June 2003 - Boost-users - lists.preview.boost.org

Problem with filesystem attributes
by richard_fanta 26 Jun '03

26 Jun '03

Hiya, I've been trying to try out the attributes code in the boost-sandbox, but am running into some snags using VC++ version 7 (that comes with VS .NYET). One simple goal here would be to discern whether a file is writeable. Can this be done with the filesystem::attributes library?? The code for attr_test.cpp from the tests directory is included below; it's been slightly modified to run stand-alone instead of through the boost test harness. Problem #1: No string() method on the cache class. Problem #2: The "<<" operator won't work. For the latter, I've seen it suggested that typedefs might help, but don't understand what the underlying issue is. Is this a lingering Microsoft (i.e. VC++) specific issue? I'd greatly appreciate any clarification that people can offer. Much thanks, Richard Fanta ----------------Errors---------------------------------------------- x:\v\ReviewAgent\AttrTest\attr_test.cpp(23) : error C2039: 'string' : is not a member of 'boost::filesystem::cache' x:\ReviewAgent\Util\boost_1_30_0_filesystem\boost\filesystem\cache.hpp(33) : see declaration of 'boost::filesystem::cache' x:\v\ReviewAgent\AttrTest\attr_test.cpp(25) : error C2676: binary '<<' : 'boost::filesystem::cache' does not define this operator or a conversion to a type acceptable to the predefined operator x:\v\ReviewAgent\AttrTest\attr_test.cpp(26) : error C2676: binary '<<' : 'boost::filesystem::cache' does not define this operator or a conversion to a type acceptable to the predefined operator x:\v\ReviewAgent\AttrTest\attr_test.cpp(26) : error C2676: binary '<<' : 'boost::filesystem::cache' does not define this operator or a conversion to a type acceptable to the predefined operator ----------------Source---------------------------------------------- #include <iostream> #include <exception> #include <string> #include "boost/filesystem/attributes.hpp" #include "boost/filesystem/path.hpp" //#include "boost/test/minimal.hpp" namespace fs = boost::filesystem; //int test_main (int argc, char **argv) int main (int argc, char **argv) { for (int i = 1; i < argc; ++i) { fs::path file (argv [i], fs::native); fs::cache pm (file); std::cout //<< "name: " << get <fs::filename> (pm).string () << "; size: " << get <fs::size> (pm) << "; owner: " << get <fs::owner> (pm) << "; group: " << get <fs::group> (pm) << "\n"; }

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Newbie lambda question
by Ian 25 Jun '03

25 Jun '03

Boosters: Try as I might, I cannot figure a way of converting the following code snippet to use std::for_each with boost::lamdba. Any ideas? unsigned int table[1000]; for ( unsigned int* it = table_; it != table_ + (sizeof(table_) / sizeof(unsigned int)); ++i ) { *it = ((int)it % 3); } The pointer to int cast is the killer, the docs mention the ret<> template briefly, but it does not seem to help... Cheers Ian

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Ublas library
by Alexey Nikitin 25 Jun '03

25 Jun '03

Hello everyone, I am try to use Ublas library and have some questions. I am want to write next code: template<class Matrix> void ProcessRecursive(Matrix& m) { typedef matrix_range<typename Matrix::matrix_type> MatrixRange; ... MatrixRange mr = project(m, range(...), range(...)); ... ProcessRecursive(mr); ... } void StartProcess() { ... matrix<double> m; ... ProcessRecursive(m); } But I have not enough type matrix_type in class matrix<...> and function template<class M> matrix_range<M> project(matrix_range<M>& data, const range& r1, const range& r2); There is almost the same function project but reciving const referens to matrix_range and compiler can't find it even using partial template ordering. Do somebody help my to write this code correctly? Or fix library? Regards, Alexey.

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boost::spirit - why won't this palindrome code work?
by joshwaxman 24 Jun '03

24 Jun '03

Hi. I just started playing with spirit and tried the following code to match palindromes of strings consisting of a's and b's. Why won't this work? (It prints 0, not 1) #include "boost/spirit/core.hpp" #include <iostream.h> using namespace boost::spirit; int main(int argc, char* argv[]) { rule <> S; S = ch_p('a') | ch_p('b') | epsilon_p | ('a' >> S >> 'a') | ('b' >> S >> 'b'); char * str = "aabaa"; cout << parse(str, S).full; return 0; }

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threads within threads
by pmedrow 23 Jun '03

23 Jun '03

Hi I am attempting to create a boost thread within an existing boost thread, i.e. a function called by the operator() function of an existing, running thread is attempting to make more threads. The new threads function objects are of the same type, but different from the parent function object type. This compiles and runs, but takes time equivalent to the threads running sequencially on a single thread. CPU usage indicates that both threads are running in parallel. Very strange... I am building with gcc v3.2.3 on red-hat linux build 2.4.20. Any ideas gratefully received!

