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

mpl::vector -> boost::tuple
by Markus Werle 09 Jul '04

09 Jul '04

Hi! The example in libs/mpl/example/tuple_from_list.cpp and gen_linear_hierarchy from http://aspn.activestate.com/ASPN/Mail/Message/boost/1166644 template< typename Types, typename Unit, typename Root = mpl::none > struct gen_linear_hierarchy { typedef typename mpl::fold<Types,Unit,Root> ::type type; // here }; /* usage example: template< class Base, class T > struct EventHander : public Base { virtual void OnEvent(T& obj, int eventID) = 0; }; typedef gen_linear_hierarchy< mpl::list<Window,Button,ScrollBar> , EventHander<_1,_2> > ::type v; */ all seem to me work fine with default constructible types. What I need is a type generator which provides a constructor, such that code like this one works for mpl::vectors (or other mpl::sequences) with arbitrary length: ------------- class C { C(std::string const & gaga) {} }; struct gen_linear_hierarchy_with_constructor // your idea missing here { // and here }; typedef gen_linear_hierarchy_with_constructor<mpl::vector<C, C> >::type mytuple; mytuple mt("test", "Thanks for your help"); ------------------ Markus P.S.: David and Aleksey, if you read this here: I could not find your "coming soon" book at awprofessional.com. What's the current state of the book I wait for so long already ...

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Relational DB Model Tools
by Hossein Haeri 09 Jul '04

09 Jul '04

Dear all, I wonder knowing where the "Relational Database Model" stuff are in the boost repository. How knows? Thanks a lot, --Hossein __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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Adapting Iterator Adaptor
by Duane Murphy 08 Jul '04

08 Jul '04

We are still using boost 1.27. We are getting to the point that there are features of the latest boost release that we want to use. Of course there are barriers. One barrier is iterator_adaptor. Iterator_adapter went through a significant rewrite. We have several (>10) iterators written using the older implementation. We are trying to gauge the impact of changing to the latest boost. Do we need to largely rewrite these iterators? Is the interface close enough for this to be a reasonably simple task? Simply how do we get our old iterators to the new adaptor? Thanks for the help, ...Duane

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Generic Class Factory
by Mark Loew 08 Jul '04

08 Jul '04

I have to create a class factory and was looking for a generic class factory that I could work with. I looked in the boost documentation but didn't find anything. Is there something there that I am missing or do I need to roll my own? Mark Loew, MCSD, MCSE Application Development Consultant Sagestone Consulting www.sagestone.com <http://www.sagestone.com/> Grand Rapids, MI 616-954-9556 x149 Microsoft Gold Certified Partner mloew(a)sagestone.com

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RE: [Boost-users] Generic Class Factory
by Jim.Hyslop 07 Jul '04

07 Jul '04

Mark Loew wrote: > I have to create a class factory and was looking for a > generic class factory that I could work with. I looked in > the boost documentation but didn't find anything. Is there > something there that I am missing or do I need to roll my own? It's not part of boost, but have a look at: http://www.cuj.com/documents/s=7994/cujcexp1906hyslop/ There's a follow-up in the July and August, 2003 print editions of CUJ. -- Jim Hyslop Senior Software Designer Leitch Technology International Inc. (http://www.leitch.com) Columnist, C/C++ Users Journal (http://www.cuj.com/experts)

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Feature request for boost::filesystem
by Delfin Rojas 07 Jul '04

07 Jul '04

Hello everybody, I'm new to this mailing list. The first thing I should say is I love boost and I think it is a great library and I'm really thankful to all its contributors. Now, that being said, I'm sending this email to ask about a feature in the boost::filesystem library that I believe would be valuable to have. Currently the only library that supports file and directory operations in boost is boost::filesystem. Thanks tot hat library I don't have to use platform specific file manipulation rutines for things like copying a file, deleting all files in a directory, iterating through a directory, etc. Now, all the operations in boost::filesystem take a boost::filesystem::path as an object encapsulating a platform independent "path" to a file or a directory. My problem is this path can only be built using a single char (ANSI) character string. This doesn't allow me to use boost::filesystem in windows with Unicode support since I cannot convert a wide string (UTF16) path to a boost::filesystem::path object. I believe it must not be too difficult to add Unicode path support to boost::filesystem since only the "path" class would need to be modified I think. Another small feature I think could be interesting is a convenience function to set the current path (cd operation). There is a function already to get the current path but not to set it. I do not know if this is the right group to ask for these features. If not please point me in the right direction. Thanks a lot Delfin Rojas Delfin(a)moodlogic.com

