November 2003 - Boost-users

Help with function and/or bind libraries
by John.Wismar＠alldata.com 30 Nov '03

30 Nov '03

Here's the situation I'm trying to remedy, boiled down: class A { public: int size() const; }; class B { public: int stretch_it(int size) const; int get_total() const; private: std::vector<A> myVec; }; int B::get_total() const { int retVal = 0; for (std::vector<A>::const_iterator it = myVec.begin(); it != myVec.end (); ++it) { retVal += stretch_it(it->size()); } return retVal; } I'd love to use std::accumulate() or equivalent instead of a hand-coded loop, but I don't know if it's possible to specify a combination of operations like I have here.... Or if the result would be readable! Any suggestions would be much appreciated! --------------------- John Wismar john.wismar(a)alldata.com

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boost::function - why does this work??
by Matt S Trentini 29 Nov '03

29 Nov '03

Heya Everyone, I am trying to create a generic way to extract a list of objects from another list of objects. Let me explain! Say I have a vector (or any container with fwd iterators and value_type) that contains objects that have a function which returns a long (could actually be any type). I want to iterate over that vector and extract each of the longs into a list (or any container that supports push_back and defines value_type). Something like the following: class HandleClass { public: long handle() const { return val_++; } private: static long val_; }; // ... std::vector<HandleClass> listOfHcs; // ... fill listOfHcs here std::list<long> needToFill; OK so far. I then wrote this extraction function (yes, there are many ways I could have done this - with a functor and using foreach is another possibility worth exploring, but not now :) ). template < class ReturnContainer, class FwdIterator > void Extract(const FwdIterator & itBegin, const FwdIterator & itEnd, ReturnContainer & container, boost::function1<ReturnContainer::value_type, FwdIterator::value_type> f) { for (FwdIterator it = itBegin ;it != itEnd; ++it) { container.push_back(f(*it)); } }; And I was able to do this: Extract(listOfHcs.begin(), listOfHcs.end(), needToFill, &HandleClass::handle); And it worked like a charm. needToFill gets filled and I was happy. :) However we also had containers of _pointers_to_ HandleClasses. So in some cases our vector looked like: std::vector<HandleClass *> listOfHcs; Yet the same code worked! I couldn't, and can't, for the life of me understand what was going on (I expected that I would have to wrap the (*it) in a boost::remove_pointer which worried me because my compiler - MSVC7.0 - doesn't support partial template specialization). Don't get me wrong, I'm happy that it work but can anyone explain what fandangelory is going on inside boost::function (or perhaps it's some C++ magic?) to allow this? Cheers, Matt

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Compilation troubles on BSD..
by Joshua Moore-Oliva 28 Nov '03

28 Nov '03

I'm having trouble compiling code on BSD with boost, specifically boost_filesystem. I'm using gcc 3.2.3 On linux, there is no problem, buit on BSD.. this is what happens. Notice that there is no trouble FINDING -lboost_filesystem to link with, but that I'm getting undefined references to anything boost-related. This compiles without any errors on both BSD and linux, but the linking on BSD is the problem. Has anyone had any experiences getting boost to work on BSD before? Thanks, Josh. <snip> signalConfigReload.o \ signalShutdown.o -o Batcher -L. -lChatsUtils -lConfig -lFfm -lFfmStream -lShared -lboost_filesystem -L/usr/local/pqxx/lib -lpqxx markFinished.o: In function `Batcher::markFinished()': /home/josh/src/mastermailings/code/daemons/Batcher/Batcher/markFinished.cpp:9: undefined reference to `boost::filesystem::path::path[in-charge](std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)' /home/josh/src/mastermailings/code/daemons/Batcher/Batcher/markFinished.cpp:9: undefined reference to `boost::filesystem::path::path[in-charge](std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)' /home/josh/src/mastermailings/code/daemons/Batcher/Batcher/markFinished.cpp:9: undefined reference to `boost::filesystem::rename(boost::filesystem::path const&, boost::filesystem::path const&)' restore.o: In function `Batcher::restore(Ffm&, std::basic_ifstream<char, std::char_traits<char> >&)': /home/josh/src/mastermailings/code/daemons/Batcher/Batcher/restore.cpp:8: undefined reference to `boost::filesystem::path::path[in-charge](std::basic_string<char, std::char_traits<char>, std::allocator<char> > const&)' /home/josh/src/mastermailings/code/daemons/Batcher/Batcher/restore.cpp:8: undefined reference to `boost::filesystem::exists(boost::filesystem::path const&)' collect2: ld returned 1 exit status

