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[BGL] Preconditioned color maps?
by Tarjei Knapstad 05 Mar '03

05 Mar '03

In an algorithm I'm working on I need to do an undirected_dfs using a visitor for analysis. I know my starting vertex, and I also want the DFS to skip one of the starting vertex's adjacent vertices (i.e. don't proceed in the "direction" from the starting vertex). Example: d-e-f / a-b-c \ g-h-i Starting vertex is 'c' and I want to eliminate the "d-e-f" branch, so the DFS finds "c-b-a" and "c-g-h-i". My first idea was to set up a vertex color map, and set the color to black for vertex 'd' in the example above, but that doesn't do much good as the undirected_dfs sets all colors to white initially. My second thought was to feed the vertex I want to eliminate and the vertex color map to my dfs_visitor implementation, something like: discover_vertex(u, g) { if (u == blocked) { vertex_colormap[u] = black; } } Will the latter approach work satisfactory? If not, is there some other way which I can use to precondition the color maps used in the BGL algorithms? Thanks, -- Tarjei

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Re: [Boost-Users] NDEBUG, affects floating point math?
by Stephen Crowley 05 Mar '03

05 Mar '03

On Fri, Feb 28, 2003 at 09:53:56AM +0100, Joerg Walter wrote: > > I wrote a small piece of C code to calculate a symmetric-matrix by > > row-matrix product by directly accessing the memory (which btw is about > > 1000% faster than ublas's generated code with gcc 3.2.3 and -O3, why is > > ublas so slow?) > > If you have *not* defined NDEBUG, ublas uses many internal consistency > checks and usually no expression templates. I was referring to the case when NDEBUG is defined and comparing symmetric_matrix by general_matrix products. uBLAS is quite slow with this operation. However, I compared my symmetric_matrix by general_matrix_transpose product and ublas was only 3-4 times slower than the optimized C, not too bad. > > And when I compile with -DNDEBUG the results differ > > by around +/- 1e-16, but when its not defined the results match almost > > perfectly. > > You've probably hit a bug, may be an old one (please consider to check > against CVS, too). Could you please send or post a small sample, if the > problem persists? I think I know the source of the problem now, and I'm not sure if it's one that boost should handle or not. I attached my test code at the end of this email, only 2.7k, I hope it isn't inappropriate for the list. 387 floating point registers are stored as 80 bits internally and rounded to 64 bits when assigned to memory. SSE2 floating-point registers are stored in the native 64-bit format. The following table lists the compiler flags used and the accumulated absolute difference between the two products over 100 randomly generated matrices. gcc version 3.2.3 20030221 (Debian prerelease) no compiler flags diff sum [5,3]((0,0,0),(0,0,0),(0,0,0),(0,0,0),(0,0,0)) -DNDEBUG diff sum [5,3]((0,0,0),(0,0,0),(0,0,0),(0,0,0),(0,0,0)) -O1 diff sum [5,3]((2.91694e-15,2.65348e-15,2.7027e-15),(4.4049e-15,3.29251e-15,3.44863e-15),(4.10436e-15,4.14816e-15,3.24393e-15),(3.57873e-15,3.75741e-15,2.64068e-15),(5.03091e-15,2.79637e-15,4.06099e-15)) -O1 -DNDEBUG diff sum [5,3]((0,0,0),(0,0,0),(0,0,0),(0,0,0),(0,0,0)) -O2 diff sum [5,3]((4.37584e-15,4.8659e-15,3.61516e-15),(4.61783e-15,3.77736e-15,4.04169e-15),(4.46691e-15,5.10876e-15,5.00576e-15),(3.64118e-15,4.91968e-15,5.17641e-15),(3.97273e-15,4.25528e-15,3.75394e-15)) -O2 -DNDEBUG diff sum [5,3]((0,0,0),(0,0,0),(0,0,0),(0,0,0),(0,0,0)) -O3 diff sum [5,3]((4.96131e-15,3.88968e-15,4.34245e-15),(5.07754e-15,5.91974e-15,4.19109e-15),(4.89539e-15,4.29279e-15,5.06344e-15),(4.79781e-15,4.66033e-15,3.77996e-15),(4.75227e-15,4.72539e-15,3.33414e-15)) -O3 -DNDEBUG diff sum [5,3]((4.60569e-15,2.67928e-15,2.7079e-15),(3.21054e-15,2.98112e-15,2.61249e-15),(3.91701e-15,3.60822e-15,2.93515e-15),(3.23006e-15,3.42434e-15,3.53363e-15),(3.18105e-15,2.77035e-15,3.67198e-15)) -O1 -mfpmath=sse,387 -march=pentium4 -msse2 diff sum [5,3]((0,0,0),(0,0,0),(0,0,0),(0,0,0),(0,0,0)) -O1 -mfpmath=sse,387 -march=pentium4 -msse2 -DNDEBUG diff sum [5,3]((0,0,0),(0,0,0),(0,0,0),(0,0,0),(0,0,0)) -O2 -mfpmath=sse,387 -march=pentium4 -msse2 diff sum [5,3]((0,0,0),(0,0,0),(0,0,0),(0,0,0),(0,0,0)) -O2 -mfpmath=sse,387 -march=pentium4 -msse2 -DNDEBUG diff sum [5,3]((0,0,0),(0,0,0),(0,0,0),(0,0,0),(0,0,0)) -O3 -mfpmath=sse,387 -march=pentium4 -msse2 diff sum [5,3]((0,0,0),(0,0,0),(0,0,0),(0,0,0),(0,0,0)) -O3 -mfpmath=sse,387 -march=pentium4 -msse2 -DNDEBUG diff sum [5,3]((3.62991e-15,3.74006e-15,4.62824e-15),(4.00548e-15,4.5311e-15,3.60129e-15),(3.48332e-15,5.11743e-15,3.08174e-15),(3.49373e-15,4.05752e-15,4.2865e-15),(4.81169e-15,4.51549e-15,4.18589e-15)) Is this perhaps a compiler bug? Part of the problem actually comes from whether the products are accumulated into a register by the compiler, or whether they are accumulated into memory. If accumulated into a 387 register it has higher-precision before it is rounded back down to 64-bits to be stored into memory. If the compiler generates code to accumulate the products directly into memory then the results of each individual product are rounded to 64-bits at every iteration and the result will be slightly less accurate. Now, when the -msse2 flag is used, the registers are 64-bit only and thus no accuracy is gained by using them, only speed. -- Stephen [Non-text portions of this message have been removed]

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GCC 3.2 compiler error using Boost::Threads::Mutex::scoped_lock
by Michael Hunley 05 Mar '03

05 Mar '03

Disclaimer: I am relatively new to gcc, linux and Boost. I'm hoping someone out in the group who is much more knowledgable about all of them can help me get past a hurdle in code I am porting from Windows. I am getting a vague error message from g++ (gcc 3.2-7 under Redhat Linux 8.0) in my code using the Boost scoped_lock. I have wrapped the Boost versions of mutex and mutex::scoped_lock as: class PMutex { public: PMutex() {} virtual ~PMutex() {} protected: boost::mutex m_Mutex; friend class PScopedLock; }; class PScopedLock { public: explicit PScopedLock( PMutex& M ) : m_ScopedLock(M.m_Mutex) {} virtual ~PScopedLock() {} static PScopedLock* Create( PMutex& M ) { return (PScopedLock*) ::new PScopedLock(M); } void Destroy( void ) { delete this; } protected: void* operator new(size_t) {} // disallowed, must declare on the stack boost::mutex::scoped_lock m_ScopedLock; friend class PCondition; }; The error is "ISO C++ forbids declarations of 'type name' with no type". I get that error on several lines, but most notably on a simple declaration like: PScopedLock Lock(MyMutex); From what little I can find on the newsgroups, this sort of error has been noted when use of template template parameters are not declared quite correctly (without the trailing ::template from what I can gather). But as far as I can tell, I should not be having that issue. I am not knowledgeable enough about templates, Boost or gcc/g++ to sort out what I am running into. Boost builds fine under gcc, the code I am porting compiles fine under MSVC6 and Kylix3, but not gcc. Can anyone help me out? thanks. michael

