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

RE: [Boost-Users] newsgroup
by Jim.Hyslop 20 Sep '02

20 Sep '02

Ihsan Ali Al Darhi [mailto:iad929@joinnet.com.jo] wrote: > how can i access the boost newsgroups? Boost and Boost Users are both mirrored through gmane.org. You should be able to point your newsreader at news.gmane.org. You can get more details at http://www.boost.org/more/mailing_lists.htm, or by going directly to gmane http://www.gmane.org -- Jim

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RE: [Boost-Users] Slightly Off-Topic, Books
by Jim.Hyslop 20 Sep '02

20 Sep '02

Your post is not "slightly" off topic, it is entirely off topic. -- Jim Hyslop moderator, boost-users(a)yahoogroups.com

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RE: [Boost-Users] Re: [BGL] Best way to abort an algorithm from w ithi n a visitor?
by Mark Storer 20 Sep '02

20 Sep '02

Using exceptions in this way just bugs me. Religious reasons I guess. As the Esteemed Mr. Hylsop ;) mentioned earlier, exceptions are for "oops". This seems alot like the whole "do{}while(0)" with various 'break' statements sprinkled in to avoid multiple returns/nested ifs. Useful, but Just Not Right. Your code has cooties! Nobody's going to want to sit next to it during recess... >So there's no way to affect feedback to the algorithm's dispatcher >without actually making modifications to the algorithm code. So modify away. Seems like a "breath_first_until" sort of thing would be quite useful. Pass in some sort of predicate, and away you go. I'm sure the community at large would be grateful. --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard; -----Original Message----- From: Chris Russell [mailto:cdr@encapsule.com] Sent: Wednesday, September 18, 2002 1:27 PM To: boost-users(a)yahoogroups.com Subject: [Boost-Users] Re: [BGL] Best way to abort an algorithm from withi n a visitor? > Now if you've got more than a hundred or so entries left to go, exceptions > really are the greener grass. > The size of the graph is not known a-priori (not at coding time anyway) but is likely to be quite large. > What's wrong with 'return', perhaps along-side some sort of 'done' status > variable? I'm only vaguely familiar with the visitor pattern, but these > would seem to be the obvious choice. > See my earlier reply. In this case I'm deriving my visitor from a base and overriding "event" handlers that receive their marching orders via const references and return void. So there's no way to affect feedback to the algorithm's dispatcher without actually making modifications to the algorithm code. "Mark Storer" <mstorer(a)cardiff.com> wrote in message news:E840F0B7E6189547BDB91DA8BF2228AB016255F8@csmail.cardiff.com... > If efficiency is your goal, exceptions are not the answer. Just enabling > exceptions at compile time makes a noticable performance hit. Actually > throwing an exception can gobble up a 1000 cycles, give or take. That's per > throw. If you catch and throw again, you'll pay again. > > Now if you've got more than a hundred or so entries left to go, exceptions > really are the greener grass. > > What's wrong with 'return', perhaps along-side some sort of 'done' status > variable? I'm only vaguely familiar with the vistor pattern, but these > would seem to be the obvious choice. > > --Mark Storer > Software Engineer > Cardiff Software > > #include <disclaimer> > typedef std::disclaimer<Cardiff> Discard; > 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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Slightly Off-Topic, Books
by James Zappia 20 Sep '02

20 Sep '02

Hello, I'm a long time C/Perl programming and would like to transition into C++. What are some books I should pick up? I have the C++ Complete Reference for all the syntax sugar. I'm more interested in books that teach how to program in the mindset of objects. Also, books that don't read like RFCs ;) I learn better with examples and such -- not just brain dumps. Thank you in advance. Regards, James

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boost::shared_ptr confusion...
by someuserat 20 Sep '02

