February 2002 - Boost-users

Threads and Smart Ptrs
by Colin Fox 16 Feb '02

16 Feb '02

Greetings, everyone. I'm currently having some trouble with a heavily multithreaded app which uses objects shared between threads via smart pointers. It's a multi-user application, where each user has a thread, and when one user sends a message to another (or broadcasts to all), a message object is created, and a smart pointer to that message is put into a queue for each thread. I'm using pthread_mutex for locking the queues for each thread. This program will sometimes work flawlessly for hours, and other times it will die within moments of starting. Pretty much every time it dies, it's because the message object has been freed while there are still smart pointers pointing to it. I know that the recent version of the smart pointer library was supposed to have added thread-safety to it, but I'm wondering if anyone else is having similar troubles. I'm using gcc 3.0.3 on Linux, and boost 1.27. I also discovered some things in the gcc documentation having to do with threads, (eg: when you compile the compiler, you have to tell it to build multi-threaded programs). And there are various threading flags that can be used during a compile, and I'm not sure which to use (or all of them?): -D_PTHREADS -D_REENTRANT -pthread : I'm using all those right now. Is that wrong? Any help would be greatly appreciated. It's driving me mad! :) Regards, Colin -- Colin Fox CF Consulting Inc. cfox(a)telus.net

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Solaris CC version of Boost
by Kostas Kavoussanakis 15 Feb '02

15 Feb '02

Hello, I need to use boost with Solaris CC. Is this possible? Many thanks in advance, Kostas

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Regex.hpp compile problem
by John Maddock 15 Feb '02

15 Feb '02

>I have some compile problems when I include regex.hpp from boost 1.27.0, >that seem to be internal to the interaction between my platform and >compiler. > >Are these known problems, and if so, what is the solution? > >ratts:~/cpp/classperf$ uname -a >Linux ratts 2.2.6 #46 Tue Apr 27 16:40:54 CDT 1999 i486 unknown >ratts:~/cpp/classperf$ gcc -v >Reading specs from /usr/lib/gcc-lib/i486-linux/2.7.2.3/specs >gcc version 2.7.2.3 Sorry, but I don't think that either boost or the regex lib has ever been testsed on a compiler that old (gcc 2.7?) You could try reading about boost's configuration options (libs/config/config.htm) and then running the configure script under libs/config. - John Maddock http://ourworld.compuserve.com/homepages/john_maddock/

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The first question: How to build???
by olexander_shyrokov 15 Feb '02

15 Feb '02

Hello. Using: Windows 2000, MSVC 6, Stlport 4.5 I got a problem with building bost using jam. Actually what I need is regex, but I want to build all of them (for practice) :). I've downloaded jam, then I even built it from tools/build/jam_src, so it looks like I do have the correct version of the jam. So I'm making cd c:\src\boost then jam -sBOOST_ROOT=. -sTOOLS="msvc-stlport" And what I've got begins from: ./tools/build\boost-base.jam:1531: in subvariant-target *** argument error * rule dll-files ( module implib ? : sources * : target-type ? ) Can anyone help me with this? Thanks.

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C++ socketstreams
by nils_ljunggren 14 Feb '02

14 Feb '02

This is not my favourite design but when using TCP/IP I belive this to be extra-ordinary: [lib.sockstream] The header <sockstream> defines four class templates and six types that associate stream buffers with sockets and assists reading and writing to and from sockets. In addittion <sockstream> defines three operators that extracts connection-oriented streams from connection-oriented server-streams. Header <sockstream> synopsis namespace sock { template <class charT, class traits= std::char_traits<charT> > class basic_socketbuf; typedef basic_socketbuf<char> socketbuf; typedef basic_socketbuf<wchar_t> wsocketbuf; template <class charT, class traits= std::char_traits<charT> > class basic_isocketstream; typedef basic_isocketstream<char> isocketstream; typedef basic_isocketstream<wchar_t> wisocketstream; template <class charT, class traits= std::char_traits<charT> > class basic_osocketstream; typedef basic_osocketstream<char> osocketstream typedef basic_osocketstream<wchar_t> wosocketstream; template <class charT, class traits= std::char_traits<charT> > class basic_socketstream; typedef basic_socketstream<char> socketstream; typedef basic_socketstream<wchar_t> wsocketstream; template <class charT, class traits> basic_isocketstream& operator >> (basic_isocketstream<charT, traits>& at, basic_isocketstream<charT, traits>& cs); template <class charT, class traits> basic_isocketstream& operator >> (basic_isocketstream<charT, traits>& at, basic_osocketstream<charT, traits>& cs); template <class charT, class traits> basic_isocketstream& operator >> (basic_isocketstream<charT, traits>& at, basic_socketstream<charT, traits>& cs); } Please reply to mailto:nlj@adr.dk [This is a Boost library proposal. - Mod]

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Regex.hpp compile problem
by Dr. Ian McDonald 14 Feb '02

