July 2006 - Boost-users - lists.preview.boost.org

Re: [Boost-users] shared_ptr implicit dynamic cast
by Andrew Holden 12 Jul '06

12 Jul '06

foo = boost::shared_ptr<Foo>(new Bar); foo = boost::shared_ptr<Bar>(new Bar); Scott McMurray wrote: > > The important difference is in the default deleter. shared_ptr<Foo>'s > default deleter will call delete on a Foo* while shared_ptr<Bar>'s > default deleter will call it on a Bar*. Since your base class's > destructor is virtual, it doesn't make any difference in the example. > If your destructor were non-virtual, then you'd have to use > shared_ptr<Bar>(new Bar) to get the correct destructors called. (But > without any virtual functions, the dynamic casting wouldn't compile.) Are you sure about that? A check of the documentation lists the signature for that constructor as template<class Y> explicit shared_ptr(Y * p); The explanation is given as follows: [This constructor has been changed to a template in order to remember the actual pointer type passed. The destructor will call delete with the same pointer, complete with its original type, even when T does not have a virtual destructor, or is void. The reset function has a similar signature.

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shared_ptr implicit dynamic cast
by eric 12 Jul '06

12 Jul '06

hello given the following class hierarchy class Foo { protected: virtual ~Foo() {} }; class Bar : public Foo {}; and declaration boost::shared_ptr<Foo> foo; is there any difference between the two assignment statements below? foo = boost::shared_ptr<Foo>(new Bar); foo = boost::shared_ptr<Bar>(new Bar); in other words, when you assign a value to a shared_ptr, does it make any difference what class you specify for that value, as long as the class of the underlying object can be dynamically cast to the class that was used to declare the shared_ptr? kind regards, eric

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Boost tests
by kirill.sukhonosenko 12 Jul '06

12 Jul '06

Hello, Are there any ready-to-use tests for boost which can be ran after build to prove consistency of the built libraries? I've tried to build several versions of Boost for TI DaVinci chip (ARM core) and failed. Both 1-31 & 1-33 versions failed. Some libraries has got built, some - not. How can one be assured that built libraries work properly? Thanks, Kirill

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boost [C++ database development library]
by Sundaram Ramasamy 12 Jul '06

12 Jul '06

Hi, Can someone help me to locate cross-platform (platform independant) and cross-database C++ database development BOOST library? Thanks and regards, Sundaram Ramasamy Sundaram.Ramasamy(a)saama.com

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fs::exists() question
by Simon Lacroix 11 Jul '06

11 Jul '06

Hello all, I started using the file system about a week ago in order to port a Windows application using win API calls to manipulate folders and file on Linux. So far it works great but I am having one issue, the fs::exists() function seems to throw an exception when I try to look for directory containing special characters like ./test[0] ./test<1> etc. Is this normal ? I can create directory with these characters using mkdir in Linux so it should be legal names. Any ideas ? Thanks for your time Simon

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c array parameter in resize method of multi_array
by Manuel.Yguel＠inrialpes.fr 11 Jul '06

11 Jul '06

Hi, is there any reason to refuse a resize method for multi_array that accept a C array as parameter ? As long as the resize method just works if the boost::extents parameter has the same dimension as the array to be resized a call like that: typedef boost::multi_array<double, 3> array_type; array_type A( boost::extents[3][4][2] ); ---> A.resize( {6;5;2} ); could be understood as: A.resize( boost::extents[6][5][2] ); without any ambiguity, am I wrong ?

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[graph] remove_if algorithm
by Loïc Joly 11 Jul '06

11 Jul '06

Hello, I'm new to the graph library, but I'm missing some algorithms that I believe are quite low level, and that I expected to find. For instance, I'd like to be able to remove nodes from a graph that meet some criterion. The closest I could find to remove_if was : - Iterate on each node manually: for (tie(vi, viend) = boost::vertices(myGraph) ; vi != viend; ++vi) { if (criterion(vi) { clear_vertex(*vi, myGraph); remove_vertex(*vi, myGraph); } } But I'm afraid of iterator invalidity - Filter, copy, swap: Graph tempGraph; { filtered_graph<Graph, keep_all, Criterion> fg (myGraph, criterion); copy_graph(fg, tempGraph); } copy_graph(tempGraph, myGraph); Will one of my attempts work ? Is there any other solution I missed ? Best regards, -- Loïc

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Re: [Boost-users] erase and iterators
by David Klein 11 Jul '06

11 Jul '06

boost-users-bounces(a)lists.boost.org wrote: > On 7/11/06, David Klein <d.klein(a)ascaron.com> wrote: >> you can use Boost.Lambda for this >> >> #include <boost/lambda/lambda.hpp> >> >> using namespace boost::lambda; >> >> std::vector<int> v; >> ... >> v.erase(std::remove_if(v.begin(), v.end(), 5 == _1)); >> > Shouldn't it be > v.erase( std::remove_if(v.begin(), v.end(), 5 == _1), v.end() > ); as you want to erase the range, not just the single element? > > ~ SWMc > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users <blush> of course, my bad (... actually i blame the heat in our office ;) ) </> -- dave

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Re: [Boost-users] erase and iterators
by David Klein 11 Jul '06

11 Jul '06

boost-users-bounces(a)lists.boost.org wrote: > On Tue, Jul 11, 2006 at 10:19:05AM +0000, Roman Neuhauser wrote: >> # kneeride(a)gmail.com / 2006-07-11 17:31:23 +1000: >>> On 7/11/06, Michael Nicolella <boost(a)mike-n.com> wrote: >>>> vec.erase( std::remove_if( vec.begin(), vec.end(), >>>> some_condition_functor >>>> ) ); >>> >>> Mike, I do like your remove_if example. >>> >>> i am not familar with this approach, can you please give me an >>> example of defining a some_condition_functor? for example when the >>> value == 5. > > What about this? > > Let's assume the vector contains ints > > class condition_functor { > > public: > > bool operator()(int elem) > { > return elem==5 > } > }; > > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users you can use Boost.Lambda for this #include <boost/lambda/lambda.hpp> using namespace boost::lambda; std::vector<int> v; ... v.erase(std::remove_if(v.begin(), v.end(), 5 == _1)); -- HTH dave

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[serialization] skipping data
by Joel de Guzman 11 Jul '06

11 Jul '06

Hi, Here's a use case that I can't seem to find a way to do using boost.serialization. Say with version 1, I want to serialize X Y and Z. These are hierarchical and expensive data structures. Now, with version 2, I do not need to create Y objects anymore. Yet, I still have to open version 1 files for backward compatibility. So, when loading version 1 files, I want to skip reading Y objects. How do I do that without having to create a temporary Y object that will be discarded later? (I'm particularly interested with XML archives. If I had control over the xml parser, that would simply mean ignoring everything from the current tag until the next matching tag is found). Regards, -- Joel de Guzman http://www.boost-consulting.com http://spirit.sf.net

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[BGL] bipartite graphs
by Heiko Bauke 11 Jul '06

11 Jul '06

Hello, how can I deal with bipartite graphs and BGL? In particular I have the problem that my graph has two kinds of nodes with different kinds of vertex properties. Any suggestions? Heiko -- -- Es gibt vielerlei Lärm. Aber es gibt nur eine Stille. -- (Kurt Tucholsky, dt. Schriftsteller, 1890-1935) -- Cluster Computing @ http://www.clustercomputing.de -- Heiko Bauke @ http://www.uni-magdeburg.de/bauke

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Serialization of boost::any
by Sliwa, Przemyslaw (London) 11 Jul '06

11 Jul '06

Does it exist somewhere? Is it planned at all? Thanks for help Kind regards Pshemek Przemyslaw Sliwa Global Foreign Exchange FX Risk Engine Development Merrill Lynch ( +44 (0)20 7995 4182 ) +44 (0)79 6325 2319 * Email: przemyslaw_sliwa(a)ml.com -------------------------------------------------------- If you are not an intended recipient of this e-mail, please notify the sender, delete it and do not read, act upon, print, disclose, copy, retain or redistribute it. Click here for important additional terms relating to this e-mail. http://www.ml.com/email_terms/ --------------------------------------------------------

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[BGL] conflict with call of boost::source
by Lars Monecke 11 Jul '06

11 Jul '06

Hi, i have reduced my problem to the following lines. I want to install a own edge property to a graph. The property as a template argument with then name "source". Here is my try: ---> code starts here <--- #include <boost/graph/adjacency_list.hpp> namespace Foo { class source { }; } namespace Bar { template <class Source> class Edge { }; } typedef Bar::Edge<Foo::source> tMyEdge; struct edge_impl_t { typedef boost::edge_property_tag kind; }; typedef boost::property <edge_impl_t, tMyEdge> edge_property_t; typedef boost::adjacency_list < boost::listS, boost::vecS, boost::undirectedS, boost::no_property, edge_property_t> tGraph; int main(int /* argc */, char* /* argv[] */) { tGraph stGraph1; tGraph stGraph2; stGraph1 = stGraph2; } ----> code ends here <--- When compiling the above code with gcc 4.1.1, i get these errors: main.cpp: In member function 'void boost::vec_adj_list_impl<Graph, Config, Base>::copy_impl(const boost::vec_adj_list_impl<Graph, Config, Base>&) [with Graph = boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, boost::property<edge_impl_t, Bar::Edge<Foo::source>, boost::no_property>, boost::no_property, boost::listS>, Config = boost::detail::adj_list_gen<boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, boost::property<edge_impl_t, Bar::Edge<Foo::source>, boost::no_property>, boost::no_property, boost::listS>, boost::vecS, boost::listS, boost::undirectedS, boost::no_property, boost::property<edge_impl_t, Bar::Edge<Foo::source>, boost::no_property>, boost::no_property, boost::listS>::config, Base = boost::undirected_graph_helper<boost::detail::adj_list_gen<boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, boost::property<edge_impl_t, Bar::Edge<Foo::source>, boost::no_property>, boost::no_property, boost::listS>, boost::vecS, boost::listS, boost::undirectedS, boost::no_property, boost::property<edge_impl_t, Bar::Edge<Foo::source>, boost::no_property>, boost::no_property, boost::listS>::config>]': /usr/local/gcc-4.1.1/boost-1.33.1/boost/graph/detail/adjacency_list.hpp:1990: instantiated from 'boost::vec_adj_list_impl<Graph, Config, Base>& boost::vec_adj_list_impl<Graph, Config, Base>::operator=(const boost::vec_adj_list_impl<Graph, Config, Base>&) [with Graph = boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, boost::property<edge_impl_t, Bar::Edge<Foo::source>, boost::no_property>, boost::no_property, boost::listS>, Config = boost::detail::adj_list_gen<boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, boost::property<edge_impl_t, Bar::Edge<Foo::source>, boost::no_property>, boost::no_property, boost::listS>, boost::vecS, boost::listS, boost::undirectedS, boost::no_property, boost::property<edge_impl_t, Bar::Edge<Foo::source>, boost::no_property>, boost::no_property, boost::listS>::config, Base = boost::undirected_graph_helper<boost::detail::adj_list_gen<boost::adjacency_list<boost::listS, boost::vecS, boost::undirectedS, boost::no_property, boost::property<edge_impl_t, Bar::Edge<Foo::source>, boost::no_property>, boost::no_property, boost::listS>, boost::vecS, boost::listS, boost::undirectedS, boost::no_property, boost::property<edge_impl_t, Bar::Edge<Foo::source>, boost::no_property>, boost::no_property, boost::listS>::config>]' /usr/local/gcc-4.1.1/boost-1.33.1/boost/graph/adjacency_list.hpp:373: instantiated from 'boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>& boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>::operator=(const boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>&) [with OutEdgeListS = boost::listS, VertexListS = boost::vecS, DirectedS = boost::undirectedS, VertexProperty = boost::no_property, EdgeProperty = boost::property<edge_impl_t, Bar::Edge<Foo::source>, boost::no_property>, GraphProperty = boost::no_property, EdgeListS = boost::listS]' main.cpp:42: instantiated from here main.cpp:7: error: 'class Foo::source' is not a function, /usr/local/gcc-4.1.1/boost-1.33.1/boost/graph/adjacency_list.hpp:464: error: conflict with 'template<class Directed, class Vertex, class OutEdgeListS, class VertexListS, class DirectedS, class VertexProperty, class EdgeProperty, class GraphProperty, class EdgeListS> Vertex boost::source(const boost::detail::edge_base<Directed, Vertex>&, const boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>&)' /usr/local/gcc-4.1.1/boost-1.33.1/boost/graph/detail/adjacency_list.hpp:2051: error: in call to 'source' I know the easiest way is to rename Foo::source but this class came from another library. Is there a chance to use this class anyway? Thanks in advance, Lars