20 Sep '02

First, many thanks to Peter Dimov for answering my earlier questions. I've gotten hung up on something that may not be directly related to shared_ptr, but it's in the mix here. I suspect the real problem is my lack of experience using the STL algorithms, but I'm making an effort not to go back to writing my own loops with this project. Using my Widget theme, here's what I've got. A WidgetManager class contains a stl::list of shared_ptr<Widget> objects. It also contains a stl::vector of shared_ptr<WidgetMap> objects. WidgetMap objects contain a B+tree. (I know, I should probably change this to stl::map or multimap, I'll do that later) The index maps a data member of a Widget to a shared_ptr to the Widget for fast lookups. It is possible that new data members can be added or removed from the Widgets, and we have functions for handling that. Additional WidgetMap objects are added to the WidgetManager for Widget data members as needed. When adding a new WidgetMap, I need to loop through the existing set of Widgets and add them to the new WidgetMap. This is the simplest example I can think of as to what I'm trying to do, however obviously this does not work... void WidgetManager::addMap(const WidgetMapPtr i){ maps_.push_back(i); // have to write a function adapter here? for_each(widgetset_.begin(),widgetset_.end(),i->insert); } Along a similar line, when a Widget's data member collection is changed, I need to remove any WidgetMap objects fromm the WidgetManager that referenced the member being deleted. void WidgetManager::dropWidgetMember(const DataMemberPtr d){ // delete any maps using the target member // how to fix this bloody line? getIndexedMember returns a DataMemberPtr to the member it is keyed on. maps_.erase(remove_if(maps_.begin(),maps_.end(),(boost::mem_fn(&WidgetMap::getIndexedMember)).equals(d))); // get rid of the member itself members_.erase(remove_if(members_.begin(),members_.end(),boost::bind(&DataMember::equals,_1,d))); // rewrite the data file, we're all dirty anyway. this->compact(); } I feel like I understand what I want to do, but I cannot find a reference that explains how to do it the 'correct' way. At least not that I can grasp. Can someone point me in the right direction? Thanks, Mark

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Regex and Unicode
by Fr�d�ric Mayot 20 Sep '02

20 Sep '02

Hi, I'm trying to use Unicode with Regex in an MFC app. The preprocessor variable UNICODE is defined. But I obtain an error on the line : regex_search(sText, oResults, pRegExp); error C2665: none of the 4 overloads can convert parameter 1 from type 'class CString' sText is a CString which has a "const wchar_t*" operator. The problem is why doesn't the regex_search prototype require a "const wchar_t*" when UNICODE is defined ? Thanks. Fred (I read the documentation, but maybe I missed something...)

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BJam output directories on NT
by yg-boost-users＠m.gmane.org 20 Sep '02

20 Sep '02

Building my application using msvc-stlport. I've set ALL_LOCATE_TARGET=d:/src/pegdevbin/build. During processing, the paths get too deep for NT and eventually the mkdir fails and then of course the build stops. Anyway to shorten the deep paths that are automatically created or should I start chopping up allyourbase.jam? I won't be doing any build variants on a per platform basis so I don't need the deep paths that specify the various options in effect. Thanks for the help (and all the great work too...) Rob

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RE: [Boost-Users] Re: Borland C++ Builder 5.5 & scoped_ptr
by Mark Storer 19 Sep '02

19 Sep '02

>>Are you saying that if I switch from >> scoped_ptr to shared_ptr the destructor will get called? Is he saying that the destructor is NOT getting called with scoped_ptr? (!) --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard; -----Original Message----- From: Peter Dimov [mailto:pdimov@mmltd.net] Sent: Thursday, September 19, 2002 11:07 AM To: Boost-Users(a)yahoogroups.com Subject: Re: [Boost-Users] Re: Borland C++ Builder 5.5 & scoped_ptr From: "Brian" <bneal(a)zeus.ia.net> > --- In Boost-Users@y..., "Gennadiy E. Rozental" <rogeeff@m...> wrote: > > This was discussed during Boost.Test review. > > Peter some time ago made a changes in boost::shared_ptr that allows > > it to be used with Borland 5.5 namely in the situation you > described. > > > > Gennadiy. > > Hi...could you clarify this? All I noticed was that shared_ptr had > that compile time check for an incomplete type removed, whereas > scoped_ptr still has it. Are you saying that if I switch from > scoped_ptr to shared_ptr the destructor will get called? Yes, shared_ptr will call the destructor. It only requires a complete type at construction time. 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] Re: [BGL] Best way to abort an algorithm from w ithi n a visitor?
by Mark Storer 19 Sep '02

