- Boost-users - lists.boost.org

A default constructor for Boost.MPI environment?
by Bo Peng 14 Dec '06

14 Dec '06

Dear boost users, I am using Boost.MPI for a python module so there is no argc, argv that can be provided to boost::parallel::mpi::environment(int & argc, char ** & argv) Because an environment object has to exist during the life time of the module, I have to define a global variable in an awkward way: int fake_argc = 0; char * fake_argv = ""; char ** ptr_argv = &fake_argv; boost::parallel::mpi::environment env(fake_argc, ptr_argv); Can a default constructor be provided? Bo

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[bjam]BorlandC++BuilderX problems staging Boost
by Jerry Schreiber 14 Dec '06

14 Dec '06

I am entirely new to Boost. I used the following command: bjam -sTOOLS=Borland stage I got a large amount of output with lots of errors indicated, but I did get quite a bit created in C:\Boost\boost_1_33_1\bin\boost\libs. As I am currently interested in using the filesystem library, I attempted to build the simple_ls.cpp example file and got the following error on the link step: ilink32 -D -ap -Tpe -x -Gn -v -LC:\CBuilderX\lib;C:\Boost\boost_1_33_1 c0x32.objwindows\Debug_Build\simple_ls.obj,C:\Boost\boost_1_33_1\libs\filesystem\windows\Debug_Build\simple_ls.exe,, cw32.lib import32.lib,, Turbo Incremental Link 5.65 Copyright (c) 1997-2002 Borland Fatal: Unable to open file 'LIBBOOST_FILESYSTEM-BCB-SD-1_33_1.LIB' Is C++BuilderX supported by Boost, and if so, what is the proper command for bjam? Is there anything else I need to do in order to get the link to work? Thanks. Jerry Schreiber

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Re: [Boost-users] HowTo Pass arguments to boost threads?
by Gabriel Ki 13 Dec '06

13 Dec '06

Hi, I am just trying the boost threads example from the link. #include <boost/thread/thread.hpp> #include <boost/thread/mutex.hpp> #include <boost/thread/tss.hpp> #include <iostream> boost::mutex io_mutex; boost::thread_specific_ptr<int> ptr; struct count { count(int id) : id(id) { } void operator()() { if (ptr.get() == 0) ptr.reset(new int(0)); for (int i = 0; i < 10; ++i) { (*ptr)++; boost::mutex::scoped_lock lock(io_mutex); std::cout << id << ": " << *ptr << std::endl; } } int id; }; int main(int argc, char* argv[]) { boost::thread thrd1(count(1)); boost::thread thrd2(count(2)); thrd1.join(); thrd2.join(); return 0; }// Output $ ./testme 10591400: 1 10591400: 2 10591400: 3 10591400: 4 10591400: 5 10591400: 6 10591400: 7 10591400: 8 10591400: 9 10591400: 10 Segmentation fault I have a few questions. 1) Why is id copied incorrectly in operator()? 2) Why does the count object get copied so many times? (i tried to write a copy constructor into count to see the id value) 3) I tried to add setstacksize in boost code and recompile. Is it a better way to do it? Thanks in advance. Gabriel ----- Original Message ---- From: Moshe Matitya <Moshe.Matitya(a)Kayote.com> To: boost-users(a)lists.boost.org Sent: Tuesday, December 12, 2006 3:40:03 AM Subject: Re: [Boost-users] HowTo Pass arguments to boost threads? Forever Kid wrote: > > What is the method boost prefers to pass arguments to boost > threads? (such as a pointer to some class > object) > > I saw the class thread_specific_ptr. > Is thread_specific_ptr designed for this purpose? > > Is there a recommended site with boost examples to check out? > Boost has good documentation, although I prefer to learn by > example and use strict documentation as I become more experienced. > > Thanks much, > Graham Take a look this introductory article on Boost.Threads by Bill Kempf: http://www.ddj.com/184401518 It addresses the question you're asking in a very clear, straightforward manner, with examples. Moshe _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users ____________________________________________________________________________________ Do you Yahoo!? Everyone is raving about the all-new Yahoo! Mail beta. http://new.mail.yahoo.com

