- Boost-users - lists.boost.org

Re: [Boost-users] boost library for SQL
by Ovanes Markarian 10 Jul '07

10 Jul '07

On Tue, July 10, 2007 08:04, Meryl Silverburgh wrote: > Hi, > > Does boost library has library in c++ for SQL? If not, does anyone know if there is a c++ library for sql? > > Thank you. > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users > Please take a look at SOCI at http://soci.sourceforge.net/ This is a really great lib! With Kind Regards, Ovanes Markarian

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boost library for SQL
by Meryl Silverburgh 10 Jul '07

10 Jul '07

Hi, Does boost library has library in c++ for SQL? If not, does anyone know if there is a c++ library for sql? Thank you.

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[serialization] hacking serialization : handles to pointers
by Sean Cavanaugh 10 Jul '07

10 Jul '07

Ok I've spent a good chunk of my day making a set of custom archive class, based on the portable_binary_iarchive and portable_binary_oarchive. I have a non-virtual class hierarchy named Asset, in memory this is a cyclic graph, but my requirements are that this structure cannot be serialized all at once, it has to be broken up at boundaries. So the archiver serializes the first Asset* (which is always the root object passed into operator&). This object serializes as normally as per the boost serialization code, except except that when subsequent Asset*'s are encountered I send the pointer into an AssetManager class and translate the Asset* into a ResourceID, and serialize the ResourceID instead of the object. This is done by directly calling operator& inside save_override. So far all of this works: The reverse case of loading, by hooking load_override almost works. Almost, because I have to apply a hack of skipping 4 bytes inside load_override, before trying to read the ResourceID structure with operator&. I can't figure out how to make it 'proper', without simply hard coding the 4 byte read. As far as I can tell before save_override some bookkeeping information is written, but the reverse operation in load_override has not yet stripped this bookkeeping information from the stream, so these functions aren't quite mirror operations. As best as I can tell the function guilty of reading the bookkeeping information is load_pointer. What I need is another function in the boost archive API that pulls the bookkeeping information out of the stream safely, that I can call from within load_override, since I have no intention of calling load_pointer through any means. Aside from the hack, it technically works, but even then I still have a few aching problems: I also have to hard-code the full list of derived Asset types and manually provide specializations for all of them in save_override and load_override. If I use the base class, I end up slicing my class down to its base, and cannot serialize it. I can't make serialize virtual, since the intrusive serialize methods are templates, but it certainly would solve the problem if it were possible. In addition the bodies of all of my overrides are completely identical except for the classname (AssetModel, AssetTexture, etc). Which means I'll be wrapping the bodies of a generic save_override and load_override in a macro, and have to manually add all Asset derived classes to a list of classes inside my archive class. Which means that my archiver cannot be generic, even though I have managed to make it a template in the sense that the passed in asset manager and base asset types are template parameters. the type ResourceID is a std::string saving... class asset_oarchive : ... void save_override(const AssetModel& t, int i) { if (!RootAssetSaved) { RootAssetSaved = true; binary_oarchive_impl::save_override(t, i); } else { AssetManagerType::ResourceID ResourceId = TheAssetManager->ResourceIdForAsset(&t); operator&(ResourceId); } } loading ... class asset_iarchive : ... void load_override(AssetModel*& t, int i) { if (!RootAssetLoaded) { RootAssetLoaded = true; binary_iarchive_impl::load_override(t, i); } else { unsigned char c[10]; for (INT x=0; x<10; ++x) { c[x] = 0xFF; } for (INT x=0; x<4; ++x) { operator&(c[x]); //hackhack } AssetManagerType::ResourceID ResourceId; operator&(ResourceId); AssetType* a = TheAssetManager->FindAsset(ResourceId); if (!a) { a = TheAssetManager->LoadAsset(ResourceId); } // TODO: throw on missing resources, potentially query asset manager for substitutes t = static_cast<AssetModel*>(a); } } So I have a working implementation, how do I make it better?

