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

Conversion warning from boost/functional/hash/detail/hash_float_generic.hpp
by Greg Ward 11 Dec '10

11 Dec '10

Hi all -- I'm getting a strange warning from <boost/functional/hash/detail/hash_float_generic.hpp>. What's strange is not the warning, but the circumstances: if I use the boost headers installed in /usr/include, no warning. But if I make a copy of /usr/include/boost and tell the compiler to use the copy, I get a warning. I can reproduce this on CentOS 5 using our custom build of GCC 4.4.4 and boost 1.44.0, and on Ubuntu 10.04 (lucid) using Ubuntu's builds of GCC 4.4.3 and boost 1.40.0. It doesn't take much code to reproduce the problem: $ cat test.cpp #include <boost/functional/hash.hpp> First, a good build using Ubuntu /usr/bin/g++ (4.4.3) and /usr/include/boost (1.40.0) $ /usr/bin/g++ -Wall -Wconversion -c test.cpp -o test.o [no warnings] Now let's make a copy of the boost headers and use the copy: $ mkdir include $ cp -rp /usr/include/boost include/. $ /usr/bin/g++ -Wall -Wconversion -I include -c test.cpp -o test.o In file included from include/boost/functional/hash/detail/hash_float.hpp:30, from include/boost/functional/hash/hash.hpp:15, from include/boost/functional/hash.hpp:6, from test.cpp:1: include/boost/functional/hash/detail/hash_float_generic.hpp: In function ‘size_t boost::hash_detail::float_hash_impl2(T) [with T = float]’: include/boost/functional/hash/detail/hash_float_generic.hpp:84: instantiated from ‘size_t boost::hash_detail::float_hash_impl(T) [with T = float]’ include/boost/functional/hash/detail/hash_float.hpp:74: instantiated from ‘size_t boost::hash_detail::float_hash_value(T) [with T = float]’ include/boost/functional/hash/hash.hpp:282: instantiated from here include/boost/functional/hash/detail/hash_float_generic.hpp:59: warning: conversion to ‘float’ from ‘size_t’ may alter its value include/boost/functional/hash/detail/hash_float_generic.hpp:84: instantiated from ‘size_t boost::hash_detail::float_hash_impl(T) [with T = float]’ include/boost/functional/hash/detail/hash_float.hpp:74: instantiated from ‘size_t boost::hash_detail::float_hash_value(T) [with T = float]’ include/boost/functional/hash/hash.hpp:282: instantiated from here include/boost/functional/hash/detail/hash_float_generic.hpp:71: warning: conversion to ‘float’ from ‘size_t’ may alter its value I get the same behaviour if include/boost is a symlink to /usr/include/boost. Changing "-I include" to an absolute path ("-I `pwd`/include") makes no difference. If I repeat the experiment on my CentOS 5 machine with custom builds of more recent versions of GCC (4.4.4) and boost (1.44.0), I see the same thing. The line numbers are slightly different: In file included from include/boost/functional/hash/detail/hash_float.hpp:30, from include/boost/functional/hash/hash.hpp:15, from include/boost/functional/hash.hpp:6, from test.cpp:1: include/boost/functional/hash/detail/hash_float_generic.hpp: In function ‘size_t boost::hash_detail::float_hash_impl2(T) [with T = float]’: include/boost/functional/hash/detail/hash_float_generic.hpp:82: instantiated from ‘size_t boost::hash_detail::float_hash_impl(T) [with T = float]’ include/boost/functional/hash/detail/hash_float.hpp:74: instantiated from ‘size_t boost::hash_detail::float_hash_value(T) [with T = float]’ include/boost/functional/hash/hash.hpp:315: instantiated from here include/boost/functional/hash/detail/hash_float_generic.hpp:56: warning: conversion to ‘float’ from ‘size_t’ may alter its value include/boost/functional/hash/detail/hash_float_generic.hpp:82: instantiated from ‘size_t boost::hash_detail::float_hash_impl(T) [with T = float]’ include/boost/functional/hash/detail/hash_float.hpp:74: instantiated from ‘size_t boost::hash_detail::float_hash_value(T) [with T = float]’ include/boost/functional/hash/hash.hpp:315: instantiated from here include/boost/functional/hash/detail/hash_float_generic.hpp:69: warning: conversion to ‘float’ from ‘size_t’ may alter its value but obviously the trace through the header files is basically the same. Any clues? Google did not turn up any similar problems from anyone else. Oh yeah: if you're wondering why I want to use a copy of (or symlink to) the real boost installation, it's because we need to support building many different versions of our software, and they don't all use the same versions of boost or gcc (or various other 3rd-party components). So each build tree has a bunch of local symlinks pointing to exactly the right versions of gcc, boost, etc. Thanks! Greg

