February 2011 - Boost - lists.preview.boost.org

Re: [boost] [Boost-users] [boost-users][ICL] ICL Compilation errors. Ticket #5207
by Joachim Faulhaber 01 Mar '11

01 Mar '11

Hi John, thanks again for all the questions. I am breaking up the long posting into smaller portions. (1) Representation of single elements with statically bounded intervals: 2011/2/23 John Reid <j.reid(a)mail.cryst.bbk.ac.uk>: > On 22/02/11 20:03, Joachim Faulhaber wrote: >> >> 2011/2/22 John Reid<j.reid(a)mail.cryst.bbk.ac.uk> >>> >>> I have started to use statically bounded intervals >>> and am finding more compilation issues. For example >>> with finding elements in a map: >>> >>> #define BOOST_ICL_USE_STATIC_BOUNDED_INTERVALS >>> #include<boost/icl/interval_map.hpp> >>> >>> void f() { >>> namespace icl = ::boost::icl; >>> icl::interval_map< float, int>().find( 0 ); >>> } >>> >>> This compiles without the #define but fails on static intervals. >> >> This is on purpose. The reason is that we can not represent a single >> element x using a right-open interval [x,?) of continuous values. >> right_open_interval is the default for statically bounded intervals, >> if BOOST_ICL_USE_STATIC_BOUNDED_INTERVALS is defined. In order to use >> find on an interval_map we have to construct an interval that >> represents a single element (internally). This is not possible in the >> logic of the ICL so this code won't compile. > > Nevertheless, users will expect to be able to locate elements in sets. How > should they do this? they could use dynamically bounded intervals for continuous interval element types :P Moreover, if we work with floating point numbers, the code float pi = 3.14159 ... ; icl::interval_set<float> icl_float_set = ... ; icl::contains( icl_float_set, pi ); would be problematic anyway since pi can not be represented precisely. right_open_interval<float> pi_itv = interval_around_pi(); icl::contains( icl_float_set, interval_around_pi() ); // better > Does > icl::contains( icl::interval_set< int >(), 0 ); > compile, but > icl::contains( icl::interval_set< float >(), 0. ); > does not for the same reason? yes. I have mentioned in the docs, that 'continuous_interval' is the only class template that allows to represent a singleton interval that contains only one element, an have provided a small example here: http://www.boost.org/doc/libs/1_46_0/libs/icl/doc/html/boost_icl/interface.… Regards, Joachim -- Interval Container Library [Boost.Icl] http://www.joachim-faulhaber.de

2 5

Re: [boost] [config] help with pathscale-4.x
by Belcourt, Kenneth 01 Mar '11

01 Mar '11

On Feb 28, 2011, at 11:30 AM, Belcourt, Kenneth wrote: > > On Feb 28, 2011, at 11:17 AM, John Maddock wrote: > >>> Here's the updated output. >>> >>> the following macros need to be defined >>> BOOST_NO_FENV_H >> >> Are you able to tell why that test is failing (should be in the >> configure >> log somewhere)? >> >> BTW the results online show Pathscale passing the config tests even >> without >> that one set... it should surely be available on Linux whatever the >> compiler? > > configure:2198: checking fenv.h (pass expected) > configure:2231: /home/kbelco/ekopath/4.0.8/bin/pathCC -o conftest - > I./../.. -I./../../libs/config/test -g -O2 conftest.cpp -lrt -lm - > lpthread >&5 > In file included from conftest.cpp:21: > ./../../libs/config/test/boost_no_fenv_h.ipp: In function 'int > boost_no_fenv_h::test()': > ./../../libs/config/test/boost_no_fenv_h.ipp:64: error: invalid > conversion from 'int (*)()throw ()' to 'int (*)(fexcept_t*, int)' It looks like this is currently unsupported in this release of the compiler. I think we can safely ignore this issue for now. -- Noel

2 1

[local] What do you think of the new syntax?
by Lorenzo Caminiti 28 Feb '11

28 Feb '11

Hello all, Before I spend 2+ weeks updating Boost.Local docs... can you please express an opinion about Boost.Local new and simplified syntax? If variadic macros are supported by your compiler: #include <boost/local/function.hpp> #include <iostream> int main() { double sum = 0.0; int factor = 10; void BOOST_LOCAL_FUNCTION_PARAMS(double num, const bind factor, bind& sum) { sum += factor * num; std::clog << "Summed: " << sum << std::endl; } BOOST_LOCAL_FUNCTION_NAME(add) add(100.0); return 0; } On all compilers (with variadic macros or not): #include <boost/local/function.hpp> #include <iostream> int main() { double sum = 0.0; int factor = 10; void BOOST_LOCAL_FUNCTION_PARAMS( (double num) (const bind factor) (bind& sum) ) { sum += factor * num; std::clog << "Summed: " << sum << std::endl; } BOOST_LOCAL_FUNCTION_NAME(add) add(100.0); return 0; } See also http://svn.boost.org/svn/boost/sandbox/local/libs/local/doc/html/index.html… Thanks a lot. -- Lorenzo

5 4

[filesystem v3] [iostreams] [interprocess] no windows access to memory mapped file
by Jeff Flinn 28 Feb '11

