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Re: [Boost-users] [boost] [Review] Boost.Endian by BEman Dawes starts today
by Hartmut Kaiser 05 Sep '11

05 Sep '11

> According to the schedule, the review of the Boost.Endian library by Beman > Dawes starts today. > > =========== > What is it? > =========== > > Boost.Endian provides facilities to manipulate the byte ordering of > integers. > > * The primary use case is binary I/O of integers for portable exchange > with other systems, via either file or network transmission. > > * A secondary use case is to minimizing storage size via integers of sizes > and/or alignments not supported by the built-in types. Integers 1, 2, 3, > 4, 5, 6, 7, and 8 bytes in length are supported. > > * Two distinct approaches to byte ordering are provided. Each approach has > a long history of successful use, and each approach has use cases where it > is superior to the other approach. > > * The explicit approach provides explicit functions to reorder bytes. > All four combinations of non-modifying or modifying, and unconditional or > conditional, functions are provided. > > * The implicit approach provides integer classes that mimic the built-in > integers, implicitly handling all byte reordering. Even if this is not a full review, I would like to vote YES to include this library into Boost. Boost.Spirit is using (and shipping) with an older version of this library for several years now and we never had any problems with its usage in Spirit. It is used as the underlying framework for the binary parsers and generators and it is functioning as advertised. As a quick test I replaced the internal (older) version of Boost.Endian in Spirit with the reviewed version. All of Spirits regression tests still pass. Regards Hartmut --------------- http://boost-spirit.com > > =================== > Getting the Library > =================== > > Docs are available at http://boost.cowic.de/rc/endian/doc/index.html > A zip file is available at http://boost.cowic.de/rc/endian/endian-rc1.zip > INSTALL instructions at http://boost.cowic.de/rc/endian/INSTALL > > Alternately, the whole library can be checked out of the sandbox: > > svn co http://svn.boost.org/svn/boost/sandbox/endian endian > > ================ > Writing a Review > ================ > > The reviews and all comments should be submitted to the developers list, > and the email should have "[Endian] Review" at the beginning of the > subject line to make sure it's not missed. > > Please explicitly state in your review whether the library should be > accepted. > > The general review checklist: > > - What is your evaluation of the design? > - What is your evaluation of the implementation? > - What is your evaluation of the documentation? > - What is your evaluation of the potential usefulness of the > library? > - Did you try to use the library? With what compiler? Did you > have any problems? > - How much effort did you put into your evaluation? A glance? A > quick reading? In-depth study? > - Are you knowledgeable about the problem domain? > > And finally, every review should answer this question: > > - Do you think the library should be accepted as a Boost library? > > Be sure to say this explicitly so that your other comments don't obscure > your overall opinion. > > > > > _______________________________________________ > Unsubscribe & other changes: > http://lists.boost.org/mailman/listinfo.cgi/boost

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Metaprogramming + Multiple Inheritance?
by Hossein Haeri 05 Sep '11

05 Sep '11

Dear all, I am looking for problems a reasonable design for solving which requires mixing (template/preprocessor) metaprogramming and multiple inheritance, say for a single class. In particular, has any part of the Boost library been designed with this mixture? TIA,--Hossein

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[meta-state-machine] Flag_AND doesn't work
by Péter Szabados 05 Sep '11

05 Sep '11

Hi, I am using Boost 1.47.0, and wrote a state machine in MSM with 2 parallel regions. In each region, one state has a flag defined. According to the documentation, when I ask the flag the following way: sm.is_flag_active<FlagStarted, StateMachine::Flag_AND>() then it returns true if both regions are in a state with the flag. However, it doesn't work for me. I have attached an example of this problem. It has the states Stopped1, Started1 and Stopped2, Started2 for the two regions respectively. The states Started1 and Started2 has the flag FlagStarted attached. The flag is checked after each call of process_event. The output of the program is the following: Entering Stopped1 Entering Stopped2 (sm.is_flag_active<FlagStarted, StateMachine::Flag_OR>()): no (sm.is_flag_active<FlagStarted, StateMachine::Flag_AND>()): no Leaving Stopped1 Entering Started1 (sm.is_flag_active<FlagStarted, StateMachine::Flag_OR>()): yes (sm.is_flag_active<FlagStarted, StateMachine::Flag_AND>()): no Leaving Stopped2 Entering Started2 (sm.is_flag_active<FlagStarted, StateMachine::Flag_OR>()): yes (sm.is_flag_active<FlagStarted, StateMachine::Flag_AND>()): no After the second transition, we are in state (Started1, Started2). The flag should be active here, but it isn't. Is there a problem with MSM, or am I doing something wrong? -- Péter