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Has anyone compiled Boost successfully on OS390?
by kant_rakesh <kant_rakesh＠yahoo.com> 05 Mar '03

05 Mar '03

Hi, I am trying to get boost compiled on OS390. Has anyone done it successfully so far? The compiler on OS390(version2 release10) is complaining of empty template parameter. It does not like 'template <>', which is being used frequently in the library. Any ideas about how to successfully build this on OS390? Thanks and Regards Rakesh Kant

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boost-users@lists.boost.org ?
by speedsnaii <speedsnaii＠yahoo.de> 04 Mar '03

04 Mar '03

I tried to subscribe to the list boost-users(a)lists.boost.org I was thinking that this is just an alias list of this one. But it seems not to be true, is it? I would prefer to use the mail interface. Can anyone enligthen me if this is possible, please? Thank you, roland

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uBLAS: reference to container data & iterator declaration
by Roland Schwarz 04 Mar '03

04 Mar '03

Hi, *) First question: I am trying to get a reference to data of a container in the following way: matrix<double> m(3,3); vector<double>& v(m.column(2)); But this seems not to be possible. Is there a way to achieve this behaviour? What I basically want to achive is having functor object that holds a reference to a row/column of my container matrix. >From my questions about argument types I know that m.column(2) is a kind of an expression. How can I get the underlying reference to data if there even is one? *) Second question: matrix<double> m(10,3); ... fill the matrix ... matrix<double>::iterator it; // wrong this does not work!! for (it = m.column(2).begin(); it != m.colum(2).end(); ++it) { cout << *it << " " << foo(*it) << endl; } How would I declare my iterator? I understand when I use std::library-algorithms the automatic template parameter defer will give me the correct type from begin(). But in my case how should I declare the iterator? Thank you for help. Roland

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multivoque application algorithms
by Alexandre Carsac 03 Mar '03

03 Mar '03

I applologize, perhaps this is the wrong place, Just wondering if the boost Graph library can be used for multivoque application. ------------------------------------------------------------------------------------------- let be : E = {x0, x1, ...,xp} F = {y0, y1, ...,yq} G': y -> {xa.....xm} and card G'(y) = constant = m G : x -> {ya.....yn} and card G(x) < M for all x belongs to E G' is the reverse application of G. G is irregular. h : x -> h(x) whose values are in [0,1] The problem is to find the y0 so that G'(y0) maximise h(xa), ...,h(xm). (assume that h(xi) near of 1 for all xi in G'(y0) ) One simple approch would be to calculate h(x) for all x associated to all y and keep the maximum, but this lead to too much calculations. ------------------------------------------------------------------------------------------------- I try to organized E into a binary tree. The idee is to shrink E so that each schink step truncate the search space. lets take x0 so that card G(x0) be maximum. We have the composed application of G with its reverse one G': G o G' (x0) = {xaa....xpa, xab,...xpb, xpa,....xpn} means that x0 is tied to some other x's in E by G. if h(x0) is the not near 1, then the y we are looking for will have fewer chance to belongs to G'(x0), so it is not worth to look at all the h(xaa), ...h(xpn). This would create a bi-partion on E and so on. --------------------------------- Do You Yahoo!? -- Une adresse @yahoo.fr gratuite et en français ! Testez le nouveau Yahoo! Mail [Non-text portions of this message have been removed]

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Re: [Boost-Users] stop a thread
by William E. Kempf 03 Mar '03

03 Mar '03

> From: "hlh771 <hlh771(a)yahoo.com.cn>" <hlh771(a)yahoo.com.cn> > > How to stop(or cancel) a thread? Suppose I have a main thread and a > worker thread, the worker thread does something looply,and when the > main thread get a message indicating the process should exit, I want > stop the worker thread,how to do that?I have read other thread > library,their thread class supply a method called stop or cancel > which stops the thread. Their Implementation is:the thread class has > a data member indicating whether the thread should stop,and the > thread function looply check the data member whether the thread > should stop.Generally the data member's type is a bool or Event. > Is it the best way to stop the thread? How the boost to deal with > this? > Thanks in advance. Today you should use a flag and a condition/mutex combination. Direct support for cancellation is being provided in a future release. William E. Kempf wekempf(a)cox.net

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Exporting references into boost::python
by Nicholas Francis 02 Mar '03

02 Mar '03

A newbie question regarding boost::python. I need to make a templatized function that returns a boost::python::object containing a reference to an object I already have. Basically: template<class T> object convertToPython (T &obj) { return object (obj) } All classes I pass through T are already wrapped (they are also not copy-constructible). I tried with the code found at python.orgs wiki: template<class T> T& identity(T& x) { return x; } template<class T> object get_object_reference (T& x) { object f = make_function (&identity<T>, return_value_policy<reference_existing_object()); return f(x); } this code gave me a compile error (on CW 8.3, Mac OS X). Apparently CW is convinced that the &identity<T> maps to void. I then tried to hardcode a type just to see if it worked at all: InputManager &identity (InputManager &x) { return x; } object get_object_reference (InputManager &x) { object f = make_function ( &identity, return_value_policy<reference_existing_object()); return f(x); } This compiled, but gave me a typeerror at runtime: (No to_python (by-value) converter found for c++ type: InputManager) I've seccesfully wrapped functions like this: InputManager &GetInputManager(); BOOST_PYTHON_MODULE (Engine) { def ( "GetInputManager", &GetInputManager, return_value_policy<reference_existing_object() ); } So it should be able to work. Any help would be greatly appreciated.... TIA, Nicholas

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VC7 says 'fatal C1067' compiling multi_array?
by Clift Norris 01 Mar '03

01 Mar '03

Greetings: I'm using VC7 and boost_1_29_0 to compile this code that is using multi_array.hpp. typedef boost::multi_array<double, 4> theta4_t; typedef theta4_t::index index; theta4_t Theta_Trun( boost::extents[10000][2][10][256] ); I'm receiving this error: "fatal error C1067: compiler limit: debug information module size exceeded" Of course, the code compiles fine using the "Release" configuration, but I need the "Debug" one also. Is there a workaround for this, other than the 'make your variables shorter' suggested in the VC7 documentation? Thanks, -Clift

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are namespaces of boost libs required to be lowercase?
by Markus Werle 28 Feb '03

28 Feb '03

Hi! If someone wants to contribute code to boost: Is she required to provide the names of all namespaces lowercase? E.g. someone provides Elefant, the big library. Is she allowed to have namespace Elefant and perhaps namespace Elefant::Private, etc. I could not find any hint except this here, which did not really help me, since I do not know the standard library's conventions. Any link/ hint appreciated: -- citation from the boost docs -- "Naming conventions rationale The C++ standard committee's Library Working Group discussed this issue in detail, and over a long period of time. The discussion was repeated again in early boost postings. A short summary: Naming conventions are contentious, and although several are widely used, no one style predominates. Given the intent to propose portions of boost for the next revision of the C++ standard library, boost decided to follow the standard library's conventions." best regards, Markus

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poisson_distribution header file
by kgolod0641 <kgolod＠engmail.uwaterloo.ca> 28 Feb '03