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RE: [Boost-users] Problem with boost random library.
by Tom Matelich 07 Jul '04

07 Jul '04

This is totally a shot in the dark, but the last time I had this problem, my static class members inside a gcc library were not getting constructed because I wasn't using gcc as my linker. Perhaps those two have static non-POD members and the others don't. > -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > Joshua Little > Sent: Saturday, July 03, 2004 8:09 PM > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] Problem with boost random library. > > > Just to make sure I answer my own mails as much as possible. > I tried a > few different random generators. Rand48, mt11213b, and > minstd_rand and > they all worked inside of my game. So it seems like mt19937 and the > lagged_fibonacci's are causing the problem. So obviously I > can use one > of the other generatrors but its still bothers me that the > mt19937 and > lagged_fibonaccis generators segfaults for reasons that are > not apparent > to me. Maybe this information will help give ideas to anyone > who might > know what might be wrong, maybe there is a difference between the > generator types that might be causing the problem? > Thanks, > Joshua. > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/bo> ost-users > ----------------------------------------------------------------------- DISCLAIMER: Information contained in this message and/or attachment(s) may contain confidential information of Zetec, Inc. If you have received this transmission in error, please notify the sender by return email. -----------------------------------------------------------------------

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thread and Mac OS X
by Tristan King 07 Jul '04

07 Jul '04

i've written a little test to see if i've installed boost properly on my mac #include <boost/thread.hpp> #include <boost/shared_ptr.hpp> #include <boost/bind.hpp> #include <iostream> void simple_thread( boost::shared_ptr<int> p ) { std::cout << (*p) << std::endl; } int main (int argc, char * const argv[]) { boost::thread_group threads; for ( int i = 0 ; i < 5 ; i++ ) { boost::shared_ptr<int> p( new int(i) ); threads.create_thread( boost::bind( &simple_thread, p ) ); } threads.join_all( ); return 0; } in xcode (a C++ Tool project) this compiles fine, however on runtime i get the following error: ZeroLink: unknown symbol '__ZN5boost12thread_groupC1Ev' boost_test has exited due to signal 6 (SIGABRT). using g++ i get the following errors (ignoring warnings) g++ main.cpp -o boost_test -I/usr/local/include/boost-1_31 -L/usr/local/lib ld: Undefined symbols: boost::thread_group::create_thread(boost::function0<void, std::allocator<boost::function_base> > const&) boost::thread_group::join_all() boost::thread_group::thread_group[in-charge]() boost::thread_group::~thread_group [in-charge]() i originally built boost using the command line sudo bjam -sTOOLS=darwin install can anyone help me with what i am missing here? thanks --Tristan

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RE: [Boost-users] [pool] Speed of pool_allocator<>
by Klaus Nowikow 06 Jul '04