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Re: [Boost-users] interested to know your opinion on possible feature
by Ovanes Markarian 11 Jul '06

11 Jul '06

On Tue, July 11, 2006 01:26, Sebastian Redl wrote: > Ovanes Markarian wrote: > >>In my current project is a need to implement an optional type, this type is considered to be >> lazy. >>I am wondering why C++ or Boost do not offer this possibility. >> >> > In what way does Boost.Optional fail to meet your needs? > > Sebastian Redl > > Thanks for your reply. I will take a look at this class in a more detailed manner. I saw it already, but thought it is not what I need. After some inspection I start to realize, that it is indeed what I might need. Thanks again. With Kind Regards, Ovanes Markarian

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erase and iterators
by bringiton bringiton 11 Jul '06

11 Jul '06

is this common practise for using an interator with erase? what i wish to do is interate through each item and delete the item if some condition is true. when i delete, i need to move back a step so that i dont miss an item. for (std::vector<int>::iterator it = vect.begin(); it != vect.end(); it++) { if ((*it) == 5) { // some condition vect.erase(it); it--; // step back } } or would it be best to use a reverse iterater? (or possible?) for (std::vector<int>::reverse_iterator it2 = vect.rbegin(); it2 != vect.rend(); it2++) { if ((*it) == 5) { // i'm not actually sure how to erase with a reverse iterator??? vect.erase(it2); } }

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weak_ptr, shared_ptr and dynamic libraries
by Kyle Girard 10 Jul '06

10 Jul '06

Hello, I was fooling around with the boost::shared_ptr and boost::weak_ptr library and dynamic libraries and I received a segmentation fault which I do not fully understand and I am hoping someone can shed some light on the situation. I am playing around with having objects in a dynamic library which are managed by shared_ptr's return weak_ptrs to the application My problem arises when the weak_ptrs aren't destroyed before the plugin is unloaded. I was hoping that the weak_ptr would become invalid when the shared_ptr it points to is unloaded but instead it causes a segmentation fault. I'm just starting to play around with dynamic libraries and shared_ptrs and stuff so I don't fully understand all the caveats that go with the territory so any information would be appreciated. Here's a small linux example which generates the error: main.cc == Application foo.cc/foo.hh == Dynamic Library make sure to set LD_LIBRARY_PATH to the appropriate directory main.cc ======= #include <iostream> #include <dlfcn.h> #include <boost/weak_ptr.hpp> #include "Foo.hh" using namespace std; int main() { typedef boost::weak_ptr<Foo> (*DoStuff) (void); void *hndl = dlopen("libFoo.so", RTLD_NOW); void *doStuff = dlsym(hndl, "doStuff"); // { //if I comment this in then the error goes away boost::weak_ptr<Foo> wpFoo = ((DoStuff)(doStuff))(); // } //if I comment this in then the error goes away dlclose(hndl); cerr << "Yay Finished" << endl; return 0; } Foo.hh ====== #ifndef FOO_HH #define FOO_HH #include <boost/weak_ptr.hpp> class Foo { }; extern "C" { boost::weak_ptr<Foo> doStuff(); } #endif //FOO_HH Foo.cc ====== #include "Foo.hh" #include <vector> #include <boost/shared_ptr.hpp> std::vector<boost::shared_ptr<Foo> > Foos; extern "C" { boost::weak_ptr<Foo> doStuff() { Foos.push_back(boost::shared_ptr<Foo>(new Foo)); return Foos[0]; } } Makefile ======== CC = g++ LIBS = -ldl .cc.o: $(CC) -ggdb -c $< default: make all OBJS = main.o test: main.o $(CC) -rdynamic -o test main.o $(LIBS) libfoo.so: Foo.o g++ -shared -Wl,-soname,libFoo.so -o libFoo.so Foo.o all: test libfoo.so clean: rm -f *.so *.o test === end of example thanks Kyle

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interested to know your opinion on possible feature
by Ovanes Markarian 10 Jul '06

10 Jul '06

Hello all, I have one issue, which I would like to discuss here. In my current project is a need to implement an optional type, this type is considered to be lazy. I am wondering why C++ or Boost do not offer this possibility. These are just some thoughts which are really not perfect, but an opinion and interest would be highly appreciated: template<class Type, class Allocator /*some other policies like threading etc.*/> class lazy_type { public: //constructors must be considered which //should it be possible to copy this type etc. //destuctor, must be considered how the object should be deallocated in regards of owning and non-owning policies operator bool()const { return ptr_!=NULL; } Type* operator->() { if(!ptr_) { //allocate ptr_ and instantiate it using an allocator or another policy type ... } return ptr_; } private: Type* ptr_; }; This type can be a mix of reference counted ptr (shared_ptr) and allocator on request. All comments and thoughts are HIGHLY appreciated. With Kind Regards, Ovanes Markarian

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Linking errors while using the test library (for a very basic program)
by Josh 10 Jul '06

10 Jul '06

I have a very simple program ******************************************************************** #include <iostream> #include <boost/test/unit_test.hpp> using boost::unit_test::test_suite; void MyTest() { BOOST_CHECK(2==2); } test_suite * init_unit_test_suite( int, char* [] ) { test_suite* test= BOOST_TEST_SUITE( "Simple test" ); test->add(BOOST_TEST_CASE( &MyTest ), 0); return test; } **************************************************************************************** I am trying to compile it using the following commands g++ -c BoostTest.cpp -I~/boost/include/boost-1_33_1/ g++ -o BT BoostTest.o -I/home/josh/boost/include/boost-1_33_1/ /home/josh/boost/lib/libboost_unit_test_framework-gcc-s.a The first step completes without a problem, the linking stage gives the following errors BoostTest.o(.text+0x15b): In function `MyTest()': : undefined reference to `boost::test_tools::tt_detail::test_and_continue_impl(bool, boost::basic_wrap_stringstream<char>&, boost::unit_test::basic_cstring<char const>, unsigned int, bool, boost::unit_test::log_level)' BoostTest.o(.text+0x258): In function `init_unit_test_suite(int, char**)': : undefined reference to `boost::unit_test::test_suite::add(boost::unit_test::test_case*, unsigned long, int)' BoostTest.o(.gnu.linkonce.t._ZN5boost9unit_test16create_test_caseEPFvvESs+0x12): In function `boost::unit_test::create_test_case(void (*)(), std::basic_string<char, std::char_traits<char>, std::allocator<char> >)': : undefined reference to `boost::unit_test::ut_detail::normalize_test_case_name(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&)' BoostTest.o(.gnu.linkonce.t._ZN5boost9unit_test18function_test_caseC1EPFvvENS0_13basic_cstringIKcEE+0x1b): In function `boost::unit_test::function_test_case::function_test_case(void (*)(), boost::unit_test::basic_cstring<char const>)': : undefined reference to `boost::unit_test::test_case::test_case(boost::unit_test::basic_cstring<char const>, bool, unsigned long, bool)' BoostTest.o(.gnu.linkonce.r._ZTVN5boost9unit_test18function_test_caseE+0x10): undefined reference to `boost::unit_test::test_case::size() const' BoostTest.o(.gnu.linkonce.t._ZN5boost9unit_test9test_caseD2Ev+0xc): In function `boost::unit_test::test_case::~test_case()': : undefined reference to `vtable for boost::unit_test::test_case' BoostTest.o(.gnu.linkonce.r._ZTIN5boost9unit_test18function_test_caseE+0x8): undefined reference to `typeinfo for boost::unit_test::test_case' ************************************************************* PLEASE HELP! Josh --------------------------------- Want to be your own boss? Learn how on Yahoo! Small Business.