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Re: [Boost-users] wrapping stdlib fstream with boost filtering streams
by Daniel Oberhoff 10 Jul '07

10 Jul '07

Hi, egoots <egoots(a)gmail.com> writes: >> 1) does the compressor flush the zlib compression buffer when I flush/ >> pop it? > > As I understand it, pop() and reset() both flush and close the current > device and then destroy it. Well, but I explicitly switched the auto_close feature off... >> 2) is fstream a bidirectional stream (my guess due to separate seekg/ >> seekp methods) or a seekable stream (one read/write head)? Because I >> currently require the former. >> >> btw: the above code runs without exceptions, but when I read back >> variables I have just written they are garbled. > > You should read the thread of messages at... there may be some relevant > info here: > http://thread.gmane.org/gmane.comp.lib.boost.user/13824 > > Especially the replies by Jonathan Turkanis Well, there he says that strict_sync is there to switch filters, but it wouldn't make sense to use it before all the data is compressed. but that is exactly the point: all the data IS compressed. Matlab files effectively consist of carefully concatenated compressed and uncompressed files. Effectively I could take out a compressed block from a matlab file and send it to gunzip. Also, in my code strict_sync returns true, unlike what the original poster in the mentioned thread has experienced, indicating that all has been flushed and written and switching filters is ok. I also check after every pop() if the fstream has been closed, and it has not. Using a different z stream wrapper (zipstream) works (mostly) and gives me the original data, while the boost approach gives me zeros. Well, I will try to make a simpler test case, since the program is quite complex. thanks 4 the reply Daniel

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Re: [Boost-users] Réf. : Problem message bis
by question boost 10 Jul '07

