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

a few boost interprocess question
by Abir Basak 14 Mar '08

14 Mar '08

Hi, i just started using boost interprocess for giving shared memory access to one of my program to the debugger. It is just superb! but as usual there are a few questions and clarifications, 1) can i find any document saying which of the stl containers are "shared memory safe" so that i dont need to use the special one provided ? esp which of the stl containers from msvc 7.1 (2003) are shmm safe . 2) how can i make my hand crafted container shmm compatible ? I take allocater as param, pointer & ref are typedef from allocater, all construct & destroy are done using allocator. thanks again for the wonderful library abir

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Undefined reference to 'main' with Boost Test. Why?
by Stephen Torri 14 Mar '08

14 Mar '08

Why in the heck did the boost unit test framework change to remove main? Why does the documentation not reflect this? Why are the example describing the old behavior? How am I now suppose to use the Boost unit test framework? The following program will NOT compile because of the change in 1.34.1 since the 1.33: /* test_grnn.cpp #include <boost/test/unit_test.hpp> using namespace boost::unit_test_framework; void test_distance_squared () { // do work } test_suite* init_unit_test_suite ( int, char** ) { test_suite* test = BOOST_TEST_SUITE ("GRNN test suite"); // Allow GRNN to allocate our memory at any location test->add ( BOOST_TEST_CASE ( &test_distance_squared ) ); return test; }

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[function] setting a function from within a call on the function?
by Cory Nelson 14 Mar '08

14 Mar '08

Hi guys, ran across a question that I'd have thought would be at least common enough to get a note in the docs, but I can't find it there. Is it safe to set a function from within a call on the function? boost::function<void()> f; void func2(); void func1() { f = func2; } void main() { f = func1; f(); } -- Cory

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[bind] VC++ 2008 compiler error
by Boris 14 Mar '08

14 Mar '08

Can anyone explain to me why VC++ 2008 refuses to compile this code: void empty() { } template <class T> void foo(T t) { // error C2664: 'void (T)' : cannot convert // parameter 1 from 'void' to 'boost::_bi::bind_t<R,F,L>' boost::bind(bar<T>, t)(); // This one works though: boost::bind(bar<T>, _1)(t); } template <class T> void bar(T t) { t(); } int main() { foo(boost::bind(empty)); } Is this a problem with the VC++ 2008 compiler or am I trying to do something which isn't supported by Boost.Bind? Boris

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[python] "Interpreter not initialized"
by Robert Dailey 13 Mar '08

13 Mar '08

Hi, When I execute the following code: BEGIN CODE -------------------------------------------------- #define BOOST_PYTHON_DEF( func ) boost::python::def( #func, func ) using namespace boost::python; static char const* PrintHelloWorld() { return "Hello World!"; } BOOST_PYTHON_MODULE(Script) { BOOST_PYTHON_DEF( PrintHelloWorld ); } void BeginPythonTest() { try { Py_Initialize(); initScript(); Py_Finalize(); } catch( error_already_set const& /*err*/ ) { PyErr_Print(); } catch( std::invalid_argument const& /*err*/ ) { PyErr_Print(); } } -------------------------------------------------- END CODE I receive the following error message: *Fatal Python error: Interpreter not initialized (version mismatch?)* This occurs when I step over the call to initScript() (in the code snippet above). I have no idea why this is happening. I'm currently linking against boost 1.34.1. I built all the libraries for boost myself using bjam. I built the multithreaded debug and release shared libraries. I'm using the SDK from Python 2.5.1. I also built the debug and release shared libraries for Python myself. My operating system is Microsoft Windows XP Professional. All help is appreciated. Thanks in advance!

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Visual C++ does not recognize lambda metafunction as such
by Matt Brown 13 Mar '08

13 Mar '08

I just tried to build this code in visual studio 2005, and got error: error C3201: the template parameter list for class template 'boost::mpl::bind2<F,T1,T2>::apply' does not match the template parameter list for template parameter 'boolfunc' This code works fine with gcc, and boost mpl portability page (http://www.boost.org/libs/mpl/doc/tutorial/portability.html) says my version of visual studio should be able to compile this. However, it appears to think the lambda< ... >::type::apply is not a metafunction. Any help will be greatly appreciated. -Matt Brown #include <iostream> #include <boost/mpl/lambda.hpp> #include <boost/type_traits/is_same.hpp> #include <boost/mpl/placeholders.hpp> template <template <typename> class boolfunc> class test { public: static void print() { if(boolfunc<int>::type::value) { std::cout << "int: true\n"; } } }; int main(void) { test< boost::mpl::lambda< boost::is_same<boost::mpl::_1, int> >::type::apply >::print(); };