19 Sep '02

>Using the Boost library as it currently stands, >it appears the best way to abort the algorithm >is to throw an exception. Granted. I'd even go so far as to say "the only way" (based on my vast experience... I've actaully vistor's code once). >Whether or not throwing an exception is >acceptable from a general programming standpoint >is a topic more suited to a general C++ >discussion list Any recommendations? Preffereably something with an archive/FAQ so we don't drag up Holy War #42... --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard;

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RE: [Boost-Users] Re: [BGL] Best way to abort an algorithm from w ithi n a visitor?
by Jim.Hyslop 19 Sep '02

19 Sep '02

Mark Storer [mailto:mstorer@cardiff.com] wrote: > If Boost's source were a closed book, and the only option was > to throw an > exception, then so be it. But that is not the case. On that note, I'm going to bring this thread back to discussion of how to use the current Boost library. Using the Boost library as it currently stands, it appears the best way to abort the algorithm is to throw an exception. Whether or not throwing an exception is acceptable from a general programming standpoint is a topic more suited to a general C++ discussion list (if anyone decides to take it there, let me know - I'd like to follow it). Whether or not to add a return value to the BGL is a topic more suited to the main Boost mailing list. -- Jim

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RE: [Boost-Users] Re: [BGL] Best way to abort an algorithm from w ithi n a visitor?
by Mark Storer 19 Sep '02

19 Sep '02

In general, I agree that taking personal issue with the use of some language feature is a little silly. In specific, I'm going to disagree with you both for exceptions and the whole do{}while(0) thang. I'm sitting next to my copy of Stroustrup's "The C++ Programming language" (2nd edition). Chapter 9 covers exceptions. This chapter makes it clear that the purpose of exceptions is to handle errors: " The fundamental idea is that a function that finds a problem that it cannot cope with /throws/ an exception, hoping that its (direct or indirect) caller can handle the problem. " Same thing with the do{}while(0) construct. Using a loop as an error handler is quite similar. One could argue that a break is far more efficient than a throw. A counter-argument is that the throw carries a great deal more information about what went wrong. Once the excreta impacts the air-pusher-thingy, speed becomes a secondary concern (far more often than not). If you want to abort a function due to an error then throw an exception. If you want to return a value then do so. And while using a language feature for something other than its original intent is not criminal, there are usually 'proper' ways to do things already built into the language, ways that often work better than subjecting some poor unsuspecting feature to your vile, unnatural manipulations. <Dudly Do-Right>You fiend!</Dudly Do-Right> In the case that brought all this up (returning a value from a graph's visitor to avoid iterating through the whole graph) the proper way to handle it is to alter the algorithm to allow for early termination. If Boost's source were a closed book, and the only option was to throw an exception, then so be it. But that is not the case. So do it right... as Chris Russell (the original poster) has decided to do. --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard; -----Original Message----- From: Peter Dimov [mailto:pdimov@mmltd.net] Sent: Thursday, September 19, 2002 9:20 AM To: Boost-Users(a)yahoogroups.com Subject: Re: [Boost-Users] Re: [BGL] Best way to abort an algorithm from withi n a visitor? From: "Mark Storer" <mstorer(a)cardiff.com> > Using exceptions in this way just bugs me. Religious reasons I guess. As > the Esteemed Mr. Hylsop ;) mentioned earlier, exceptions are for "oops". > This seems alot like the whole "do{}while(0)" with various 'break' > statements sprinkled in to avoid multiple returns/nested ifs. Useful, but > Just Not Right. A common misconception. Many people try to project their own ideas/expectations on language features, rather than simply using them as tools where appropriate. There is nothing "oops"-y about exceptions. They are a control flow mechanism; one that has interesting properties, but a control flow mechanism nonetheless. If it works and leads to a better code, it's foolish to avoid it without a technical reason. A similar example is when people don't use "struct" for C++ classes because it "doesn't feel right", or when trying to choose between "typename" and "class" for template parameters. The language features simply do not carry this kind of religious/emotional payload. It's all in your mind. 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] Re: [BGL] Best way to abort an algorithm from w ithi n a visitor?
by Garriss, Michael 19 Sep '02