2 3

mpi: is_mpi_datatype
by Hicham Mouline 11 Dec '10

11 Dec '10

Hello A polymorphic struct with 2 doubles and 1 virtual function is not intended to be marked as is_mpi_datatype : mpl_true, is it? regards,

2 1

Problem compiling: 64bit, link=shared, runtime-link=shared
by Thomas 11 Dec '10

11 Dec '10

Hallo, I need help compiling boost. My setup: Windows SDK v7.0 Boost 1.45 My configuration: bjam --prefic=c:\boost --with-thread --with-system --with-filesystem --with-program_options --with-date_time link=shared threading=multi address-model=64 runtime-link=shared toolset=msvc stage in boost/config/user.hpp I activated #define BOOST_ALL_DYN_LINK Linking fails with: thread.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __cdecl boost::gregorian::greg_month::greg_month(unsigned short)" (__imp_??0greg_month@gregorian@boost@@QEAA@G@Z) referenced in function "public: __cdecl boost::gregorian::date::date(enum boost::date_time::special_values)" (??0date@gregorian@boost@@QEAA@W4special_values@date_time@2@@Z) bin.v2\libs\thread\build\msvc-9.0\release\address-model-64\threading-multi\boost_thread-vc90-mt-1_45.dll : fatal error LNK1120: 1 unresolved externals Thanks!

1 0

Range - Char literal question
by Rao, Anant 10 Dec '10

10 Dec '10

Hi, I need to iterate thru strings (For various reasons, I can't use string or vector<char> containers). I found that boost::range exactly fits the bill for me. I get all the convenience of an iterator (from as_literal.hpp). I have a piece of code char* char_s = "I am fine"; char *cp; std::size_t sz = strlen(char_s); const char* str_end1 = str_begin( char_s ) + sz; for (cp = str_begin(char_s); cp != str_end(char_s); ++cp) cout << *cp; I have couple of questions: 1. In the loop, boost::range seems to be calling strlen every iteration. This is an overhead. I was wondering if there's a way I can pass in the length myself so that boost::range would use it and avoid calling strlen(). 2. If it's not possible, is there a way for me to use iterators (boost or non-boost) over char strings? Thanks so much in advance for your help, Anant The information contained in this email message and its attachments is intended only for the private and confidential use of the recipient(s) named above, unless the sender expressly agrees otherwise. Transmission of email over the Internet is not a secure communications medium. If you are requesting or have requested the transmittal of personal data, as defined in applicable privacy laws by means of email or in an attachment to email, you must select a more secure alternate means of transmittal that supports your obligations to protect such personal data. If the reader of this message is not the intended recipient and/or you have received this email in error, you must take no action based on the information in this email and you are hereby notified that any dissemination, misuse or copying or disclosure of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by email and delete the original message.