10 Jul '07

> Now I do:> cd C:\Documents and Settings\Administrateur\Bureau\boost_1_33_1\boost_1_33_1\tools\build\jam_src> C:\Documents and Settings\Administrateur\Bureau\boost_1_33_1\boost_1_33_1\tools\build\jam_src\build.bat> Then I set the following variables:> BOOST_ROOT= C:\Documents and Settings\src\boost> and BOOST_BUILD_PATH=C:\Documents and Settings\Administrateur\Bureau\boost_1_33_1\boost_1_33_1\tools\build\v2. The problem is the same. I don't know what to do now in order not to get the message any more. Thank you for your response. > To: boost-users(a)lists.boost.org> Wrom: HAALPTCXLYRWTQTIPWIGYOKSTTZRCLBDXRQBGJSNBOHMKHJYFMYXOEAIJJPHSCRTNHGSWZIDREXCAXZOWCONEUQZAAFXISHJEXXIMQZUIVOTQNQEMSFDULHPQQWOYIYZUNNYCGPKYLEJGDGVCJVTLBXFGGMEPYOQKEDOTWFAOBUZXUWLSZLKBRNVWWCUFPEGAUTFJMVRESKPNKMBIPBARHDMNNSKVFVWRKJVZCMHVIBGDADRZFSQHYUCDDJBLVLMHAALPTCXLYRWTQTIPWIGYOKSTTZRCLBDXRQBGJSNBOHMKHJYFMYXOEAIJJPHSCRTNHGSWZIDREXCAXZOWCONEUQZAAFXISHJEXXIMQZUIVOTQNQEMSFDULHPQQWOYIYZUNNYCGPKYLEJGDGVCJVTLBXFGGMEPYOQKEDOTWFAOBUZXUWLSZLKBRNVWWCUFPEGAUTFJMVRESKPNKMBIPBARHDMNNSKVFVWRKJVZCMHVIBGDADRZFSQHYUCDDJBLVLMHAALPTCXLYRWTQTIPWIGYOKSTTZRCLBDXRQBGJSNBOHMKHJYFMYXOEAIJJPHSCRTNHGSWZIDREXCAXZOWCONEUQZAAFXISHJEXXIMQZUIVOTQNQEMSFDULHPQQWOYIYZUNNYCGPKYLEJGDGVCJVTLBXFGGMEPYOQKEDOTWFAOBUZXUWLSZLKBRNVWWCUFPEGAUTFJMVRESKPNKMBIPBARHDMNNSKVFVWRKJVZCMHVIBGDADRZFSQHYUCDDJBLVLMHAALPTCXLYRWTQTIPWIGYOKSTTZRCLBDXRQBGJSNBOHMKHJYFMYXOEAIJJPHSCRTNHGSWZIDREXCAXZOWCONEUQZAAFXISHJEXXIMQZUIVOTQNQEMSFDULHPQQWOYIYZUNNYCGPKYLEJGDGVCJVTLBXFGGMEPYOQKEDOTWFAOBUZXUWLSZLKBRNVWWCUFPEGAUTFJMVRESKPNKMBIPBARHDMNNSKVFVWRKJVZCMHVIBGDADRZFSQHYUCDDJBLVLMHAALPTCXLYRWTQTIPWIGYOKSTTZRCLBDXRQBGJSNBOHMKHJYFMYXOEAIJJPHSCRTNHGSWZIDREXCAXZOWCONEUQZAAFXISHJEXXIMQZUIVOTQNQEMSFDULHPQQWOYIYZUNNYCGPKYLEJGDGVCJVTLBXFGGMEPYOQKEDOTWFAOBUZXUWLSZLKBRNVWWCUFPEGAUTFJMVRESKPNKMBIPBARHDMNNSKVFVWRKJVZCMHVIBGDADRZFSQHYUCDDJBLVLMHAALPTCXLYRWTQTIPWIGYOKSTTZRCLBDXRQBGJSNBOHMKHJYFMYXOEAIJJPHSCRTNHGSWZIDREXCAXZOWCONEUQZAAFXISHJEXXIMQZUIVOTQNQEMSFDULHPQQWOYIYZUNNYCGPKYLEJGDGVCJVTLBXFGGMEPYOQKEDOTWFAOBUZXUWLSZLKBRNVWWCUFPEGAUTFJMVRESKPNKMBIPBARHDMNNSKVFVWRKJVZCMHVIBGDADRZFSQHYUCDDJBLVLMHAALPTCXLYRWTQTIPWIGYOKSTTZRCLBDXRQBGJSNBOHMKHJYFMYXOEAIJJPHSCRTNHGSWZIDREXCAXZOWCONEUQZAAFXISHJEXXIMQZUIVOTQNQEMSFDULHPQQWOYIYZUNNYCGPKYLEJGDGVCJVTLBXFGGMEPYOQKEDOTWFAOBUZXUWLSZLKBRNVWWCUFPEGAUTFJMVRESKPNKMBIPBARHDMNNSKVFVWRKJVZCMHVIBGDADRZFSQHYUCDDJBLVLMHAALPTCXLYRWTQTIPWIGYOKSTTZRCLBDXRQBGJSNBOHMKHJYFMYXOEAIJJPHSCRTNHGSWZIDREXCAXZOWCONEUQZAAFXISHJEXXIMQZUIVOTQNQEMSFDULHPQQWOYIYZUNNYCGPKYLEJGDGVCJVTLBXFGGMEPYOQKEDOTWFAOBUZXUWLSZLKBRNVWWCUFPEGAUTFJMVRESKPNKMBIPBARHDMNNSKVFVWRKJVZCMHVIBGDADRZFSQHYUCDDJBLVLMHAALPTCXLYRWTQTIPWIGYOKSTTZRCLBDXRQBGJSNBOHMKHJYFMYXOEAIJJPHSCRTNHGSWZIDREXCAXZOWCONEUQZAAFXISHJEXXIMQZUIVOTQNQEMSFDULHPQQWOYIYZUNNYCGPKYLEJGDGVCJVTLBXFGGMEPYOQKEDOTWFAOBUZXUWLSZLKBRNVWWCUFPEGAUTFJMVRESKPNKMBIPBARHDMNNSKVFVWRKJVZCMHVIBGDADRZFSQHYUCDDJBLVLMHAALPTCXLYRWTQTIPWIGYOKSTTZRCLBDXRQBGJSNBOHMKHJYFMYXOEAIJJPHSCRTNHGSWZIDREXCAXZOWCONEUQZAAFXISHJEXXIMQZUIVOTQNQEMSFDULHPQQWOYIYZUNNYCGPKYLEJGDGVCJVTLBXFGGMEPYOQKEDOTWFAOBUZXUWLSZLKBRNVWWCUFPEGAUTFJMVRESKPNKMBIPBARHDMNNSKVFVWRKJVZCMHVIBGDADRZFSQHYUCDDJBLVLMHAALPTCXLYRWTQTIPWIGYOKSTTZRCLBDXRQBGJSNBOHMKHJYFMYXOEAIJJPHSCRTNHGSWZIDREXCAXZOWCONEUQZAAFXISHJEXXIMQZUIVOTQNQEMSFDULHPQQWOYIYZUNNYCGPKYLEJGDGVCJVTLBXFGGMEPYOQKEDOTWFAOBUZXUWLSZLKBRNVWWCUFPEGAUTFJMVRESKPNKMBIPBARHDMNNSKVFVWRKJVZCMHVIBGDADRZFSQHYUCDDJBLVLMHAALPTCXLYRWTQTIPWIGYOKSTTZRCLBDXRQBGJSNBOHMKHJYFMYXOEAIJJPHSCRTNHGSWZIDREXCAXZOWCONEUQZAAFXISHJEXXIMQZUIVOTQNQEMSFDULHPQQWOYIYZU _________________________________________________________________ David Guetta a réuni les sons les plus connus de Messenger dans le Mix Messenger, le son de l’été ! Téléchargez-le gratuitement ! http://specials.divertissements.fr.msn.com/mixmessenger