19 Sep '02

I agree. I hate to see the return -1 (for example) on some "exceptional" case in a function when an exception makes more sense. It's not necessarily an "oops" case, it's an "exception." Either way the caller has to check the special case. There is a good reason that exceptions are named exceptions and not errors. Mike Garriss -----Original Message----- From: Peter Dimov [mailto:pdimov@mmltd.net] Sent: Thursday, September 19, 2002 10:20 AM To: Boost-Users(a)yahoogroups.com Subject: Re: [Boost-Users] Re: [BGL] Best way to abort an algorithm from withi n a visitor? From: "Mark Storer" <mstorer(a)cardiff.com> > Using exceptions in this way just bugs me. Religious reasons I guess. As > the Esteemed Mr. Hylsop ;) mentioned earlier, exceptions are for "oops". > This seems alot like the whole "do{}while(0)" with various 'break' > statements sprinkled in to avoid multiple returns/nested ifs. Useful, but > Just Not Right. A common misconception. Many people try to project their own ideas/expectations on language features, rather than simply using them as tools where appropriate. There is nothing "oops"-y about exceptions. They are a control flow mechanism; one that has interesting properties, but a control flow mechanism nonetheless. If it works and leads to a better code, it's foolish to avoid it without a technical reason. A similar example is when people don't use "struct" for C++ classes because it "doesn't feel right", or when trying to choose between "typename" and "class" for template parameters. The language features simply do not carry this kind of religious/emotional payload. It's all in your mind. Yahoo! Groups Sponsor ADVERTISEMENT <http://rd.yahoo.com/M=234081.2377872.3808768.2225242/D=egroupweb/S=17050067 88:HM/A=1225247/R=0/*http://ad.doubleclick.net/clk;4547223;7007303;y?http:// www.ameriquestmortgage.com/welcome.html?ad=Yahoo01> <http://us.adserver.yahoo.com/l?M=234081.2377872.3808768.2225242/D=egroupmai l/S=:HM/A=1225247/rand=147617524> Info: < http://www.boost.org <http://www.boost.org> > Wiki: < http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl <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 the Yahoo! Terms of Service <http://docs.yahoo.com/info/terms/> . [Non-text portions of this message have been removed]

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lambda lib & mingw gcc 2.95.2?
by Mynhard Rudolph 19 Sep '02

19 Sep '02

Hi all Does the lambda library compile under mingw with gcc 2.95.2? I'm a newbie and I can't figure out what's wrong with the following test example: #include <boost/lambda/bind.hpp> #include <boost/lambda/lambda.hpp> using namespace boost; using namespace boost::lambda; struct A { int d; }; int main (int argc, int argv[]) { A* a = new A(); int b = (a ->* &A::d); int c = (_1 ->* &A::d)(a); return c - b; } g++ test.cpp -Wall -Ix:/boost_1_28_0/ -D__PROCESSOR_X86__ -D__WIN32__ -D__GCC__ -o test.o test.cpp: In function `int main(int, int *)': test.cpp:12: no match for `const boost::lambda::lambda_functor<boost::lambda::pl aceholder<1> > & ->* int A::*' make: *** [test.exe] Error 1 Would appreciate any clues. ;-) Mynhard

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RE: [Boost-Users] [BGL] Best way to abort an algorithm from withi n a visitor?
by Mark Storer 18 Sep '02

18 Sep '02

If efficiency is your goal, exceptions are not the answer. Just enabling exceptions at compile time makes a noticable performance hit. Actually throwing an exception can gobble up a 1000 cycles, give or take. That's per throw. If you catch and throw again, you'll pay again. Now if you've got more than a hundred or so entries left to go, exceptions really are the greener grass. What's wrong with 'return', perhaps along-side some sort of 'done' status variable? I'm only vaguely familiar with the vistor pattern, but these would seem to be the obvious choice. --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard;

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[BGL] Best way to abort an algorithm from within a visitor?
by Chris Russell 18 Sep '02

18 Sep '02

Is there a way to abort an algorithm while it's processing? Can I throw an exception out of a visitor method? I have a case where I need the algorithm to crunch on a large graph until some condition dependent on property data is reached. If and when the condition is met, I would like to skip the processing of the remaining vertices/edges and save the cycles. Does using exceptions sound like a reasonable approach? - Thanks Chris P.S. Thanks for the help with properties and property maps the other day. I cleaned up my code and eventually tracked the source of my considerable confusion to a bug in an operator= defined on the object that I'm using as an internal property. This bug manifested itself by re-initializing previously set data seemingly at random >8|-~ Arg... My bad.