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graph library: internal property problem
by Vasco Lohrenscheit 28 Nov '03

28 Nov '03

Hello, I have some problems with graph properties. For a project I created a layer above the boost graph library. So i have: template <typename N, typename E, typename GT> GraphNode : public N {} template <typename N, typename E, typename GT> GraphEdge : public E {} template <typename N, typename E> Graph {} with BGL properties like: typedef GraphNode<N,E,GraphTraits> tNode; typedef property <typename tNode::vertex_property, tNode*> NodeProperty; As internal graph properties i use pointers to GraphNode and GraphEdge with property tags defined in N and E, e.g. class LogicState { public: enum vertex_state_t {vertex_state=123;} static const vertex_state_t PropertyTag; } const LogicState::vertex_state_t LogicState::PropertyTag=vertex_state; and template specialization for property_kind: template <> struct property_kind <GraphEdge<LogicState, LogicConstraint, GraphTraits> > { typedef vertex_property_tg type; }; with using put(tNode::PropertyTag, graph, somestate); i get the following compile error: error C2679: binary '=' : no operator found which takes a right-hand operand of type 'GraphEdge<N,E,G> ' (or there is no acceptable conversion) with [ N=LogicState, E=LogicConstraint, G=Graph<LogicState,LogicConstraint>::tGraphTraits ] in line 316 in property_map.hpp: "static_cast<const PropertyMap&>(pa)[k] = v;" I'm using the current cvs version of boost and vc++7.1. Any ideas what can cause this problem ? Why there exist no "=" operator ? Where should it be defined/generated in normal cases ? Without my layer, with pure BGL and BOOST_INSTALL_PROPERTY I had it already working. Shouldn't it also be of type GraphEdge<N,E,G>* ? I've checked my code and everywhere I used pointers (in the property definition and with the put). Then another questions: The online docs for the BGL weren't very helpfull for me. Is the BGL book better, or is it only an enhanced version of the online docs ? best regards, Vasco Lohrenscheit

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Re: [Boost-install] Installing BOOST1_30_2 under HP UX 11.11 - URGENT
by David Abrahams 27 Nov '03

27 Nov '03

"Lalit Seth" <laalit_seth(a)hotmail.com> writes: > hi all, > > I m trying to install BOOST1_30_2 under HPUX11.11 > i did bjam to make > I m hving gcc3.2 on HPUX11.11 > > Its giving me failed 22 targets, > skipped 15 targets > done 384 targets. > > Is this right or do i have to change / add parameters to bjam. > > ITS QUITE URGENT. > > Rgds > Lalit Seth Lalit, First please take your Boost installation problems to the Boost.Users list or Boost.Build list (http://www.boost.org/more/mailing_lists.htm#jamboost) This list is out of commission. Second of all, though I am not sure why we don't have the 1.30.2 regression logs posted so I can check, it's not entirely surprising to see 22 targets failing with GCC-3.2. IIRC It does have bugs which prevent a few libraries from compiling. -- Dave Abrahams Boost Consulting www.boost-consulting.com

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C++Builder and Boost Graph Library
by Guilherme Mello de Moura 26 Nov '03