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Re: [Boost-users] std::vector< boost::shared_ptr<int> >::pop_back()
by Andrew Holden 10 Jul '06

10 Jul '06

You would manually call destructors when you do your own memory management (like std::vector). In this case, you would also need to manually call constructors too. Here is a modified version of your test program that doesn't double-destruct the object. class A { public: A() { counter = 0; } ~A() { counter++; std::cout << "~A(): " << counter << std::endl; } int counter; }; int main(int argc, char* argv[]) { A *a; //Allocate memory using C functions, which do not call constructors a = (A*) malloc (sizeof (A)); cout << a << ' ' << a->counter << std::endl; //Manually call the constructor. The (a) tells the compiler which pointer we are initializing new (a) A (); cout << a << ' ' << a->counter << std::endl; //Manually call the destructor a->~A(); cout << a << ' ' << a->counter << std::endl; //Free memory using C functions, which do not call destructors free (a); return 0; } _____ From: bringiton bringiton [mailto:kneeride@gmail.com] Sent: Monday, July 10, 2006 10:28 AM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] std::vector< boost::shared_ptr<int> >::pop_back() holy! you learn something every day. you can call the destructor of an object (before destruction) this is a trap for me because i dont clean up my variables in destructors. class A { public: A() { counter = 0; } ~A() { counter++; std::cout << "~A(): " << counter << std::endl; } int counter; }; int main(int argc, char* argv[]) { A a; a.~A(); return 0; } NOTE: destructor gets called twice. (so it's probably a good idea to NULL pointers in destructors) On 7/11/06, bringiton bringiton <kneeride(a)gmail.com> wrote: >>just look at the include files: i looked at the header, but got a little confused. i don't see how you can call a destruct of a a memory space that still exists. ie a C version of a vector. shared_ptr<int> list[1024]; int n = 0; // add an item shared_ptr<int> newItem(new int(1)); list[n++] = newItem; // remove the tail item n--; // destructor never called is it possible to call a destructor of an object that exists? what then happens then the object goes out of scope? the destructor will be called twice. (or maybe i am completely missing the point) BTW: not sure if above code compiles (did it in my head) On 7/10/06, Boris Breidenbach < Boris.Breidenbach(a)physik.uni-erlangen.de <mailto:Boris.Breidenbach@physik.uni-erlangen.de> > wrote: On Mon, Jul 10, 2006 at 03:58:19PM +1000, bringiton bringiton wrote: > This question is based on curiosity. How does std::vector::pop_back() call > the destructor of the item getting removed? > > i understood std::vector to be a contigious array of memory, therefore an > item's memory does not go out of scope when being popped. ie the item goes > out of scope when the entire array goes out of scope. just look at the include files: bits/stl_vector.h says: void pop_back() { --this->_M_impl._M_finish; std::_Destroy(this->_M_impl._M_finish); } so the destructor is called in std::_Destroy. Which can be found in bits/stl_construct.h: /** * @if maint * Destroy the object pointed to by a pointer type. * @endif */ template<typename _Tp> inline void _Destroy(_Tp* __pointer) { __pointer->~_Tp(); } It just calls the destructor. _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Re: [Boost-users] std::vector< boost::shared_ptr<int> >::pop_back()
by Andrew Holden 10 Jul '06

10 Jul '06

True. I would not expect a guarantee that malloc/free would be suitable for objects, since they came from a language that doesn't have objects. I was merely looking for a way to demonstrate manually calling both the constructor and destructor without calling either twice, and that happened to work on my platform, and I think will probably work on most. Well, that and I didn't know you could use operator new and operator delete like this. We all learn something new every day. _____ From: Michael Nicolella [mailto:boost@mike-n.com] Sent: Monday, July 10, 2006 2:54 PM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] std::vector< boost::shared_ptr<int> >::pop_back() I would avoid malloc() and prefer the global operator new... I'm not sure if the standard guarantees that memory allocated with malloc is suitable for constructing an object in. My guess is there's no such guarantee, but there is that guarantee for operator new. Or maybe I'm off my rocker.

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[serialization] save_construct_data problem
by Hugh Hoover 10 Jul '06

10 Jul '06

I have a structure I'm trying to serialize that contains an STL vector of pointers to an abstract base type. When I serialize it, the save_construct_data free function is NOT called - the inline default version is always used. On de-serializing, the load_construct_data IS called! but, of course, fails because the data for it isn't there (although it throws archive_exception (archive_exception::unregistered_class) when it fails). I'm using declarations only for all serialization code, with all definitions in .s.cpp files along with explicit instantiations. Not sure if that affects the problem here. Just in case, I've tried all combinations of save_construct_data with (const)? (Base|Derived) (*|&), and none of them are called. I've also tried putting my declarations before and after the serialization.hpp header with the default declaration/definition. I'm using gcc4 currently. Any notion what might be wrong here?

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Missing example in boost::graph doc
by Loïc Joly 10 Jul '06

10 Jul '06

Hello, In boost::graph doc, I can read (http://www.boost.org/libs/graph/doc/file_dependency_example.html) > A compilation system such as make has to be able to answer a number of questions: > > 1. If we need to compile (or recompile) all of the files, what order should that be done it? > 2. What files can be compiled in parallel? > 3. If a file is changed, which files must be recompiled? > 4. Are there any cycles in the dependencies? (which means the user has made a mistake and an error should be emitted) > I'd like to do something related to the point #3, and looked in the doc, but could not find it. Since I'm not at all a graph expert, I'd like to know whether there is a basic graph algorithm that can be used to remove from a graph all nodes who are not marked as modified and whose all dependencies (recursively) are not marked as modified either. -- Loïc

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memory leaks with signal::connect()
by Elisabeth Benoit 10 Jul '06

10 Jul '06

Hello, I'm sending this message a second time (I didn't receive any response and still have this problem) I'm using boost::bind and boost::signal with VC6. VC6 is detecting some memory leak for a certain type of signal.connect(). I've done a little test program to check if the problem was due to some bug or special configuration in my main program, but the memory leaks are still detected in the test situation. Let me explain the structure of my test program. I have a main, and in the main, an object CCloneAppRecipe named clone. The class CCloneAppRecipe contains a member m_PtrTestMem (a shared pointer, but a raw point or an object does the same thing) of the class CTestMem. CTestMem contains 3 instances of the class CTestTab, and the class CTestTab contains a boost signal typedef boost::signal0<void> TypeSignalTest; TypeSignalTest m_SignalTest; In my main, I invoke clone.connectPtrTestMem(). clone.connectPtrTestMem() then invokes CTestMem::ConnectSignalTriplePtrTab(boost::bind(&CloneAppRecipe::test, this)); ConnectSignalTriplePtrTab() then invokes ConnectSignal(TypeSignalTest::slot_type slot) for each of the 3 instances of the class it contains. ConnectSignal then calls m_SignalTest.connect(slot). And I have a memory leak: 2 blocks of 16 bytes. If I connect only one instance of CTestTab, no leak. Two instances, one leak of 16 bytes. Three, two leaks of 16 bytes, and so on. I connect the m_SignalTest with a CCloneAppRecipe's slot. If I connect it to a CTestMem slot, I have no leak. Or if I place 3 instances of CTestTab directly in the CCloneAppRecipe class (so I don't use CTestMem anymore), I have no leak. But that's not what I need to do. I've tested plenty of variations (shared_pointer or object, etc.) Does anybody have a clue. Thanks #include "stdafx.h" #include "CloneAppRecipe.h" #ifdef _DEBUG #define new DEBUG_NEW #undef THIS_FILE static char THIS_FILE[] = __FILE__; #endif int main() { CloneAppRecipe t; // cree un leak t.connectPtrTestMem(); getchar(); return 0; } void CloneAppRecipe::connectPtrTestMem() { //m_ptrTestMem is a boost::shared_ptr m_ptrTestMem->ConnectSignalTriplePtrTab(boost::bind(&CloneAppRecipe::test, this)); } void CloneAppRecipe::test() const { } void CTestMem::ConnectSignalTriplePtrTab(const TypeSignaTest::slot_type& slot) { //m_ptrTestTab are boost::shared_ptr m_ptrTestTab1->ConnectSignal(slot); m_ptrTestTab2->ConnectSignal(slot); m_ptrTestTab3->ConnectSignal(slot); } void CTestTab::ConnectSignal(const TypeSignalTest::slot_type& slot) { m_SignalTest->connect(slot); } CTestTab::~CTestTab() { m_SignalTest->disconnect_all_slots(); }

2 5

std::vector< boost::shared_ptr<int> >::pop_back()
by bringiton bringiton 10 Jul '06

10 Jul '06

This question is based on curiosity. How does std::vector::pop_back() call the destructor of the item getting removed? i understood std::vector to be a contigious array of memory, therefore an item's memory does not go out of scope when being popped. ie the item goes out of scope when the entire array goes out of scope. example code: the reference count is decremented when the item is popped from the vector. boost::shared_ptr<int> item1(new int(1)); std::vector< boost::shared_ptr<int> > vect1; vect1.push_back(item1); std::cout << item1.use_count() << std::endl; vect1.pop_back(); std::cout << item1.use_count() << std::endl;

3 5

vc-8_0-stlport target : Building Boost with VS2005 & STLPort 5 ?
by Sagnes, Frederic 10 Jul '06

10 Jul '06

Hello, Now that STLPort works for VS2005, I'd like to know if a BJam target for Visual Studio 2005 and STLPort 5.0.2 is available (as a patch for the 1.33 Boost distribution). Is STLPort 5.0 too young for inclusion, or is this target to be available only in the 1.34 version of the Boost libraries distribution? Regards _______________________________________________ Frédéric Sagnes, A&D AS RD DH K3 Siemens AG Karlsruhe

