <class Key, class Eq, class Hash, class Alloc> struct container_traits< BOOST_STD_EXTENSION_NAMESPACE::hash_set<Key,Eq,Hash,Alloc> > { typedef set_tag category; typedef stable_tag iterator_stability; // is this right? };" Class hash_set is defined in STL as follows: template<class _Kty, class _Tr = hash_compare<_Kty, _STD less<_Kty> >, class _Alloc = _STD allocator<_Kty> > class hash_set : public _Hash<_Hset_traits<_Kty, _Tr, _Alloc, false> > {...}; which has only 3 params. Regards liquid

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[serialization] appending elements
by Agustín K-ballo Bergé 08 Apr '09

08 Apr '09

Is it possible to append serialized elements to an existing archive? I need to keep a set of records on a file, and periodically add new entries to it (kind of like a database table). Reading the whole set, adding the new records, and serializing the set back is not an option since I expect the set to go pretty big. I have tried to keep several archives at the same stream (with no_header and no_tracking flags), but then I don't know how to read them. Reading them as if they were a single archive does not work, should it? Agustín K-ballo Bergé.-

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