28 Feb '03

Hi, I am using boost_1_29_0 to implement random distribution functions. The standard download included implementation of uniform, normal and exponential distributions - and they work great. I also need an implementation of poisson distribution, and I have noticed that poisson_distribution.hpp was added to CVS last October. I got the file, and put it into the boost/random/ directory, with the other random distribution files. However, when I try using poisson distribution, I get a series of 0's instead of a series of random numbers, although I'm using it exactly the same way as with the other distributions. I am not sure whether the problem is due to incorrect installation of the new file, or due to bugs in the implementation. I tried cleaning the boost_1_29_0 directory, and running bjam again, but still no luck. Is there anything else I should do to include this new header file? Any help would be greatly appreciated. Thank you, Ksenia

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NDEBUG, affects floating point math?
by Stephen Crowley 28 Feb '03

28 Feb '03

I'm getting some seriously strange problems with regard to numerical accuracy when computing matrix products that depends on whether or not NDEBUG is defined when I compile. I wrote a small piece of C code to calculate a symmetric-matrix by row-matrix product by directly accessing the memory (which btw is about 1000% faster than ublas's generated code with gcc 3.2.3 and -O3, why is ublas so slow?) And when I compile with -DNDEBUG the results differ by around +/- 1e-16, but when its not defined the results match almost perfectly. Is there something strange going on with regard to FPU control words or types or anything? I'm using type double btw. If more info is needed I can post a test case, but I thought it'd make a quick inquery to see if there is a fast answer. -- Stephen -------- This message was scanned for viruses by Digital Passage.

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Re: [Boost-Users] Problem with time_period
by Jeff Garland 28 Feb '03

28 Feb '03

Alex wrote: >... start omitted ... >time_period p(ptime(date(2003, 03, 25)), ptime(date(2003, 04, >25))); >date_duration duration(days(1)); >p.shift(duration); >---------------------------------------------------- I'm not sure where 'days' is coming from -- its not a class in the library. Based on the compiler error it looks like the issue is using date_duration intead of time duration with the time_period. So instead you could do something like: hours duration(24); Or if you really want a class called days you can do something like: class days : public boost::posix_time::time_duration { public: days(int day_count) : boost::posix_time::time_duration(day_count*24) {} }; HTH. And, BTW in the upcoming 1.30 release you will be able to get rid of all the DATE_TIME_INLINE stuff... Jeff

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mpl::if_ or mpl::apply_if?
by Markus Werle 27 Feb '03

27 Feb '03

Hi! I am trying to migrate some parts of my code from loki to boost::mpl. Q1: which is the best way to perform nested if-then-else? Assume given "values": bool B1, bool B2; class ff, class tf, class ft, class tt; I replaced ----------------------------------------------------------- typedef typename Loki::Select<B1, typename Loki::Select<B2, tt, tf>::Result, typename Loki::Select<B2, ft, ff>::Result >::Result type; ----------------------------------------------------------- with typedef typename apply_if < bool_c<B1>, apply_if < bool_c<B2>, identity<tt>, identity<tf> >, apply_if < bool_c<B2>, identity<ft>, identity<ff> > >::type type; Q2: Is apply_if always to be preferred over if_? Q3: (OT) Is there a mpl-equivalent to run-time case? best regards, Markus

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Re: [Boost-Users] Re: are namespaces of boost libs required to be lowercase?
by Beman Dawes 27 Feb '03

27 Feb '03

At 11:37 AM 2/27/2003, William E. Kempf wrote: > >Markus Werle said: >> A hard burden You lay on developers. > >It's not a burden. > >> So maybe the code has to be piped through a >> code de-beautifier when it comes to a boostification. > >That's a bit harsh. If *you* don't care for the style, you're welcome to >that opinion, but voicing it in this manner isn't going to help anyone to >agree with you. > >> IMHO (UsingThisConventionHere == CommonPracticeElsewhere) > >It's not common practice everywhere (I know of as many places that follow >the C++ standard naming conventions as those that follow what I'll call >"Java" naming conventions). But the important thing is that the whole >point of Boost is to be a test bed and development area for libraries that >*might* be considered for inclusion in the standard. As such, we have to >follow the standard naming conventions. Exactly. And it isn't just a theoretical "*might* be considered for inclusion in the standard". A bunch of the Boost libraries *are* under consideration by the Standards Committee right now, and more will be in the future. For a library to be considered seriously for standardization, it helps a great deal if every aspect, including names, has been subject to prior use. That flushes out issues that otherwise would be hidden. So there is little chance Boost will change naming conventions. I suppose we might accept a library which used a different set of conventions if there was some special rationale. But I can't imagine what that rationale would be. It certainly would not be just that a developer prefers another convention. --Beman

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boost 1.29.0: shared_from_this with const argument
by Michael Brinkmann 27 Feb '03

27 Feb '03

Hi, In my opinion, the call "shared_from_this(T* p)" in the file "boost/shared_ptr.hpp" is meant to be "shared_from_this(T const* p)" Am I right? kind regards Michael

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UBLAS: advice on argument types please
by speedsnaii <speedsnaii＠yahoo.de> 27 Feb '03

27 Feb '03

I am trying to find a good choice for argument types to a function. (Please be patient, I am a poor user of C++ who has not yet understood all this expression template magic.) I'd like to have a function: void foo( whattype arg) { } matrix<double> m(3,3); vector<double> v(6); and call it like: foo(m.column(0)); foo(m.row(0)); foo(v); Is this feasible? Should I use iterators for whattype? (how do I access size information then?) Am I trying to misuse the ublas when asking such a question? (Which container should I use in this case?) In the hope anyone can shade some light on it. Thank you, Roland

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Building with Sun Workshop 6
by markrday <markrday＠yahoo.com> 27 Feb '03

27 Feb '03

I've searched the archives, and haven't found a report of successfully building Boost using the Sun Workshop compiler, though some messages imply that people are using at least some of the libraries with Workshop. Although I realize we could build the libraries with gcc, we have quite a few projects set up in the workshop environment, and I'd like to have the option to use Boost libraries with them. Obviously nobody has built an appropriate toolset. In my naive attempts to create a toolset definiton, and in trying to create a static library from components like Date-Time library, I get error messages like: add_const.hpp, line 34: Warning: Too few arguments in macro BOOST_PP_CHECK_2. There are also errors involving BOOST_PP_LIST_FOR_EACH_I_M (among others). Can anyone offer me hints on how to get started in resolving these? Ultimately I'd like to have the whole suite compiled, but for the time being I'd be happy just using Date-Time. I'm willing to build a toolset file for this compiler, but I don't seem to have the expertise. If there's anyone that is able to provide guidance, I can put some time into this, and submit a toolset definition file so others can use Boost with this compiler.

