February 2003 - Boost-users

regex_match() Division By Zero
by Glover Barker 13 Feb '03

13 Feb '03

I am using boost::regex (1.29.0) under MSVC++ 6.0. Whenever I call regex_match(), I get: "Unhandled exception in filename.exe: 0xC0000094: Integer Divide by Zero." I have tried various ways to make the call (including the snippets posted on www.boost.org) Even this simple example fails: regex expression("abc"); cmatch what; if ( regex_match("xyz", what, expression) ) { // Whatever ... } Breakpoints reveal that after expression is set, the value of _expression_len is still 0. So when regex_match() is called, it in turn sends the value of expression.size() (which is just _expression_len) to re_detail::_priv_match_data(), which sends this value to estimate_max_state_count(). Then estimate_max_state_counts(), which calls this value "states", does the following: states *= states; // and later ... if(dist > (difference_type)(lim / states)) Since states is 0, this last expression causes division by 0, and the resulting exception. In case my environment matters, I am building my program under MSVC++ 6.0, running with boost_regex.dll. I am defining BOOST_REGEX_NO_LIB and BOOST_REGEX_USE_CPP_LOCALE, and linking in boost_regex.lib. What am I doing wrong? Glover Barker

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Compile problem with regex.hpp and VS6SP5
by soulofsealion <dworthem＠symyx.com> 13 Feb '03

13 Feb '03

When I included regex.hpp into my project: #include <boost\regex.hpp> I received the following errors c:\cvsprojectsroot\renaissance\3rdpartyfiles\boostlibrary\boost\regex. hpp(860) : error C2899: typename cannot be used outside a template declaration c:\cvsprojectsroot\renaissance\3rdpartyfiles\boostlibrary\boost\regex. hpp(440) : error C2899: typename cannot be used outside a template declaration So at lines 440-2 template <class iterator, class Allocator = #if !(defined(BOOST_MSVC) && (BOOST_MSVC <= 1300)) BOOST_DEFAULT_ALLOCATOR(typename re_detail::def_alloc_param_traits<iterator>::type) > I Tried the following: //This section was altered to handle the problem of the VS6 compiler not handling of a typename in a macro for a template parameter-DWW 02/06/2003 template<class iterator> class def_alloc_param_traits_fixclass { public: typedef typename re_detail::def_alloc_param_traits<iterator>::type def_alloc_param_traits_fix; }; template <class iterator, class Allocator = #if !(defined(BOOST_MSVC) && (BOOST_MSVC <= 1300)) //BOOST_DEFAULT_ALLOCATOR(typename re_detail::def_alloc_param_traits<iterator>::type) > BOOST_DEFAULT_ALLOCATOR (def_alloc_param_traits_fixclass<iterator>::def_alloc_param_traits_fix ) > //End of section altered to handle the problem of the VS6 compiler not handling of a typename in a macro for a template parameter-DWW 02/06/2003 And at lines 858-862 namespace re_detail{ template <class iterator, class Allocator = BOOST_DEFAULT_ALLOCATOR (typename def_alloc_param_traits<iterator>::type) > class match_results_base { I tried: namespace re_detail{ //This section was altered to handle the problem of the VS6 compiler not handling of a typename in a macro for a template parameter-DWW 02/06/2003 template<class iterator> class def_alloc_fixclass { public: typedef typename def_alloc_param_traits<iterator>::type def_alloc_fix; }; //template <class iterator, class Allocator = BOOST_DEFAULT_ALLOCATOR (typename def_alloc_param_traits<iterator>::type) > template <class iterator, class Allocator = BOOST_DEFAULT_ALLOCATOR(def_alloc_fixclass<iterator>::def_alloc_fix) > //End of section altered to handle the problem of the VS6 compiler not handling of a typename in a macro for a template parameter-DWW 02/06/2003 class match_results_base { This compiled OK, has any one else had this problem and any comments on this fix or is there anything else that I missed so I do nto have to change the regex.hpp file? it appeared to me that the VS6 compile has a problem with a typename as a parameter in a macro that is in turn a template parameter. Thank you for any help.