1 0

[boost.python] use of multi_array in python
by Sebastien Fortier 10 Jul '06

10 Jul '06

I'm having some problems with the use of multi_array's with python. What I'm trying to do is to export some functions that create multi_array's and pass these multi_array's to other functions that will extract other array's from them and display them. Lets say I have this as an example. //ArrayRef2D.h typedef for a 2D multi_array of doubles #ifndef ARRAYREF2D_H_ #define ARRAYREF2D_H_ #include <boost/multi_array.hpp> typedef boost::const_multi_array_ref < double, 2 > const_array_type2D_ref_d_t; typedef boost::multi_array < double, 2 > array_type2D_d_t; #endif /*ARRAYREF2D_H_*/ //Fstd.h 2D multi_array generator #ifndef FSTD_H_ #define FSTD_H_ #include "ArrayRef2D.h" #include <string> using namespace std; class Fstd { public: Fstd(string filename) : filename_(filename){} array_type2D_d_t get2Dfield() { array_type2D_d_t matrix(boost::extents[2][2]); matrix[0][0] = 0; matrix[0][1] = -1; matrix[1][0] = 20; matrix[1][1] = -30; return matrix; } private: string filename_; }; #endif /*FSTD_H_*/ //MatrixAlgorithm2D.h provides methods for displaying and manipulating matrices #ifndef MATRIXALGORITHM2D_H_ #define MATRIXALGORITHM2D_H_ #include "ArrayRef2D.h" #include <cassert> #include <cmath> #include <iostream> using namespace std; class MatrixAlgorithm2D { public: static array_type2D_d_t windChill(const_array_type2D_ref_d_t TT, const_array_type2D_ref_d_t UV) { assert((TT.shape()[0] == UV.shape()[0]) && (TT.shape()[1] == UV.shape()[1])); array_type2D_d_t RE(boost::extents[TT.shape()[0]][TT.shape()[1]]); for (unsigned int x = 0; x < TT.shape()[0]; x++) { for (unsigned int y = 0; y < TT.shape()[1]; y++) { if ((TT[x][y] <= 0.0) && (UV[x][y] >= 5.0)) { RE[x][y] = ( 13.1200 + 0.6215 * (TT[x][y]) + (0.3965 * (TT[x][y]) - 11.3700) * (pow((UV[x][y]),0.16))); } else { RE[x][y] = (TT[x][y]); } } } return RE; } static void display_d(const_array_type2D_ref_d_t a) { for (unsigned int x = 0; x < a.shape()[0]; x++) { for (unsigned int y = 0; y < a.shape()[1]; y++) { cout << a[x][y]; if(y < a.shape()[1] - 1) { cout << ", "; } } cout<<endl; } } }; #endif /*MATRIXALGORITHM2D_H_*/ //matrix.cpp boost.python interface file generated with pyste // Boost Includes ============================================================== #include "boost/python.hpp" #include "boost/cstdint.hpp" // Includes ==================================================================== #include "Fstd.h" #include "MatrixAlgorithm2D.h" // Using ======================================================================= using namespace boost::python; // Module ====================================================================== BOOST_PYTHON_MODULE(matrix) { class_< Fstd >("Fstd", init< const Fstd& >()) .def(init< std::string >()) .def("get2Dfield", &Fstd::get2Dfield) ; class_< MatrixAlgorithm2D >("MatrixAlgorithm2D", init< >()) .def(init< const MatrixAlgorithm2D& >()) .def("windChill", &MatrixAlgorithm2D::windChill) .def("display_d", &MatrixAlgorithm2D::display_d) .staticmethod("windChill") .staticmethod("display_d") ; } I generated my so file with bjam and then Python 2.3.5 (#2, Sep 4 2005, 22:01:42) [GCC 3.3.5 (Debian 1:3.3.5-13)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import matrix >>> dir(matrix) ['Fstd', 'MatrixAlgorithm2D', '__doc__', '__file__', '__name__'] >>> m = matrix.Fstd("HELLO") >>> l = m.get2Dfield() Traceback (most recent call last): File "<stdin>", line 1, in ? TypeError: No to_python (by-value) converter found for C++ type: boost::multi_array<double, 2, std::allocator<double> > So you see I can't use my code, what am I doing wrong? I would have liked to declare 2 arrays with get2Dfield() and pass these array to my windChill function to get another 2d matrix which I could then display with my display_d function. -- Sébastien Fortier

2 8

[shmem] Bug I can't workaround
by Berenguer Blasi 10 Jul '06

10 Jul '06

Hi, first of all congratulations to Ion for this great library. I am trying to use shmem for a very large project and I have stumbled several bugs (you can read about them at the sourceforge bugtracker) I have workarounded so far, but there's one I can't workaround. Maybe somebody has found a solution? How to reproduce: 1- Any sample code will do (you can use the sample source at 'Quick Guide for the Impatient' -> 'Using STL containers and mapping the memory at a fixed address') 2- Change to a fixed_named segment, if it isn´t so already in your sample, and increase the segment size to 104857600. I guess it's not a matter of this specific size but something that happens for large segments. 3- Leave process A running in the background, run process B and you get a segmentation fault... 4- You won't have the problem for sizes: 1048576 or 10485760. Has anybody experienced something similar? Thanks in advance. It's driving me crazy! and I am so close to finishing my code. Only this bug pending! Environment: FC 5, gcc4.1.1-1

1 0

[variant].[apply_visitor] Binary visitation: Build related problem.
by Prashant Thakre 10 Jul '06

10 Jul '06

Hi, Compiler instantiates the second Binary visitor instead of the first one even though the template parameters are same. regards, Prashant --------------------------------------------------------------------------- struct add_tuple_visitor: public boost::static_visitor<bool> { // Expected this to be instantiated by the compiler. // 1. template <typename T> bool operator()( T & lhs, const T & rhs) const { lhs += rhs ; return true; } // Compiler considers this as an appropriate fit .. // 2. template <typename T, typename U> bool operator()( T & lhs, const U & rhs) const { lhs += rhs ; return true; } }; struct agg_calc { public: template <typename T> bool operator () ( T & lhs, const T & rhs ) const { for( std::size_t curr_oper = 0; curr_oper < num_operations; ++v ) { switch( agg_operators.at(curr_oper) ) { case '+' : boost::apply_visitor( agg_visitor, lhs.at(curr_oper), //vector of variants rhs.at(curr_oper) //vector of variants ); break; default: break; }; } // for loop return true; } //Store the aggregation operators agg_types agg_operators; std::size_t num_operations; // Create visitor objects for delayed form of apply_visitor add_tuple_visitor agg_visitor; }; ---------------------------------------------------------------------------

1 0

[variant] apply_visitor to rvalue variant
by Marc Mutz 10 Jul '06

10 Jul '06

Hi, My gcc 4.0 doesn't let me call apply_visitor on an rvalue variant. This is due to the Variant argument being a non-const reference, I guess. Is this a deliberate design decision (if so, the rationale should be documented), an oversight (in that case, it should be fixed), or a compiler bug (highly unlikely, since all of gcc 3.2 through 4.1 would then have it). Testcase (== usecase) attached. Thanks, Marc -- Marc Mutz -- marc(a)klaralvdalens-datakonsult.se, mutz(a)kde.org Klarälvdalens Datakonsult AB, Platform-independent software solutions

1 0

Problems trying to use boost book
by Robert Ramey 10 Jul '06

10 Jul '06

I'm interested in setting up quickbook/boostbook/docbook for my windows NT machine. To that end I've religously followed the instructions in http://www.boost.org/regression-logs/cs-win32_metacomm/doc/html/boostbook/g… (Not including installing Java) I get to "Running Boost Book". Following the instructions there I invoke bjam --v2 and get: the following response $ bjam --v2 warning: Python location is not configured warning: the Boost.Python library won't be built Building Boost.Regex with the optional Unicode/ICU support disabled. Please refer to the Boost.Regex documentation for more information (and if you don't know what ICU is then you probably don't need it). warning: no toolsets are configured. warning: you won't be able to build C++ programs. warning: please consult the documentation at warning: http://boost.org/boost-build2/doc/html/bbv2/advanced/configuration.html I've verified the current directory $ pwd C:/BoostHead/doc and that xsltproc is in my path $ xsltproc Usage: xsltproc [options] stylesheet file [file ...] Options: --version or -V: show the version of libxml and libxslt used --verbose or -v: show logs of what's happening --output file or -o file: save to a given file --timing: display the time used --repeat: run the transformation 20 times --debug: dump the tree of the result instead --dumpextensions: dump the registered extension elements and functions t o stdout --novalid skip the Dtd loading phase --nodtdattr do not default attributes from the DTD --noout: do not dump the result --maxdepth val : increase the maximum depth --maxparserdepth val : increase the maximum parser depth --html: the input document is(are) an HTML file(s) --param name value : pass a (parameter,value) pair value is an UTF8 XPath expression. string values must be quoted like "'string'" or use stringparam to avoid it --stringparam name value : pass a (parameter, UTF8 string value) pair --path 'paths': provide a set of paths for resources --nonet : refuse to fetch DTDs or entities over network --nowrite : refuse to write to any file or resource --nomkdir : refuse to create directories --writesubtree path : allow file write only with the path subtree --catalogs : use SGML catalogs from $SGML_CATALOG_FILES otherwise XML Catalogs starting from file:///etc/xml/catalog are activated by default --xinclude : do XInclude processing on document intput --load-trace : print trace of all external entites loaded --profile or --norman : dump profiling informations Project libxslt home page: http://xmlsoft.org/XSLT/ To report bugs and get help: http://xmlsoft.org/XSLT/bugs.html Same goes for doxygen $ doxygen Doxyfile not found and no input file specified! Doxygen version 1.4.7 Copyright Dimitri van Heesch 1997-2006 You can use doxygen in a number of ways: 1) Use doxygen to generate a template configuration file: doxygen [-s] -g [configName] If - is used for configName doxygen will write to standard output. 2) Use doxygen to update an old configuration file: doxygen [-s] -u [configName] 3) Use doxygen to generate documentation using an existing configuration file: doxygen [configName] If - is used for configName doxygen will read from standard input. 4) Use doxygen to generate a template style sheet file for RTF, HTML or Latex. RTF: doxygen -w rtf styleSheetFile HTML: doxygen -w html headerFile footerFile styleSheetFile [configFile] LaTeX: doxygen -w latex headerFile styleSheetFile [configFile] 5) Use doxygen to generate an rtf extensions file RTF: doxygen -e rtf extensionsFile If -s is specified the comments in the config file will be omitted. If configName is omitted `Doxyfile' will be used as a default. ************ I don't get any .html files created in the html directory. So now I'm stuck. Please help. FYI - a couple of comments on getting/started.html (very strange name!) Its not altogether clear from reading the documentation whether things like DOCBOOK_XSL_DIR should be an exported environmental variable with the value set to the appropriate directory or if the actual directory name should be substitued where DOCBOOK_XSL_DIR appears in the example. I presumed the former. I've double checked this like so: $ ls "$DOCBOOK_XSL_DIR" AUTHORS RELEASE-NOTES.txt javahelp BUGS RELEASE-NOTES.xml lib COPYING TODO manpages ChangeHistory.xml.zip VERSION params ChangeLog.xml catalog.xml profiling INSTALL common slides LOG eclipse template NEWS extensions test.sh NEWS.html fo tools NEWS.xml html uninstall.sh README htmlhelp website RELEASE-NOTES.html images wordml RELEASE-NOTES.pdf install.sh xhtml $ ls "$DOCBOOK_DTD_DIR" ChangeLog catalog.xml dbhierx.mod docbook.cat soextblx.dtd README dbcentx.mod dbnotnx.mod docbookx.dtd calstblx.dtd dbgenent.mod dbpoolx.mod ent $ So what am I missing? Robert Ramey