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Problem with time_period
by Alejandro Escalante Medina <alejandro_escalante_medina＠yahoo.com.mx> 27 Feb '03

27 Feb '03

The following simple code doesn't compile: ---------------------------------------------- #define DATE_TIME_INLINE #include <boost/date_time/gregorian/gregorian.hpp> #include <boost/date_time/posix_time/posix_time.hpp> using namespace boost; using namespace boost::posix_time; using namespace boost::gregorian; ... time_period p(ptime(date(2003, 03, 25)), ptime(date(2003, 04, 25))); date_duration duration(days(1)); p.shift(duration); ---------------------------------------------------- the compiler (VC++ 7.0) gives the following: error C2664: 'boost::date_time::period<class boost::posix_time::ptime,class boost::posix_time::time_duration>::shift' : cannot convert parameter 1 from 'boost::gregorian::date_duration' to 'const boost::posix_time::time_duration &' Reason: cannot convert from 'boost::gregorian::date_duration' to 'const boost::posix_time::time_duration' No constructor could take the source type, or constructor overload resolution was ambiguous I think this should work out of the box, since I've been doing lots of other things with date_time and they work fine. Any ideas? Thanks in advance, Alex

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uBLAS - Matrix Inversion
by Thomas Reisinger 25 Feb '03

25 Feb '03

Dear Newsgroup, I'm new in the field of numeric computing and I would like to learn more about it. To solve my problem I need to invert a matix and use the intermediate result as the input for following calculations. I browsed the uBLAS library and played a little bit with it but I didn't find a routine for matrix inversion. Is there any possibility to preform it in a single step? Is this package the wrong tool for doing this and I should use LAPACK++ or similar stuff? Thanks in advance, Thomas -- Thomas Reisinger Braunschweig Germany mailto:t.reisinger@tu-bs.de

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date_time problems
by Eric Crampton 25 Feb '03

25 Feb '03

I'm trying to test the date_time functionality of boost and am having some difficulties. I would like to simply get the current local time into a ptime and write it out as an ISO-8601 string. Using Boost 1.29 and g++ 3.2, when I compile the following code I get a number of *linker* errors. Code: #include <boost/date_time/posix_time/posix_time_types.hpp> #include <boost/date_time/posix_time/time_formatters.hpp> int main() { boost::posix_time::ptime pt = boost::posix_time::second_clock::local_time(); std::cout << boost::posix_time::to_iso_extended_string(pt) << std::endl; } That code seems pretty straightforward to me. The linker errors look like the following: test.cpp:7: undefined reference to `boost::date_time::gregorian_calendar_base<boost::date_time::year_month_day_base<boost::gregorian::greg_year, boost::gregorian::greg_month, boost::gregorian::greg_day>, unsigned long>::day_number(boost::date_time::year_month_day_base<boost::gregorian::greg_year, boost::gregorian::greg_month, boost::gregorian::greg_day> const&)' test.cpp:6: undefined reference to `boost::date_time::gregorian_calendar_base<boost::date_time::year_month_day_base<boost::gregorian::greg_year, boost::gregorian::greg_month, boost::gregorian::greg_day>, unsigned long>::from_day_number(unsigned long)' (snipped...) Best as I can tell (cd $BOOST_ROOT/boost/date_time && find . -name '*.cpp' -print), there are no .cpp files to be compiled... Anyone know what's up? --Eric _________________________________________________________________ Protect your PC - get McAfee.com VirusScan Online http://clinic.mcafee.com/clinic/ibuy/campaign.asp?cid=3963

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Please help! Problem with histogram.cpp needed for project.
by agiatojon <JonAgiato＠nyc.rr.com> 25 Feb '03

25 Feb '03

Hello all, I have been unable to successfully compile histogram.cpp in the random library folder, version 1_29_0, using Visual Studio.NET. I obtain the following errors: c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(49): warning C4267: 'argument' : conversion from 'size_t' to 'std::streamsize', possible loss of data c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(101): error C2065: 'gen' : undeclared identifier c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type It appears to me that all of these messages will go away when the second one, c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base', is corrected. Any assistance is greatly appreciated! Thank you. Jon Agiato JonAgiato(a)nyc.rr.com

1 0

Is implicit casting with boost::any possible?
by Matthew Dempsky 25 Feb '03

25 Feb '03

I'm curious if there's any way to get code like the following to work: boost::any a = char(10); int i = boost::any_cast<int>(a); More specifically, what I mean is, I'd like to be able to place a value of type T1 in 'a' and then retrieve it as type T2 which it can be implicitly cast to. Is this possible without the part that extracts the value from 'a' adding a lot of extra code to test all possibilities? What I would like to do is fill a map<string, any> with function pointers/objects/etc. and pass it to a function which casts the any values to slot types to connect to different signals whose type is determined at runtime. Basically something like this (but with MySig an unknown type until runtime). int func(char c, int i = 10); boost::any a = &func; typedef boost::signal<void (char)> MySig; MySig sig; sig.connect(boost::any_cast<MySig::slot_type>(a)); sig('j'); -jivera

2 1

C++ object from PyObject pointer
by mghiggins <mghiggins＠yahoo.com> 24 Feb '03

24 Feb '03

Excuse my newbiness if this question is too dumb... :) I've built a python extension from a C++ class using boost - it all seems to work fine. However, now another C++ function is receiving a pointer to a PyObject that represents an instance of this "boosted" python class. How do I pick off a pointer to the underlying C++ object from the PyObject pointer?

2 1

Re: [Boost-Users] lexical_cast bug.
by Terje Slettebø 23 Feb '03

23 Feb '03

>From: "Eduardo Chao" <efchao(a)hotmail.com> > I am a new suscriber to the list. > I want to report what I consider a bug in lexical_cast conversion template. > First, I wanted to use it to convert things to std::string (Target). > It throws a bad_lexical_cast_exception when I pass an empty std::string object (one > that is default-constructed or constructed with "") as the Source argument. > It throws it because the condition (interpreter >> result ) evaluates to > false. Yes, this is a bug in the current version, see (http://www.boost.org/libs/conversion/lexical_cast.htm#future) There's a proposition which fixes this and other problems here (http://groups.yahoo.com/group/boost/files/lexical_cast_proposition/lexical_ cast_proposition.zip). It's scheduled to be reviewed by the author, Kevlin Henney, or Björn Karlsson (Boost's maintenance wizard), before Boost release 1.30. If they find it ok, a notice will also be posted at the Boost list, so that others may give feedback before the release, as well. > My solution was to specialize the function template this way: > > template<> lexical_cast<std::string>(const std::string &str) > { > return str; > } The proposition handles it in a similar way. However, it's not possible to partially specialise function templates (e.g. to handle all T -> std::basic_string conversions), so function template overloading is used, instead. This is because it needs to handle conversion from any type to std::basic_string, as there may be other types which output empty strings or whitespace, as well. > but it is not so general to support const std::string or const std::string& > as Target type or perhaps std::string or const std::string etc as Source. > Correct me if I am wrong, so I learn from you more experienced Boost (and then C++) users. No, you're right. However, it's only necessary to handle T -> std::basic_string (not cv-qualification or reference) in this case, because: lexical_cast<std::string>(...); // Ok lexical_cast<const std::string>(...); // Error, can't write to a const string lexical_cast<const std::string &>(...); // Error, can't return a reference to the result (it would then return a dangling reference, as the result would be a temporary) lexical_cast<std::string>(const_cast<const std::string>(...)); // Ok, top-level cv-qualifiers are ignored when matching the call Regards, Terje

1 0

random/histogram.cpp
by agiatojon <JonAgiato＠nyc.rr.com> 23 Feb '03

23 Feb '03

Hello all, I have been unable to successfully compile histogram.cpp in the random library folder, version 1_29_0, using Visual Studio.NET. I obtain the following errors: c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(49): warning C4267: 'argument' : conversion from 'size_t' to 'std::streamsize', possible loss of data c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(101): error C2065: 'gen' : undeclared identifier c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2066: cast to function type is illegal c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2059: syntax error : ')' c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.base' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(111): error C2228: left of '.sum' must have class/struct/union type c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(113): error C2228: left of '.squaresum' must have class/struct/union type It appears to me that all of these messages will go away when the second one, c:\Documents and Settings\Agiato\My Documents\Visual Studio Projects\histogramTest\driver.cpp(97): error C2061: syntax error : identifier 'base', is corrected. Any assistance is greatly apprechiated! Thank you. Jon Agiato JonAgiato(a)nyc.rr.com