7 15

[Units] derived units of SI system (newbie)
by André Berthe 10 Dec '10

10 Dec '10

Dear List, I would like to calculate a shear stress based on a shear rate and a viscosity using Boost.Units. Here I have problems using derived dimensions and conversion factors based on a existing system. The error messages of my compiler are in German, so I tried to document my problems with a test code: <main.cpp> #include <boost/units/systems/si/dynamic_viscosity.hpp> #include "stress.h" #include "shearrate.h" namespace bu = boost::units; namespace SI = bu::si; main(){ //Define a quantity of unit stress. Unfortunately there is no //realization of the defined physical dimension stress in si. //So a user defined type from stress.h (see below) is used: bu::quantity<SI::stress> WSS_x; //Define a shear rate. I did not understand how to use a //inverse time as dimension. Therefore I defined the derived //dimension per_time in shearrate.h. Is it possible to add it to //the si system (as I tried) or do I have to define //my own system and a conversion factor? bu::quantity<SI::per_time> WSR_x(1*per_second); //There is a existing si type for the dynamic viscosity. //However, there is no defined constant. How is the //correct way to assign a value? Should I define this //constant? bu::quantity<SI::dynamic_viscosity> eta; //Calculation of the shear stress. It seems that this calculation //tries to use a »sizeof« on eta, that seems to have a // incomplete type //(»boost::STATIC_ASSERTION_FAILURE<false>«). And there //seems to be something wrong with the conversion. //Do I have to define a conversion factor? Or is this error //caused by my previous mistakes? WSS_x=WSR_x/eta; } </main.cpp> Included header file 1: <stress.h> #include <boost/units/systems/si/base.hpp> #include <boost/units/physical_dimensions/stress.hpp> #include <boost/units/make_system.hpp> namespace boost { namespace units { namespace si { typedef unit<stress_dimension,si::system> stress; } // namespace si } // namespace units } // namespace boost </stress.h> Included header file 2: <shearrate.h> #include <boost/units/base_dimension.hpp> #include <boost/units/derived_dimension.hpp> #include <boost/units/io.hpp> #include <boost/units/quantity.hpp> #include <boost/units/static_constant.hpp> #include <boost/units/unit.hpp> #include <boost/units/base_unit.hpp> #include <boost/units/systems/si/time.hpp> namespace boost { namespace units { namespace si { typedef derived_dimension< time_base_dimension,-1>::type per_time_dimension; // [1/m] typedef unit< si::per_time_dimension, si::system > per_time; static const per_time per_second; static const per_time per_seconds; } } } Thank you, André

2 1

Possible bug: ostringstream
by Jammy Cheng Chen 10 Dec '10

10 Dec '10

Hi All, I have come across a bug associated the following code, it work fine in VS2008 release mode and crash in debug mode, I did some research found it should be a bug in the microsoft implementation of ostringstream, Is anybody know how to fix this or alternative way? Any ideas would be appreciated. BTW: I must use std::ostringstream because actually lot of dependencies dll was developed with std::ostringstream.str() return. I don't want change the dependencies project it wastes too much. std::string result( "" ); size_t length = source.size(); std::ostringstream offset; long offsetsToSource = 12135L; offset << offsetsToSource; std::string nsource = offset.str(); result.reserve( nsource.length() * 1.6 ); std::for_each( nsource.begin(), nsource.end(),ToXML( result, "\"&<>" ) ); msvcp90d.dll!std::_Container_base_secure::_Orphan_all() Line 223 + 0x5 bytes C++ msvcp90d.dll!std::_Container_base_secure::~_Container_base_secure() Line 115 C++ msvcp90d.dll!std::_String_base::~_String_base() + 0x11 bytes C++ msvcp90d.dll!std::_String_val<unsigned short,std::allocator<unsigned short> >::~_String_val<unsigned short,std::allocator<unsigned short> >() + 0x11 bytes C++ msvcp90d.dll!std::basic_string<char,std::char_traits<char>,std::allocato r<char> >::~basic_string<char,std::char_traits<char>,std::allocator<char> >() Line 917 + 0xf bytes C++ getMetaData.dll!getQMAttributes(Av::Generic::ContainerIF * pcFile=0x026a0924, Av::Generic::MasterMobIF * pMasterMob=0x0278d234, Av::Generic::TapeMobIF * pTapeMob=0x0279275c, MobInfo & mobInfo={...}) Line 748 + 0x73 bytes C++