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RE: [Boost-Users] [BGL] Best way to abort an algorithm from withi n a visitor?
by Jim.Hyslop 18 Sep '02

18 Sep '02

Steve M. Robbins [mailto:steven.robbins@videotron.ca] wrote: > I use that technique to abort the Dijkstra shortest path > search when I find my > goal node. It works fine, as far as I can tell, but I'd be > interested to > learn if there is a better way. It seems anti-idiomatic to me. Exceptions are intended to signify exceptional circumstances that you would not normally expect to encounter (at least according to one school of thought). An exception tells me "Oops, something went wrong here" not "we succeeded, here's the answer". Many of the exceptions I catch are called "oops": try { /* ... */ } catch (std::exception &oops) { /* ... */ } One possible snag might be if your code interacts with someone else's code, which will catch the exception and not pass it on to you. In the context we're talking about, though, I don't see that as a significant problem. An exception is certainly an easy way to abort the search, and since I don't have an alternative to offer, I'll shut up now ;=) -- Jim

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Levenshtein Distance algorithm
by Philippe Lalande 18 Sep '02

18 Sep '02

Hi, I was wondering if anyone could tell me if Boost contains a function that could perform a 'Levenshtein distance' calculation on a sequence. The Levenshtein distance is a measure of the similarity between two strings calculated as the number of deletions, insertions, or substitutions required to transforms the source string to the target string. IMO, it is an interesting algorithm that could apply to any kind of sequence. I'd be happy to discuss interface and implementation on the dev list if such algorithm does not exist yet. Thank you Philippe

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RE: [Boost-Users] Re: Newbie needs help w/VC6 & filesystem (take 2)
by Jim.Hyslop 18 Sep '02

18 Sep '02

John B. Williston [mailto:yg-boost-users@gmane.org] wrote: > On Tue, 17 Sep 2002 12:40:53 -0400, Douglas Gregor <gregod(a)cs.rpi.edu> > wrote: > > >Could you copy 'n' paste some of the link errors you are > getting? It seems > >like you did the right thing (at least, I don't know of a > better way), but > >perhaps knowing what symbols are being redefined would help > isolate the > >problem. > > I sure can. The following is the compile output: > > --------------------Configuration: TestFs - Win32 > Debug-------------------- > Compiling... > Main.cpp > Linking... > LINK : warning LNK4075: ignoring /INCREMENTAL due to /FORCE > specification > msvcprtd.lib(MSVCP60D.dll) : warning LNK4006: "public: __thiscall > [...] already > defined in Main.obj; second definition ignored I've typically found these errors when you have mixed the run-time library usage, or MFC usage. One part of your project wants to link in the C run-time library as a DLL, but another part of your project wants to link it in as a static library. Make sure that all the projects, including the ones that build any libraries you're linking with, use the same "Use runtime library" option (Project | Settings, "C/C++" tab, "Code Generation" category), and also that all projects use the same "Microsoft Foundation Class" option (on the General tab). -- Jim

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checked_delete with pointer template parameter
by Craig Henderson 18 Sep '02

18 Sep '02

I need to free memory from a container with elements of pointers, where the container value_type is a pointer type. I cannot use the checked_delete template as it is, as the template parameter is defined without the '*' pointer. For example, the following fails (obviously): typedef std::vector<char *> X; X x; ... std::for_each(x.begin(), x.end(), boost::checked_delete<X::value_type>); I'm using VC7, so have no partial specialization available, so using the type traits library remove_pointer<> does not work: typedef boost::remove_pointer<typename X::value_type>::type type; std::for_each(x.begin(), x.end(), boost::checked_delete<type>); My existing solution uses a unary functor, as below, but this met with critism on the Boost Developers' list. What would be the 'boost' solution to this problem? template<typename T> class free_heap_ptr : public std::unary_function<T, void> { public: free_heap_ptr() { } ~free_heap_ptr() { } void operator() (T p) { delete p; } }; ... std::for_each(changes_.begin(), changes_.end(), free_heap_ptr<typename change_list::value_type>()); TIA -- Craig

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Is there a Type2Type in boost ?
by Baptiste Lepilleur 17 Sep '02

17 Sep '02

Hi everyone, I've looked around and failed to find the Type2Type template, detailed by Andrei Alexandrescu in a CUJ article (http://cuj.com/experts/1810/alexandr.htm?topic=experts) in boost. While the implementation is trivial: template<typename Type> struct Type2Type { typedef Type original_type; }; I'd rather have it in a well known library. Has it been replaced by something else ? Baptiste.

