April 2004 - Boost - lists.preview.boost.org

Re: [boost] [multi_index] composite keys: request for advice
by JOAQUIN LOPEZ MU?Z 25 Apr '04

25 Apr '04

----- Mensaje original ----- De: Jeremy Maitin-Shepard <jbms(a)attbi.com> Fecha: Sábado, Abril 24, 2004 11:13 pm Asunto: Re: [boost] [multi_index] composite keys: request for advice > Joaquin M Lopez Munoz <joaquin(a)tid.es> writes: > > > [snip: composite key system] > > > composite_key</* as before*> ck; > > ck(record(1,2,3))<=make_tuple(1,2); // yields true > > This is not lexicographical order. According to lexicographical > ordering: > > (1, 2) < (1, 2, 3) > I did not claim that composite_key results and tuples are ordered lexicographically. What I said is that, given that a composite_key induces a lexicographical order on the elements of the multi_index_container it is used in, this can be taken advantage of to perform searches where only the first keys are given. For this to work, (1, 2) must be equivalent to (1,2,3) (meaning that !((1, 2)<(1,2,3)) and !((1,2,3)<(1,2)). I don't think there's any flaw with this approach, my doubt is about whether the fact that ck(record(1,2,3))<=make_tuple(1,2) and make_tuple(1,2)<=ck(record(1,2,3)) is reason enough to also make ck(record(1,2,3))==make_tuple(1,2) hold true. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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max elapsed time of boost::timer
by Toon Knapen 24 Apr '04

24 Apr '04

The documentation of boost::timer states that 'The maximum measurable elapsed time may be as low as 596.5 hours (or even less) ...'. Well on many 32bit platforms this would probably even be about 71 hours. Apparantly POSIX requires CLOCKS_PER_SEC to be 10e6, so if clock_t is 32 bit, the maximum of ( clock() / CLOCKS_PER_SEC ) is 4294 seconds. Because accuracy for clock() is generally about 1 sec, using clock() is not very usefull for doing timings of short (in time) events. Even more, for short events, the boost::timer might also influence the timing too much. So clock() is generally interesting for longer timings (from 10 sec onwards). But for long events the clock_t wraps around too fast (as mentioned above). And if you're unlucky that you _start_time = clock() is or a bit smaller than std::numeric_limits< clock_t >::max() (thus near the wrap-around point), directly afterwards the expression 'clock() - start' will result in a negative value. So I would like to suggest for boost::timer to use std::time_t and use std::time(NULL) instead of clock() and use std::difftime to calculate the elapsed time. toon

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A question to preprocessor gurus
by Arkadiy Vertleyb 24 Apr '04

24 Apr '04

Hi all, The MS preprocessor has the __COUNTER__ extension that expands to the next integer every time when used. Can something like this be achieved in a portable manner, maybe with the help of Boost.Preprocessor library? Thanks, Arkadiy

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[circular buffer] Status of Circular Buffer lib
by Jeff Garland 24 Apr '04

24 Apr '04

I'm looking at using circular buffer on a project. With only minor adaptation it does exactly what I need. I know it has been accepted, but isn't yet in CVS. So I have a few questions: 1) Is 3.6 from the files section the latest version? 2) Any showstopper bugs I should be aware of? 3) I'm assuming it works with VC7.1 and gcc 3.x? 4) Looks like my interface needs will be pretty basic: push_back, erase, clear. I assuming review changes won't impact these, correct? 5) Any reason it is NOT ready for prime time? Thx for the great submission! Jeff

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[Boost-bugs] [ boost-Bugs-940941 ] failure in boost jam unit tests on cygwin
by SourceForge.net 23 Apr '04

23 Apr '04

Bugs item #940941, was opened at 2004-04-23 12:45 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=940941&group_i… Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Kannan Goundan (cakoose) Assigned to: Nobody/Anonymous (nobody) Summary: failure in boost jam unit tests on cygwin Initial Comment: Boost Jam Version 3.1.9 The unit tests seem to assume that the "/cygdrive" mount exists. I had changed mine to "/drive" and when I tried to build, I got an assertion failure: assertion "self->size < self->capacity" failed: file "strings.c", line 16 self->size == -165761813 self->capacity == 64 backtrace: assert_invariants (strings.c:15) string_free (strings.c:44) var_expand (expand.c:410) var_expand_unit_test (expand.c:696) run_unit_tets (jam.c:197) main (jam.c:299) Even if it's not worth it to accomodate non-standard Cygwin setups such as mine, I wouldn't expect the assertion failure to occur in strings.c. I think this can be reproduced by changing the "/cygdrive/c/foo/bar" string constants to invalid paths (in expand.c on lines 682 and 702) ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=940941&group_i… ------------------------------------------------------- This SF.net email is sponsored by: The Robotic Monkeys at ThinkGeek For a limited time only, get FREE Ground shipping on all orders of $35 or more. Hurry up and shop folks, this offer expires April 30th! http://www.thinkgeek.com/freeshipping/?cpg=12297 _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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gcc34: undefined reference to `__gcov_init'
by Neal D. Becker 23 Apr '04