06 Jul '04

Peter Dimov wrote: > Klaus Nowikow wrote: > > template <class Allocator> > > double Test() > > { > > std::vector<Allocator::value_type, Allocator> Vector; > > boost::timer Timer; > > > > for(int i = 0; i < NUM_ELEMENTS; ++i) > > { > > Vector.push_back(i); > > } > > > > return Timer.elapsed(); > > } > > If I read the code correctly, you don't create or delete > objects. You create > and delete (large) arrays of objects. I changed the test program (see below). Now I use object_pool<> to create and destroy a number of elements (I use a vector<C*> to store them in the meantime). The results are even worse than before: new/delete: 0.08s object_pool: 25.20s Note that I created a class non_pool with an interface similar to object_pool to be able to use one function template for both tests. // MemoryPoolTest.cpp #include <boost/timer.hpp> #include <boost/pool/object_pool.hpp> #include <vector> #include <iostream> enum { NUM_ELEMENTS = 100000 , CHUNK_SIZE = NUM_ELEMENTS }; class C { int i_; char c_; }; struct Empty { }; template <class T, class U = Empty> struct non_pool // create, destroy with new and delete { explicit non_pool(int) { } T* construct() const { return new T; } void destroy(T* pT) { delete pT; } }; template <template <class, class> class Pool> double Test() { Pool<C> P(CHUNK_SIZE); boost::timer Timer; std::vector<C*> V; for(int i = 0; i < NUM_ELEMENTS; ++i) { V.push_back(P.construct()); } for(std::vector<C*>::iterator pos = V.begin(), end = V.end(); pos != end; ++pos) { P.destroy(*pos); } return Timer.elapsed(); } int main(int, char**) { std::cout << "Starting memory pool test" << std::endl; double Time; std::cout << "Allocating with new : "; Time = Test<non_pool>(); std::cout << Time << "s" << std::endl; std::cout << "Allocating with boost::object_pool<>: "; Time = Test<boost::object_pool>(); std::cout << Time << "s" << std::endl; return 0; }

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errors building boost on Mac OS X
by Tristan King 06 Jul '04

06 Jul '04

Hi, i get a few errors when building the following libraries on Mac OS X 10.3.4 libboost_test_exec_monitor libboost_unit_test_framework i'm building using bjam, and the following command line bjam -sTOOLS-darwin install sniplets of the errors are as follows: darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_prg_exec_monitor.dylib/darwin/debug/shared-linkable-true/libboost_prg_exec_monitor-d-1_31.dylib ld: Undefined symbols: cpp_main(int, char**) .... darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_test_exec_monitor.dylib/darwin/debug/shared-linkable-true/libboost_test_exec_monitor-d-1_31.dylib ld: Undefined symbols: test_main(int, char**) .... darwin-Link-DyLib-action bin/boost/libs/test/build/libboost_unit_test_framework.dylib/darwin/debug/shared-linkable-true/libboost_unit_test_framework-d-1_31.dylib ld: Undefined symbols: init_unit_test_suite(int, char**) am i missing something here? thanks --Tristan

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Problem using exported C++ functions to python
by mayankg＠iiitb.ac.in 06 Jul '04

06 Jul '04

Hi, I have the following type of functions in a class say "MyClass", which I have exported to python. 1) func1(long *plong) 2) func2(TempClass **pptempclass) (where TempClass is some other class) Now, I exported these using the following: .def("func1", &MyClass::func1) .def("func2", &MyClass::func2) and it compiled well. But now when I try to use them in a python script, I have no clue as to how I create and pass: 1) a long pointer as argument to func1 2) a double pointer to TempClass as argument to func2 How do I achieve this behaviour? 1) Do I have to wrap the above functions> If yes, then how? How will they be used in python then? OR 2) I can still use the same functions in python but then how to create (instantiate and initialize) the above pointers in python? Thanks, Mayank

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RE: [Boost-users] Re: detect unneded includes
by Ben Hutchings 05 Jul '04

05 Jul '04

Adrian Stoica <adrian_stoica(a)btinternet.com> wrote: > I'm not aware of any such tools, but it could be done with a Perl > script that removes the includes one at a time, and then invokes the > compiler. If the file compiles ok, it's probably safe to remove that > include. No, unfortunately not. A header might appear to be redundant because it is included by another, yet this may be a mere implementation detail which is subject to change and should not be relied upon. In the absence of a true module system this is impossible to determine. Also it could be that the header defines template specialisations, or macros with the same names as functions/objects. Removing such a header might not make the program ill-formed but could still break it subtly. Instantiating a template in one translation unit for the same template arguments for which there is an explicit specialisation in another translation unit results in undefined behaviour. With sufficient testing you can *probably* avoid such mishaps but I would be very wary of trying to automate this.