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Ah.......Boost Socket.....
by hjlee＠hurim.net 12 Feb '03

12 Feb '03

Anyone who knows when boost socket library is comming and where I can get beta version..? [Non-text portions of this message have been removed]

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boost::bind/function and C function pointers
by Thomas Pollinger 12 Feb '03

12 Feb '03

Apologies if this topic has already been discussed. I have looked around on various mailing lists, in addition I have tried to make it work with the current C++ STL standard with std::mem_fun and std::bind1st but with no success. The problem is basically to bind a member function pointer with an instance of its declaring class and to assign the result to an existing C library function that expects a C style function pointer. This certainly works for ordinary C functions and static C++ functions, however fails for bound member function pointers. Here is what I am trying to achieve: #include <boost/bind.hpp> // C function declared in some library struct E; extern void setCallBack(void (*callback_fct)(E*)); class A { public: void init(); void callBack(E *e); .... }; void A::init() {setCallBack(boost::bind(&A::callBack, this));} void A::callBack(E *e) {...} I tried also using the STL calls, but without success either: ... setCallBack(std::bind1st(std::mem_fun(&A::callBack), this)); I like the elegant approach of boost::bind and would like to use it for this case. The workaround would be to declare a static function and to store the instance somewhere to access the other members of the A instance - but I'd prefer the other way if there is a solution to make it work. BTW, I am using gcc v 3.2 on Linux/i386 - but I guess that this is a more general problem than a specific compiler issue. The error I've gotten is /opt/src/boost/boost/bind.hpp: In instantiation of `boost::_bi::result_traits<boost::_bi::unspecified, void (A::*)(E*)>': /opt/src/boost/boost/bind/bind_template.hpp:16: instantiated from `boost::_bi::bind_t<boost::_bi::unspecified, void (A::*)(E*), boost::_bi::list1<boost::_bi::value<A*> > >' controller.cpp:28: instantiated from here /opt/src/boost/boost/bind.hpp:59: `void (A::*)(E*)' is not a class, struct, or union type Chaning boost::bind(...) to boost::bind<void>(...) to explicitly delclare the return type yields: controller.cpp:28: cannot convert `boost::_bi::bind_t<void, void (A::*)(E*), boost::_bi::list1<boost::_bi::value<A*> > >' to `void (*)(E*)' for argument `1' to `void setCallBack(void (*)(E*))' which probably reveals the root of the problem, that of not being able to cast a boost function pointer type to a regular C function type. I tried applying some cast operators, but that failed already in the syntactical stage of the parser, e.g. static_cast<void (*)(E*)>. -Thomas

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up-to-date documentation dor boost.python
by Pierre Barbier de Reuille 12 Feb '03

12 Feb '03

Hi ! I'm totally new with boost.python and I need to use some tool to wrap C++ code into python interpreter. The problem I have is that, apparently, the tutorial given with boost.python does not reflect the current implementation. Is there any way to have an up to date tutorial or an organized list of the modifications I can refer to when looking at the tutorial ? Thanks, -- Pierre Barbier de Reuille INRA - UMR Cirad/Inra/Cnrs/Univ.MontpellierII AMAP Botanique et Bio-informatique de l'Architecture des Plantes TA40/PSII, Boulevard de la Lironde 34398 MONTPELLIER CEDEX 5, France tel : (33) 4 67 61 65 77 fax : (33) 4 67 61 56 68

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RE: Re: [Boost-Users] Re: building threads lib with latest from C VS
by William E. Kempf 11 Feb '03

11 Feb '03

> From: Mark Storer <mstorer(a)cardiff.com> > > >The MS APIs do not give you any means with which to cleanup data > >allocated to TLS, and they recommend you add this in DllMain. > > What can you do in DllMain that you can't do with atexit, or some Loki-like > priority singleton system? Handle destruction of TLS data _at thread termination_. The atexit approach would only clean up the data at program termination, which isn't good enough. From what I recall of Loki, it won't apply here either. William E. Kempf wekempf(a)cox.net

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RE: Re: [Boost-Users] Re: building threads lib with latest from C VS
by Mark Storer 11 Feb '03

11 Feb '03

>The MS APIs do not give you any means with which to cleanup data >allocated to TLS, and they recommend you add this in DllMain. What can you do in DllMain that you can't do with atexit, or some Loki-like priority singleton system? --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard;

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Re: Re: [Boost-Users] Re: building threads lib with latest from CVS
by William E. Kempf 11 Feb '03