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program_options variable_value as cast explodes
by Edward Z. Yang 13 Dec '06

13 Dec '06

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I'm using program_options in a few programs that I'm doing, and I'd like to clarify what's going on at certain points. vm.count("key") appears to tell us the number of times a flag is specified, but the documentation here: <http://www.boost.org/doc/html/variables_map.html> doesn't seem to say anything about it. Where is it specified? Does abstract_variables_map actually inherit off of std map? Why don't we use !vm["key"].empty() instead? (slightly more verbose, but it's clearer about what it's doing). The vm["term"].as<int>() template seems to combust spectacularly (as in cause a stack dump) when it turns out that vm["term"] doesn't actually exist. This doesn't seem very robust, and according to the documentation, an exception ought to be thrown. Am I just misunderstanding the docs? What is the preferred method determining that no parameters were passed? I'm currently using argc == 1, which seems a bit hacky, and doesn't catch errant parameters. Thanks. This might seem a little pedantic, but I'm trying to do things right. :-) -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFFf2sIqTO+fYacSNoRAqz5AJ9nBOEz87v8H4HjRB6mM2NSvNSllQCaA+SE s0kcqXiQXy7+ID7ugotbDKc= =NvIj -----END PGP SIGNATURE-----

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thread: scoped_try_lock
by Robert Marion 12 Dec '06

12 Dec '06

Hello all, I have many good examples of how to use a scoped_lock, but I can find almost none on a scoped_try_lock. Can anyone point me to some good examples of this? Is there any decent documentation for this? I found the boost docs, by the author, a bit difficult to follow. Thanks, Rob ____________________________________________________________________________________ Do you Yahoo!? Everyone is raving about the all-new Yahoo! Mail beta. http://new.mail.yahoo.com

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[ANN] Boost.Time_series: feedback requested
by Eric Niebler 12 Dec '06

12 Dec '06

I'm pleased to announce the availability of a new library for computing with time series (http://en.wikipedia.org/wiki/Time_series) From the documentation: > The purpose of the Boost.Time_series library is to provide data structures, numerical operators and algorithms to operate on time series. A time series is a series of data points, sampled at regular intervals. The library provides numerous time series containers, each with different time/space trade-offs, and a hierarchy of concepts which allow the time series to be manipulated generically. The library also provides operators and algorithms which use the generic interfaces to perform calculations on time series and accumulate various statistics about them. > > Boost.Time_series does not yet contain all the algorithms one might want in order to perform full time series analysis. However, the key contribution of Boost.Time_series is the framework and the rich hierarchy of concepts with which such algorithms can be written to efficiently and generically process series of data with widely divergent in-memory representations and performance characteristics. Boost.Time_series provides several such series containers, as well as mechanisms for defining additional series types and algorithms that fit within the framework. Some examples of series types that are provided are: dense, sparse, piecewise constant, heaviside and others, as well as adaptors for providing shifted, scaled and clipped series views. The documentation can be found here: http://boost-sandbox.sf.net/libs/time_series/doc/html/index.html The code is in time_series.zip, which can be downloaded here: http://boost-consulting.com/vault/index.php?directory=Math%20-%20Numerics Any suggestions for improvements are most welcome. -- Eric Niebler Boost Consulting www.boost-consulting.com

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bjam problems under cygwin/mingw
by Bo Peng 12 Dec '06

12 Dec '06

Dear boost-users, I compiled boost-1.33.1 under cygwin/mingw and experienced two problems: 1. using the .exe installer, build/jam_src/build.sh uses dos newlines. The latest cygwin can not execute this script because of this. dos2unix has to be used. 2. Before I figure out the dox2unix solution, I compiled bjam using msvc. The generated bjam.exe ignores -sTOOLSET=mingw and use msvc even when cl is not in the path. Cheers, Bo