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boost::filesystem build in MS Visual Studio .NET 2003
by Stuart C. Schaffner 23 Jun '03

23 Jun '03

Sorry if this is a repost. I am having trouble with my mail system. I tried to build the boost libraries per the instructions on "Building Boost Libraries" at www.boost.org, but most of the builds failed. I did set up the two variables for msvc. However, I noticed that vcvars32.bat is not in the directory that the build script specifies. I can fix this, but I suspect that other things are also in different places in .NET 2003. Any suggestions? Stu Schaffner The MITRE Corp.

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Passing shared_ptr to function that creates obj that shared_ptr points to
by Drew 23 Jun '03

23 Jun '03

[Moderator's note: The only apparent connection this message has to Boost is in the subject line. I am approving it on the assumption that the missing declarations for ParentPtr and DerivedPtr are typedefs using boost::shared_ptr.] Hello everyone... I am attempting to do the following: class Parent { public: int m_value; }; class Derived : public Parent { }; void Fn(ParentPtr& pObj) { pObj = ParentPtr(new Parent()); pObj->m_value = 10; } int main() { ParentPtr pParent; DerivedPtr pDerived; Fn(pDerived); return 0; } If I pass the parent pointer, it compiles and works fine. If I pass the derived pointer I get: error C2664: 'Fn' : cannot convert parameter 1 from 'DerivedPtr' to 'ParentPtr &' Does anyone know how to solve my problem? TIA, Drew

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[BGL] negative_edge thrown inside dijsktra for boost' file dependency example.
by Dan Dimerman 23 Jun '03

23 Jun '03

Hello, The problem I'm having is that I get an exception thrown when I run the example related to File precedency on parallel compilation, using dijkstra algorithm. I mean, there's no code of mine at all, so that reduces the probabilities of it being me to a 75%... ;) thanks...

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Signals library safety
by Eugene Talagrand  22 Jun '03

22 Jun '03

Hello to all, I'm looking into using the Boost.Signals. The library claims not to be thread safe. What does this mean exactly? When using Boost.Threads, can I make concurrent calls to connect as long as I wrap each call in a Mutex? If this is possible, do tackable objects also still work (if two trackable objects get destroyed in two different threads there might be a problem from what I understand) On an different note, I am trying to use Boost.Signals for network event handling. I'd like to set it up so that it uses something similar to he JavaScript event model, where every slot returns a boolean value. If that value is false, the remaining slots are not called. Would anyone have any recommendations on how to do this? Should I wrap each slot in a function that takes the return value and sets a global flag, then every subsequent slot checks the flag? It looks like combiners would not be appropriate, as it appears they are used after each slot is called (unless the InputIterator' opeator* actually calls the slot??) Thanks for any help -Eugene

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FW: [Spirit-general] RE: [Boost-Users] boost::spirit and asts
by HartmutKaiser＠t-online.de 22 Jun '03

22 Jun '03

-----Original Message----- From: Giovanni Bajo [mailto:giovannibajo@libero.it] Sent: Sunday, June 22, 2003 1:39 AM To: Hartmut Kaiser Subject: Fw: [Spirit-general] RE: [Boost-Users] boost::spirit and asts You may want to forward this to boost-users, the mail bounced because I'm not subscribed to it. Giovanni Bajo Giovanni Bajo <giovannibajo(a)libero.it> wrote: > Hartmut Kaiser <hartmutkaiser(a)t-online.de> wrote: > > >>> [AST] >>> a problem -- I can't seem to figure out how to put right-to-left >>> associative operators into the tree properly. I had this as a guess, >>> but I'm really not sure: r = value | value >> root_node_d[ch_p('=')] >>> >> r; > >> Meanwhile I'll >> forward this message to the Spirit mailing list, maybe somebody >> remebers it. Giovanni? > > > The proposed code should work as expected wrt tree generation, but you need > to left-factor it to make it actually work: > > r = value >> !(root_node_d[ch_p('=')] >> r); > > Giovanni Bajo > > > > ------------------------------------------------------- > This SF.Net email is sponsored by: INetU > Attention Web Developers & Consultants: Become An INetU Hosting > Partner. Refer Dedicated Servers. We Manage Them. You Get 10% Monthly > Commission! INetU Dedicated Managed Hosting > http://www.inetu.net/partner/index.php > _______________________________________________ > Spirit-general mailing list > Spirit-general(a)lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/spirit-general

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