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zip_iterator documentation: probably malformed example
by Krzysztof Żelechowski 05 Sep '11

05 Sep '11

At [http://www.boost.org/doc/libs/1_47_0/libs/iterator/doc/zip_iterator.html Zip Iterator]: is:: {{{zip_it->get<0>() = 42.0;}}} (syntax error) works:: {{{zip_it -> template get <0> () = 42.0;}}}

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exceptions from boost::filesystem not catchable on os/x 10.6.8 boost-1.47.0
by david x callaway 05 Sep '11

05 Sep '11

os/x 10.6.8 uname -a Darwin apple1 10.8.0 Darwin Kernel Version 10.8.0: Tue Jun 7 16:33:36 PDT 2011; root:xnu-1504.15.3~1/RELEASE_I386 i386 boost 1.47.0 ./bootstrap.sh --prefix=$HOME/boost ./b2 link=static --disable-filesystem2 install # I've tried without disabling filesystem2, same result gcc -v Using built-in specs. Target: i686-apple-darwin10 Configured with: /var/tmp/gcc/gcc-5666.3~6/src/configure --disable-checking --enable-werror --prefix=/usr --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program-transform-name=/^[cg][^.-]*$/s/$/-4.2/ --with-slibdir=/usr/lib --build=i686-apple-darwin10 --program-prefix=i686-apple-darwin10- --host=x86_64-apple-darwin10 --target=i686-apple-darwin10 --with-gxx-include-dir=/include/c++/4.2.1 Thread model: posix gcc version 4.2.1 (Apple Inc. build 5666) (dot 3) test app compiled: g++ -Wall -I $HOME/boost/include fs.cpp -L$HOME/boost/lib -lboost_filesystem -lboost_system otool -L a.out a.out: /usr/lib/libstdc++.6.dylib (compatibility version 7.0.0, current version 7.9.0) /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 125.2.11) source below. when I run it with a non-existent filename I expect to catch an exception, but instead nothing happens, i.e. I just return to the shell prompt. I tried defining a struct locally and throwing it and the catch works fine. any ideas? thx dxc ------------------------------------------------------------ #include <iostream> #include <stdlib.h> #include "boost/filesystem.hpp" int main(int argc, const char** argv) { if(argc != 2) { std::cout << "usage: a.out filename\n"; exit(1); } const char* a_path = argv[1]; try { boost::filesystem::exists(a_path); } catch(const boost::filesystem::filesystem_error& e) { std::cout << "caught filesystem_error\n"; std::cout << e.what() << "\n"; exit(1); } catch(const std::exception& e) { std::cout << "caught some other error\n"; std::cout << e.what() << "\n"; exit(1); } catch(...) { std::cout << "caught unknown exception\n"; exit(1); } return 0; }

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Using boost function input iterator with class member functions
by Michael King 05 Sep '11