3 6

trouble with bind+signals
by Brendan Miller 10 Jul '06

10 Jul '06

I'm relatively new to the boost library and I'm having a problem with boost::signals and bind. I've reproduced the problem I'm hitting here. c++: typedef boost::signal <LRESULT (ISigSource &, LPCREATESTRUCT)> SigWMCreate; SigWMCreate sig; LPARAM x; boost::bind(boost::ref(sig), boost::ref(*this), _1)((LPCREATESTRUCT)(x)); The above function application generates the following warning on msvc 8/vs2005: Error 1 error C2664: '__w64 long boost::_bi::bind_t<R,F,L>::operator ()<LPCREATESTRUCT>(A1 &) const' : cannot convert parameter 1 from 'LPCREATESTRUCT' to 'LPCREATESTRUCT &' c:\documents and settings\catphive\my documents\visual studio 2005\projects\game\game\mainfrm.cpp 20 Now, this problem goes away if x is of type LPCREATESTRUCT to start with instead of another type converted to LPCREATESTRUCT within the parentheses of the function application. This seems a bit odd to me. Also, I'd like to avoid changing how the function application is performed and get to the root of the problem since in my *actual* code, the application is performed in a system macro, and I'd like to avoid changing external headers (and having to remember what I changed in case of an update to the headers) if possible. My guess is that performing the cast creates an intermediary result that I'm not allowed to take a reference of. Is this the case? Does this happen on other compilers with analogous types? Is there a way to work around this? Thanks

2 2

[parameter] Interface questions
by Cromwell Enage 09 Jul '06

09 Jul '06

1. Will BOOST_PARAMETER_IMPL(name) expand to the name of the function that actually "owns" the main body of code? 2. Will there be a way to define a Boost.Parameterized member function outside the class definition? Or should we let the compiler decide whether or not to inline such a function? Cromwell D. Enage __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

2 4

uint_t<bits>::value where bits is a template parameter fails to compile
by Phil Endecott 07 Jul '06

07 Jul '06

Dear All, I am having trouble using the integer library. The following fails to compile: #include <boost/integer.hpp> template <int bits> void fn(void) { //typedef boost::uint_t<8>::least t; typedef boost::uint_t<bits>::least t; t var; } int main(int argc, char* argv) { fn<8>(); } With g++ 4.0.0 on Linux and Boost 1.32, I get: boost_int_test.cc: In function â€˜void fn()â€™: boost_int_test.cc:7: error: expected initializer before â€˜tâ€™ boost_int_test.cc:8: error: â€˜tâ€™ was not declared in this scope boost_int_test.cc:8: error: expected `;' before â€˜varâ€™ The problem seems to occur when I use a template parameter - "bits" in this case - as the template parameter to uint_t. If I use a constant (as in the commented-out line) it works. Is this a C++ feature, or a bug somewhere? Can anyone suggest a workaround? Thanks, Phil.

2 1

[spirit] working with end_p
by james.jones＠firstinvestors.com 07 Jul '06

07 Jul '06

From: Neil Hunt <boost(a)thehunts.id.au> > Hello all, > > Given a simple spirit grammar (simplified from my real grammer and > untested) such as: > > file = *line; > line = sensible_line >> ending >> *comment; > sensible_line = confix_p( '\"', *c_escape_ch_p, '\"' ); > comment = !( ch_p(';') >> ( anychar_p - eol_p ) ) >> ending; > ending = *blank_p >> ( eol_p | end_p ); > > > Note: any given line can be legitimately terminated by the end of the > file or end of line > > And there can be arbitrary numbers of comment lines between sensible lines. > > However since 'comment' is terminated with 'ending', the parser ends up > in an infinite loop matching the kleene star on end_p because it returns > zero length (doesn't advance the scanner). At least I think this is the > problem. Indeed. You can fix it by adjusting your grammar thus: line = sensible_line >> (ending >> comment)* >> ending; sensible_line ... as before comment = !( ch_p(';') >> ( anychar_p - eol_p ) ); ending ... as before - James Jones Administrative Data Mgmt. Webmaster 375 Raritan Center Pkwy, Suite A Data Architect Edison, NJ 08837

1 0

[serialization] Facets for writing and reading infinity and nan to text streams
by Johan Råde 07 Jul '06

07 Jul '06

Following a suggestion of Robert Ramey's, I have put together facets for writing and reading non-finite floating point numbers, such as infinity and nan, to text streams, in a consistent and portable way. This is useful when serializing to text archives, but should have other applications as well. I have attached a zip file. It contains three files: 1. the actual code: non_finite_num_facets.hpp 2. documentation: non_finite_num_facets_doc.txt 3. tests: non_finite_num_facets_test.cpp The code handles char and wchar_t. It handles float, double and long double. The code has been tested with VC++ 7.1 but should work with other compilers as well. Any feedback is wellcome. --Johan Råde (rade(a)maths.lth.se)

2 3

std::find_if, boost::mem_fn and boost::not1
by Pete Hodgson 06 Jul '06

06 Jul '06

Hi All, I'm just getting into using boost and stl algorithms, and I'm getting some indecipherable compiler errors that I'd like some help understanding. Here's some sample code: <------------------------SNIP------------------------> #include <boost/shared_ptr.hpp> #include <boost/functional.hpp> #include <boost/bind.hpp> class CEgg { public: bool IsHatched() const; }; typedef std::vector< boost::shared_ptr<CEgg> > tEggsVector; //this function compiles with no problems bool SomeEggsHaveHatched() { tEggsVector basketOfEggs; tEggsVector::const_iterator it = std::find_if( basketOfEggs.begin(), basketOfEggs.end(), boost::mem_fn( &CEgg::IsHatched ) ); bool bSomeEggsHaveHatched = ( it != basketOfEggs.end() ); return bSomeEggsHaveHatched; } //this function doesn't compile, //presumably because of the boost::not1 usage bool AllEggsHaveHatched() { tEggsVector basketOfEggs; tEggsVector::iterator it = std::find_if( basketOfEggs.begin(), basketOfEggs.end(), boost::not1( boost::mem_fn( &CEgg::IsHatched ) ) ); bool bSomeEggsHaventHatched = ( it != basketOfEggs.end() ); return !bSomeEggsHaventHatched; } <------------------------SNIP------------------------> When I try and compile this in Visual C++ 2003 I get the following compile errors for AllEggsHaveHatched(): c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\include\algorithm(64) : error C2664: 'bool boost::unary_negate<Predicate>::operator ()(const boost::call_traits<T>::param_type) const' : cannot convert parameter 1 from 'std::allocator<_Ty>::value_type' to 'const boost::call_traits<T>::param_type' with [ Predicate=boost::_mfi::cmf0<bool,CEgg>, T=boost::unary_traits<boost::_mfi::cmf0<bool,CEgg>>::argument_type ] and [ _Ty=boost::shared_ptr<CEgg> ] and [ T=boost::unary_traits<boost::_mfi::cmf0<bool,CEgg>>::argument_type ] No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called c:\WORK\4DCapture_Soln\VideoCapture\PixelinkCaptureFacade.h(46) : see reference to function template instantiation '_InIt std::find_if<std::vector<_Ty>::iterator,boost::unary_negate<Predicate>>(_InIt,_InIt,_Pr)' being compiled with [ _InIt=std::vector<boost::shared_ptr<CEgg>>::iterator, _Ty=boost::shared_ptr<CEgg>, Predicate=boost::_mfi::cmf0<bool,CEgg>, _Pr=boost::unary_negate<boost::_mfi::cmf0<bool,CEgg>> ] Any idea why boost::not1 seems to be causing problems? Should I be using std::not1? or boost::mem_fun instead of boost:mem_fn? Cheers and TIA, Pete

3 6

Boost compile fails on Visual C++ 6, warnings on VS8
by Sagnes, Frederic 06 Jul '06

06 Jul '06

Hello, I'm using the Boost libraries for my project (archive, threads, program_options, date_time) and these are really helpful, saved me a lot of time and the great designs make them easy to use. I'm compiling my project with Visual Studio 2005 (8.0) and gcc 4.0.1. Both work quite well, I only have warnings on VS8 because it seems to render integer operation in 64 bit and no cast is being done (a static cast would fix this), some deprecation warning which are normal, and the GCC build works well. But the VC++ 6 compilation is a real pain, here is the command line for BJam: bjam "-sTOOLS=msvc" "-sMSVC_ROOT=C:\Programme\Microsoft Visual Studio\VC98" "-sVISUALC=C:\Programme\Microsoft Visual Studio\VC98" --prefix=D:\ALM\Boost\msvc install I get a lot of compilation errors, including internal compiler errors which are quite alarming. I thought Boost libraries were meant to be portable and compile on VS6. The archive library for instance fails to build. Is there a workaround to build Boost libraries on VS6? Did I miss a switch or setting? Is VS6 that bad that it can't render complex but standard C++ code? Where can I check with which compiler Boost libraries are compatible? Best regards _______________________________________________ Frédéric Sagnes, A&D AS RD DH K3 Siemens AG Karlsruhe

2 1

boost::bind question
by Surya Kiran Gullapalli 06 Jul '06

06 Jul '06

Hi, I've a std::map with the following structure. std::map < int, tuple<std::string, std::string> > mapTuple ; typedef map < int, tuple<string, string> > mapTuple ; Now i've say 10 elements in this container. Now i'd like to iterate thru this container and find a specific element which matches a certain criteria. Right now I'm doing this. MapIntTuple::iterator iter ; for (iter = mymap.begin(); iter != mymap.end(); ++iter) { if (iter->second.get<0>() == current_field) break ; } I'd like to iterate thru the container and find the element whose first string in the tuple matches with my search string. How can i do this using boost::lamdba::bind and std::find_if. May be that will help me in understanding boost::bind better. iter = find_if (mymap.begin(), mymap.end(), ???) ; Thanks in advance, Surya

1 0

[date_time] unused parameter warnings with gcc
by Brian Neal 05 Jul '06

05 Jul '06

Just a suggestion: We like to compile with lots of warning turned on and try to strive for warning free builds. Under gcc, with the -Wall -W options, we get a lot of "warning: unused parameter" warnings with the date_time library. For example, /usr/include/boost-1_33/boost/date_time/time_facet.hpp:202: warning: unused parameter 'a_ref' It looks like a lot of these could be fixed by /* commenting out */ the unused parameter names; e.g. explicit time_facet(::size_t /* a_ref */ = 0) ... Thanks.

1 0

Re: [Boost-users] [boost] [Announce] Boost Installer for Visual C++ 7.1/8.0
by Trent Nelson 05 Jul '06

05 Jul '06

> Boost Consulting is pleased to announce the availability of a Windows > installer for the current Boost release (1.33.1). See: > > http://www.boost-consulting.com/download.html Any plans to make the .nsi file you're using public? There may be a few of us out there that have experience with Nullsoft and could contribute to the installer in some way, shape or form. Trent.

