May 2008 - Boost-users - lists.preview.boost.org

boost::any question
by Hansi 21 May '08

21 May '08

Hello, I want to use boost::any in a project where I want store different values or pointers. What is the fastest solution to make the different actions for different value types? Using the type() member function? Is it also possible to detect if the value is a pointer or a value? Best regards Hansjörg

4 6

ptr_set
by Surya Kiran Gullapalli 21 May '08

21 May '08

Hello all, I'm trying to use ptr_set with my class Hierarchy. Base is an abstract base class with a bunch of pure virtual functions. I've some derived classes with those virtual functions defined in them. I'm using this Base class hierarchy in another class (say Other). So I've declared a member variable of Other as ptr_set<Base> m_items ; this works fine on linux with gcc-4.2 but with VS2005, I'm getting a compilation error, saying that It cannot instantiate base class as it is having pure virtual functions. Am I doing some thing wrong here ? Surya

9 17

Boost::intrusive container of pointers
by Swadhin Bhide 21 May '08

21 May '08

Is it possible to store CBaseObject* (base class pointers) in slist, hashtable, rbtree and avl tree? I am deriving CBaseObject from slist_base_hook, set_base_hook etc. But when using member_hook<CBaseObject*,...) and rbtree<CBaseObject*,...>, I am getting compiler errors. Boost documentation provides examples about objects and smart pointers. But can we store raw pointers in intrusive containers?

2 1

[intrusive] slist: strange behaviour when using cache_last
by Christian Rössel 21 May '08

21 May '08

Hi, I have two slists and transfer items between them via splice() methods. Without cache_last everything works as expected. With cache_last the third call to splice does not transfer the list element. Am I using something wrong or is this a bug in intrusive? Thanks, Christian #include <boost/intrusive/slist.hpp> #include <boost/intrusive/slist_hook.hpp> #include <cassert> using namespace boost::intrusive; class MyClass : public slist_base_hook<> { int int_; public: MyClass(int i) : int_(i) {} }; typedef slist<MyClass, cache_last<true> > MyList; int main () { MyList freeList; for (int j = 0; j < 5; ++j) { freeList.push_front (*(new MyClass (j))); } MyList listInUse; // transfer first element of freeList to listInUse size_t free = freeList.size (); size_t inUse = listInUse.size (); listInUse.splice (listInUse.begin (), freeList, freeList.begin ()); assert (freeList.size () == free - 1); assert (listInUse.size () == inUse + 1); // transfer all elements of listInuse to freeList free = freeList.size (); inUse = listInUse.size (); freeList.splice (freeList.begin (), listInUse); assert (listInUse.empty ()); assert (freeList.size () == free + inUse); // again, transfer first element of freeList to listInUse free = freeList.size (); inUse = listInUse.size (); listInUse.splice (listInUse.begin (), freeList, freeList.begin ()); assert (freeList.size () == free - 1); // fails, sizes are 5 and 0 assert (listInUse.size () == inUse + 1); // release memory omitted return 0; }

2 3

shared container class with read/write mutex
by Selçuk Giray Özdamar 21 May '08

21 May '08

Hi everyone, can anyone send a simple container class implementation, which supports concurrent reads and exclusive write. I'm seeking for the usage of shared_lock for read/write mutex. My simple template class snippet is shown below, please reply how to fill the comments for locking. Thnx. // std includes #include <vector> // boost includes #include <boost/thread/shared_mutex.hpp> template <typename T> class SharedContainer { public: SharedContainer (void){} ~SharedContainer (void){} void push_back(const T& value); const T& at(int index) const; private: std::vector<T> m_buffer; boost::shared_mutex rw_mutex; //is this the correct class for rw mutex? }; template <typename T> void EntityUpdateBuffer<T>::push_back( const T& value ) { // how to acquire a write lock? m_buffer.push_back(value); } template <typename T> const T& EntityUpdateBuffer<T>::at( int index ) const { // how to acquire read lock? return m_buffer.at(index); } Selcuk Giray