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Newbie needs help with VC6 & filesystem library
by John B. Williston 17 Sep '02

17 Sep '02

Greetings, Though I'm an "old hand" at C++, I'm a complete newbie when it comes to Boost. The piece that really caught my eye, in light of my current project, is the directory iterator. To date, however, I haven't had any success getting it to compile and function under Win32 with MSVC6, so I thought I would post here. I first have a couple of general questions about using Boost, and then one specific question about the problems with my project at hand. (1) Is there a "right" way to include Boost stuff with VC6? Adding the Boost base directory to my list of include directories seems to work for the official stuff, but it clearly doesn't work for the filesystem stuff because Directory.h is not in the base\boost directory. I can put it there myself, of course, but I'm wondering if there is some intended way to use the beta libraries before they become a part of the whole. (2) Is there a "right" way to link Boost stuff with VC6? The filesystem stuff, like the regex stuff and some other pieces, requires actual compilation and cannot simply be included as header files. I have already built all the official libraries using the bjam utility, but I cannot help noticing they're each stored in hideously long paths beneath the boost base directory. Is there a "right" directory under the Boost hierarchy into which the resulting libs should be copied for ease of inclusion in VC6? Or should I copy them into my project directories as needed? Or should I simply come up with my own system? To get to the more specific question, let me explain how I've addressed (1) and (2) for the time being. Regarding (1), I've copied Directory.h and Boost.h into the base\boost directory so that they may be included without changing the existing source code. That was simple enough. Regarding (2), I've decided to add Directory.cpp to my project and compile it as a module, rather than try to get the linking to work externally. Having said that, consider the following code: #include <windows.h> #include "boost/directory.h" int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) { using namespace boost::filesystem; std::string strFilename; for (dir_it it("./"); it != dir_it(); ++it) if (!get<is_hidden>(it)) strFilename = *it; return 0; } This is an extremely minimal test case of integrating the filesystem stuff into a Win32 application. When compiling the application, I get the following lengthy and inscrutable (to me, at least) error message: WinMain.obj : error LNK2001: unresolved external symbol "__declspec(dllimport) public: __thiscall boost::filesystem::get<struct boost::filesystem::is_hidden>::get<struct boost::filesystem::is_hidden>(class boost::filesystem::dir_it const &)" (__imp_ ??0?$get@Uis_hidden@filesystem@boost@@@filesystem@boost@@QAE@ABVdir_it@12@@Z) The error message seems to suggest that the filesystem stuff isn't available in my project. I find that confusing because the Directory.cpp module compiles without any errors, and I am thus inclined to think that, in fact, all of the filesystem stuff is in my project. Thus, I must also ask the third question: (3) Can anyone explain to me what I might be doing wrong and, more importantly, how I might correct it? Thanks much to all the Boost authors for an interesting set of tools. And thanks in advance to any who respond for all the help with my specific issue. John

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Newbie needs help w/VC6 & filesystem (take 2)
by John B. Williston 17 Sep '02

