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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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problem with lexical_cast<int>(std::wstring)
by Ronnie Lazar 24 Nov '03

24 Nov '03

Hi, I'm trying to use lexical_cast<int>(std::wstring), on msvc6 with STLPort, and I get compilation errors. The reason for them is that DISABLE_WIDE_CHARS_SUPPORT is defined in the beginning of lexical_cast.hpp. If I add a line to undef this, in the file, it compiles and works fine, which leads me to belice that this define sould not really be defined. I searched a little more and found that it is defined because BOOST_NO_INTRINSIC_WCHAR_T is defined. My understanding is that this define specifies that the environment does not have wchar_t as a real type, but as a typedef. Why should this interfere with lexical_cast? Any suggestions on how to work around this (apart from changing lexical_cast.hpp source at my site? Thanks Ronnie Lazar

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problem using function lib in MSVC6
by Kim 22 Nov '03

22 Nov '03

Boost version: 1.30.2 Boost Lib: Function OS: Windows XP Pro SP 1 Dev. Env.: Microsoft VS6 SP 6, .NET 2003 Platform SDK Feb 2003, DirectX9 SDK Problem: Can't get an example similar to the one found in the tutorial to work. // ************************************* #include <boost/function.hpp> #include <functional> struct X { int foo(int v) { return v;} }; int main(int argc, char* argv[]) { boost::function1<int, int> f; X x; f = std::bind1st ( std::mem_fun(&X::foo), &x ); f(5); // Call x.foo(5) return 0; } //*************************************** I get this error message: : error C2784: 'class std::mem_fun_t<_R,_Ty> __cdecl std::mem_fun(_R (__thiscall _Ty::*)(void))' : could not deduce template argument for '<Unknown>' from 'int (__thiscall X::*)(int)'

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Boost.Thread problem with thread_specific_ptr<>::release ?
by Roland 21 Nov '03

21 Nov '03

Dear Boosters! As I am still trying to figure out how to use the thread local storage pointer I found another strange behaviour. Perhaps I am misunderstanding the docs, or this might be a bug. System: VC6.0 CVS Head Problem: When using release on a tss variable, the associated automatic cleanup routine seems not to be updated correctly as it tries to delete the original pointer, instead of the 0-pointer. Example (simple modification of tss.cpp example): boost::thread_specific_ptr<int> value; void increment() { int* p = value.get(); ++*p; } void thread_proc() { value.reset(new int(0)); // initialize the thread's storage for (int i=0; i<10; ++i) { increment(); int* p = value.get(); assert(*p == i+1); } //******** added the following two lines int* p = value.release(); delete p; // deleting the released pointer //******* } int main(int argc, char* argv[]) { boost::thread_group threads; for (int i=0; i<5; ++i) threads.create_thread(&thread_proc); threads.join_all(); } In the debug version the program faults at exit, as the pointers are beeing freed a second time. I suspect the problem lies in the following function, as it does not set the cleanup handler if the value is 0 bool tss::set(void* value) { if (value && m_cleanup) { cleanup_handlers* handlers = get_handlers(); assert(handlers); if (!handlers) return false; cleanup_info info(m_cleanup, value); (*handlers)[m_key] = info; } return !!TlsSetValue(m_key, value); } Regards, Roland Schwarz

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When to use which functors?
by Bruce Johnston 21 Nov '03

21 Nov '03

I'm somewhat new to Boost, but pretty familiar with STL and Loki. I'm a bit puzzled by the wide array of similar-sounding libraries in Boost for dealing with function objects: Lambda, Function, Functional, and Bind/Mem_fn. Why are there so many of these libraries and under what circumstances would I want to choose one over the other? Thanks. - Bruce Johnston Simba Technologies

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RE: [Boost-users] lexical_cast causes level 4 warnings w/ VC7.1
by Sam Partington 21 Nov '03