11 Feb '03

> From: Michael Hunley <mhunley(a)pocketpurchase.com> > At 09:56 AM 2/11/2003 -0500, you wrote: > >Sorry, I forget that some acronyms aren't known by everyone. TLS stands > >for "thread local storage", also known as TSS or "thread specific storage". > > > > Thanks for clearing that up. > > >Testing and development. I compile against 5 compilers, and with both > >static and dynamic libraries this means compiling 10 variants at a minimum > >(through in both debug and release and you have 20 variants), which is > >time consuming. But the real kicker is that boost::thread itself is going > >to rely on TLS shortly, making it so you'll always need a DLL on the > >Windows platforms. > > Understand & sympathize. What about people who want to bundle that part > into their own DLL (which is largely what I'm doing)? Does it hurt to > leave the build in and doc it as untested? Short term, probably not. Long term even this won't work. > Also, why would inclusion of > TLS require it to be a DLL? By itself, TLS doesn't require this. However, TLS cleanup *does* require this. (We're still trying to find an alternative, because even this approach to TLS cleanup is fraught with peril.) The MS APIs do not give you any means with which to cleanup data allocated to TLS, and they recommend you add this in DllMain. This is why you have incompatible thread creation routines such as CreateThread, _beginthread(ex) and AfxBeginThread. > It would seem like including TLS could also be > done in a static lib or am I being completely obtuse? TLS, yes, TLS cleanup, no. > On an almost related note, I saw mention of a cooperative cancel policy > from another post of yours. Do you have any ETA on that and any info on > what it will support vs what it won't support? Is that info on the > developer mailing list? It's partially implemented in CVS on a branch named "thread_dev" (though this isn't stable). ETA is hopefully very soon, as the C++ standards meeting looms. William E. Kempf wekempf(a)cox.net

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RE: [Boost-Users] Re: HP, aCC and the standards
by Tom Matelich 11 Feb '03

11 Feb '03

actually I talked with one of the people on the aCC dev team and they are looking into adding boost into their test procedues. > -----Original Message----- > From: dlux42 <dlux(a)spam.sch.bme.hu> [mailto:dlux@spam.sch.bme.hu] > Sent: Monday, February 10, 2003 2:15 PM > To: Boost-Users(a)yahoogroups.com > Subject: [Boost-Users] Re: HP, aCC and the standards > > > > > While many compiler vendors strive to be able to compile boost, > > > is this really a measure of Standard C++ conformance? > > > > A pretty good one. That's why they use it as a test. > > It may be true, but HP won't accept it. We help them a lot if we can > point to a part of the standard and can show an "aCC -E" output and an > "aCC -c" output and say: "this point is badly implemented, because it > is not compiled, although the standard said it should". > > > > > > ------------------------ Yahoo! Groups Sponsor > ---------------------~--> > Get 128 Bit SSL Encryption! > http://us.click.yahoo.com/LIgTpC/vN2EAA/xGHJAA/EbFolB/TM > -------------------------------------------------------------- > -------~-> > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > > ----------------------------------------------------------------------- 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] Re: building threads lib with latest from CVS
by Michael Hunley 11 Feb '03

11 Feb '03

At 09:56 AM 2/11/2003 -0500, you wrote: >Sorry, I forget that some acronyms aren't known by everyone. TLS stands >for "thread local storage", also known as TSS or "thread specific storage". > Thanks for clearing that up. >Testing and development. I compile against 5 compilers, and with both >static and dynamic libraries this means compiling 10 variants at a minimum >(through in both debug and release and you have 20 variants), which is >time consuming. But the real kicker is that boost::thread itself is going >to rely on TLS shortly, making it so you'll always need a DLL on the >Windows platforms. Understand & sympathize. What about people who want to bundle that part into their own DLL (which is largely what I'm doing)? Does it hurt to leave the build in and doc it as untested? Also, why would inclusion of TLS require it to be a DLL? It would seem like including TLS could also be done in a static lib or am I being completely obtuse? On an almost related note, I saw mention of a cooperative cancel policy from another post of yours. Do you have any ETA on that and any info on what it will support vs what it won't support? Is that info on the developer mailing list? thanks again for all your info. michael

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Re: [Boost-Users] Re: building threads lib with latest from CVS
by William E. Kempf 11 Feb '03