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newbie: need example (call python from c++)
by Peter Piehler 04 Jul '04

04 Jul '04

Hello, I use call<void>(pyFunc,arg1,..) to call a python function with standard double, int etc. What must I do to call a function with a c++ object as argument? psydocode: class MyAnimal { /*...*/ std::string __strName; public: MyAnimal() : __strName("Tux") {} /*...*/ std::string getName() { return __strName;} void setName(const std::string &strName) { __strName = strName; } }; int main() { /*...*/ MyAnimal* pTux = new Animal; /*do something with pTux*/ /*use a python function with pTux*/ call<void>(pyFunc1, ?pTux? ); /*change attributes pTux in pyFunc2*/ dog = call<MyAnimal>(pyFunc2, ?pTux?); /*if it possible to call by reference?*/ call<void>(pyFunc3, ?pTux?); pTux->getName();// return Cat } python module: def py_func1(a): print a.getName() def py_func2(a): a.setName('Dog') return a def py_funnc3(a): a.setName('Cat') ___________________________________________________________ Gesendet von Yahoo! Mail - Jetzt mit 100MB Speicher kostenlos - Hier anmelden: http://mail.yahoo.de

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Problem with boost random library.
by Joshua Little 04 Jul '04

04 Jul '04

Hi all, I'm trying to use the randome number generators but I am having some problems. I'm using boost 1.31.0 and gcc 3.2 on Windows 2000. Here is my code : printf(" Die \n "); //std::cout << "Die Rolls" << std::endl; try { boost::mt19937 rng; // produces randomness out of thin air // see pseudo-random number generators boost::uniform_int<> six(1,6); // distribution that maps to 1..6 // see random number distributions boost::variate_generator<boost::mt19937, boost::uniform_int<> > die(rng, six); // glues randomness with mapping int x = die(); printf(" Die %d\n ",x); } catch(...) { std::cout << "exception" << std::endl; printf(" Die exception \n "); } I basically copied the example code off the web site to see if I could get it to work but I'm not having any luck. If I have the variate_generator defined as above I do not not get any output to the console after the declaration of die. I tried printf's and stream output but neither works, I never see the "Die %d" printed out and I do not see either of the outputs in the catch(...) section. printed either. I even had a throw in the try block at one time to see if it could get to the catch section and did not see output. When I remove the die declaration (and comment out the code that uses it) but leave the generator and the distribution then I can see output again and if I throw after the distribution declaration then I see both output statements in the catch block. So it seems like if I have the variate generator declared then I can't see any output after that, but when I comment it out I can see output again. I'm not sure what I'm doing wrong since I am basically copying a pretty simple example from the book I just can't get it to work. Ah and just incase this makes a difference I'm running this code as a test case in a boost test suite. I wanted to try to get it to work there before putting it into my main app. Thanks, Joshua.

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building boost program options
by Christopher Baus 03 Jul '04

03 Jul '04

I'm trying to build the boost sandbox project program_options and am failing. Anyone know what version of boost is compiles cleanly with? -- Christopher Baus http://www.baus.net/

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RE: [Boost-users] Re: boost test doesn't track validation outside autofunctions
by Rozental, Gennadiy 02 Jul '04

02 Jul '04

> > > void validate(X args) { > > > if (some tests) > > > BOOST_ERROR("message"); > > > } > > > BOOST_AUTO_UNIT_TEST(testfunction) { > > > // set up arguments > > > validate(args) > > > } [...] > I think the problem is a think-o on my part. > In the pseudo-code above, BOOST_ERROR is not executed unless > "some tests" is true. So if the tests are OK, BOOST_ERROR is > never hit. > > I think the report of 0 (boost) tests being run is therefore > accurate, though confusing. It should actually say that 1 test cases being run, but no assertions executed. > Does that sound right? > > Is there a way to signal to boost that you are doing a test, > without the error? You have 2 choices. 1. Rewrite your test, so that it looks like: ... BOOST_CHECK_MESSAGE( some_test, "message" ); 2. Or you could write it like this: .... If(some_test) BOOST_ERROR("message") else BOOST_MESSAGE( "no error" ); I prefer first solution usually. HTH, Gennadiy