21 Nov '03

Peter Dimov <mailto:pdimov@mmltd.net> wrote: > Sam Partington wrote: >> >> 4511 and 4512 are useless warnings. They are telling you that the >> copy constructor and assignment operator are inaccessible. Even >> though you're not trying to call them. [...] > >> C4127 is also awkward. As it gives warnings for some common idioms. >> It refers to conditional expressions being constant. > > These warnings can be annoying, but they aren't useless. They do find > bugs. I agree that 4127 can help you find bugs. But I can't think of any situation where 4511 or 4512 will help you find a bug. If you actually try to call an inaccesible copy constructor or assignement operator, then the compiler (correctly) fails to compile it. Thats why I used the word "awkward" rather than "useless" for 4127. I'll happily be proved wrong though. Sam ****************** This e-mail has been sent from Imagination Technologies Limited. PowerVR, Metagence, Ensigma and PURE Digital are divisions of Imagination Technologies Limited. The information contained in this e-mail, including any attachment, is confidential and may be legally privileged. It is intended solely for the addressee(s) and access to this e-mail by anyone else is unauthorised. If you are not the intended recipient, any disclosure, copying or distribution or use of the information contained in this e-mail, is prohibited and may be unlawful. If you have received this e-mail in error, please notify the sender by return e-mail and then delete it from your system. Internet communications cannot be guaranteed to be secure, error or virus-free. The sender does not accept liability for any errors or omissions which arise as a result. Any views expressed in this message are those of the author, except where the author specifies and, with authority, states them to be the views of Imagination Technologies Ltd.

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RE: [Boost-users] boost::shared_ptr performance
by Tom Matelich 21 Nov '03

21 Nov '03

> -----Original Message----- > From: Matthew Wilson [mailto:stlsoft@hotmail.com] > Sent: Friday, November 14, 2003 4:23 PM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] boost::shared_ptr performance > > > [I posted this in boost.devel, but got no response. > Presumably that was the > wrong group. :)] > I'm going to respond, but I don't have much to say. I would think that with all the work you put into making this comparison that you could probably determine why smart_ptr is slower than yours. To me this comparison is interesting but not without comparing your code with smart_ptr. Given the lack of code, I have to assume you're waiting for someone to say something like, "WOW!!! I gotta get me some of that!" boost::smart_ptr is already a well used class, so if you're looking to contribute, either post your code so we can maybe see how it is better, or see what it is that is missing from your code to make it faster. Benchmarks are useless without more information. Please make your code available so we can improve boost. If that is not your goal, come out and say so. Tom Matelich Boost Lover ----------------------------------------------------------------------- DISCLAIMER: Information contained in this message and/or attachment(s) may contain confidential information of Zetec, Inc. If you have received this transmission in error, please notify the sender by return email. -----------------------------------------------------------------------

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RE: [Boost-users] lexical_cast causes level 4 warnings w/ VC7.1
by Sam Partington 20 Nov '03

20 Nov '03

Bruce Johnston <mailto:c_kernel@hotmail.com> wrote: > I'm working on a project with strict requirements for the > build settings, > including mandatory warning level 4 and "treat warnings as errors". I > discovered that lexical_cast causes warnings C4127, C4511, > and C4512 when > compiling with warning level 4 using VC7.1. Try the following > code for a > quick repro: 4511 and 4512 are useless warnings. They are telling you that the copy constructor and assignment operator are inaccessible. Even though you're not trying to call them. Take the following code class noncopyable { private: noncopyable(const noncopyable&); noncopyable& operator=(const noncopyable&); }; class a_resource : noncopyable { // ... }; // ... { a_resource res; } Clearly a_resource is not meant to be copied, the developer has gone to lengths to make that clear. Indeed it never is copied, or assigned, yet the warnings will still be issued. C4127 is also awkward. As it gives warnings for some common idioms. It refers to conditional expressions being constant. So : do { XXX } while(0); Gives the warning, which is a common implementation of an ASSERT() macro, and likewise // in an header : const bool debug = false; // in code : if (debug) { } does also. None of these technigues indicate a possible error in code. Ideally all three of these warnings would be disabled in config.hpp. > As an aside, what warning level is typically used by > developers working on > Boost? On VC6 we build on warning level 3, 4 is just too noisy with the built in headers. On VC7.1 we use level 4, but with C4127, C4511, C4512 switched off. HTH Sam ****************** This e-mail has been sent from Imagination Technologies Limited. PowerVR, Metagence, Ensigma and PURE Digital are divisions of Imagination Technologies Limited. The information contained in this e-mail, including any attachment, is confidential and may be legally privileged. It is intended solely for the addressee(s) and access to this e-mail by anyone else is unauthorised. If you are not the intended recipient, any disclosure, copying or distribution or use of the information contained in this e-mail, is prohibited and may be unlawful. If you have received this e-mail in error, please notify the sender by return e-mail and then delete it from your system. Internet communications cannot be guaranteed to be secure, error or virus-free. The sender does not accept liability for any errors or omissions which arise as a result. Any views expressed in this message are those of the author, except where the author specifies and, with authority, states them to be the views of Imagination Technologies Ltd.

