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Boost Serialization library with Berkeley-DB
by Surya Kiran Gullapalli 21 Feb '07

21 Feb '07

Hello all, Has any body ever used Boost serialization library with Berkeley-DB database to store/retrieve data. I'd like some pointers on how to use it?. Sample code would be most appreciated. Thanks, Surya

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How to build guid lib?
by Christian Henning 21 Feb '07

21 Feb '07

Hi there, it's not as easy as I thought it would be. I copied the guid files in the appropriate folders in my boost/ directory. And then I tried: bjam -sTOOLS=vc-7_1 --with-guid But that doesn't work. So, how do I do that? I really have no clue about bjam, etc. Thanks in advance, Christian

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[graph] Crash in breadth_first_search
by Jens Müller 21 Feb '07

21 Feb '07

Can someone help me with the following program? It crashes with Boost 1.33.1 on gcc34 (GCC) 3.4.3 20050113 (Red Hat 3.4.3-16): $ ./1 make_map_as_colormap entered writing something to MapAsColorMap Speicherzugriffsfehler I have tracked down the crash to this line in <boost/graph/breadth_first_search.hpp>: for (tie(ei, ei_end) = out_edges(u, g); ei != ei_end; ++ei) { But I don't know what happens there ... I'm quite sure the bug is NOT in my color map proxy ... Thanks a lot in advance! Cheers, Jens // //======================================================================= // Copyright 2007 University of Karlsruhe // Author: Jens Mueller // // Distributed under the Boost Software License, Version 1.0. (See // accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) //======================================================================= // #ifndef BFS_DISTMAP_8737 #define BFS_DISTMAP_8737 /* Use distance map (or anything else which suits the following requirements) as a color map. Write operations are just ignored. Read operations work as follows: When the value in the underlying map equals a specified value, e.g. -1 in a distance map, or the null pointer in a predecessor map, the 'White' value is returned, otherwise the 'Black' value is returned. Note: This only is usable for application where there is no need to distinguish gray and black non-tree edge targets. Note: Setting the value in the underlying map so that it no longer corresponds to a 'White' value will have to be done by the visitor on the discover_vertex event. */ /* Template parameters: - ColorValue (default value used by helper function: default_color_type) - ReadablePropertyMap (underlying map) */ /* Runtime parameters: - ReadablePropertyMap pm - ReadablePropertyMap::value_type white (must be == comparable) */ #include <boost/property_map.hpp> #include <iostream> template<typename ReadablePropertyMap, typename ColorValue> class MapAsColorMap { private: typename boost::property_traits<ReadablePropertyMap>::value_type white_; const ReadablePropertyMap& pm_; public: typedef typename boost::property_traits<ReadablePropertyMap>::key_type key_type; typedef ColorValue value_type; typedef ColorValue reference; typedef boost::read_write_property_map_tag category; ColorValue get(key_type key); MapAsColorMap(const ReadablePropertyMap& pm, typename boost::property_traits<ReadablePropertyMap>::value_type white): white_(white), pm_(pm) { /* nothing */ }; }; template<typename ReadablePropertyMap> MapAsColorMap<ReadablePropertyMap, boost::default_color_type> make_map_as_colormap(const ReadablePropertyMap& pm, typename boost::property_traits<ReadablePropertyMap>::value_type white) { std::cout << "make_map_as_colormap entered" << std::endl; return MapAsColorMap<ReadablePropertyMap, boost::default_color_type>(pm, white); } template<typename ReadablePropertyMap, typename ColorValue> ColorValue MapAsColorMap<ReadablePropertyMap, ColorValue>::get(key_type key) { std::cout << "get entered" << std::endl; std::cout << key << " " << boost::get(pm_, key) << std::endl; return (boost::get(pm_, key)==white_) ? boost::color_traits<ColorValue>::white() : boost::color_traits<ColorValue>::black(); } template<typename ReadablePropertyMap, typename ColorValue> ColorValue get(MapAsColorMap<ReadablePropertyMap, ColorValue> pmap, typename boost::property_traits<ReadablePropertyMap>::key_type key) { return pmap.get(key); } template<typename ReadablePropertyMap, typename ColorValue> void put(MapAsColorMap<ReadablePropertyMap, ColorValue> pmap, typename boost::property_traits<ReadablePropertyMap>::key_type key, typename boost::property_traits<ReadablePropertyMap>::value_type value) { std::cout << "writing something to MapAsColorMap" << std::endl; /* nothing */ } #endif

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local variable shadow
by Chris Saunders 21 Feb '07

21 Feb '07

I find local variable shadow warnings helpful, but when I include various boost libraries, I have to remove a lot of shadowing within the boost functions themselves. Note that I'm not refering to name conflicts with my own code. How can I submit patches to remove these type of warnings? Thanks, -Chris