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boost test doesn't track validation outside auto functions
by Ross Boylan 02 Jul '04

02 Jul '04

I have a test program that looks like this, in stylized form: -------------------------- #include <boost/test/auto_unit_test.hpp> using namespace boost::unit_test_framework; void validate(X args) { if (some tests) BOOST_ERROR("message"); } BOOST_AUTO_UNIT_TEST(testfunction) { // set up arguments validate(args) } ---------------------------------- When I run this with report-level detailed, it reports that there are 0 assertions in testfunction. Furthermore, the assertions done in validate are not even added to the overall number of assertions reported for the run. I know the checks are being run, because I have seen errors from them. Also, the error messages include the name "testfunction", so it is available at run time. It would be nice if the error reporting and logging functions got their info at run-time; apparently they are grabbing it from some pre-processor magic at the moment (I haven't examined the code in detail; that's just an inference from the behavior). Since the tests do seem to be run, this is basically a cosmetic problem, but it would be nice to fix. If any easy fixes occur to anyone, I'd love to know. Boost 1.31.0 on Debian. P.S. The module's author is listed as rogeeff(a)fusemail.com in the documentation, but that address doesn't work. -- Ross Boylan wk: (415) 502-4031 530 Parnassus Avenue (Library) rm 115-4 ross(a)biostat.ucsf.edu Dept of Epidemiology and Biostatistics fax: (415) 476-9856 University of California, San Francisco San Francisco, CA 94143-0840 hm: (415) 550-1062

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Sun Solaris Forte 8 and boost_1_31_0
by Tom Aratari 02 Jul '04

02 Jul '04

Hello, Has anyone gotten boost_1_31 to compile with Forte 8.0 (__SUNPRO_CC = x550) ? I get errors for the boost::iterator. Also, does anyone know if the next release of boost will be compatible with forte 8.0? Thanks Tom

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Boost Test Tutorial
by Sebastian Stein 02 Jul '04

02 Jul '04

I have written a small tutorial how to use boost test within the KDE project. If you are interested, you will find it under: http://www.hpfsc.de/boosttest/ Sebastian -- http://www.hpfsc.de/ - die Seite rund um: Assembler, Bundeswehr, TFT LCDs, Halle/Saale, Fahrradtouren, Neuseeland, Wanderstaat Mauma, Raumschiff USS Nathan, Enemy Room, MLCAD Tutorial

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standard way to specify undefined values
by Erik Thiele 02 Jul '04

02 Jul '04

hi, i have a userdefined type "foobar". it has a special value that means "undefined". is there a standard way to specify which value is undefined? i do not want to use boost::optional here, as foobar itself can be "undefined". you know: class foobar { static const foobar undefined(blablabla); int a,b,c; } but is this "standard"? cya erik -- Erik Thiele

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RE: [Boost-users] Re: [mpl] Alexandrescu's hierarchy generators
by Klaus Nowikow 02 Jul '04

02 Jul '04

David Abrahams wrote: > [..] > template<class T, class Base> > struct node; > > typedef mpl::vector<int, char, long> types; > > // node<int, node<char, node<long, mpl::empty_base> > > > typedef mpl::inherit_linearly< > types > , node<_2,_1> > >::type lin; > [...] > HTH. That helps a lot. Thank you! -- Klaus Nowikow

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iterator_adaptor problem (mpl?)
by Angus Leeming 01 Jul '04