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boost::lambda::bind - a better name?
by Maciek Godek 10 Jul '07

10 Jul '07

Wouldn't it be better if boost::lambda::bind was named boost::lambda::call (or boost::lambda::eval, to make it more lispish), in order to: -avoid the confusion and potential overlap with boost::bind -make the name more sensible within lambda expressions, especially when "binding" nullary functions, ie. int six() { return 6; } if_(call(six) == 6) [ ... ] IMHO looks better than if_(bind(six) == 6) [ ... ] Yours, Chuj

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boost::lambda library, error with << operator (on g++ with SGI STL)
by Maciek Godek 10 Jul '07

10 Jul '07

Hi, I've tried to compile the following code on linux/g++ (version 3.3.4 and 4.1.2), boost version 1.34: -- CODE BEGINS -- #include <iostream> using namespace std; #include "boost/function.hpp" #include "boost/ref.hpp" using namespace boost; #include "boost/lambda/lambda.hpp" #include "boost/lambda/bind.hpp" #include "boost/lambda/if.hpp" using namespace boost::lambda; int main(int argc, char *argv[]) { function<void (int, int)> f = if_(_1 == _2) [ cout << cref("arguments are equal\n") ].else_[ cout << cref("arguments differ\n") ]; f(1, 1); f(1, 2); } -- CODE ENDS -- On g++ 3.3.4 I got a (scarcely readable) error that std::ios_base copy constructor is private (the more recent compiler gave much more trashy output, but I've infered that the reason is probably the same). The error wouldn't appear if I had supplied at least one placeholder to the operator<< in both if's cases in the lambda expression above. Is there any way to overcome this limitation?

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Does boost offer a random permutation function?
by Jeffrey Holle 09 Jul '07

09 Jul '07

I am looking for a function that randomly selects a permutation of a sequence. For instance given "1,2,3", it would produce something like "2,1,3" randomly selected from all possible permutations. I could code this myself by creating a container with all possible permutations and randomly selecting one, but this isn't reasonably if the size of the sequence gets larger. I've looked on the web and found an old 4 line FORTRAN subroutine that appears to do this. If boost don't already have this, I will attempt to convert this to C++.