2 1

Design question (something like properties)
by Hansi 21 May '08

21 May '08

Hello, at the moment I want to solve the following problem: I have a data struct which has several fields. Now I need to expose this fields as name/value pairs (the best would be if the value is a ref parameter). Okay I can write this things by hand. But is there some solution available to automate this? e.g. some metaprogramming with which I can solve this problem? Has anyone an idea? Best regards Hansjörg

2 2

Named mutex..
by Jason Robertson 21 May '08

21 May '08

Hi, I'm trying to create simple locks based on a string name. I looked at the interprocess module which has a named mutex, but it seems not well suited/efficient for use in a single process, though I know it's supposed to work. Instead, I'm just creating a map<string,weak_ptr<mutex>> in a NamedMutexManager class. It's used as a singleton and uses brute force locking to implement a named lock pattern. Main method is shared_ptr<mutex> GetMutex(string name) { BigLock (only one thread at a time can get a lock so we synchronize access to map) check map if we have entry, make sure weak_ptr hasn't been reclaimed If so, make a new shared_ptr, save weak_ptr by name, return shared_ptr If not, return shared_ptr copy from weak_ptr.lock() If we habe no entry, make a new shared_ptr, save weak_ptr by name, return shared_ptr } I'm just getting back to C++ after years, so I'm 99% sure there's probably a much better way. Is there a better way to do an intra-process, reliable mutex by std::string name so I can lock things by name? How are other people doing this, do you find interprocess:named_mutex suitable for use in-process? I had problems with it. Thanks! Jason

4 3

Boost.Python Quickstart Test Fails/segfaults with 64-bit Python 2.5
by Eric Newhuis 20 May '08