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Re: [Boost-users] Re: filesystem::directory_iterator::operator++() never returns <--never mind
by Beman Dawes 20 Nov '03

20 Nov '03

At 07:02 PM 11/19/2003, John.Wismar(a)alldata.com wrote: > >OK, I found it. > >Upon yet another search of the archive, I found it: I was using the >single-threaded version of the library in a multi-threaded app. > >Sorry for the bandwidth! Actually, it is helpful. It gives us more incentive to work on reliability enhancements. Thanks, --Beman

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RE: [Boost-users] Re: boost::shared_ptr performance
by Tom Matelich 20 Nov '03

20 Nov '03

> -----Original Message----- > From: Matthew Wilson [mailto:stlsoft@hotmail.com] > Sent: Wednesday, November 19, 2003 11:27 AM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] Re: boost::shared_ptr performance > > > > > > > > [I posted this in boost.devel, but got no response. > > > Presumably that was the > > > wrong group. :)] > > > > > > > I'm going to respond, but I don't have much to say. I > would think that > with all the work you put into making this comparison that you could > probably determine why smart_ptr is slower than yours. To me this > comparison is interesting but not without comparing your code with > smart_ptr. Given the lack of code, I have to assume you're > waiting for > someone to say something like, "WOW!!! I gotta get me some of that!" > > No, I was seeking information, as I said. > > "There are environment settings for which boost::shared_ptr will > perform much better. If that's so, can someone help me out > with suggestions > of what defines to make?" > > It turns out that there are. > > If I was wanting to make a splash, I'd got for a dip down at > the beach. :) Sorry for any appearance of hostility. I'll check out the devel thread. ----------------------------------------------------------------------- DISCLAIMER: Information contained in this message and/or attachment(s) may contain confidential information of Zetec, Inc. If you have received this transmission in error, please notify the sender by return email. -----------------------------------------------------------------------

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lexical_cast causes level 4 warnings w/ VC7.1
by Bruce Johnston 20 Nov '03

20 Nov '03

I'm working on a project with strict requirements for the build settings, including mandatory warning level 4 and "treat warnings as errors". I discovered that lexical_cast causes warnings C4127, C4511, and C4512 when compiling with warning level 4 using VC7.1. Try the following code for a quick repro: #include <string> #include <iostream> #include "boost/lexical_cast.hpp" int main() { std::string helloFactor = boost::lexical_cast<std::string>( 7 ) ; std::cout << "Hello # " << helloFactor << std::endl ; return 0 ; } Builds fine at warning level 3, fails with /W4 and /WX. As an aside, what warning level is typically used by developers working on Boost? -Bruce Johnston Simba Technologies

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Re: filesystem::directory_iterator::operator++() never returns <--never mind
by John.Wismar＠alldata.com 20 Nov '03