14 Feb '02

Hi, I have some compile problems when I include regex.hpp from boost 1.27.0, that seem to be internal to the interaction between my platform and compiler. Are these known problems, and if so, what is the solution? ratts:~/cpp/classperf$ uname -a Linux ratts 2.2.6 #46 Tue Apr 27 16:40:54 CDT 1999 i486 unknown ratts:~/cpp/classperf$ gcc -v Reading specs from /usr/lib/gcc-lib/i486-linux/2.7.2.3/specs gcc version 2.7.2.3 g++ performer.cpp In file included from /usr/local/include/boost/regex.hpp:44, from classperf.h:5, from performer.cpp:1: /usr/local/include/boost/regex/detail/regex_stack.hpp:47: parse error before `<' /usr/local/include/boost/regex/detail/regex_stack.hpp:52: `Allocator' was not declared in this scope /usr/local/include/boost/regex/detail/regex_stack.hpp:52: template argument 2 is invalid /usr/local/include/boost/regex/detail/regex_stack.hpp:52: `type' is not a class or namespace /usr/local/include/boost/regex/detail/regex_stack.hpp:52: warning: ANSI C++ forbids typedef which does not specify a type /usr/local/include/boost/regex/detail/regex_stack.hpp:52: confused by earlier errors, bailing out Thanks, Ian -- Dr. Ian McDonald Website Developer, No Fuss Websites.com T: +44 (0) 20 761 32110 F: +44 (0) 20 769 25461 -- Dr. Ian McDonald Website Developer, No Fuss Websites.com T: +44 (0) 20 761 32110 F: +44 (0) 20 769 25461

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Distribution guidelines
by Edward Diener 12 Feb '02

12 Feb '02

I didn't see any guidelines for distributing the Boost header files in an implementation. Are there any ? As an example I may use only a small number of the header files for my distribution, so I assume I am not constrained to deliver all the header files nor am I constrained to deliver the full Boost distribution for any given version. While I can query the end-user during installation about having a specific version of Boost, and not install Boost files if the user does have a specific version, it does not seem as if I have to install the entire distribution, or even the entire set of header files if I am installing locally to my own directory structure. It would be nice if Boost actually had an install in its distribution because then , under Windows where I work, there would be a registry entry which I could read during the installation of any product which uses Boost. Has anyone ever suggested this, or is it seen as outside the boundaries of Boost ?

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Regex questions
by Edward Diener 12 Feb '02

12 Feb '02

1) Support for Borland's C++ Builder 3 was dropped in moving the Regex++ implementation to Boost. Was this dropped because BCB3 can not support Boost, or Regex++, or was it just too much work to get it working with the Boost Regex++ version ? 2) Configuring Regex++ builds. Do I use user.hpp to configure the build, or is this used at the point of usage, or both ? If so, how do I know if BOOST_REGEX_NO_TEMPLATE_SWITCH_MERGE applies to a given compiler, and what does BOOST_REGEX_NO_W32 actually do. Finally what do the locale defines actually do ? Does defining the CPP or C locales constrain the Boost classes to use those locales or is it just setting a default locale which I can switch when instantiating the template classes ?

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Poll results for Boost-Users
by Boost-Users＠yahoogroups.com 12 Feb '02

12 Feb '02

The following Boost-Users poll is now closed. Here are the final results: POLL QUESTION: Yahoo! groups can be configured so that only the moderators can view membership list, or so that membership lists can be viewed by anyone (email addresses are always munged for non-moderators; my email address would appear as something like jim.hyslop@.le...) Do you want the membership list to be freely available to be viewed by anyone, or do you want the membership list kept private so only the moderators can view the list? CHOICES AND RESULTS - I want only the moderators to be able to view the membership list, 0 votes, 0.00% - I want anyone to be able to view the membership list, 0 votes, 0.00% For more information about this group, please visit http://groups.yahoo.com/group/Boost-Users For help with Yahoo! Groups, please visit http://help.yahoo.com/help/us/groups/

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Possible interest in select_by_predicate?
by Jonathan Brownell 11 Feb '02

11 Feb '02

I work in doing programming involving quite a bit of data analysis, and lately I've gotten sick and tired of doing routine searches on vectors and other linear containers to pull out maximum/minimum values. I ended up sitting down and writing a unary function object that retains a value based on any predicate. An example is worth a thousand words: int array[10] = { 5, 4, 6, 3, 9, 0, 7, 2, 8, 1 }; int maximum = std::for_each(&array[0], &array[10], select_by_predicate<int, std::greater>()); int minimum = std::for_each(&array[0], &array[10], select_by_predicate<int, std::less>()); assert(maximum == 9 && minimum == 0); Another example, using select_by_predicate independently: select_by_predicate<int, std::greater> max_error(0); for(loop through data samples) { double error; ... analyze data sample error ... max_error.compare(error); // same as max_error(error) } std::cout << "Maximum error: " << max_error; Is select_by_predicate something that boost users would be interested in? It's been helpful to me in all kinds of contexts. -Jonathan

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