1 0

[BGL] Using external edge properties
by yg-boost-users＠m.gmane.org 22 Feb '03

22 Feb '03

I have a graph which might change during it's lifetime. I want to attach external properties to this graph. Now, it seems like that in order to be able to attach external properties, I need to have an internal property with edge indices, ie that enumerates the edges. These indices need to be continuous as I gather, since they are used to index for instance a vector of num_edges() elements. Does this mean that I have to re-enumerate all edges if I remove one? This seems to me very cumbersome and also time consuming if the graph is large and changes a lot. Is there another way? Björn Lindberg

2 2

bug in shared_ptr
by Simone Finotti 22 Feb '03

22 Feb '03

hi all, I don't know if this is the right place to report bug, if it's not please forgive me. I was trying to use boost/shared_ptr.hpp class, so I defined BOOST_NO_EXCEPTIONS because my compiler doesn't support C++ exceptions, but I receive this error: ..\..\boost_1_29_0\boost/detail/shared_count.hpp(122) : error C2039: 'use_count_is_zero' : is not a member of 'boost' ..\..\boost_1_29_0\boost/detail/shared_count.hpp(122) : error C2065: 'use_count_is_zero' : undeclared identifier in detail, here's an excerpt from shared_count.hpp, where the compiler gives the error: void add_ref() { #ifdef BOOST_HAS_THREADS mutex_type::scoped_lock lock(mtx_); #endif if(use_count_ == 0 && weak_count_ != 0) boost::throw_exception(boost::use_count_is_zero()); ++use_count_; ++weak_count_; } use_count_is_zero is not defined because it's defined, in the same file, as: #ifndef BOOST_NO_EXCEPTIONS class use_count_is_zero: public std::exception { public: virtual char const * what() const throw() { return "boost::use_count_is_zero"; } }; #endif is there a way to make it work? -- Simone

2 1

Can one "nest" regular expressions ?
by yg-boost-users＠m.gmane.org 22 Feb '03

22 Feb '03

Hello folks, I believe my question applies to regular expression libraries generally and not just to regexp++. I want to know if it is possible to refer to or use one regular expression within another. What I wish to do is parse a string of html code for img tags, and if they have the clause ALT="whatever" replace the whole image tag with 'whatever'. So I decided to make regular expression for an image tag which had an ALT part, and have a sub-match on the contents of quoted part of the ALT. (I broke this up a bit, explaining what each part is for . . .) This will match img tags: static const boost::regex find_imgs(" <\\s*img Matches <, 0 or many whitespace, IMG \\s+src\\s* Matches 1 or more whitespace, SRC, 0 or many whitespace =\\s* Matches = followed by 0 or more whitespace \"\\s* Matches " followed by 0 or more whitespace ([^\"]*) Matches any number of characters that are not " ([^>]*>) Matches any number of chars that not >, followed by a > ", boost::regbase::normal | boost::regbase::icase); Ok, so now look at this one. I'm trying to do the same as above except I want to sub-match the quoted part of the alt part so I can use it. I can't do "anything except the word 'alt'" because it will interpret the [^(alt)] as "anything except 'a', 'l', or 't'". static const boost::regex find_imgs_with_alt(" <\\s*img Matches <, 0 or many whitespace, IMG \\s+src\\s* Matches 1 or more whitespace, SRC, 0 or many whitespace =\\s* Matches = followed by 0 or more whitespace \"\\s* Matches " followed by 0 or more whitespace [^\"]* Matches any number of chars not " \\s+ Matches 1 or more whitespace [^alt]* I would like match anything except the word ALT, but the regexp stuff interprets this as anything but 'a', 'l', or 't' alt\\s*= Matches ALT, 0 or whitespace, = \"(^\")\" Matches ", anything except a " as a group that I can reference, then another " [^>]*> Matches any number of chars not >, followed by a > ", boost::regbase::normal | boost::regbase::icase); So what I want to do is make another regular expression which matches "alt", and in the part that says [^alt]* do instead something like [^@alt]* where '@' would indicate that 'alt' was the name of another regular expression, such as static const boost::regex alt("alt", boost::regbase::normal | boost::regbase::icase); I can see how to do what I want to do without this; I would get the whole IMG tag and do a separate regexp_search on the match. But it seems to make it so much easier if it were possible, especially leaving me with fewer lines of regular expression code to have bugs in. If this is possible I'd like to know. Thanks in advance, and I'll post the regular expressions I end up using here if anyone might find them of use. --Rob

4 9

lexical_cast bug.
by Eduardo Chao 22 Feb '03

22 Feb '03

Hello, I am a new suscriber to the list. I want to report what I consider a bug in lexical_cast conversion template. First, I wanted to use it to convert things to std::string (Target). It throws a bad_lexical_cast_exception when I pass an empty std::string object (one that is default-constructed or constructed with "") as the Source argument. It throws it because the condition (interpreter >> result ) evaluates to false. My solution was to specialize the function template this way: template<> lexical_cast<std::string>(const std::string &str) { return str; } but it is not so general to support const std::string or const std::string& as Target type or perhaps std::string or const std::string etc as Source. Correct me if I am wrong, so I learn from you more experienced Boost (and then C++) users. That's all for now. Thanks in advance. Eduardo Chao. [Non-text portions of this message have been removed]

1 0

Testing Boost:threads on windows w/ cygwin/gcc help
by sam <samijackson＠yahoo.com> 21 Feb '03

21 Feb '03

Howdy, I have cygwin running on a WinXP box and am trying to get the threads up and running. I built the Boost.Threads and things look good. Then I try: "bjam -sTOOLS=gcc test" from the /lib/thread/test directory and the test fails with: <build> ...found 1203 targets... ...using 1 temp target... ...updating 181 targets... ...using <libs!thread!test/test_thread.test/gcc/debug/runtime-link-static/threa ding-multi>test_thread.run... succeeded-test-file ../../../libs/thread/test/bin/test_thread.test/gcc/debug/runtime-link- static/threading-multi/test_thread.test Syntax error: "fi" unexpected (expecting "then") <chomp/> echo "*" echo "***************** failed above test: test_thread ********************" echo "*" </build> My question is, how do I correctly get Boost to use either native or pthreads and pass the tests above? I've checked the FAQs, Googled and all that, but can't seem to find an answer. I'm sure it's easy, but can't get it right. thanks Sam