20 Nov '03

OK, I found it. Upon yet another search of the archive, I found it: I was using the single-threaded version of the library in a multi-threaded app. Sorry for the bandwidth! --------------------- John Wismar john.wismar(a)alldata.com In a previous state of enlightnment, I wrote: I'm using the fielsystem library's directory_iterator class to collect information about the files in a directory. I'm using VC7.0, and Boost 1.30.2. My logic looks something like this: ---------------------------------------------------------------------- class DirInfo { public: DirInfo(fs::path aPath) : myPath(aPath){} void scan(); void addFile(fs::path); private: fs::path myPath; } void DirInfo::scan () { fs::directory_iterator itEnd; for (fs::directory_iterator it(myPath); it != itEnd; ++it) { TRACE("File: %s\n", it->string().c_str()); if (!fs::is_directory(*it)) { addFile(*it); } } } DirInfo di(fs::path("C:\\temp\\", fs::native); di.scan(); ---------------------------------------------------------- This successfully goes through all of the files (and subdirectories) in the given directory, but after the last item, the next call to fs::directory_iterator::operator ++() never returns. If anyone has any suggestions or ideas, I would love to hear them!! Thanks! The call stack at the point where execution seems to lock up looks like this: ntdll.dll!NtDelayExecution() + 0xc kernel32.dll!_Sleep@4() + 0xb MyApp.exe.exe!boost::detail::lightweight_mutex::scoped_lock::scoped_lock(boost::detail::lightweight_mutex & m={...}) Line 96 + 0xa C++ MyApp.exe.exe!boost::detail::sp_counted_base::release() Line 132 + 0xf C++ MyApp.exe.exe!boost::detail::shared_count::~shared_count() Line 380 C++ MyApp.exe.exe!boost::shared_ptr<boost::filesystem::directory_iterator::dir_itr_imp>:: ~shared_ptr<boost::filesystem::directory_iterator::dir_itr_imp>() + 0x2e C++ MyApp.exe.exe!boost::shared_ptr<boost::filesystem::directory_iterator::dir_itr_imp>::reset () Line 217 C++ MyApp.exe.exe!boost::filesystem::directory_iterator::m_inc() Line 256 C++ > MyApp.exe.exe!boost::filesystem::directory_iterator::operator++() Line 88 + 0x2b C++ MyApp.exe.exe!DirInfo::scan() Line 63 + 0x1a C++ --------------------- John Wismar john.wismar(a)alldata.com

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filesystem::directory_iterator::operator++() never returns
by John.Wismar＠alldata.com 19 Nov '03

19 Nov '03

I'm using the fielsystem library's directory_iterator class to collect information about the files in a directory. I'm using VC7.0, and Boost 1.30.2. My logic looks something like this: ---------------------------------------------------------------------- class DirInfo { public: DirInfo(fs::path aPath) : myPath(aPath){} void scan(); void addFile(fs::path); private: fs::path myPath; } void DirInfo::scan () { fs::directory_iterator itEnd; for (fs::directory_iterator it(myPath); it != itEnd; ++it) { TRACE("File: %s\n", it->string().c_str()); if (!fs::is_directory(*it)) { addFile(*it); } } } DirInfo di(fs::path("C:\\temp\\", fs::native); di.scan(); ---------------------------------------------------------- This successfully goes through all of the files (and subdirectories) in the given directory, but after the last item, the next call to fs::directory_iterator::operator ++() never returns. If anyone has any suggestions or ideas, I would love to hear them!! Thanks! The call stack at the point where execution seems to lock up looks like this: ntdll.dll!NtDelayExecution() + 0xc kernel32.dll!_Sleep@4() + 0xb MyApp.exe.exe!boost::detail::lightweight_mutex::scoped_lock::scoped_lock(boost::detail::lightweight_mutex & m={...}) Line 96 + 0xa C++ MyApp.exe.exe!boost::detail::sp_counted_base::release() Line 132 + 0xf C++ MyApp.exe.exe!boost::detail::shared_count::~shared_count() Line 380 C++ MyApp.exe.exe!boost::shared_ptr<boost::filesystem::directory_iterator::dir_itr_imp>:: ~shared_ptr<boost::filesystem::directory_iterator::dir_itr_imp>() + 0x2e C++ MyApp.exe.exe!boost::shared_ptr<boost::filesystem::directory_iterator::dir_itr_imp>::reset () Line 217 C++ MyApp.exe.exe!boost::filesystem::directory_iterator::m_inc() Line 256 C++ > MyApp.exe.exe!boost::filesystem::directory_iterator::operator++() Line 88 + 0x2b C++ MyApp.exe.exe!DirInfo::scan() Line 63 + 0x1a C++ --------------------- John Wismar john.wismar(a)alldata.com