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passing comma to macro
by Warlich, Christof (Christof) 13 Mar '08

13 Mar '08

Hi, the following code does not compile: #include <boost/preprocessor/if.hpp> #include <boost/preprocessor/comma.hpp> #include <boost/type_traits/is_convertible.hpp> #include <iostream> class A {}; int main(void) { BOOST_PP_IIF(boost::is_convertible<A BOOST_PP_COMMA() A>::value, // condition std::cout << "ifbranch";, // then std::cout << "elsebranch";); // else return 0; } With gcc, it gives the following errors: tst.cc:9:30: error: macro "BOOST_PP_IIF_I" passed 4 arguments, but takes just 3 tst.cc: In function int main(): tst.cc:7: error: BOOST_PP_IIF_I was not declared in this scope I would have expected that BOOST_PP_COMMA() has just been provided to deal with cases like this! I'm just new to Boost, so my apologies if I have overseen something obvious. Thanks for any help, Christof

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GraphProperty with adjacency_list cause a VC++ internal compiler error.
by Schick, Thorben (ITUC; ADITG/DFG) 13 Mar '08

13 Mar '08

I know this is a known problem and what i really want to know is, wether this problem is fixed with the upcoming version 9 of Visual Studio? Or maybe someone knows about a quite easy work-around to solve this problem. Regards Thorben

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Re: [Boost-users] [Mutex] behaviour??
by Yasmina Berber 13 Mar '08

13 Mar '08

Yasmina Berber wrote: > Hi, everybody > I have a problem to understand mutex behaviour in a server client program . > basically there are two threads that execute different code in two > different classes but manipulate the same resource: > fisrt Class is Subscriber with these members : > > public: > ACE_Unbounded_Set<client_reference> m_set; > typedef boost::recursive_mutex Mutex; > typedef boost::recursive_mutex::scoped_lock Lock; > Mutex mutex_set; > > and methods: > Subscribe (client_reference) : inserts (add) a reference client > to the set > { ... > Lock theScope( mutex_set); > m_set.insert (client_reference) > ... > } > Unsubscribe(client_reference) : removes a reference client from the set > { ... > Lock theScope( mutex_set); > m_set.remove (client_reference) > } > > > the second class is Manager that has a shared pointer to Subscriber > (SubscriberPtr) and does a specific opeartion on each > client_reference inside a for loop in the method > Manage() > { > boost::recursive_mutex::scoped_lock scoped_lock(subscriberPtr->mutex_set) > for (Subscriber::Set_Iterator iter (subscriberPtr->m_set); iter.next > (...) != 0 ; iter.advance ()) > { > specific opeartion on each client reference > } > } > What happens is that a client can be removed (call to Unsubscribe()) by > the first thread during the second one is executing manage() : the set > is not well protected and this causes of course seg fault. > > I probably do something wrong, > If you need more details please let me know. > Regards. > > > Hi Could any one help me in this forum? Thank you

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Another Regex Question
by Dave DeLong 13 Mar '08

13 Mar '08

This is both a Regex syntax and a boost question (in, so here goes... I've got the following code to strip out all <a>, <frame>, and <iframe> tags from a webpage and parse them for their href or src attributes (yes, I realize that it can potentially grab an <a src=""> or an <iframe href="">, but that's ok for this project). Surprise surprise, it doesn't work quite as I'd hoped, and I was wondering if you could help me ascertain the problem: (pageSource is a pointer to a string containing the source of the page; the project specifications allow for the attribute to be formatted with either a single or double quote or neither around the actual URL. It correctly finds each tag and attribute, but it's grabbing the URL and also the "> that follow it.) How can I get rid of the closing "> ? void Page::parseLinks() { boost::regex linkTagRegex("(?i)<(a|i?frame)[^>]*>"); boost::regex linkRegex("(?i)(href|src)\\s*?=[\\w]*?([\\W]*?)[\\w]+?"); boost::sregex_token_iterator p(pageSource->begin(), pageSource->end(), linkTagRegex, 0); boost::sregex_token_iterator end; for (; p != end; p++) { string tag(p->first, p->second); boost::cmatch matches; if (boost::regex_search(tag.c_str(), matches, linkRegex)) { string * newLink = new string(matches[2].first); URL * foundLink = new URL(newLink); delete newLink; foundLink->resolveWithRespectTo(pageURL); foundLinks->add(foundLink); } } } Thanks! Dave

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