26 Nov '03

Hi guys, My name is Guilherme and I'm trying to use Boost Graph Library with Borland C++Builder.. I'm getting several compilation errors.. I downloaded the latest BGL version (1.30.2) and tried to compile the first graph example I saw.. Here's what I got: Using Boost Graph Library (BGL) version 1.30.2 with C++Builder 5.0 (6.0).. [C++ Error] tuple_basic.hpp(158): E2434 Template declaration missing template parameters ('template<...>') [C++ Error] tuple_basic.hpp(158): E2238 Multiple declaration for 'element<N,T>' [C++ Error] tuple_basic.hpp(143): E2344 Earlier declaration of 'element<N,T>' I also tried to compile the example tests that come with BGL .. And I got some problems with some of them .. Has anybody had the same problem ?!?! Am I doing something wrong ?!?! Regards, Guilherme Mello de Moura

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unit_test_framework - redirect output
by Steven Ketcham 25 Nov '03

25 Nov '03

Perhaps I am making this difficult or even missing the point but... Can I create tests with the unit_test_framework and redirect the output to a GUI? As it stands this is not possible because of int main(...) being defined. Using Windows 2000. Thanks! -- Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

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[BGL] Using default_dfs_visitor on a graph with std::list as the vertex type
by sashan 25 Nov '03

25 Nov '03

I'm trying to use a vistitor class on a graph I have defined. The visitor class is very simple and inherits from default_dfs_visitor: class OpenGLVisitor : public boost::default_dfs_visitor { public: OpenGLVisitor(void); virtual ~OpenGLVisitor(void); }; My graph type is: typedef adjacency_list < vecS, listS, directedS > graph_t; The code to perform a dfs on the graph is as follows: graph_t g; depth_first_search(g, visitor(OGLVisitor)); However I get the compiler error (see attachment). If I change the typedef to typedef adjacency_list < vecS, vecS, directedS > graph_t; then there is no error. This seems odd since it should also work when the vertices of the graph use the std::list as their container class. I'm using VC++7.1.

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Using boost::lamba with a vector of shared_ptr's
by Allen Bierbaum 24 Nov '03

24 Nov '03

Hello all. I am having trouble with the boost lambda library. I am convinced that my troubles come from some little thing I am overlooking, but for the life of me I can't seem to find the problem. I have been looking at it for the entire afternoon with no solution in sight. I have included some sample code below showing the basic idea of what I am trying to accomplish. Can anyone provide me with a working solution? The summary is: - I have a vector of shared_ptr's to a class A - That class has a method that returns a value I would like to test for in a find_if call ============================================================ namespace bl = boost::lambda class A { int getInt(); }; class Foo { A bar(); } std::vector<shared_ptr<Foo> > foos; shared_ptr<Foo> foo_ptr; A test_val; test_val = (bl::_1 ->* &Foo::bar )(foo_ptr); int find_int = 10; iter found = find_if(foos.begin(), foos.end(), (bl::_1->* &Foo::bar).getInt() == child_guid); ==================================================================== Can anyone tell me how I can call a method from a lamda method iterating over a sequence of shared_ptrs? And then how do I have this method also call another method? Thanks, Allen

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regex question
by Paul Scruby 24 Nov '03

24 Nov '03

I have question about match_result. How can I find out what was matched from the regular expression? In the boost documentation, the example for regex_search does something similar to this... regex needle("foo|bar"); string haystack("blah bar blah"); string::const_iterator start = haystack.begin(); string::const_iterator end = haystack.end(); boost::match_results<string::const_iterator> what; *unsigned* *int* flags = boost::match_default; * while*(regex_search(start, end, what, expression, flags)) { // please output 'bar' string match(string(what[5].first, what[5].second) + std::string(what[6].first, what[6].second)); cout << "Found '" << match << "'\n"; start = what[0].second; flags |= boost::match_prev_avail; flags |= boost::match_not_bob; } However, this is outputing nothing. I also tried what.str(), but that gave me nothing too. Thanks again, Paul

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