11 Feb '03

> > From: "hunleyexpress <mhunley(a)pocketpurchase.com>" <mhunley(a)pocketpurchase.com> > Date: 2003/02/10 Mon PM 03:47:57 EST > To: Boost-Users(a)yahoogroups.com > Subject: [Boost-Users] Re: building threads lib with latest from CVS > > > Intentionally removed. In the current library it's easier to deal > with a single build type, and since a DLL is required for TLS usage, > the static build was removed. In the next version of the library, > the implementation is going to have to make use of TLS as well, so > you'll always need a DLL, making it pointless to continue providing > both a static library and the threadmon.dll. > > > > If you mean something other than Transport Layer Security when you > say TLS, disregard the rest of this and just let me know what it > means in boost-ese. Sorry, I forget that some acronyms aren't known by everyone. TLS stands for "thread local storage", also known as TSS or "thread specific storage". > I don't quite understand why the threading lib > depends on TLS. I am only including the threading lib to write > thread handling and don't want or need security aspects (I'm handling > those specifically myself for a custom app). I ultimately need to > bundle all of it into a *very* small DLL (or shared lib on Linux) of > my own and don't want to require a separate boost DLL. Why would you > tie the two together, they seem completely orthoganal. BTW: I have > found it rather easy to have Jam build both. I guess it is just more > headache from a testing standpoint. > I appreciate the info. Testing and development. I compile against 5 compilers, and with both static and dynamic libraries this means compiling 10 variants at a minimum (through in both debug and release and you have 20 variants), which is time consuming. But the real kicker is that boost::thread itself is going to rely on TLS shortly, making it so you'll always need a DLL on the Windows platforms. William E. Kempf wekempf(a)cox.net

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Compiling the BGL-Graphviz library: libbgl-viz.a
by Jeff Holle 11 Feb '03

11 Feb '03

The source code that should be able to produce this library is in directory "boost_1_29_0/libs/graph/src". In running the Makefile, the following error is produced: /bin/mv graphviz_parser.tab.h graphviz_parser.h /bin/mv: cannot stat `graphviz_parser.tab.h': No such file or directory. Does anybody know how to fix this problem?

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boost::function2's copy constructor expensive - why?
by Markus Werle 11 Feb '03

11 Feb '03

Hi! Today's profiling of my code (which massively uses boost::function to collect formulas) showed that boost::function2' copy constructor is called zillions of times. OK, I disabled inlining to get some more details, but this I do not understand. The functors are created, stored in an array and do not get copied again, but rather referenced there. Before I dig in that code: where do those copies come from? Is that the normal behaviour triggered ny operator() or is that a hint that I use them the wrong way? Any experience? At present the boost::function overhead kills my application. Tuning tipps? best regards, Markus

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Support for chain graph
by Matthieu P. 11 Feb '03

11 Feb '03

I am interested in an algorithm in Bayesian Networks which uses chain graph, that is a graph that contains both directed and undirected edges. Since the declaration of the template seem to include one or the other, i am looking for ideas on implementing these graph. Any suggestions? Thanks, Matthieu

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Can shared_ptr release ownership of a pointer without destroy it?
by Black Ice 11 Feb '03

11 Feb '03

As following manner: shared_ptr<Foo> ptr(new Foo()); ... Foo * p = ptr.release(); -- /*******************/ ×ÔÓÉ£šliberty£©ÎÞ·ÇŸÍÊÇÕâÑùÒ»ÖÖ³ÐÅµ£ºÃ¿žöÈËœ«»áµÃµœÒ»ÖÖ±£ÕÏ£¬±£ÕÏÎÒÃÇ¿ÉÒÔÓë ÈšÍþ¡¢¶àÊý¡¢Á÷Ë×Œ°ÓßÂÛµÄÓ°ÏìÏà¿¹ºâ¡£ /*******************/

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Fwd: Re: [Boost-Users] HP, aCC and the standards
by Toon Knapen 10 Feb '03