4 4

vectors with multiindex
by Adán Cosgaya 05 Jul '06

05 Jul '06

hi, i am new using the multiindex library, and I need to do the following. I have a set of d-dimensional points (e.g (3,5,8,9,5) is a 5-dimensional point), and I need to sort the points on each of the coordinates. I want to store the points in a vector, and use multiindex to have all the points (vectors in this case) sorted in each of the coordinates. E.g. sorted by x: x y z w ----------- 0 0 0 0 1 2 7 4 2 3 1 1 3 1 3 3 4 5 2 9 sorted by y: 0 0 0 0 3 1 3 3 1 2 7 4 2 3 1 1 4 5 2 9 etc... would you mind pointing me in the right direction with an example of how to do it with multiindex library? thanks

3 3

[mpl] a few questions about set and map
by Yuval Ronen 05 Jul '06

05 Jul '06

I spent some time reading the mpl docs, and I have a few questions about mpl::set and mpl::map. 1. The docs assert there is a 'front' algorithm for set and map. This sounds weird to me, as the order of the types is them unspecified. But if I'm wrong, and 'front' is in place, then where is 'back'? 2. Where's multiset and multimap? In the boost/mpl directory I see something about multiset, but no real boost/mpl/multiset.hpp header, and there's absolutely nothing about multimap. 3. The docs say that the size of joint_view is the arithmetic sum of the sizes of the sequences of which it's composed. Is that true also in the case of set/map? For an mpl newbie it sounds reasonable that it will removed duplicates and might end up with a size that is smaller than the sum of its components. If it's not, then it sounds quite useless to use it for set/map. Thanks, Yuval

4 20

How to find ancestor nodes in a graph, thanks
by sean yang 05 Jul '06

05 Jul '06

Hi folks, I want to find all the nodes that can reach a specific node 'target_n'. Let's say, an example graph looks like this: G= (V, E), where V={A, B, C, target_1, target_2, D, E, F}, and E= { (A-->B), (B-->target_1), (C-->target_2), (A-->target_2), (D-->E), (E-->F), (F-->D), } In this example, I want to find out(say print them out) 'A', 'B', 'C'. Now, I have a graph representation like the following one . ------------------------------ typedef adjacency_list<vecS, vecS, bidirectionalS, VertexNameProperty > Graph; Graph travel; --------------------------------- And I have already read in the above information to the Graph travel. One way I am thinking of to achieve the above goal is: reverse the direction of edges in G, i.e., getting a G', first; and then do BFS from target_n nodes. My question is: (1) is there an easy (some API, sorry I am not familar with the library) way to reverse edge direction? (2) is there an easy way to add a 'printf()' during BFS? Thanks, Sean _________________________________________________________________ FREE pop-up blocking with the new MSN Toolbar get it now! http://toolbar.msn.click-url.com/go/onm00200415ave/direct/01/

2 1

[serialization] infinite floating point values
by Johan Råde 05 Jul '06

05 Jul '06

I just replaced the binary archives by text archives in an app, to make sure that the archives will be portable between 32 and 64 bit platforms. But when I use text archives, the app crashes. The problem is: Text archives do not handle infinite values of type float and double. --- Example ---------------------------------------------------------- #include <iostream> #include <limits> #include <sstream> #include <boost/archive/text_iarchive.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/format.hpp> int main() { std::stringstream ss; { boost::archive::text_oarchive oa(ss); double inf1 = std::numeric_limits<double>::infinity(); std::cout << boost::format("Save: %1%\n") % inf1; oa << inf1; } { boost::archive::text_iarchive ia(ss); double inf2; ia >> inf2; std::cout << boost::format("Load: %1%\n") % inf2; } } --- Output ---------------------------------------------------------- Save: 1.#INF Load: 1 --------------------------------------------------------------------- There are two infinite values of type double, std::numeric_limits<double>::infinity() and -std::numeric_limits<double>::infinity(). These could be represented as "inf" and "-inf" in the archive. I would be very useful for me if this functionality were added to the serialization library. (Otherwise I will have to do a lot of code rewriting, or stick binary archives.) One could also consider handling nan (not a number), but that is maybe a lower priority. --Johan Råde rade(a)maths.lth.se

2 4

[spirit] working with end_p
by Neil Hunt 05 Jul '06

05 Jul '06

Hello all, Given a simple spirit grammar (simplified from my real grammer and untested) such as: file = *line; line = sensible_line >> ending >> *comment; sensible_line = confix_p( '\"', *c_escape_ch_p, '\"' ); comment = !( ch_p(';') >> ( anychar_p - eol_p ) ) >> ending; ending = *blank_p >> ( eol_p | end_p ); Note: any given line can be legitimately terminated by the end of the file or end of line And there can be arbitrary numbers of comment lines between sensible lines. However since 'comment' is terminated with 'ending', the parser ends up in an infinite loop matching the kleene star on end_p because it returns zero length (doesn't advance the scanner). At least I think this is the problem. By using: ending = *blank_p >> eol_p ; the parser runs to completion, but any given line must be terminated by an end of line sequence. Any suggestions on how to fix this problem? Thanks for any help offered, Neil Hunt

2 1

error using lambdas: conversion from 'x' to non-scalar type 'y'
by klaus triendl 05 Jul '06

05 Jul '06

Hi, I'm rather new to lambdas. I wanted to use them to stream objects into a special stream (not a stl stream). the following code outlines the situation: ---- #include <iostream> #include <list> #include <algorithm> #include <boost/ref.hpp> #include <boost/shared_ptr.hpp> #include <boost/lambda/lambda.hpp> using namespace std; using namespace boost; using boost::lambda::_1; class MyStream { public: MyStream() {} }; class MySubStream: public MyStream { public: MySubStream(MyStream*) {} }; MyStream& operator <<(MyStream& os, const int&) { return os; } int main() { list<shared_ptr<int> > cont; MyStream osTop; MySubStream osSub(&osTop); for_each(cont.begin(), cont.end(), ref(osSub) << *_1); return 0; } ---- g++ outputs error: '/usr/include/boost/lambda/detail/operator_lambda_func_base.hpp:212: error: conversion from 'MyStream' to non-scalar type 'MySubStream' requested'. MS VC 2003.net says: boost\lambda\detail\operator_lambda_func_base.hpp(212) : error C2664: 'MySubStream::MySubStream(MyStream *)' : cannot convert parameter 1 from 'MyStream' to 'MyStream *'. The question is whether my code is correct at all and how I could use lambdas the right way. Thanks! Klaus Triendl

2 4

Re: [Boost-users] shared_ptr + const_cast woes
by Evan Drumwright 04 Jul '06

04 Jul '06

Hi guys, Thanks for your help, in particular Stefan's reworked code fragment. I actually did read the documentation for shared_ptr (in particular, the section on const_pointer_cast), but got confused by the counterexample (I thought that it was saying not to use a temporary). Thanks again, Evan >Message: 5 >Date: Wed, 28 Jun 2006 10:33:19 -0400 >From: me22 <me22.ca(a)gmail.com> >Subject: Re: [Boost-users] shared ptr + const_cast woes >To: boost-users(a)lists.boost.org >Message-ID: <fa28b9250606280733u5125fa01p92da87e1e8f9ad0f(a)mail.gmail.com> >Content-Type: text/plain; charset=UTF-8; format=flowed >Take a closer look at what this is doing: >> boost::shared_ptr<const int> y(const_cast<const >int*>(x.front().get())); >To be more explicit, it's the same as > int *ip = x.front().get(); > int const *cip = ip; > boost::shared_ptr<const int> y( cip ); >At y you're creasing another shared_ptr to the same address that >doesn't share ownership with the one in x.front(). > >What you really want is const_pointer_cast : >http://boost.org/libs/smart_ptr/shared_ptr.htm#const_pointer_cast > >From the documentation for the above-mentioned const_pointer_cast: >Notes: the seemingly equivalent expression >shared_ptr<T>(const_cast<T*>(r.get())) >will eventually result in undefined behavior, attempting to delete the same >object twice. >Which is exactly your problem. > >~ Scott McMurray ------------------------------ >Message: 6 >Date: Wed, 28 Jun 2006 11:59:12 -0230 >From: Stefan Tarrant <stefan.tarrant(a)c-core.ca> >Subject: Re: [Boost-users] shared ptr + const_cast woes >To: boost-users(a)lists.boost.org >Message-ID: <44A29238.9040800(a)c-core.ca> >Content-Type: text/plain; charset=ISO-8859-1; format=flowed >When you use get() all bets are off. You are basically taking >responsibility for the ownership of the returned pointer yourself, which is >generally a bad idea. Use a const_pointer_cast<T> instead. >Here is my re-worked example: > >#include <vector> >#include <iostream> >#include <boost/shared_ptr.hpp> > >int main() >{ > std::vector<boost::shared_ptr<int> > x; > x.push_back(boost::shared_ptr<int>(new int)); > *x.front() = 4; > std::cout << "use count: " << x.front().use_count() << std::endl; > boost::shared_ptr<const int> y = x.front(); > std::cout << "use count: " << x.front().use_count() << std::endl; > std::cout << "use count: " << y.use_count() << std::endl; > boost::shared_ptr<int> z = boost::const_pointer_cast<int>(y); > std::cout << "use count: " << z.use_count() << std::endl; > std::cout << "use count: " << y.use_count() << std::endl; > x.pop_back(); > std::cout << *y << std::endl; > std::cout << "use count: " << z.use_count() << std::endl; > std::cout << "use count: " << y.use_count() << std::endl; > > y.reset(); > std::cout << "use count: " << z.use_count() << std::endl; > std::cout << "use count: " << y.use_count() << std::endl; >} > >And the output: > >use count: 1 >use count: 2 >use count: 2 >use count: 3 >use count: 3 >4 >use count: 2 >use count: 2 >use count: 1 >use count: 0 >Press any key to continue . . . > >-- >Stefan Tarrant >Senior Project Engineer >C-CORE >Captain Robert A. Bartlett Building >Morrissey Road >St. John's, NL >Canada A1B 3X5

1 0

boost pool
by michelle Tchicaya 04 Jul '06

04 Jul '06

Hello, I am very new to C++. And I want to use Boost thread and Boost Pool to create a multithreaded application which will handle real time messages. I need ONE Boost Pool. But I dont know how to combine it with thread Thank a lot for your help mimi

1 0

Re: [Boost-users] [boost] Convert function pointer type to function type
by Peter Soetens 04 Jul '06

04 Jul '06

Quoting Peter Dimov: > Peter Soetens wrote: >> Hi, >> >> I'm desperately seeking for doing this conversion using the boost >> libraries. User code often provides a function pointer, while library >> code often works with function types. [...] > > One obvious way is > > template<class F> boost::function<F> function_wrapper( F * pf ) > { > return boost::function<F>( pf ); > } > > but a more interesting question is why do you need a function_wrapper at > all. Everything that you could do with the returned function<F> (call it) is > also possible with pf itself. Looking at the simplicity of that answer, this was clearly a boost-users question :-]. Sorry. This was a minimalistic example, removing the context. The big picture uses boost::function<F> to store partially bound objects, since this is a way to store the result of boost::bind for later use in a not templated class. I got confused by the boost::function_traits<T>, which only takes a "function type" and not a "function pointer type." I assumed one was not convertible to the other. I tried using boost::remove_pointer<F>, which didn't work and confirmed back then my assumption (confusingly, is_pointer<F> did work, but I could not remove it using type_traits...) My books write about function pointer types but do not mention 'function types'. These concepts appear to me underdocumented in standard C++ works. *Thanks a lot*. Peter -- www.fmtc.be ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.