3 5

boost::mutex, Borland C++Bulder 6 and CodeGuard
by Russell Hind 21 Feb '03

21 Feb '03

I have been running into CodeGuard problems using boost 1.29.0 with BorlandC++Builder 6Pro update 2 and CodeGuard. The test project is a console app, multi-threading but no vcl (don't know if the VCL enabled affects it or not). The code is #include <boost/thread/mutex.hpp> int main(int argc, char* argv[]) { boost::mutex m; return 0; } I get a resource type mismatch on exit which is down to the mutes. I have linked directly with the source and found where the problem lies. It could be down to 2 places: a) boost allocates the mutex (mutex.cpp line 39) using the nowthrow operator new m_mutex = reinterpret_cast<void*>(new(std::nothrow) CRITICAL_SECTION); and then deletes it using the standard delete (mutex.cpp line 48) delete reinterpret_cast<LPCRITICAL_SECTION>(m_mutex); This causes slight problems as codeguard treats allocations from new and malloc differently to check you free the memory correctly. nothrow new uses malloc, so a standard delete is the incorrect way to free the mutex here from CodeGuards point of view. I have changed the delete to operator delete (reinterpret_cast<LPCRITICAL_SECTION>(m_mutex), std::nothrow); which calls the nothrow version of delete. Unfortunately, the next part of the problem: b) For some reason, the mutex is using the roguewave stl new.h which defines the nothrow operators as such (oldstl\new.h line 143) inline void * _RTLENTRY operator new (size_t size, const std::nothrow_t &nt) { size = size ? size : 1; return malloc(size); } (oldstl\new.h line 152) inline void _RTLENTRY operator delete (void *v, const std::nothrow_t &nt) { ::operator delete (v); // The standard operator doesn't throw any exceptions } Here, there is a conflict in the allocation and deallocation. changing line 154 to free(v); along with the change to mutex to use the nothrow version of delete fixes it so codeguard can be used. Looking in the stlport new, it forces us to use RogueWave's new because of these lines in stlport\new line 49 # if !defined (_STLP_NO_NEW_NEW_HEADER) # include _STLP_NATIVE_CPP_RUNTIME_HEADER(new) # else # include <new.h> # endif which makes it include roguewaves version of new. So C++Builder 6 is still reliant on roguewave stl even when set to use STLPort. Possible solutions are a) Make boost::thread use nothrow version of delete but this requires a fix in the borland/rogue wave header for the delete to make it use free. or b) mutex could use malloc and free directly for borland. Which would people prefer or can anyone think of another solution? Cheers Russell

2 1

Boost::Threads condition variable on Win32 and IO completion routines
by Russell Hind 21 Feb '03

21 Feb '03

The start of the do_wait() method of a boost::condition (in 1.29.0) for Win32 looks like this void condition::do_wait() { int res = 0; res = WaitForSingleObject(reinterpret_cast<HANDLE>(m_queue), INFINITE); assert(res == WAIT_OBJECT_0); This waits indefinitely until m_queue is signalled. Would it be safe to change this so the thread is alertable for IO completion routines? Something like int res = 0; while ((res = WaitForSingleObjectEx(reinterpret_cast<HANDLE>(m_queue), INFINITE, true)) == WAIT_IO_COMPLETION) { } assert (res == WAIT_OBJECT_0); We make fairly heavy use of Waitable Timers in our statemachines. The completion routine for a timer is called back in the context of the thread that started it, when the thread is alertable. WaitForSingleObject doesn't allow the thread to be alertable. We currently use this in our own thread (with Windows events) but are looking to update the message queue code and thread code to use boost. With out this change, it would currently break a lot of code if we were to use condition variables. Thanks Russell

3 2

Regex++
by Yutaka Emura 21 Feb '03

21 Feb '03

Hi John "(?!foo)bar" matches "bar" in the last three lines of the following: foobar ??bar barfoo bar?? bar Why doesn't it match "bar" in all the lines? Yutaka Emura --------------- > I am using RegEx in Boost v1.29.0. > (?= ) and (?! ) expressions do not seem to work at a certain > condition. > > In the following example, "(?=a)b" should match "b" in "xyzabcdefg", > but does not. Which is correct: (?=a) is a forward lookahead *possitive* assertion, so (?=a)b can never match anything since the next character can't be both an 'a' and a 'b' at the same time! > Similarly, "(?!a)b" should not match "b" in "xyzabcdefg" but it does. It should match: (?!a) will match anything except 'a' so (?!a)b will match the next 'b' that it finds.

2 2

UBLAS: postincrement broken on VC60 ?
by speedsnaii <speedsnaii＠yahoo.de> 21 Feb '03

21 Feb '03

When I specify the following: matrix<double>::iterator1 it; it++; I get: (sorry for the paste of the complete error, I can't figure out what is really relevant; ++it works however) ============================================================ c:\program files\boost\boost\numeric\ublas\iterator.hpp(324) : error C2059: syntax error : 'static_cast' S:\test\ublas\ublas.cpp(30) : see reference to function template instantiation 'class boost::numeric::ublas::matrix<double,struct boost::numeric::ublas::row_major,class boost::numeric::ublas::unbounded_array<double> >::iterator1 __cdecl boos t::numeric::ublas::operator ++(struct boost::numeric::ublas::random_access_iterator_base<struct boost::numeric::ublas::dense_random_access_iterator_tag,class boost::numeric::ublas::matrix<double,struct boost::numeric::ublas::row_major,class boost::n umeric::ublas::unbounded_array<double> >::iterator1,double,int> &,int)' being compiled c:\program files\boost\boost\numeric\ublas\iterator.hpp(325) : error C2664: '__thiscall boost::numeric::ublas::matrix<double,struct boost::numeric::ublas::row_major,class boost::numeric::ublas::unbounded_array<double> >::iterator1::boost::numeric::u blas::matrix<double,struct boost::numeric::ublas::row_major,class boost::numeric::ublas::unbounded_array<double> >::iterator1(const class boost::numeric::ublas::matrix<double,struct boost::numeric::ublas::row_major,class boost::numeric::ublas::unbou nded_array<double> >::iterator1 &)' : cannot convert parameter 1 from 'class boost::numeric::ublas::matrix<double,struct boost::numeric::ublas::row_major,class boost::numeric::ublas::unbounded_array<double> >::iterator1 &(void)' to 'const class boos t::numeric::ublas::matrix<double,struct boost::numeric::ublas::row_major,class boost::numeric::ublas::unbounded_array<double> >::iterator1 &' Context does not allow for disambiguation of overloaded function S:\test\ublas\ublas.cpp(30) : see reference to function template instantiation 'class boost::numeric::ublas::matrix<double,struct boost::numeric::ublas::row_major,class boost::numeric::ublas::unbounded_array<double> >::iterator1 __cdecl boos t::numeric::ublas::operator ++(struct boost::numeric::ublas::random_access_iterator_base<struct boost::numeric::ublas::dense_random_access_iterator_tag,class boost::numeric::ublas::matrix<double,struct boost::numeric::ublas::row_major,class boost::n umeric::ublas::unbounded_array<double> >::iterator1,double,int> &,int)' being compiled c:\program files\boost\boost\numeric\ublas\iterator.hpp(326) : error C2563: mismatch in formal parameter list S:\test\ublas\ublas.cpp(30) : see reference to function template instantiation 'class boost::numeric::ublas::matrix<double,struct boost::numeric::ublas::row_major,class boost::numeric::ublas::unbounded_array<double> >::iterator1 __cdecl boos t::numeric::ublas::operator ++(struct boost::numeric::ublas::random_access_iterator_base<struct boost::numeric::ublas::dense_random_access_iterator_tag,class boost::numeric::ublas::matrix<double,struct boost::numeric::ublas::row_major,class boost::n umeric::ublas::unbounded_array<double> >::iterator1,double,int> &,int)' being compiled Error executing cl.exe. ============================================================

2 2

Crash with regex, setlocale() return 0 on CW
by msternerkthse <msterner＠kth.se> 20 Feb '03

20 Feb '03

The following code on line 841 of c_regex_traits.cpp in the regex library caused a crash when I used it in CodeWarrior 8.1 under OSX: std::string l(std::setlocale(LC_CTYPE, 0)); Afaict the crash was caused by setlocale() returning 0. To fix this I had to resort to the following ugly hack: namespace std { const char* mysetlocale(int, const char*) { return "C"; } }; #include "boost/regex.hpp" #define setlocale mysetlocale #include "boost/regex/src.cpp" The C locale was used because I had BOOST_REGEX_USE_C_LOCALE defined. I didn't want to use the C++ locale since it doesn't even provide the basic 0x00-0xFF unicode case mapping that's built into the C locale (due to limited locale support in CW I guess). I'm using the wregex class. Mikael Sterner

3 2

UBLAS: copy on write for matrix & vector?
by speedsnaii <speedsnaii＠yahoo.de> 19 Feb '03