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regex static lib for x86 emulator
by Reuti＠sdc.canon.co.in 19 Nov '03

19 Nov '03

I can build static library for ARM processor. But when building for X86 emulator I am getting following error. LINK : fatal error LNK1104: cannot open file 'boost_regex_vc6_sss.lib' Please help. Thanks in advance. Reuti

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gregorian: explicit date::date(date_int_type) ?
by Michael Haubenwallner 19 Nov '03

19 Nov '03

Hi, I'm preparing my company's step from C to C++, and when i use boost::date_time::*, there's a great danger to make mistakes like this with boost-1.30.2: #include <time.h> #include <iostream> #include <boost/date_time/posix_time/posix_time.hpp> using namespace boost::posix_time; using namespace boost::gregorian; int main() { time_t now = time(0); try { ptime time(now); // mistake cerr << to_simple_string(time) << endl; } catch (exception const& e) { cerr << "error: " << e.what() << endl; } } The problem is that the time_t in this case is treated as a day-count from which a gregorian::date() is implicitly constructed. When digging through the gregorian::date, i see that the constructors of date_time::date() from date_int_type and date_rep_type protected. So, wouldn't it be better to make the gregorian::date() constructors from date_int_type and date_rep_type explicit, to get a compile-time error with this sample rather than the out-of-range-exception "Year is out of valid range: 1400..10000" ? And another reason to make this constructor explicit might be that date_rep_type is the internal representation of date(), so when constructing date() with a day_count, you have to know the epoch, and then constructing date() should be done explicitly... What do you think about this ? Thanks, Michael Haubenwallner -- Michael Haubenwallner SALOMON Automation GmbH Forschung & Entwicklung A-8114 Friesach bei Graz T +43 3127 200 308 F +43 3127 200 22 mailto:michael.haubenwallner@salomon.at http://www.salomon.at

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Invert Matrix
by JEFFREY CULLINA 18 Nov '03

18 Nov '03

I have devoleped code to derive a simple matrix expression: [K]*[D]=[R] wher D is an unknown vector. I am looking for code to do two things: 1. Invert [K] to get the expression [D]=inv([K])*[R] 2. Solve the equation in 1 It looks like the UBLAS toolkit provides a function _t_sv to solve the equation, but I do not see anything to help me invert the matrix. Is there code available to help me invert a matrix? While I am at it, I may as well ask if _t_sv is the best function to use to solve the system. Thanks, Jeff

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Smart pointers and STL allocators
by Mark A. Gibbs 18 Nov '03

18 Nov '03

I have a couple of questions about combining smart pointers and STL allocators. First of all, am I right in assuming that I can use the shared_* templates right out of the box, as long as I define a custom deleter that uses the allocator's deallocate function? But if that's so, how exactly is it done? Part of my confusion comes from the fact that the STL allocator documentation I've come across isn't exactly clear on the semantics of allocators (I don't have a copy of the standard). For instance, I'm not 100% sure whether or not I have to call construct() after allocate() and destroy() before deallocate(). This is what I have so far: class allocator_helper { public: allocator_helper(allocator_type& a) : a_(a) {} void operator()(void const* p) const { a_.deallocate(static_cast<allocator_type::pointer>(p)); } private: allocator_type& a_; }; foo* bar = static_cast<foo*>(get_allocator().allocate(1)); shared_ptr<foo> p_foo(bar, allocator_helper(get_allocator())); foo* baz = static_cast<foo*>(get_allocator().allocate(10)); shared_array<foo> p_foo(baz, allocator_helper(get_allocator())); Now, for scoped_* I would probably have to rewrite them to use the allocator, right? Or is there a way to use allocators with the existing scoped_* templates? Mark

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