20 May '08

[Boost.Python] On my platform: Linux 2.6.9-67.0.1.ELsmp #1 SMP Fri Nov 30 11:57:43 EST 2007 x86_64 GNU/Linux I verified that the boost python tests fail only when I provide a user-config.jam file that points to a 64-bit Python 2.5. If I don't provide such a file then the default choices made by BJAM result in a passing test. It doesn't matter if threading=single or multi or variant=debug or release. I get similar results. Does anyone have a clue what is going on and how to fix this? #0 0x0000000000000000 in ?? () #1 0x0000002a998830fc in ~object_base (this=0x7fbfffb0f0) at ../../../../boost/python/object_core.hpp:436 #2 0x0000002a998830c5 in ~object (this=0x7fbfffb0f0) at ../../../../boost/python/slice_nil.hpp:16 #3 0x0000002a99a254d1 in ~dict_base (this=0x7fbfffb0f0) at ../../../../boost/python/dict.hpp:89 #4 0x0000002a99a254b9 in ~dict (this=0x7fbfffb0f0) at ../../../../libs/python/src/object/enum.cpp:139 #5 0x0000002a99a28a6b in boost::python::objects::(anonymous namespace)::new_class (name=0x2a9988812a "hello", num_types=1, types=0x7fbfffb1e8, doc=0x0) at ../../../../libs/python/src/object/class.cpp:539 #6 0x0000002a99a27969 in class_base (this=0x7fbfffb250, name=0x2a9988812a "hello", num_types=1, types=0x7fbfffb1e8, doc=0x0) at ../../../../libs/python/src/object/class.cpp:546 #7 0x0000002a9988328c in class_<boost::python::init<std::string, mpl_::void_, mpl_::void_, mpl_::void_, mpl_::void_, mpl_::void_, mpl_::void_, mpl_::void_, mpl_::void_, mpl_::void_, mpl_::void_, mpl_::void_, mpl_::void_, mpl_::void_, mpl_::void_> > (this=0x7fbfffb250, name=0x2a9988812a "hello", i=@0x7fbfffb230) at ../../../../boost/python/class.hpp:207 #8 0x0000002a99882e77 in init_module_extending () at extending.cpp:32 #9 0x0000002a99a416be in boost::detail::function::void_function_ref_invoker0<void (*)(), void>::invoke (function_obj_ptr=@0x7fbfffb358) at ../../../../boost/function/function_template.hpp:193 #10 0x0000002a99a40fa8 in boost::function0<void, std::allocator<boost::function_base> >::operator() (this=0x7fbfffb350) at ../../../../boost/function/function_template.hpp:824 #11 0x0000002a99a409fb in boost::python::handle_exception_impl (f= {<boost::function_base> = {vtable = 0x2a99b752e0, functor = {obj_ptr = 0x7fbfffb378, const_obj_ptr = 0x7fbfffb378, func_ptr = 0x7fbfffb378, bound_memfunc_ptr = {memfunc_ptr = {__pfn = 0x7fbfffb378, __delta = 548682052496}, obj_ptr = 0x2a99a4144f}, data = 120 'x'}}, static args = <optimized out>, static arity = <optimized out>}) at ../../../../libs/python/src/errors.cpp:25 #12 0x0000002a99a414d9 in boost::python::handle_exception<void (*)()> (f=0x2a99882e4c <init_module_extending()>) at ../../../../boost/python/errors.hpp:29 #13 0x0000002a99a41347 in boost::python::detail::init_module (name=0x2a99888120 "extending", init_function=0x2a99882e4c <init_module_extending()>) at ../../../../libs/python/src/module.cpp:39 #14 0x0000002a99882e49 in initextending () at extending.cpp:29 #15 0x0000002a95647e43 in _PyImport_LoadDynamicModule (name=0x7fbfffc630 "extending", pathname=0x7fbfffb530 "/home/users/ericn/boost_1_35_0/libs/python/example/quickstart/bin/gcc-3 .4.6/debug/threading-multi/extending.so", fp=0x632280) at ./Python/importdl.c:53 #16 0x0000002a956450a0 in load_module (name=0x7fbfffc630 "extending", fp=0x632280, buf=0x7fbfffb530 "/home/users/ericn/boost_1_35_0/libs/python/example/quickstart/bin/gcc-3 .4.6/debug/threading-multi/extending.so", type=3, loader=0x0) at Python/import.c:1758 #17 0x0000002a956466e0 in import_submodule (mod=0x2a957be230, subname=0x7fbfffc630 "extending", fullname=0x7fbfffc630 "extending") at Python/import.c:2400 #18 0x0000002a95645ff5 in load_next (mod=0x2a957be230, altmod=0x2a957be230, p_name=0x7fbfffd668, buf=0x7fbfffc630 "extending", p_buflen=0x7fbfffc628) at Python/import.c:2220 #19 0x0000002a956457b7 in import_module_level (name=0x0, globals=0x60de80, locals=0x60de80, fromlist=0x2a991b8710, level=-1) at Python/import.c:2001 #20 0x0000002a95645b1b in PyImport_ImportModuleLevel (name=0x2a991be32c "extending", globals=0x60de80, locals=0x60de80, fromlist=0x2a991b8710, level=-1) at Python/import.c:2072 #21 0x0000002a9561dec4 in builtin___import__ (self=0x0, args=0x2a95b20d08, kwds=0x0) at Python/bltinmodule.c:47 #22 0x0000002a955ce52a