19 Feb '03

A question on use of the matrix and vector classes: Should I: matrix<double> foo(const matrix<double> a) { matrix >double> r; ... return r; } or void foo(matrix<double>& r, const matrix<double> a) { ... } In other words: is it expensive to construct the temporary in case one? As I understand, the class would need an underlying 'copy on write' to be cheap, similar as strings do. I tried, to answer this question from the documentation, but sorry I did not get through. Thank you for help. Roland

4 8

Using boost::test without library-supplied main? (newbie)
by Hannu Helminen 18 Feb '03

18 Feb '03

Hi All! Can the boost::test used without the library-provided main()? Rationale: - the application does not have main() but WinMain() - it is built on top of MFC so even the WinMain() is already supplied by the framework - I would like to control the execution of unit tests myself, e.g. include a menu item "Run unit tests now" Can anyone help me? Hannu Helminen Finland

2 1

How to connect arbitrary memeber function in boost::signals?
by yjwang_bj <yjwang_bj＠yahoo.com> 18 Feb '03

18 Feb '03

Hi, all. I'm working in a project that need loosely coupling. I find boost::signals is perfect for that, save one exception. My question is that I want to connect arbitrary member function to signal. How to do it? Thanks in advanc. Yujiang Wang Feb. 15th, 2003

3 3

RE: [Boost-Users] Re: How to connect arbitrary memeber function i n boost::signals?
by Tom Matelich 18 Feb '03

18 Feb '03

#define myslot(obj, mem) boost::bind(mem, obj, _1) > -----Original Message----- > From: yjwang_bj <yjwang_bj(a)yahoo.com> [mailto:yjwang_bj@yahoo.com] > Sent: Tuesday, February 18, 2003 9:05 AM > To: Boost-Users(a)yahoogroups.com > Subject: [Boost-Users] Re: How to connect arbitrary memeber > function in > boost::signals? > > > > Use the Bind or Lambda library. An example: > > > > class X { > > public: > > void foo(int); > > }; > > > > X* x; > > boost::signal<void (int)> sig; > > > > // So the signal will call x->foo(y) when sig(y) is called: > > sig.connect(boost::bind(&X::foo, x, _1)); > > > > Doug > > It works but with the unusual C++ syntax. In libsigc++, I can do like > this: > sig1.connect(slot(x, &X::foo)); > > Hope boost has something like this though the boost's way is more > powerful. > > Thanks a lot, doug. > > Yujiang Wang > > > ------------------------ Yahoo! Groups Sponsor > ---------------------~--> > Get 128 Bit SSL Encryption! > http://us.click.yahoo.com/FpY02D/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. -----------------------------------------------------------------------

1 0

Is there a library for Set/Reset events?
by Russell Hind 18 Feb '03

18 Feb '03

I have just started using the boost::threads library (and associated mutexes). I wondered if there was, or is in progress, a library for set/reset event synchronisation objects or are there plans to add these to the boost::threads library? Cheers Russell

2 2

boost::threads support for Forte6u1/Solaris2.6
by garymmann <gary＠mann.uk.net> 17 Feb '03

17 Feb '03

Firstly, apologies if this is a FAQ. What is the current status of boost::threads on Solaris 2.6 using the Forte 6u1 (5.2) compiler? Is this a "supported" platform/compiler combination. If it "kind of works", are there any known issues which I will need to code around, or is it completely broken. Is the issue with the Solaris pthreads or with the broken compiler? Does the compiler work well enough to be able to compile just the threads module. I'm looking for a threading abstraction portable to at least GCC/Linux, MSVC/Win32 and Forte/Solaris. Is boost::threads likely to be able to satisfy this requirement right now, or am I going to have to look elsewhere. If I do need to look elsewhere, can anyone recommend an alternative to paying large amounts of money away to Rogue Wave! Hope someone can help, regards, Gary

1 0

problem with induced subgraphs
by David Minor <david-m＠orbotech.com> 17 Feb '03

17 Feb '03

I'm using an edge visitor to create subgraphs. I do a simple sub_graph = myGraph.create_subgraphs(), to create a subgraph and then I add vertices using add_vertex(vertex,sub_graph). The vertices are added but the corresponding edges are not. My basic typedefs are: ////////// typedef boost::property<boost::edge_index_t, int> Tmp; typedef boost::property<boost::edge_info_t, GES_EdgeInfo, Tmp> GES_EdgeProperty; typedef boost::property<boost::vertex_color_t, int> Tmp2; typedef boost::property<boost::vertex_self_t, SYS_String, Tmp2> Tmp3; typedef boost::property<boost::vertex_name_t, SYS_String, Tmp3> GES_VertexProperty; typedef boost::adjacency_list< boost::vecS, boost::vecS ,boost::directedS ,GES_VertexProperty ,GES_EdgeProperty> GES_AdjacencyList; typedef boost::subgraph<GES_AdjacencyList> GES_RTGraph; ////////// That is, the graph type is the same as the sub-graph type, which I think is right? Does anybody have any idea why the edges aren't being transferred to the sub-graph?

1 0

Why scoped_ptr dost provide custom deallocation?
by Black Ice 17 Feb '03

17 Feb '03

As following manner: template<class D> scoped_ptr(Y * p, D d); Any suggestion are appreciated. -- /*******************/ ×ÔÓÉ£šliberty£©ÎÞ·ÇŸÍÊÇÕâÑùÒ»ÖÖ³ÐÅµ£ºÃ¿žöÈËœ«»áµÃµœÒ»ÖÖ±£ÕÏ£¬±£ÕÏÎÒÃÇ¿ÉÒÔÓë ÈšÍþ¡¢¶àÊý¡¢Á÷Ë×Œ°ÓßÂÛµÄÓ°ÏìÏà¿¹ºâ¡£ /*******************/

4 7

covariance of shared_ptr types
by Vaclav Vesely 16 Feb '03

16 Feb '03

Hi, in C++ it's possible to write this: class A {}; class B: public A {}; class X { virtual A* f() { ... }; }; class Y: public X { virtual B* f() { ... }; // B* is covariant from A* }; However it is NOT possible to write that with shared_ptr: class X { shared_ptr<A> f() { ... }; }; class Y: public X { virtual shared_ptr<B> f() { ... }; // Error: shared_ptr<B> is NOT covariant from shared_ptr<A> }; I don't know C++ standard very well (in fact I've never read it). So my question is: it's possible to adjust shared_ptr to allow such constructions? Thank you, Wasek [Non-text portions of this message have been removed]