3 3

[Fusion] Runtime complexity of boost::fusion::find?
by Clinton Mead 10 Dec '10

10 Dec '10

Hi everyone On the following documentation page: http://www.boost.org/doc/libs/1_45_0/libs/fusion/doc/html/fusion/algorithm/… It mentions that the computational complexity for "find" is linear. However, I can not understand how this is the case. As far as I understand all find needs to do is to look through types, simply iterating through the sequence types at compile time using result_of::next<X>::type where where X is initially result_of::begin<SEQ>::type. So I can't see how any actual work is done by find. Am I missing something here? I'm working on a parameter library, and I assumed things like "find" used constant or no time to execute. Could people please explain how find could use linear time? Thanks Clinton

2 1

Re: [Boost-users] variant over base and derived classes
by Hicham Mouline 09 Dec '10

09 Dec '10

> ----Original Message----- >From: "Dave Abrahams" [dave(a)boostpro.com] >Date: 09/12/2010 05:00 PM >To: boost-users(a)lists.boost.org >Subject: Re: [Boost-users] variant over base and derived classes >At Thu, 09 Dec 2010 09:15:45 -0500, >Hicham Mouline wrote: >> >> >> >Subject: Re: [Boost-users] variant over base and derived classes >> >> >(sorry if this is a top post, my phone shows no msg quotes) >> >> >I'm no expert on this, but isn't there an compile time function to >> >testing if an instance is derived from another (in introspection or >> >something)? You could then maybe sort the variant types for most to >> >least derived and then test untill you find the suitable cast? >> >> >Just brainstorming pretty much. Hope its useful! >> >Best, >> >Dee >> >> yes, there is boost::is_base_of or some metafct like that in type_traits. >> not quite sure how to implement the sort though? >> will checkout mpl::sort with binary predicate base_or_derived. >> I have under 10 types, so compile time should be ok >> thanks, >I haven't looked at your use-case in detail, but it's a bit of a >stretch to imagine a case in which runtime polymorphism via virtual >functions would be useful inside a variant, since you need to know the >most derived type of each stored thing anyhow. Are you going to be >referring to the stored items via a base class pointer? >-- >Dave Abrahams >BoostPro Computing >http://www.boostpro.com I have a class hierarchy that I want to be able to mpi::broadcast. mpi::broadcast not being able to polymorphically receive the object on the receiver's end forced me to wrap all the hierarchy in a variant, which I can send and it works at reception as well. at reception, mpi::broadcast requires the real object to exist already. The code that sends with mpi::broadcast receives a base class reference (or pointer). The code that receives with mpi::broadcast doesn't know what it is receiving. Apparently, boost::serialization can deal with base pointers fine, and I think it creates on the heap the loaded objects, or? The solution w variant works here, I am trying to simplify. thanks,

1 0

lib - errata
by Tim St. Clair 09 Dec '10

09 Dec '10

Is there a simple loc to see a libraries errata over versions? -- Cheers, Timothy St. Clair

1 0

Re: [Boost-users] variant over base and derived classes
by Hicham Mouline 09 Dec '10

09 Dec '10

>-----Original Message----- >From: "Diederick C. Niehorster" [dcnieho(a)gmail.com] >Date: 09/12/2010 01:51 PM >To: boost-users(a)lists.boost.org >Subject: Re: [Boost-users] variant over base and derived classes >(sorry if this is a top post, my phone shows no msg quotes) >I'm no expert on this, but isn't there an compile time function to >testing if an instance is derived from another (in introspection or >something)? You could then maybe sort the variant types for most to >least derived and then test untill you find the suitable cast? >Just brainstorming pretty much. Hope its useful! >Best, >Dee yes, there is boost::is_base_of or some metafct like that in type_traits. not quite sure how to implement the sort though? will checkout mpl::sort with binary predicate base_or_derived. I have under 10 types, so compile time should be ok thanks,

2 1