10 Feb '03

On Tuesday 04 February 2003 17:18, Tom Matelich wrote: > Who is running those tests, and what version of aCC is that? I am. I'm using aCC version 53800 currently installed on an HPUX11i. You might notice on the HP website that the latest release was 53700 so it's newer than new ;-) Nevertheless, conformance is still bad. There were quite some messages on the boost-ml on the support for HP recently. > > -----Original Message----- > > From: Toon Knapen [mailto:toon.knapen@si-lab.org] > > Sent: Tuesday, February 04, 2003 12:15 AM > > To: Boost-Users(a)yahoogroups.com > > Subject: Re: [Boost-Users] HP, aCC and the standards > > > > On Monday 03 February 2003 18:06, Tom Matelich wrote: > > > I would recommend contacting the aCC support people. They > > > > are generally > > > > > quite reasonable. In fact, the hp status tables (which > > > > appear a bit out of > > > > > date) at http://www.boost.org/status/cs-hpux.html are run > > > > remotely on a box > > > > > provided by HP for boost to use. > > > > For an updated status-page, check out : > > http://boost.sourceforge.net/regression-logs/ > > and you see that aCC has the highest failure rate ! > > I also recently talked to an HP representative and he was > > under the impression > > that aCC was very confirming. > > > > ------------------------ Yahoo! Groups Sponsor > > ---------------------~--> > > Get 128 Bit SSL Encryption! > > http://us.click.yahoo.com/LIgTpC/vN2EAA/xGHJAA/EbFolB/TM > > -------------------------------------------------------------- > > -------~-> > > > > Info: <http://www.boost.org> > > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > > > > Your use of Yahoo! Groups is subject to > > http://docs.yahoo.com/info/terms/ > > ----------------------------------------------------------------------- > 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. > ----------------------------------------------------------------------- > > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ -------------------------------------------------------

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Re: [Boost-Users] building threads lib with latest from CVS
by William E. Kempf 10 Feb '03

10 Feb '03

> > From: "hunleyexpress <mhunley(a)pocketpurchase.com>" <mhunley(a)pocketpurchase.com> > Date: 2003/02/10 Mon PM 02:07:11 EST > To: Boost-Users(a)yahoogroups.com > Subject: [Boost-Users] building threads lib with latest from CVS > > I am fairly new to boost (and jamfiles). I am using the threads > library for cross platform thread support. Under the stable build a > library libboost_thread.lib is created to staticly link in to my > project, with seperate libs if I am using the DLL STL or static STL. > > That build config is gone in the latest version under CVS, replaced > by a boost_thread dll set up. I want (and need) the old static > version. I have successfully added it back into the jam file so that > all 3 (including the threadmon) are built now, but that isn't > something I really want to have to maintain as I get updates. Is the > static lib intentionally and permanently removed or is it an > oversight/temporary change? Intentionally removed. In the current library it's easier to deal with a single build type, and since a DLL is required for TLS usage, the static build was removed. In the next version of the library, the implementation is going to have to make use of TLS as well, so you'll always need a DLL, making it pointless to continue providing both a static library and the threadmon.dll. William E. Kempf wekempf(a)cox.net

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building threads lib with latest from CVS
by hunleyexpress <mhunley＠pocketpurchase.com> 10 Feb '03

10 Feb '03

I am fairly new to boost (and jamfiles). I am using the threads library for cross platform thread support. Under the stable build a library libboost_thread.lib is created to staticly link in to my project, with seperate libs if I am using the DLL STL or static STL. That build config is gone in the latest version under CVS, replaced by a boost_thread dll set up. I want (and need) the old static version. I have successfully added it back into the jam file so that all 3 (including the threadmon) are built now, but that isn't something I really want to have to maintain as I get updates. Is the static lib intentionally and permanently removed or is it an oversight/temporary change? thanks.

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BGL: cycles in undirected graph
by Tarjei Knapstad 10 Feb '03

10 Feb '03

(Disclaimer: My knowledge of graph theory isn't too broad, so have me excused if this is completely trivial...) I'm struggling a bit with finding cycles in an undirected graph. Doing a DFS/BFS and recording back edges, thus detecting the number of cycles and a connected vertex pair for each one is simple enough. However, I'd also like to find the sequence(s) of vertices that make up the cycle. There's and example in the book that does this, but relies on a graph with direction in the second step where a DFS is done from both back-edge vertices and the results intersected. This won't work in the case of an undirected graph as every vertex is reachable from any other (if there's only one "connected component"), so I would just end up with the complete set of vertices in every case. My idea is to use BFS and the record_predecessors visitor, but I can't seem to wrap my head around how to find the sequence of vertices connecting the cycle(s) from this. Could anyone offer some pointers? (hopefully not NULL :) ) Regards, -- Tarjei

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bug report: boost::tokenizer with VC6
by Navi Singh 09 Feb '03