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Re: [Boost-users] [BGL] All Possible Matchings (Hossein Haeri)
by Grégoire Dooms 04 Jul '06

04 Jul '06

boost-users-request(a)lists.boost.org wrote: Message: 9 Date: Mon, 3 Jul 2006 16:46:55 +0100 (BST) From: Hossein Haeri <powerprogman(a)yahoo.com> Subject: [Boost-users] [BGL] All Possible Matchings To: boost-users(a)lists.boost.org Message-ID: <20060703154655.35182.qmail(a)web53405.mail.yahoo.com> Content-Type: text/plain; charset=iso-8859-1 > Dear all, > > I have a bipartite graph, and want to generate all its > possible matchings. Any suggestions? > You should have a look at Constraint Programming and the Alldifferent constraint. In CP, the task of filtering for a constraint over some integer variables amounts to partitioning, for each of its variables, the potential values into three categories: the values participating in all solutions (obviously at most one per variable), the values participating in some solutions, and the values participating in no solutions. In the case of the Alldifferent constraint, it can be reinterpreted in graph matching terms: Build a bipartite variable-value graph. A solution to the Alldifferent constraint is a maximum matching covering all variables in this graph. Hence filtering can be done by identifying edges which belong to some/all/no max matching. In a nutshell, the following property of matchings is used [Peterson] [Berge] : M1 (+) M2 = P M1 (+) P = M2 where P is an alternating path (for instance, look at the LEDA book for a good exposition of this property and matching algorithms). This property is used in matching algorithms with P an augmenting alternating path. If you consider "maintaining" paths (eg. non-augmenting and non-decreasing -- even length, starting at a free node and ending at a covered node, or an alternating cycle) and apply them on a max matching you get another max matching. Here are a few references: Ref. to the original paper : http://citeseer.ist.psu.edu/context/210815/0 A survey on this subject: http://citeseer.ist.psu.edu/579391.html (or http://www.cs.cornell.edu/~vanhoeve/papers/alldiff.pdf for a more recent/in progress version) Slides by JC Regin: http://www.constraint-programming.com/people/regin/papers/GraphAndCP.pdf Finally, an open-source implementation: http://www.gecode.org/gecode-doc-latest/distinct_2dom_8icc-source.html Hope this helps, -- Grégoire Dooms.

1 0

When to use thread.join()
by Simon Reye 04 Jul '06

04 Jul '06

My apologies if this has been covered. I am new to boost and have been working with the boost thread class. I assume that the join() function waits for the thread to finish execution. But what if the thread has already finished executing? Can I still call join() and have it not wait for infinity? Simon

2 2

[Spirit] puts namespace std into the global scope
by Johan Råde 04 Jul '06

04 Jul '06

It seems that the header boost/spirit.hpp puts the entire namespace std into the global scope. That is not very nice! --- Example 1 -------- #include <string> #include <sstream> #include <fstream> #include <vector> #include <boost/spirit.hpp> void f() { string s; istringstream iss; ofstream ofs; vector<int> v; } ---------------------- Example 1 should not compile (undefined symbols), but does compile. If the line #include <boost/spirit.hpp> is removed, then Example 1 does not compile. --- Example 2 -------- #include <boost/filesystem/path.hpp> #include <boost/filesystem/fstream.hpp> #include <boost/spirit.hpp> using boost::filesystem::path; using boost::filesystem::ifstream; void g() { path p; ifstream ifs(p); } ---------------------- Example 2 should compile but does not. The compiler complains that the symbol ifstream is ambigous. If the line #include <boost/spirit.hpp> is removed, then Example 2 does compile. I´m using Boost 1.33.1 and MSVC 7.1 on a Windows XP computer. --Johan Råde rade(a)maths.lth.se

3 3

auto-diff expression templates-> MPL
by Russell L. Carter 03 Jul '06

03 Jul '06

Greetings, This is a beginner question about the MPL. I'm building a general purpose simulation program which will have an optimization module as well as an internal ODE solver which requires derivatives of the implemented algorithm in various forms. Around 1998-2002 there was a lot of enthusiasm for generating the derivatives automatically using expression templates. I'm not quite through with an exhaustive review of the literature but it appears the various efforts ran to ground on the compilation memory and cpu requirements that evaluating expression templates in their original form required. So 1st question, has anybody done something like this with mpl/fusion sequences and algorithms? Has there been an improvement in compile time performance? Do you have any pointers to trivial examples? I've read Alexandrescu, and Abrahams & Gurtovoy and it's not clear to me how to map the expression templates as described in the earlier efforts onto mpl sequences and algorithms. That's probably enough for now. Thanks for any help. Russell

1 0

[shmem] and kernel 2.4 / linuxthreads
by Sascha Lumma 03 Jul '06

03 Jul '06

Hi all, I noticed that kernel 2.6 is a requirement for shmem on linux. Is it possible to get shmem to run - maybe with constraints - together with kernel 2.4 and the older pthread version (linuxthreads)? A start on a kernel 2.4 box produces a segmentation fault in shared_memory.hpp. To reach most users as possible, it would be nice to be compatible or if not possible to get as a minimum a normal termination. Sascha Lumma

2 2

[BGL] python bindings build graph from edge list
by John Reid 03 Jul '06

03 Jul '06

Hi, I was trying to build a graph from an edge list and ran into some problems. The following code throws an exception on write_graphviz(). I think it is because there's no property map called node_id in the graph. import boost.graph as bgl edges = [ ( 'a', 'b' ), ( 'b', 'c' ), ( 'c', 'a' ) ] g = bgl.Graph( edges ) g.write_graphviz( 'bind-copy.dot' ) I get the following: Traceback (most recent call last): File "<stdin>", line 1, in ? KeyError: 'node_id' I couldn't manage to generate the node_id property map automatically. So after you have built the graph with the edge list constructor how do you know which vertex is which? I ended up using the following code to create the graph: def build( edges ): # Create a graph to build g = bgl.Graph() # Construct some property maps node_ids = g.vertex_properties[ 'node_id' ] = g.vertex_property_map( 'string' ) color = g.vertex_properties[ 'color' ] = g.vertex_property_map( 'string' ) centrality = g.vertex_properties[ 'centrality' ] = g.vertex_property_map( 'float' ) weight = g.edge_properties[ 'weight' ] = g.edge_property_map( 'float' ) length = g.edge_properties[ 'len' ] = g.edge_property_map( 'float' ) # create the edges and vertices name_2_vertex = { } for ( name1, name2 ) in edges: if not name_2_vertex.has_key( name1 ): v1 = name_2_vertex[ name1 ] = g.add_vertex() node_ids[ v1 ] = name1 else: v1 = name_2_vertex[ name1 ] if not name_2_vertex.has_key( name2 ): v2 = name_2_vertex[ name2 ] = g.add_vertex() node_ids[ v2 ] = name2 else: v2 = name_2_vertex[ name2 ] e = g.add_edge( v1, v2 ) weight[ e ] = 0.1 length[ e ] = 4 # Color articulation points red for v in bgl.biconnected_components( g ): color[ v ] = 'red' # Assign centrality values to property map bgl.brandes_betweenness_centrality( g, centrality ) return g This code seems to works fine. So I thought I'd post this just to see if I was missing something obvious and/or in the hope someone else might find it useful. Best, John.

3 6

[BGL] All Possible Matchings
by Hossein Haeri 03 Jul '06

03 Jul '06

Dear all, I have a bipartite graph, and want to generate all its possible matchings. Any suggestions? TIA, --Hossein ___________________________________________________________ Yahoo! Messenger - with free PC-PC calling and photo sharing. http://uk.messenger.yahoo.com

1 0

[BGL] Bipartite Graphs
by Hossein Haeri 03 Jul '06

03 Jul '06

Dear all, Any special facility there is in BGL for bipartite graphs? TIA, --Hossein ___________________________________________________________ All New Yahoo! Mail Tired of Vi@gr@! come-ons? Let our SpamGuard protect you. http://uk.docs.yahoo.com/nowyoucan.html

2 2

[BGL]Customising the Adjacency List Storage
by Louis Lavery 03 Jul '06

03 Jul '06

According to the book [BGL p232], in order to customise the EdgeList I need to define a container generator and parallel edge traits class, and over load the push() and erase() functions for the custom container [BGL p234]. My custom container is user::PushBackList<T>... namespace user { template<typename ValueType> struct PushBackList { //... }; struct PushBackListS { }; } ...and I've put the (specialised) container_gen and parallel_edge_traits classes in namespace boost... namespace boost { template<typename ValueType> struct container_gen<user::PushBackListS,ValueType> { typedef user::PushBackList<ValueType> type; }; template<> struct parallel_edge_traits<user::PushBackListS> { typedef allow_parallel_edge_tag type; }; } ...now all I need do is overload the push() and erase() functions. The problem is they are in nested namespace graph_detail and are called with full qualification (i.e. boost::graph_detail::push(...)) from adjacency_list class. That means I need to put my overloads in boost::graph_detail. Is that right? Thanks, Louis.