17 Sep '02

Greetings, I'm sorry for my earlier post. I didn't realize that the dir_it beta stuff was not what was being referred to as the "filesystem". I now know better, and I'm trying to make the filesystem stuff work instead. Unfortunately, I'm having no better luck. Consider the following code: #include "boost/filesystem/operations.hpp" // includes boost/filesystem/path.hpp #include "boost/filesystem/fstream.hpp" // ditto #include <iostream> // for cout int main(int iArgc, char** pArgv) { namespace fs = boost::filesystem; int iNumNodes = 0; fs::directory_iterator end_itr; // default construction yields past-the-end for (fs::directory_iterator itr("debug"); itr != end_itr; ++itr) { if (fs::is_directory(*itr)) std::cout << (*itr).file_path() << " (dir)" << std::endl; else std::cout << (*itr).file_path() << std::endl; iNumNodes++; } std::cout << iNumNodes << " total." << std::endl; return 0; } That's a relatively brain-dead use, I should think, to enumerate the contents of the debug folder to the console. Unfortunately, when I try compiling this, the linker complains horribly about all kinds of symbols already being defined in the filesystem object modules. To ditch the linker errors, I've temporarily used the /force switch, but that's hardly illuminating. First, can anyone tell me how to avoid getting a plethora of multiply-defined symbol errors? Or is /force my only real option? Second, if I use the /force switch, I get all kinds of unhandled exception errors when the directory iterator is constructing. Changing the string I pass to it at construction just changes which exception it emits. With the code above as written, the culprit is: template<typename Y> void reset(Y * p) // Y must be complete { BOOST_ASSERT(p == 0 || p != px); // catch self-reset errors this_type(p).swap(*this); } That's lines 181-185 of boost/shared_ptr.hpp, and I haven't a clue why it's freaking out. Tracing through all the code shows that the exception is occurring AFTER the swap seems to succeed. I'm stumped as to what the problem might be. But I sure would appreciate any advice y'all can offer. So far I have to say that I'm impressed with the Boost library features, but it seems a cast-iron bitch to make it actually compile and link in any real-world programs. John

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Advantage to STLport w VC7?
by dick.bridges＠tais.com 17 Sep '02

17 Sep '02

I'm preparing an upgrade from VC6 SP5 to VC7. I'm told the VC7 STL was improved but specifics are hard to come by. Can anyone tell me if there's still an advantage, <emphasis> with respect to the Boost libraries</emphasis>, to using STLport with VC7? TIA for any suggestions.

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regex 1.28.0 build (question - and problem report)
by acarsac 17 Sep '02

17 Sep '02

Hi, 2 things while upgrading from 1.25 to 1.28 : -I was trying to build the regex library (1.28.0) with msvc-stlport configuration. vc6.bat set STLPORT_PATH="c:\Mes Documents\STLport-4.5.3" nmake -fvc6-stlport.mak will fail. i had to erase some lines in vc6-stlport.mak because i guess it does not support space in path. i do the install by hand too. unless that, it work fine for me. -I was just wondering why the boost build system (jam) makes the regex library if i need to rebuild them with nmake whereas i specify the good target os for both ? Alex.

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question about edge_property_type
by wei guo 16 Sep '02

16 Sep '02

Hi, group: I have a problem of using edge_property_type. in the example file: undirected.cpp, I added several lines like: template < typename DirectedGraph > void directed_graph_demo() { const int V = 2; DirectedGraph digraph(V); typename graph_traits < DirectedGraph >::vertex_descriptor u, v; typedef typename DirectedGraph::edge_property_type Weight; typename property_map < DirectedGraph, edge_weight_t >::type weight = get(edge_weight, digraph); typename graph_traits < DirectedGraph >::edge_descriptor e1, e2; bool found; ......... Weight w1 = get(weight, e1); // <<----------- added line Weight w2 = get(weight, e2); // put( weight, e1, w1*w2/(w1+w2) ); // <<----------- added line std::cout << "weight[(u,v)] = " << get(weight, e1) << std::endl; std::cout << "weight[(v,u)] = " << get(weight, e2) << std::endl; } I got following compiling errors with KAI compiler: "undirected.cpp", line 83: error: no operator "*" matches these operands operand types are: Weight * Weight put( weight, e1, w1*w2/(w1+w2) ); ^ detected during instantiation of "void directed_graph_demo<DirectedGraph>() [with DirectedGraph=DirectedGraph]" "undirected.cpp", line 83: error: no operator "+" matches these operands operand types are: Weight + Weight put( weight, e1, w1*w2/(w1+w2) ); ^ detected during instantiation of "void directed_graph_demo<DirectedGraph>() [with DirectedGraph=DirectedGraph]" 2 errors detected in the compilation of "undirected.cpp". however, if I change the put statement in the example code to be: put( weight, e1, get(weight, e1)*get(weight, e2)/(get(weight, e1)+get(weight, e2)) ); it compiled successfully. So, what do I missing here, and what is the return type of get(weight, e2) ? and how it connected with DirectedGraph::edge_property_type ? thanks in advance! weiqing --------------------------------- Do you Yahoo!? Yahoo! News - Today's headlines [Non-text portions of this message have been removed]

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