in PyCFunction_Call (func=0x2a95abb5f0, arg=0x2a95b20d08, kw=0x0) at Objects/methodobject.c:77 #23 0x0000002a95599373 in PyObject_Call (func=0x2a95abb5f0, arg=0x2a95b20d08, kw=0x0) at Objects/abstract.c:1861 #24 0x0000002a9562bb14 in PyEval_CallObjectWithKeywords (func=0x2a95abb5f0, arg=0x2a95b20d08, kw=0x0) at Python/ceval.c:3442 #25 0x0000002a95628562 in PyEval_EvalFrameEx (f=0x6158d0, throwflag=0) at Python/ceval.c:2067 #26 0x0000002a9562a7b6 in PyEval_EvalCodeEx (co=0x2a95b26af8, globals=0x60de80, locals=0x60de80, args=0x0, argcount=0, kws=0x0, kwcount=0, defs=0x0, defcount=0, closure=0x0) at Python/ceval.c:2836 #27 0x0000002a95623a42 in PyEval_EvalCode (co=0x2a95b26af8, globals=0x60de80, locals=0x60de80) at Python/ceval.c:494 #28 0x0000002a9562dc05 in exec_statement (f=0x630de0, prog=0x2a95b26af8, globals=0x60de80, locals=0x60de80) at Python/ceval.c:4177 #29 0x0000002a95626e60 in PyEval_EvalFrameEx (f=0x630de0, throwflag=0) at Python/ceval.c:1666 #30 0x0000002a9562a7b6 in PyEval_EvalCodeEx (co=0x2a989b5828, globals=0x518bb0, locals=0x0, args=0x617f80, argcount=4, kws=0x617fa0, kwcount=0, defs=0x0, defcount=0, closure=0x0) at Python/ceval.c:2836 #31 0x0000002a9562c5b2 in fast_function (func=0x2a991bc230, pp_stack=0x7fbfffe080, n=4, na=4, nk=0) at Python/ceval.c:3669 #32 0x0000002a9562c311 in call_function (pp_stack=0x7fbfffe080, oparg=3) at Python/ceval.c:3594 #33 0x0000002a95628e6e in PyEval_EvalFrameEx (f=0x617dd0, throwflag=0) at Python/ceval.c:2272 #34 0x0000002a9562a7b6 in PyEval_EvalCodeEx (co=0x2a989b5990, globals=0x518bb0, locals=0x0, args=0x5209c0, argcount=2, kws=0x5209d0, kwcount=0, defs=0x2a991b7978, defcount=3, closure=0x0) at Python/ceval.c:2836 #35 0x0000002a9562c5b2 in fast_function (func=0x2a991bc398, pp_stack=0x7fbfffe450, n=2, na=2, nk=0) at Python/ceval.c:3669 #36 0x0000002a9562c311 in call_function (pp_stack=0x7fbfffe450, oparg=1) at Python/ceval.c:3594 #37 0x0000002a95628e6e in PyEval_EvalFrameEx (f=0x5207e0, throwflag=0) at Python/ceval.c:2272 #38 0x0000002a9562a7b6 in PyEval_EvalCodeEx (co=0x2a989bb378, globals=0x518bb0, locals=0x0, args=0x520780, argcount=1, kws=0x520788, kwcount=1, defs=0x2a98d5fbe8, defcount=9, closure=0x0) at Python/ceval.c:2836 #39 0x0000002a9562c5b2 in fast_function (func=0x2a991b95f0, pp_stack=0x7fbfffe820, n=3, na=1, nk=1) at Python/ceval.c:3669 #40 0x0000002a9562c311 in call_function (pp_stack=0x7fbfffe820, oparg=257) at Python/ceval.c:3594 #41 0x0000002a95628e6e in PyEval_EvalFrameEx (f=0x5205e0, throwflag=0) at Python/ceval.c:2272 ---Type <return> to continue, or q <return> to quit--- #42 0x0000002a9562a7b6 in PyEval_EvalCodeEx (co=0x2a95b18300, globals=0x524510, locals=0x0, args=0x568f08, argcount=0, kws=0x568f08, kwcount=0, defs=0x2a95b244a8, defcount=1, closure=0x0) at Python/ceval.c:2836 #43 0x0000002a9562c5b2 in fast_function (func=0x2a95b11938, pp_stack=0x7fbfffebf0, n=0, na=0, nk=0) at Python/ceval.c:3669 #44 0x0000002a9562c311 in call_function (pp_stack=0x7fbfffebf0, oparg=0) at Python/ceval.c:3594 #45 0x0000002a95628e6e in PyEval_EvalFrameEx (f=0x568d80, throwflag=0) at Python/ceval.c:2272 #46 0x0000002a9562a7b6 in PyEval_EvalCodeEx (co=0x2a95b11648, globals=0x524510, locals=0x524510, args=0x0, argcount=0, kws=0x0, kwcount=0, defs=0x0, defcount=0, closure=0x0) at Python/ceval.c:2836 #47 0x0000002a95623a42 in PyEval_EvalCode (co=0x2a95b11648, globals=0x524510, locals=0x524510) at Python/ceval.c:494 #48 0x0000002a95650e3c in run_mod (mod=0x51e130, filename=0x7fbffff4be "test_extending.py", globals=0x524510, locals=0x524510, flags=0x7fbffff050, arena=0x543950) at Python/pythonrun.c:1273 #49 0x0000002a95650dc6 in PyRun_FileExFlags (fp=0x501010, filename=0x7fbffff4be "test_extending.py", start=257, globals=0x524510, locals=0x524510, closeit=1, flags=0x7fbffff050) at Python/pythonrun.c:1259 #50 0x0000002a9564fdcf in PyRun_SimpleFileExFlags (fp=0x501010, filename=0x7fbffff4be "test_extending.py", closeit=1, flags=0x7fbffff050) at Python/pythonrun.c:879 #51 0x0000002a9564f711 in PyRun_AnyFileExFlags (fp=0x501010, filename=0x7fbffff4be "test_extending.py", closeit=1, flags=0x7fbffff050) at Python/pythonrun.c:698 #52 0x0000002a9565c5c2 in Py_Main (argc=2, argv=0x7fbffff1c8) at Modules/main.c:523 #53 0x0000000000400793 in main ()