28 Feb '11

Filesystem V3 does a great job of handling unicode/utf8 paths in a windows/posix independent manner. boost::interprocess::file_mapping's constructor takes a raw const char* and explicitly calls CreateFileA to get a handle to a memory mapped file disallowing access to paths with non-ascii characters. boost::iostreams::mapped_file has a 7 month old ticket #4485 outlining the problems using it with filesystem V3. There is some path width switching logic that dispatches to CreateFileA or CreateFileW when the mapped_file is constructed with a filesystem V2 wpath. I tried faking things out by creating a wpath class in the filesystem namespace, but gave up and created a mapped file class for windows that uses filesystem::path and CreateFileW. I posted the issue with interprocess and Ion was of the opinion that this shorcoming needs to be addressed. I'm not sure if Steven is maintaining iostreams, or if he has given thought to how to address the iostreams implementation. My opinion is that boost libraries using paths in their interfaces should be using filesystem v3 paths. Beman, I think, suggested in the recent utf8 thread that boost libraries should use the wide version of the windows api passing path.wstring().c_str() where appropriate. Do others have thoughts on this issue? Are the windows wide api usage part of boost guidelines? Should they be? Thanks, Jeff

4 5

[config] help with pathscale-4.x
by Belcourt, Kenneth 28 Feb '11

28 Feb '11

Hi John, Any chance you can take a look at the attached configure generated user.hpp and recommend changes to Boost.config for supporting the Pathscale compiler? -- Noel Belcourt

2 4

[Gauge for interest] Surrogate template
by Alan sinde 28 Feb '11

28 Feb '11

Hi all, Recently I've an surrogate/proxy pattern implemented for storing related type as value. It is based on chapter 5 of Rumination on C++ by Andrew Koenig and Barbara moo. Original version required stored object to define their own virtual copy constructor. I have updated it to template version. Besides, it also relief user from defining virtual copy constructor by moving virtual copy inside surrogate. Thanks to template constructor making this possible. Drawback: 1) Each copy construction of surrogate incurs 2 virtual calls instead of 1 in the original. 2) Object compositing surrogate that has interface taking derived class must change to template member function in order to use template constructor of surrogate. Does anybody interested to include it as boost::surrogate? Example Usage: class boy { public: virtual void tell() = 0; }; class happy_boy : public boy { ... }; class study_boy : public boy { ... }; void say_hi(boy& the_boy) { the_boy.tell(); } int main() { std::cout << "Hello boost::surrogate!" << std::endl; happy_boy Terry; study_boy Thomas; std::vector<boost::surrogate<boy> > boy_list; boy_list.push_back(boost::surrogate<boy>(Terry)); boy_list.push_back(boost::surrogate<boy>(Thomas)); std::for_each(boy_list.begin(), boy_list.end(), say_hi); std::cin.get(); } Regards, Alan Tong

3 4

[GSOC] Coding on Boost for GSoC
by Erwann Gentric 28 Feb '11

28 Feb '11

Hello, As a French student preparing a Master in computer science, I'm highly motivated about coding on Boost C++ for the Google Summer of Code. I'm interested in the "Checks and Hashes" part in particular, and I would like to contact developers in order to specify my project, identifying what I'm expected to do, and to learn more about programming on Boost. Thanks! -- Erwann.

2 1

[interprocess] sharing memory between 32 bit and 64 bit Windows processes
by Arno Schödl 28 Feb '11

28 Feb '11

Hello Ion, ticket #5230 is the patch against the current development head. It would be great if you could review it soon. Our currently shipping product crashes on customer machines, and the patch may rot pretty quickly because there are so many size_t/ptrdiff_t -> size_type/difference_type replacements... Feel free to call if you want a quick answer to a question. Thanks! Arno -- Dr. Arno Schödl | aschoedl(a)think-cell.com Technical Director think-cell Software GmbH | Chausseestr. 8/E | 10115 Berlin | Germany http://www.think-cell.com | phone +49 30 666473-10 | US phone +1 800 891 8091 Amtsgericht Berlin-Charlottenburg, HRB 85229 | European Union VAT Id DE813474306 Directors: Dr. Markus Hannebauer, Dr. Arno Schoedl

2 2

[move] missing in 1.46
by Oliver Kowalke 28 Feb '11

28 Feb '11

I'm still missing boost.move in the current release (it was accepted in may 2010)! Should I use in the meanwhile <interprocess/detail/move.hpp>? Oliver -- GMX DSL Doppel-Flat ab 19,99 Euro/mtl.! Jetzt mit gratis Handy-Flat! http://portal.gmx.net/de/go/dsl

4 5

Filename length limit for Boost library
by Edward Diener 28 Feb '11

28 Feb '11

In the "Boost Library Requirements and Guidelines Page" in the "Directory Structure and Filenames" topic, it says: 'The maximum length of directory and file names is 31 characters.' and the rationale is: 'We had to draw the line somewhere, and so the limit imposed by a now obsolete Apple file system was chosen years ago. It still seems a reasonable limit to aid human comprehension.' I do not think that there are any real OSs that impose such a limit anymore and would like to see this limit lifted. I have already hit this limit many times, especially in naming test files for my sandbox libraries. I would rather create filenames which described well what a file is about rather than have a 31 character limit for a filename, which is not only highly arbitrary, but almost certainly obsolete in this day and age.

2 2