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Test Library documentation URL errors
by Number Cruncher 09 Jul '07

09 Jul '07

I was trying to browse the Unit Test Framework (part of Boost Test Library) and received the following: An error has been encountered in accessing this page. 1. Server: boost.org 2. URL path: /libs/test/doc/components/utf/getting_started/index.html 3. Error notes: File does not exist: /home/groups/b/bo/boost/htdocs/libs/test/doc/components/utf/getting_started/index.html 4. Error type: 404 5. Request method: GET 6. Request query string: 7. Time: 2007-07-09 03:07:29 PDT (1183975649) Also, none of the example source code seems to be linked, e.g: http://boost.org/libs/test/example/unit_test_example1.cpp

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[Boost.Python] Issues When Object Created in C++ and Then Used From Python
by Lawrence Spector 09 Jul '07

09 Jul '07

I created an example of code that demonstrates the error. Here's what the code looks like, as of right now: PythonPassReference.cpp: #include <boost/python.hpp> #include "TestClass.hpp" #include "TestClassWrap.hpp" #include <iostream> using namespace boost::python; int main() { try { Py_Initialize(); object main_module(( handle<>(borrowed(PyImport_AddModule("__main__"))))); object main_namespace = main_module.attr("__dict__"); TestClass testClass(std::cout, 3, 9.6f, 'Q'); { handle<> ignored((PyRun_String( "import PythonInterface" , Py_file_input , main_namespace.ptr() , main_namespace.ptr()) )); } TestClassWrap testClassWrapper(testClass); boost::python::object pyTestClass(testClassWrapper); // Works: pyTestClass.attr("output")(); { handle<> ignored((PyRun_String( // Works: "pyTestClass = PythonInterface.TestClass(6, 8.3, 'W')\n" "pyTestClass.output()\n" // Error unless the previous line is uncommented , Py_file_input , main_namespace.ptr() , main_namespace.ptr()) )); } } catch(boost::python::error_already_set& e) { std::cerr << "Caught error_already_set" << std::endl; if (PyErr_Occurred() != 0) { PyErr_Print(); } // end if } catch(...) { std::cerr << "Caught unknown error" << std::endl; } // end try-catch std::cin.get(); return 0; } // end main TestClass.hpp: #pragma once #include <iostream> class TestClass { private: std::ostream& m_outStream; int m_x; float m_y; char m_z; public: TestClass(std::ostream& p_outStream, int p_x, float p_y, char p_z) : m_outStream(p_outStream), m_x(p_x), m_y(p_y), m_z(p_z) { } // end TestClass ~TestClass() { } // end TestClass void output() { m_outStream << "x = " << m_x << ", y = " << m_y << ", z = " << m_z << "\n"; } // end callMethod }; // end TestClass TestClassWrap.hpp: #pragma once #include "TestClass.hpp" class TestClassWrap { private: TestClass m_testClass; public: TestClassWrap(const TestClass& p_testClass) : m_testClass(p_testClass) { } // end TestClassWrap TestClassWrap(int p_x, float p_y, char p_z) : m_testClass(std::cout, p_x, p_y, p_z) { } // end TestClass ~TestClassWrap() { } // end TestClass void output() { m_testClass.output(); } // end callMethod }; // end TestClassWrap PythonInterface.cpp (Built with BJam, makes PythonInterface.pyd, PythonInterface.lib): #include <string> #include <boost/python.hpp> #include <iostream> #include "TestClass.hpp" #include "TestClassWrap.hpp" using namespace boost::python; BOOST_PYTHON_MODULE(PythonInterface) { class_<TestClassWrap>("TestClass", init<int, float, char>()) .def("output", &TestClassWrap::output) ; } // end module As you can see in the example above, I have an object which I wrap and then pass to python as follows: TestClassWrap testClassWrapper(testClass); boost::python::object pyTestClass(testClassWrapper); This works just fine, and I can call methods on the object. However, when I try to run it as a string (as it would be if read from a .py script file), I get an error. Here's the code for that: { handle<> ignored((PyRun_String( "pyTestClass.output()\n" // Error unless the previous line is uncommented , Py_file_input , main_namespace.ptr() , main_namespace.ptr()) )); } Which produces the following error (based on my catching and outputting the error): Caught error_already_set Traceback (most recent call last): File "<string>", line 1, in <module> NameError: name 'pyTestClass' is not defined So, I guess the question is, how do I expose an instance called pyTestClass, in such a way, that I can call methods on it from a script? Or is there some mistake I'm making, that's preventing this from fully working? Thanks in advance, Lawrence

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