09 Feb '03

The boost release 1.28.0 of the tokenizer library has the following problem: There are 5 examples, namely, simple_example_1.cpp thru simple_example_5.cpp If I change the main() in each of the 5 to to main1() thru main5() and return 0; the vc60 compiler generates an internal compiler error when parsing the file boost\iterator_adapters.hpp on line 869, where it is parsing the following lines: reference operator*() const { return policies().dereference(*this); }

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multi_array iterators
by gareth_stockwell2003 <gareth＠ebi.ac.uk> 09 Feb '03

09 Feb '03

This may be a naieve question... Is there a simple way to iterate over all elements in a multi-array (or a view thereof), regardless of the number of dimensions and the size of each dimension? I don't care about the order of this access.

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bjam question
by Stephen Crowley 09 Feb '03

09 Feb '03

I have a library that depends on boost and is built with bjam. It puts sepearate targets in $(BAYES_ROOT)/target/bin/libBayesFilter.a/gcc/release/runtime-link-dynamic/libBayesFilter.a and the other debug directory as well. I am also working on a library using the same system that must link with libBayesFilter. My question is, how do I specify the library dependency on BayesFilter properly without having to specify the complete path to the target directory (which will change depending on the build features specified). I tried <lib>$(BAYES_ROOT)/BayesFilter/BayesFilter but it dies with: unknown dependent target <IdentityTest!/!home!stephenc!cvs!Bayes++!BayesFilter>libBayesFilter.a Am i missing something? -- Stephen

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Conflict with winapi.hpp and windows.h (manifested in ACE)
by Tom Matelich 08 Feb '03

08 Feb '03

Intel C++ 7.0 for Windows, STLPort 4.5.3, boost 1.29, ACE 5.3 Intel was warning a bunch of bad code in my source base, so I turned on warnings as errors, then I hit a problem where ACE was calling InitializeCriticalSection with a pointer to its typedef of CRITICAL_SECTION, and it was using the declaration of InitializeCriticalSection in winapi.hpp. Turns out, in the standard (by my interpretation), section 7.5/6 that if you put an extern "C" declaration in a namespace, its also accessible by ::. The call failed because boost::detail::winapi::critical_section != CRITICAL_SECTION. I ended up ifdef'ing the declaration of critical_section like so: #ifndef _WINBASE_ //header guard for winbase.h. struct critical_section { struct critical_section_debug * DebugInfo; long_type LockCount; long_type RecursionCount; handle_type OwningThread; handle_type LockSemaphore; ulong_ptr_type SpinCount; }; #else typedef CRITICAL_SECTION critical_section; #endif Please advise if you have a better solution. Tom Matelich Pardon the disclaimer... ----------------------------------------------------------------------- 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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UBLAS: m[i] notation not supported on const ?
by speedsnaii <speedsnaii＠yahoo.de> 08 Feb '03

08 Feb '03

Since I did not get an answer on a related question, I am trying to state it different. It seems as if the "[]" access is not supported for const objects. Is there a reason for this, or is it a bug? Example: ========================================================== #include <boost/numeric/ublas/config.hpp> #include <boost/numeric/ublas/vector.hpp> #include <boost/numeric/ublas/matrix.hpp> using namespace boost::numeric::ublas; void foo(vector<double>& v, const vector<double>& a) { } int main(int argc, char* argv[]) { vector<double> v (3); const matrix<double> m(3,3); foo(v, m[0]); } ========================================================== my compiler does not compile this. This is a problem when I get the matrix as a "const matrix<>& " parameter via the argument list. Regards, Roland

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thread_group behavior question
by sdussin <sdussin1＠tampabay.rr.com> 07 Feb '03

07 Feb '03

I've been using Boost for several months now, and I must say I've been very happy with it. I've primarily been using the threads and regex stuff from the library, and I have a question regarding the behavior of the thread_group.join_all method. In my current situation, I have a thread_group which launches several threads of execution for background servers, on an as-needed basis. If it becomes necessary to shutdown those background servers, I issue a join_all on the thread_group to wait for all activity to cease, then I can clear up the server instances themselves. If I issue a join_all from a thread and, while waiting for the join_all to exit, another thread creates a thread within my thread_group, what is expected? Will the join_all now wait for the original threads, as well as the newcomer, or will it only wait on the threads which were running at the time the join_all was called?? Thanx, Steve Dussinger

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