01 Jul '04

Consider a container such as std::vector<std::pair<int, std::string> > my_container; I want to be able to iterate over the ints of this container so, following the tutorial to the iterator_adaptor docs, came up with template <typename BaseIterator> class first_iter : public boost::iterator_adaptor< first_iter<BaseIterator>, BaseIterator, boost::use_default, boost::use_default, typename BaseIterator::value_type::first_type & > { // snip body }; This works fine so long as BaseIterator::value_type is not const, but falls over when it is because I've defined the 'super_t::reference' type to be mutable. I guess that I need a piece of metafunction magic, but my naive implementation fails typename boost::mpl::apply_if< boost::is_const<typename BaseIterator::value_type> , typename BaseIterator::value_type::first_type const & , typename BaseIterator::value_type::first_type & >::type trial.C:38: error: no type named `type' in `struct boost::mpl::apply_if< boost::is_const<std::pair<int, std::string> >, const int&, int&>' I must admit I'm a bit baffled. There plainly is a 'type' in the apply_if class template. Any pointers? I attach the code as I have it. While I'm at it, is there not something in the MPL that will return the appropriate const-qualified reference for me? None of the header file names in boost/mpl jump out and grab me, but I may well be looking in the wrong place. Regards, Angus

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RE: [Boost-users] [pool] Speed of pool_allocator<>
by Klaus Nowikow 01 Jul '04

01 Jul '04

Peter Dimov wrote: > Klaus Nowikow wrote: > > > > I changed the test program (see below). Now I use object_pool<> > > to create and destroy a number of elements (I use a vector<C*> to > > store them in the meantime). The results are even worse than before: > > > > new/delete: 0.08s > > object_pool: 25.20s > > [...] > > > template <template <class, class> class Pool> > > double Test() > > { > > Pool<C> P(CHUNK_SIZE); > > boost::timer Timer; > > > > std::vector<C*> V; > > for(int i = 0; i < NUM_ELEMENTS; ++i) > > { > > V.push_back(P.construct()); > > } > > for(std::vector<C*>::iterator pos = V.begin(), end = V.end(); pos != > > end; ++pos) { > > P.destroy(*pos); > > } > > > > return Timer.elapsed(); > > } > > Your test is still very unrealistic. You create a large > number of objects in > one batch, then destroy them afterwards. A more realistic > scenario would > have creation and destruction interleaved. > > The most accurate test would be to try Boost.Pool with your actual > application and see how it affects its real-world > performance. It's still > possible for it to be slower, of course, but at least you'd > measure the real > thing. Of course you're right. Obviously I broke the "don't optimize what does not have to be optimized" rule ;-). When creating and deleting 100000 Objects with new/delete takes only 0.1 seconds I won't have to look for something more efficient. I will do what you suggest: write my code and see if it needs optimization. Regards, Klaus

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[mpl] Alexandrescu's hierarchy generators
by Klaus Nowikow 01 Jul '04

01 Jul '04

Greetings! Does boost.mpl provide type hierarchy generators like GenScatterHierarchy and GenLinearHierarchy as described in "Modern C++ Design"? I must confess I do not understand the mpl completely yet ;-) Best regards, Klaus

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RE: [Boost-users] [pool] Speed of pool_allocator<>
by Klaus Nowikow 01 Jul '04

01 Jul '04

Peter Dimov wrote: > Klaus Nowikow wrote: > > I am in the process of writing a program which has to > > handle large numbers (~200000 - 400000) objects of the same class. > > These objects will be created and deleted frequently, so I thought > > some kind of specialized memory management would be handy. > > > > I wrote a test program (see below) to check what boost.pool > would gain > > me. The results make me think that I have done something wrong: > > > > [...] > > > > i.e., std::allocator was more than 3 times faster than > > boost::pool_allocator (Win2k, 256MB). Any ideas what i have done > > wrong? > > [...] > > > template <class Allocator> > > double Test() > > { > > std::vector<Allocator::value_type, Allocator> Vector; > > boost::timer Timer; > > > > for(int i = 0; i < NUM_ELEMENTS; ++i) > > { > > Vector.push_back(i); > > } > > > > return Timer.elapsed(); > > } > > If I read the code correctly, you don't create or delete > objects. You create > and delete (large) arrays of objects. Hmm. I'll have to think about this. Maybe the test was a bit over-simplified. The real program would have a vector<C*> where C is my class. I'll change the example (using object_pool) and post the results.

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