23 Apr '04

Any clues? I am trying to rebuild an app that worked with boost_1_31_0 and gcc3.3, now with gcc3.4. I completely rebuilt boost_1_31_0 libs using: PYTHON_ROOT=/usr PYTHON_VERSION=2.3 bjam -sTOOLS=gcc -sGXX=g++34 -sGCC=gcc34 PYTHON_ROOT=/usr PYTHON_VERSION=2.3 bjam -sTOOLS=gcc -sGXX=g++34 -sGCC=gcc34 stage Then I clean out all objects from my build, and rebuilt with g++34, but I got this error: g++34 -Wl,-rpath,/usr/local/src/boost_1_31_0.gcc34/stage/lib,-rpath,./ -o Test2 Test2.o -L/usr/local/src/boost_1_31_0.gcc34/stage/lib -L. -lshannon -lboost_program_options-gcc -lrfftw -lfftw Test2.o(.text+0x7d6e): In function `global constructors keyed to _Z21DesignImpulseResponseRKN10__gnu_norm6vectorISt7complexIdESaIS2_EEE_GCOV': /home/nbecker/shannon/TestAloha/Test2.cc:360: undefined reference to `__gcov_init'

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[serialization] and shared_ptr
by Jeff Flinn 23 Apr '04

23 Apr '04

The following code produces and access violation when loading the NULL shared_ptr. Is this an issue of not having registered the type pointed to? What would I need to do to appropriately handle this situation? #include <boost/serialization/shared_ptr.hpp> #include <boost/serialization/string.hpp> #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/archive/binary_oarchive.hpp> #include <boost/archive/binary_iarchive.hpp> #include <boost/archive/xml_oarchive.hpp> #include <boost/archive/xml_iarchive.hpp> #include <fstream> typedef std::string tName; class PointedToClass { tName mName; friend class boost::serialization::access; template< class Archive > void serialize( Archive &ar, unsigned int version ) { ar & boost::serialization::make_nvp( "Name", mName ); } public: ~PointedToClass(){} PointedToClass():mName("def"){} }; typedef boost::shared_ptr<PointedToClass> tPtr; class SomeClass { tName mName; tPtr mPtr; friend class boost::serialization::access; template< class Archive > void serialize( Archive &ar, unsigned int version ) { ar & boost::serialization::make_nvp( "Name", mName ); ar & boost::serialization::make_nvp( "Ptr", mPtr ); } public: SomeClass():mName("abc"),mPtr(){} }; int main( int argc, char* argv[] ) { SomeClass lSomeClass; { std::ofstream lOut( "SomeClass.archive", std::ios_base::out | std::ios_base::trunc ); if( lOut.good() ) { boost::archive::xml_oarchive oa( lOut ); oa & boost::serialization::make_nvp( "SomeClass", lSomeClass ); } } { std::ifstream lIn( "SomeClass.archive" ); if( lIn.good() ) { boost::archive::xml_iarchive ia( lIn ); ia & boost::serialization::make_nvp( "SomeClass", lSomeClass ); } } return 0; }

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numeric_cast
by Dill, John 23 Apr '04

23 Apr '04

I am wondering about the use-case of numeric_cast in this sample. unsigned char uchar_max = std::numeric_limits<unsigned char>::max(); char schar_value = 0; try { schar_value = boost::numeric_cast<char>( uchar_max ); } catch ( boost::bad_numeric_cast ) { std::cout << "Overflow occurred..." << std::endl; } When I execute this sample, I don't get the exception. What's the background on this behavior? I'm using gcc 3.3.1. John

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Assignment Library Review Result
by Tom Brinkman 23 Apr '04

23 Apr '04

Assignment Library Review Result Thanks to Thorsten Otteson for creating the Assignment Library. Review Comments: * Participation by boost members in the review was minimal, but the comments were generally constructive. * Considering that library is relatively small and the scope is fairly limited, less than normal review participation by boost members is to be expected. * The basic functionality of the library relieves the c++ developer from typing redundent c++ code for inserting/appending hard-coded data into containers. * Some issues about how the library is organized remain, but are easily resolved by seperating the headers and removing global dependencies. * There are many issues regarding the advanced functionality of this library that were not resolved during the review period. An additional review period should be provided to discuss advanced/optimized techniques for container population. * The name of the library should be changed. The name 'Assignment' does not fully describe the functionality of this library and could be improved. Review Conclusion: This library should be accpeted into boost under the following conditions: 1) Add a header file for each wrapped stl container. One header file containing all of the commonly used headers should also be provided. 2) Remove the global += operator. 3) Rename routines to reflect whether they are initializing, appending or inserting data. 4) Move all routines that extend boost libraries to the examples folder. 5) Documentation should broken up into a basic section and advanced section. 6) Documentation should add a short description about the advantages and disadvantage of each method provided by the library. 7) The library needs to add a boost test file. 8) Routines provided by the Assignment library having boost dependencies will require additional discussion during the post review period. 9) Basic library useage should not require any boost libraries outside of the boost::asignment library headers itself. 10) The techniques provided in the basic functionality of the library may not be optimal. Consideration of techniques for advanced generalized container initialization should be made. A post review period will be required to address advanced library useage. Thanks again and congratulations to Thorsten Otteson for creating a useful set of routines for the boost community. Review Manager, Tom Brinkman __________________________________ Do you Yahoo!? Yahoo! Photos: High-quality 4x6 digital prints for 25� http://photos.yahoo.com/ph/print_splash