3 3

Problems building RegExp3
by kekogomez <kekogomez＠yahoo.es> 15 Feb '03

15 Feb '03

Hello to all, I have tried to build the RegExp3 library... but I get some errors... I'm using Vc++ Net. I execute the command nmake vc7.mak and I get the nexts error results... could someone help me? .... .... .... link kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib /nologo /dll /incremental:yes /pdb:"vc7/boost_regex_vc7_m did.pdb" /debug /machine:I386 /out:"vc7/boost_regex_vc7_mdid.dll" /imp lib:"vc7/boost_regex_vc7_mdid.lib" /LIBPATH:\lib vc7/boost_regex_vc7_mdid/c_regex_traits.obj vc7/boost_regex_vc7_mdid/c_regex_traits_common.obj vc7/boost_regex_vc7_mdid/cpp_regex_traits.obj vc7/boost_regex_vc7_mdid/cregex.obj vc7/boost_regex_vc7_mdid/fileiter.obj vc7/boost_regex_vc7_mdid/instances.obj vc7/boost_regex_vc7_mdid/posix_api.obj vc7/boost_regex_vc7_mdid/regex.obj vc7/boost_regex_vc7_mdid/regex_debug.obj vc7/boost_regex_vc7_mdid/regex_synch.obj vc7/boost_regex_vc7_mdid/w32_regex_traits.obj vc7/boost_regex_vc7_mdid/wide_posix_api.obj vc7/boost_regex_vc7_mdid/winstances.obj Creating library vc7/boost_regex_vc7_mdid.lib and object vc7/boost_regex_vc7_mdid.exp regex_synch.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp w32_regex_traits.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp wide_posix_api.obj : error LNK2019: unresolved external symbol __RTC_CheckEsp referenced in function _regerrorW@16 winstances.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp fileiter.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp instances.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp posix_api.obj : error LNK2019: unresolved external symbol __RTC_CheckEsp referenced in function _regerrorA@16 regex.obj : error LNK2019: unresolved external symbol __RTC_CheckEsp referenced in function "public: __thiscall boost::match_results<char const *,class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::match_results<char const *,class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >(class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> const &)" (??0?$match_results@PBDV? $allocator_adapter@DVsimple_alloc@detail@boost@@@detail@boost@@@boost@ @QAE@ABV?$allocator_adapter@DVsimple_alloc@detail@boost@@@detail@1@@Z) c_regex_traits.obj : error LNK2019: unresolved external symbol __RTC_CheckEsp referenced in function "unsigned int __cdecl `anonymous namespace'::re_get_message(unsigned short *,unsigned int,unsigned int)" (?re_get_message@?A0xc953bc5d@@YAIPAGII@Z) c_regex_traits_common.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp cpp_regex_traits.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp cregex.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp regex_synch.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 w32_regex_traits.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 wide_posix_api.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 winstances.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 fileiter.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 instances.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 posix_api.obj : error LNK2019: unresolved external symbol @_RTC_CheckStackVars@8 referenced in function _regerrorA@16 regex.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 c_regex_traits.obj : error LNK2019: unresolved external symbol @_RTC_CheckStackVars@8 referenced in function "unsigned int __cdecl `anonymous namespace'::re_get_message(unsigned short *,unsigned int,unsigned int)" (?re_get_message@?A0xc953bc5d@@YAIPAGII@Z) c_regex_traits_common.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 cpp_regex_traits.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 cregex.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 regex_synch.obj : error LNK2001: unresolved external symbol __RTC_Shutdown w32_regex_traits.obj : error LNK2001: unresolved external symbol __RTC_Shutdown wide_posix_api.obj : error LNK2001: unresolved external symbol __RTC_Shutdown winstances.obj : error LNK2001: unresolved external symbol __RTC_Shutdown fileiter.obj : error LNK2001: unresolved external symbol __RTC_Shutdown instances.obj : error LNK2001: unresolved external symbol __RTC_Shutdown posix_api.obj : error LNK2019: unresolved external symbol __RTC_Shutdown referenced in function _regerrorA@16 regex.obj : error LNK2001: unresolved external symbol __RTC_Shutdown c_regex_traits.obj : error LNK2001: unresolved external symbol __RTC_Shutdown c_regex_traits_common.obj : error LNK2001: unresolved external symbol __RTC_Shutdown cpp_regex_traits.obj : error LNK2019: unresolved external symbol __RTC_Shutdown referenced in function "public: __thiscall boost::re_detail::message_data<char>::message_data<char>(class std::locale const &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??0? $message_data@D@re_detail@boost@@QAE@ABVlocale@std@@ABV? $basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@4@@Z) cregex.obj : error LNK2001: unresolved external symbol __RTC_Shutdown regex_synch.obj : error LNK2001: unresolved external symbol __RTC_InitBase w32_regex_traits.obj : error LNK2001: unresolved external symbol __RTC_InitBase wide_posix_api.obj : error LNK2019: unresolved external symbol __RTC_InitBase referenced in function _regerrorW@16 winstances.obj : error LNK2001: unresolved external symbol __RTC_InitBase fileiter.obj : error LNK2001: unresolved external symbol __RTC_InitBase instances.obj : error LNK2001: unresolved external symbol __RTC_InitBase posix_api.obj : error LNK2001: unresolved external symbol __RTC_InitBase regex.obj : error LNK2001: unresolved external symbol __RTC_InitBase c_regex_traits.obj : error LNK2001: unresolved external symbol __RTC_InitBase c_regex_traits_common.obj : error LNK2001: unresolved external symbol __RTC_InitBase cpp_regex_traits.obj : error LNK2019: unresolved external symbol __RTC_InitBase referenced in function "public: __thiscall boost::re_detail::message_data<char>::message_data<char>(class std::locale const &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??0? $message_data@D@re_detail@boost@@QAE@ABVlocale@std@@ABV? $basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@4@@Z) cregex.obj : error LNK2001: unresolved external symbol __RTC_InitBase vc7/boost_regex_vc7_mdid.dll : fatal error LNK1120: 4 unresolved externals

2 1

boost::thread and MinGW
by Russ 14 Feb '03

14 Feb '03

Hi, I was previously using the threading library with MinGW (latest release version) with no problems. Yesterday I came across a segfault that occurred when accessing a shared pointer so I updated the boost-cvs version I was using to see if it was a known problem that had been fixed; however when attempting to build the new version it appeared that threading had been disabled for MinGW? Is this the case or is it a problem with the way I'm building my code. Any help greatly appreciated, Russ

3 3

RE: [Boost-Users] Re: Why scoped_ptr dost provide custom dealloca tion?
by bjorn.karlsson＠readsoft.com 14 Feb '03

14 Feb '03

> From: Peter Dimov [mailto:pdimov@mmltd.net] [snip] > A zero-overhead scoped_ptr<X, D> would require a helper class here: Yes, and I shouldn't have said scoped_ptr<X,D>, but scoped_ptr<X> with custom deallocation capabilities... I'd be willing to pay for the increase in size, but I realize not everyone would. The case is real, however. > scoped_ptr<void, void (*) (void *)> p(hPrinter, &ClosePrinter); > > that would increase sizeof(scoped_ptr) and is of questionable > utility. :-) Actually, I kind of like it. :-) > There is always the option to define a dedicated printer > class, of course. Yep, but there are hundreds of cases like this, which is why the feature would be useful. One could argue the same for the resource management of any type, right? ;-) Bjorn Karlsson

1 0

RE: [Boost-Users] Re: Why scoped_ptr dost provide custom dealloca tion?
by bjorn.karlsson＠readsoft.com 14 Feb '03

14 Feb '03

> From: Peter Dimov [mailto:pdimov@mmltd.net] [snip] > (An example of a convincing case: "In my project I have > encountered the > following situation: <description with real(istic sounding) > identifiers> and > I believe that scoped_ptr<X, D> would be a perfect fit." Some > non-examples: > "Someone might find it useful." "Wouldn't it be cool if...") In my project I have encountered the following situation: A lot of the code needs to handle (no pun intended) resources that are represented by indiscriminate types, such as void* or long. Different resources (and different functions for allocation/deallocation) use this handle type, so specialization is not an option. It's possible to use shared_ptr to handle lifetime management of the resource: HANDLE hPrinter=0; OpenPrinter(_T("Some printer"),&hPrinter,0); if (boost::shared_ptr<void> p(hPrinter,&ClosePrinter)) { } While this works, it doesn't convey the intent of the code (nor preserve it): the resource should typically not be shared, only scoped, and I believe that scoped_ptr<X,D> would be a perfect fit. There are other tools in Boost (outside too, of course) for solving this type of problem, but I think it would be more than cool for scoped_ptr to have this feature; I'd definitely use it in real code. Bjorn Karlsson

2 1