1 0

SSL and http proxy
by Kurata Sayuri 20 May '08

20 May '08

I want to use asio::ssl over the http proxy. sample code: ---- io_service i; tcp::socket t( i ); ssl::context c( i, ssl::context::sslv3_client ); ssl::stream<tcp::socket&> s( t, c ); tcp::resolver r( i ); tcp::resolver::query q( "proxy.example.com", "3128" ); t.connect( *r.resolve( q ) ); write( t, buffer( "CONNECT www.example.com:443 HTTP/1.0\r\n\r\n" ) ); asio::streambuf res; read_until( t, res, "\r\n\r\n" ); cout << &res; // => "HTTP/1.0 200 Connection established\r\n\r\n" error_code e; s.handshake( ssl::stream_base::client, e ); if( e ){ cout << "handshake() failed: " << e.message() << endl; // e.message() => "End of file" return 1; } write( s, buffer( "GET / HTTP/1.0\r\n\r\n" ) ); while( read( s, res, transfer_at_least(1), e ) ) cout << &res; ---- The http proxy returns correct response. But handshake() failed. What should I do?

1 1

Boost.Python Build Warnings on x86_64 RedHat Linux
by Eric Newhuis 20 May '08

20 May '08

[Boost.Python] On my platform... Linux frln27.foxriver.com 2.6.9-67.0.1.ELsmp #1 SMP Fri Nov 30 11:57:43 EST 2007 x86_64 x86_64 x86_64 GNU/Linux I get the following warnings. Are they benign? 1. ../../../../libs/python/src/str.cpp: In function `boost::python::ssize_t boost::python::detail::<unnamed>::str_size_as_py_ssize_t(size_t)' : ../../../../libs/python/src/str.cpp:29: warning: comparison between signed and unsigned integer expressions 2. ../../../../libs/python/src/object/class.cpp: In function `boost::python::api::object boost::python::objects::<unnamed>::new_class(const char*, size_t, const boost::python::type_info*, const char*)': ../../../../libs/python/src/object/class.cpp:510: warning: comparison between signed and unsigned integer expressions 3. ../../../../libs/python/src/object/function.cpp: In member function `PyObject* boost::python::objects::function::call(PyObject*, PyObject*) const': ../../../../libs/python/src/object/function.cpp:169: warning: comparison between signed and unsigned integer expressions

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