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lightweight replacement for boost::format
by John Torjo 23 Apr '04

23 Apr '04

Dear boosters, When needing to dump a lot of data into a string, we usually use boost::format. However, there have been lots of times when I needed a simple and lightweight replacement. I've used one for quite a while (see attachement). Basic usage: str_stream() << "str" << s << "int " << i; // automatic conversion to string. Example: std::string msg = str_stream() << "There have been " << users << " users logged on so far"; Also, attached an example. Any interest in something like this in boost? Best, John <cid:part1.07010200.01010400@torjo.com> ////////////////////////////////////////////////////////////////////// // example.cpp #include "str_stream.hpp" #include <iomanip> std::basic_ostream< wchar_t> & width_4( std::basic_ostream< wchar_t> & out) { out.width( 4); return out; } void print_c_like_str( const char * str) { std::cout << str << std::endl; } void test() { using namespace boost; // for wide strings. std::wstring str = wstr_stream() << std::oct << 8; str = wstr_stream() << std::setfill( L'0') << width_4 << 35 << std::endl; std::wcout << str; // for strings int users = 45; std::string s = str_stream() << "There have been " << users << " users logged on so far"; std::cout << s << std::endl; int words = 78; s = str_stream( "We found ") << words << " words."; std::cout << s << std::endl; // convert it to C-like string print_c_like_str( (str_stream() << "testing " << 1 << 2 << 3).c_str() ); std::cin.get(); } int main() { test(); } ////////////////////////////////////////////////////////////////////// // str_stream.h #ifndef BOOST_STR_STREAM__HPP_JT_2003MAR04 #define BOOST_STR_STREAM__HPP_JT_2003MAR04 // Copyright John Torjo 2003-2004 // Use, modification, and distribution is subject to 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) #include <string> #include <sstream> #include <iosfwd> namespace boost { namespace stream_detail { template< class char_type, class char_traits> struct as_c_str_res { typedef std::basic_string<char_type,char_traits> str_type; as_c_str_res( const str_type & str) { m_str = str; } operator const char_type*() const { return m_str.c_str(); } private: str_type m_str; }; } // basic_str_stream - allow stream usage, and then conversion to string template< class char_type, class char_traits = std::char_traits<char_type> > class basic_str_stream { typedef std::basic_stringstream< char_type, char_traits> stringstream_type; typedef std::basic_string< char_type, char_traits> string_type; typedef stream_detail::as_c_str_res<char_type,char_traits> c_like_str_type; public: // default construction basic_str_stream() {} // allow to_string like usage template< class type> basic_str_stream( const type & value) { *this << value; } stringstream_type & underlying_stream() const { return m_out; } // implicit conversion operator string_type() const { return m_out.str(); } // explicit conversion to string string_type str() const { return m_out.str(); } // explicit conversion to C-like string c_like_str_type c_str() const { return c_like_str_type( m_out.str() ); } private: mutable stringstream_type m_out; #ifndef NDEBUG public: void recalculate_string() const { m_string = m_out.str(); } private: mutable string_type m_string; #endif }; // class basic_str_stream typedef basic_str_stream< char> str_stream; typedef basic_str_stream< wchar_t> wstr_stream; template< class char_type, class char_traits, class type> inline const basic_str_stream< char_type, char_traits> & operator<< ( const basic_str_stream< char_type, char_traits> & out, const type & value) { out.underlying_stream() << value; #ifndef NDEBUG out.recalculate_string(); #endif return out; } // allow function IO manipulators template< class char_type, class char_traits> inline const basic_str_stream< char_type, char_traits> & operator<< ( const basic_str_stream< char_type, char_traits> & out, std::ios_base & (*func)( std::ios_base&) ) { func( out.underlying_stream()); return out; } template< class char_type, class char_traits> inline const basic_str_stream< char_type, char_traits> & operator<< ( const basic_str_stream< char_type, char_traits> & out, std::basic_ios< char_type, char_traits> & (*func)( std::basic_ios< char_type, char_traits> &) ) { func( out.underlying_stream()); return out; } template< class char_type, class char_traits> inline const basic_str_stream< char_type, char_traits> & operator<< ( const basic_str_stream< char_type, char_traits> & out, std::basic_ostream< char_type, char_traits> & (*func)( std::basic_ostream< char_type, char_traits> &) ) { func( out.underlying_stream()); return out; } } // namespace boost #endif // End of file

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