2 1

[BGL] Budled Properties
by Hossein Haeri 03 Jul '06

03 Jul '06

Dear BGL-ers, I'm so new to BGL, and a little mixed up about the properties. Is the "Six Degrees of Kevin Bacon" example in the documentation of 1.33.0 using Bundled Properties? Or, is it using that old style "using_adjacency_list.html" strongly recommended me to leave it? TIA, --Hossein ___________________________________________________________ All New Yahoo! Mail Tired of Vi@gr@! come-ons? Let our SpamGuard protect you. http://uk.docs.yahoo.com/nowyoucan.html

2 1

Re: [Boost-users] Retrieve multindex value type?
by JOAQUIN LOPEZ MU?Z 03 Jul '06

03 Jul '06

----- Mensaje original ----- De: Francesco Biscani <bluescarni(a)gmail.com> Fecha: Domingo, Julio 2, 2006 6:19 pm Asunto: [Boost-users] Retrieve multindex value type? > Hello, > > is there a way to retrieve from a multiIndex container the type of > its content? > > I need to do something like this: > > template <class T> > class my_class > { > private: > T set; > > public: > void insert(const T::value_type &); <------ ? > }; > > Here T is a multiIndex container, and the insert function should > add a term to the set. Hence "insert" must accept as input the > kind of values that are stored in the multiIndex container. Is > there a way to do so or should I just add another parameter to > the template and use that as argument for insert? > Thanks, Hello Francesco, Indeed, multi_index_container provides a nested value_type typedef that you can use exactly in the way you describe. Have you encountered any problem in doing so? Thank you for using Boost.MultiIndex, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

3 2

boost 64bit support on windows x64 on amd64 hardware
by Chu-Ming Ng 03 Jul '06

03 Jul '06

Hi, I am porting some code that uses boost from 32-bit to the 64-bit platform and would like to know if the boost library supports this platforms. thanks! Chu-Ming

7 7

Retrieve multindex value type?
by Francesco Biscani 02 Jul '06

02 Jul '06

Hello, is there a way to retrieve from a multiIndex container the type of its content? I need to do something like this: template <class T> class my_class { private: T set; public: void insert(const T::value_type &); <------ ? }; Here T is a multiIndex container, and the insert function should add a term to the set. Hence "insert" must accept as input the kind of values that are stored in the multiIndex container. Is there a way to do so or should I just add another parameter to the template and use that as argument for insert? Thanks, Francesco

1 0

Locking smart pointer
by Mattias Brändström 02 Jul '06

02 Jul '06

Hello! I have a small class to show you and perhaps get some comments on: <code> #include <boost/shared_ptr.hpp> #include <boost/thread.hpp> template <typename T> class LockPointer { public: class LockProxy { public: LockProxy(boost::shared_ptr<T> p, boost::shared_ptr<boost::recursive_mutex> mutex) : p_(p), lock_(new boost::recursive_mutex::scoped_lock(*mutex)) { } boost::shared_ptr<T> operator->() { return p_; } private: boost::shared_ptr<T> p_; boost::shared_ptr<boost::recursive_mutex::scoped_lock> lock_; }; LockPointer(boost::shared_ptr<T> o) : p_(o), mutex_(new boost::recursive_mutex()) { } LockProxy operator->() { return LockProxy(p_, mutex_); } private: boost::shared_ptr<T> p_; boost::shared_ptr<boost::recursive_mutex> mutex_; }; </code> The purpose of this class is to lock a mutex before each method call on an object of class T, and unlock the mutex when that call returns. It seems that this would be something that one would like to have in some cases. Maybe so many cases that it might be part of boost somewhere? I haven't found any library in boost that does this. Is there one? I haven't done anything like this before so it would be nice if anyone here could make some comments on the code. Will it do what I think it does or will it blow up in my face? :-) Regards, Mattias

3 2

[serialization] Out of memory with Borland C++ Builder 60
by Federico Feller 02 Jul '06

02 Jul '06

Hi everyone. Im having problems compiling some code with Borland C++ Builder 6 that includes libboost serialization. In particular Im having troubles registrating a new class in order to be serialized. The new class, say A3, is a subclass of antother that is declared abstract, say A. A has already some subclases (A1, A2) that are serialized correctly. As I did for other subclasses on the same hierarchy, I added the instruction ar.register_type(static_cast<A3 *>(NULL)); in the load/save method of another class that serializes a pointer to the base class of the hierarchy. After doing that, I tried to compile the code and got the following error from the compiler: [C++ Fatal Error] if.hpp(72): F1008 Out of memory I really have no idea whats going on. Any ideas? Thanks Federico __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

4 7

Re: [Boost-users] Boost.Variant: char[], a bool or std::string ?
by Nindi Singh 01 Jul '06

01 Jul '06

This has the desired effects BUT ... I am not a software engineer .. so I would like to know is it would the proffessionals would consider ugly code ? #include<string> #include<boost/variant.hpp> typedef boost::variant< bool,std::string> BoostVariant; struct MyVariant:public BoostVariant { template<typename type> MyVariant(const type &theType):BoostVariant(theType){} MyVariant(const char *theCString):BoostVariant(std::string(theCString)){} }; int main () { MyVariant v("A String"); std::string &Sref(boost::get<std::string&>(v)); // NOw this does NOT throw bool &Bref(boost::get<bool&>(v)); // but this does return 0; }

2 1

Re: [Boost-users] Boost.Variant: Is a char * really a bool ?
by Nindi Singh 01 Jul '06

01 Jul '06

Hi Yuval sorry .. i will ensure I put a RE: on my furtue replies ... but i have posted a reply with subject 'Boost.Variant: char[], a bool or std::string ? ' N

1 0

Boost.Variant: char[], a bool or std::string ?
by Nindi Singh 01 Jul '06

01 Jul '06

I sort of guessed that this implicit conversion was taking place ... but unfortunatley it wil make my variant very error prone .. and on the other hand I do want the capability to construct from a C string appropriatley. I think one possible soultion would be to derive from boost::variant<bool,std::string> and put in an explicit constructor for const char *, this will also let me get around other similar problems. However deriving from boost::variant .... ??? not sure how healthy that is. >To answer the question in the subject line: char* isn't bool, but it's >implicitly convertible to bool, which is probably (haven't really >checked, just an educated guess) what's causing you trouble. > >Nindi wrote: >> When I have a Boost.Variant templated on a bool and a std::string, I get >> the following behaviour .. >> >> #include<string> >> >> #include<boost/variant.hpp> .> >> typedef boost::variant< bool,std::string> BoostVariant; >> >> int main () { >> >> BoostVariant v("A String"); >> >> bool &Bref(boost::get<bool&>(v)); // this is ok >> >> std::string &Sref(boost::get<std::string&>(v)); // But this throws >> >> return 0; >> >> } > >Instead of > BoostVariant v("A String"); >try > BoostVariant v(std::string("A String")); > >I think it will solve your problems.

1 0

Boost.Variant: Is a char * really a bool ?
by Nindi 01 Jul '06

01 Jul '06

When I have a Boost.Variant templated on a bool and a std::string, I get the following behaviour .. #include<string> #include<boost/variant.hpp> typedef boost::variant< bool,std::string> BoostVariant; int main () { BoostVariant v("A String"); bool &Bref(boost::get<bool&>(v)); // this is ok std::string &Sref(boost::get<std::string&>(v)); // But this throws return 0; }

2 1

Boost.Variant: char[], a bool or std::string ?
by Nindi Singh 01 Jul '06

01 Jul '06

... .. but this works fine .. #include<string> #include<boost/variant.hpp> typedef boost::variant<std::string> BoostVariant; int main () { BoostVariant v("A String"); std::string &Sref(boost::get<std::string&>(v)); // NOW this does NOT throw return 0; }

1 0

Boost.Variant: char[], a bool or std::string ?
by Nindi Singh 01 Jul '06

01 Jul '06

If I instantiate a Boost.Variant templated on a bool and a std::string , then I get the following behaviour ... not sure why #include <string> #include <Boost/Variant.hpp> typedef boost::variant< bool,std::string> BoostVariant; int main () { BoostVariant v("A String"); bool &Bref ( boost::get<bool &>(v)) ; // this is ok std::string &Sref ( boost::get<std::string> &(v) ) ; // but this throws return 0; } Is this what is supposed to happen ? Ninds

1 0

[serialization] Error serializing std::wstring to text_oarchive on VC++
by William Kemper 01 Jul '06

01 Jul '06

The fill method on mb_from_wchar calls std::wctomb, which is backed by 'WideCharToMultiByte'. This function uses the codepage defined in the current locale, however, the utf-8 codepage does not function properly on VC++ 7 or 8. Would it be difficult to have the conversion use the code_cvt facet defined for the stream underlying the archive? It also seems that doing so would ensure serialization / deserialization would be more consistent and self-sufficient, since neither process would depend on a (mutable) global locale setting. At any rate, the serialization library works with certain window's codepages, but *not* with the utf-8 codepage (65001). It would be nice to have the library use its own utf8_code_cvt facet to translate wide characters to multibyte. If there is some work around I'm not aware of, I would appreciate any advice. Thanks.

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Compile-time constant CRCs
by Michael Marcin 01 Jul '06

01 Jul '06

I didn't tag this because I'm not sure if it should belong to [preprocessor], [mpl] or [crc]. Given the black-box (macro, function, class, whatever) I'll call ConstCRC32 that is assignable to a unsigned int is there a way to write: unsigned int hash = ConstCRC32( "HELLO" ); and have an optimized build yield the equivalent of: unsigned int hash = 0x58a10fc0; I had a solution (although obviously non-portable) in msvc7.1 but after moving to msvc8 and stepping through the code I noticed that msvc8's "improved" optimizing compiler cannot optimize away the calculation like msvc7.1's could. I also doubt that the code would work if I ever had to port it to another compiler. I tried using simple TMP techniques I've used in the past but couldn't find a way to access the characters of the string. So looking around I came upon boost.crc which is geared towards computing crcs of blocks of data which isn't really what I care about right now. I also found boost.mpl which is very cool but I have a hard time grasping still. The problems seems solvable with mpl if I could transform the data into boost::mpl::list_c<char,'H','E','L','L','O'> but I still coulnd't find a way to access the characters of the string and I think others at my company would rather revert to the old #define CRC( str, crc ) crc unsigned int hash = CRC( "HELLO", 0x58a10fc0 ); than move to that syntax directly. So looking further I found boost.preprocessor which I haven't explored enough to see if there is away to have PP calculate the CRC directly or have it transform the string into the boost::mpl::list_c form. Can anyone offer some advice? Thanks Mike P.S. The old version was actually fairly simple it just used a precomputed static const unsigned int lookup table and did a strlen and a for loop with a lookup into the table for each character (in a __forceinline function that took a const char * const string).

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Replacing C functions with boost::function for callback functions in OpenGL
by Stephen Torri 01 Jul '06

01 Jul '06

I have a main file from my OpenGL program which contains global variables and the functions that are used by OpenGL as callback functions. For example: int a; float b; void display () { .... display code calls ... } int main (int argc, char **argv) { glutDisplayFunc( display ); } Now I thought I would put all the variables and functions into a class and use that in the main. Here is where I am getting stuck on the use of boost::function. I changed the code to look something like the following: class MyMain { int a; float b; void display() { ... display code calls ... } } int main (int argc, char **argv) { MyMain m_ref; boost::function<void()> disp_func = boost::bind ( &MyMain::display, &m_ref ); glutDisplayFunc ( disp_func ); } What I am getting back from the g++ compiler is the following error message: error: cannot convert `boost::function<void ()(), std::allocator<void> >' to `void (*)()' for argument `1' to `void glutDisplayFunc(void (*)())' Any ideas where I am going wrong? Stephen

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