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Re: [Boost-users] shared_ptr with custom free function
by james.jones＠firstinvestors.com 12 Dec '06

12 Dec '06

From: "Phil Endecott" <spam_from_boost_users(a)chezphil.org> > I have a C library that returns pointers to structs, and has special > free functions that I must call to finalise and free these structs. Is > there any way that I can create a shared_ptr that will call this > special library free function when the last copy is destroyed? I was > hoping that there would be some way of achieving this by overloading > operator delete, but it seems not. Any ideas? I would think one solution would be simply to wrap your C struct in a C++ class with a constructor and a destructor, then use shared_ptr on the C++ struct. Example: C: struct blob { ... }; blob * create_blob (); void free_blob(blob *); C++: class foo { public: foo() : data(create_blob()) {} ~foo() { free_blob(data); } private: blob * data; }; Now use shared_ptr< foo > as you usually would. This also gives you the flexibility NOT to use shared_ptr if you choose. - James Jones Administrative Data Mgmt. Webmaster 375 Raritan Center Pkwy, Suite A Data Architect Edison, NJ 08837

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[iostreams] : bug in <boost/iostreams/copy.hpp> ?
by Mathieu Peyréga 12 Dec '06

12 Dec '06

Hello, i'm a new user to these great boost libraries... I think i found a bug in <boost/iostreams/copy.hpp> (version 1.33.1) the current code starting line 80 is template<typename Source, typename Sink> std::streamsize copy_impl( Source& src, Sink& snk, std::streamsize buffer_size, mpl::false_, mpl::true_ ) { // Copy from an indirect Source to a direct Sink. using namespace std; typedef typename char_type_of<Source>::type char_type; typedef pair<char_type*, char_type*> pair_type; detail::basic_buffer<char_type> buf(buffer_size); pair_type p = snk.output_sequence(); streamsize total = 0; bool done = false; while (!done) { streamsize amt; done = (amt = iostreams::read(src, buf.data(), buffer_size)) == -1; std::copy(buf.data(), buf.data() + amt, p.first + total); if (amt != -1) total += amt; } return total; } I think it should be somthing like template<typename Source, typename Sink> std::streamsize copy_impl( Source& src, Sink& snk, std::streamsize buffer_size, mpl::false_, mpl::true_ ) { // Copy from an indirect Source to a direct Sink. using namespace std; typedef typename char_type_of<Source>::type char_type; typedef pair<char_type*, char_type*> pair_type; detail::basic_buffer<char_type> buf(buffer_size); pair_type p = snk.output_sequence(); streamsize total = 0; streamsize amt = 0; //bool done = false; while ((amt = iostreams::read(src, buf.data(),buffer_size))!= -1) { std::copy(buf.data(), buf.data() + amt, p.first + total); total += amt; } return total; } The current code happens to crash whereas the proposed version works properly... Did I miss something or a I right ? Regards, Mathieu -- http://matioupi.free.fr/

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[random] Four-Tap Shift Register RNG
by Sebastian Weber 12 Dec '06

12 Dec '06

Hello everyone! I'm using quite a lot of Boost libraries and have by the time implemented some bits which enhance some parts of the library. E.g. I ported a four-tap shift register random number generator to the random number library. I herby post the code as it might be interesting for others since this type of random number generator is known to produce random numbers with very low 2 and 3 point correlations (see http://arxiv.org/abs/cond-mat/9710104 ). The code is partially taken from the gsl-library and extended to 64bit unsigned integers which gives random numbers of very high precision. However, you can use this code only with the latest random number library from Boost CVS as the numbers returned use the full range of 32bit or 64bit unsigned ints, which causes overflows with the code in boost 1.33.1 and 1.34_RC. So please have look at the code and submit it into CVS if the code is any good. Greetings, Sebastian Weber

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