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[boost::program_options] got stuck with some options scenario
by Ovanes Markarian 21 Feb '07

21 Feb '07

I have some requirement for input parameters: Some of my input parameters represent a pair of files. Is there any way to parse this kind of a form: -I "file1" "file1_related_file" Trying to use the construct with: po::value< std::pair<std::string,std::string> >() produces a compilation error within a lexical cast, that there is no operator >> defined. I know I could pass smth like: -I "fiel1+related_file", but then I would need to split the string, what I would like to do, since I see this as a task of program_options lib. With Kind Regards, Ovanes Markarian

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question about pool::get_next_size/set_next_size
by Stefan Felkel 21 Feb '07

21 Feb '07

Hi, is there a way to access pool::get_next_size, pool::set_next_size from my own fast_pool_allocator without modifying the boost source (1.33.1). This my_fast_pool_allocator is a copy of fast_pool_allocator that tries to allocate the requested memory with next_size divided by 2 if malloc returns NULL. I added static member functions get_next_size/set_next_size to singleton_pool which works, but is there a way without modifying the boost source. If not, would it make sense to add these two methods in a future boost release. This is the allocate method of my_fast_pool_alloctor: template <typename T, typename UserAllocator, typename Mutex, unsigned NextSize> class my_fast_pool_allocator { ... static pointer allocate(const size_type n) { typedef boost::singleton_pool<boost::fast_pool_allocator_tag, sizeof(T), UserAllocator, Mutex, NextSize> mypool; pointer ret = NULL; for( ; !ret; ) { if (n == 1 ) { ret = static_cast<pointer>( mypool::malloc() ); } else { ret = static_cast<pointer>( mypool::ordered_malloc(n) ); } size_t nsize = mypool::get_next_size(); if( !ret ) // not enough memory available { if( nsize <= n ) // even less than we really need break; nsize >>= 1; // request half the size nsize = std::max( nsize, n ); // at least as much as we really need } mypool::set_next_size(nsize); } if (ret == 0) throw std::bad_alloc(); return ret; } ... }; Regards, Stefan

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question about boost::interval
by Marco Correia 21 Feb '07

21 Feb '07

Hi, I'm a little bit confused about the documentation in http://www.boost.org/libs/numeric/interval/doc/rounding.htm, in the subsection "Transcendental functions". Does the "Please note" paragraph means that the provided classes for transcendal functions (_opp and _std) do not guarantee the inclusion property? From what I understood it says that it depends on the implementation of the std::* math functions, that, in most cases, don't obey current rounding mode. Am I getting this right? In case I am, does anyone knows if I'm safe with gcc std library (perhaps by using the -frounding-math switch)? Thanks! Marco -- Marco Correia <mvc(a)di.fct.unl.pt>

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missing files?
by Jan Van den bosch 21 Feb '07

21 Feb '07

Hi, I'm trying to build the examples of the Channel event framework ( channel.sourceforge.net) Apparently, the Boost archives at sourceforge (.zip, .tar.gz and .tar.bz2 files) are missing several necessary files, like serialization/array.hpp. When I do a CVS checkout of Boost however, those files are included. Are they still part of Boost? Thanks in advance, Jan

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split_iterator<string::iterator> example
by Meryl Silverburgh 21 Feb '07

21 Feb '07

hi, Can someone please tell me where I can find example of split_iterator<string::iterator> If I have 2 split_iterator<string::iterator>s, how can I compare the 2 strings that the split_iterator pointing to? Thank you.

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[Boost][bind] problem using bind with non-copyable class members?
by Darren Garvey 21 Feb '07

21 Feb '07

Hi, I'm trying to use bood::bind and I'm having a problem with compilation when I'm passing an object that holds a std::stringstream. The errors are to do with std::ios_base and std::streambuf's copy constructors being private, but as far as I knew (and understand from the docs), boost::bind passes by reference, so nothing should be copied. I'm sure I'm missing something fundamental here, so any enlightening would be very welcome. My setup is gcc 4.1.2 on Ubuntu 6.10. Here's an example program that fails: #include <sstream> > #include <boost/bind.hpp> > #include <boost/thread.hpp> > > using namespace boost; // sorry > using namespace std; // oops > > > struct holder > { > std::ostringstream oss; > }; > > void sub_main( holder& h ) > { > return; > } > > class event_handler > { > public: > void operator() ( holder& h ) > { > thread t( bind( &sub_main, h ) ); > t.join(); > } > }; > > int main( int, char** ) > { > event_handler e_h; > holder h; > > e_h(h); > > return 0; > } Regards, Darren

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