05 Sep '11

Hello, I am trying to use a class member function in conjunction with boost's function input iterator, and am having trouble coming up with a solution which can in any way be considered elegant... My initial thought process was to do something like : std::copy( // does not work because the functor (1st arg to make_function_input iterator ) cannot be temporary... or something like that boost::make_function_input_iterator(boost::bind(&My_Class::my_function, 0)), boost::make_function_input_iterator(boost::bind(&My_Class::my_function, 10)), std::ostream_iterator<result_type>(std::cout, " ") ); However, this fails as noted above. Thus, i had to look at some compiler error messages in order to figure out the return type of boost::bind and create some boost::bind object producing the working code below, however, this looks pretty terrible. Can anyone suggest a more convenient solution to the problem I am trying to solve? Thanks, Michael King #include<iostream> #include<iterator> #include<boost/bind.hpp> #include<boost/iterator/function_input_iterator.hpp> class foo { public: typedef double result_type; result_type return_random() const { return drand48(); } }; int main() { foo bar; // found type from compiler error message... boost::_bi::bind_t< double, boost::_mfi::cmf0< double, foo>, boost::_bi::list1< boost::_bi::value<foo> > > f = boost::bind(&foo::return_random, bar); std::copy( boost::make_function_input_iterator(f, 1), boost::make_function_input_iterator(f, 10), std::ostream_iterator<double>(std::cout, "\n") ); return 0; }

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linking with libboost_graph not enough, but libboost_regex required?
by Oliver Kullmann 04 Sep '11

04 Sep '11

Hello, we have some legacy code, which after a change of system no longer runs: The new system is Boost 1.44.0 under Linux (Suse 11.4 for the record), but compiling with gcc version 4.1.2. > uname -a Linux csnereid 2.6.37.1-1.2-desktop #1 SMP PREEMPT 2011-02-21 10:34:10 +0100 i686 i686 i386 GNU/Linux We have a simple application which reads a graph-file and performs a simple computation. It links to libboost_graph. Apparently that draws in the libboost_regex, but that used to work: On the older installation (Suse 10.0 for the record) we had for the application > ldd Application libboost_graph.so.1.44.0 => /home/csoliver/SAT-Algorithmen/OKplatform/ExternalSources/Installations/Boost/4.1.2/1_44_0/lib/libboost_graph.so.1.44.0 (0x00002aaaaabc2000) libboost_regex.so.1.44.0 => /home/csoliver/SAT-Algorithmen/OKplatform/ExternalSources/Installations/Boost/4.1.2/1_44_0/lib/libboost_regex.so.1.44.0 (0x00002aaaab6f5000) and we see that at that time, also with Boost 1.44.0, linking was established to the local Boost installation, the same for libboost_graph and libboost_regex. However, now this implicit addition of the regex-link-library (which is managed by the Graph-library itself, not visible to the user --- I can't find the boost-regex-library anywhere mentioned in the Boost-Graph-documentation) does not work anymore --- if there is a system-wide Boost installation, it uses that, and otherwise it breaks: libboost_graph.so.1.44.0 => /home/csoliver/OKplatform/ExternalSources/Installations/Boost/4.1.2/1_44_0/lib/libboost_graph.so.1.44.0 (0x00007f8170fbe000) libboost_regex.so.1.44.0 => /usr/lib64/libboost_regex.so.1.44.0 (0x00007f81701c1000) libboost_graph.so.1.44.0 => /compsci/saturn/staff/csoliver/OKplatform/ExternalSources/Installations/Boost/4.1.2/1_44_0/lib/libboost_graph.so.1.44.0 (0xb7774000) libboost_regex.so.1.44.0 => not found I guess linking explicitly to libboost_regex would solve the problem, but that's under the circumstances not so easy to do, and furthermore something seems wrong here, and I would like to know what (it shouldn't be needed to link to libboost_regex, or, if so, then it should be documented). Thanks for your consideration! Oliver

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boost::zip_iterator does not work with std::istreambuf_iterator
by Krzysztof Żelechowski 04 Sep '11

04 Sep '11

1. boost::zip_iterator requires a readable iterator. 2. std::istreambuf_iterator is a readable iterator. 3. boost::zip_iterator cannot dereference std::istream_iterator because std::istreambuf_iterator returns by value while boost::zip_iterator returns by reference; the exact error message is invalid initialization of non-const reference of type ‘char&’ from an rvalue of type ‘std::istreambuf_iterator<char, std::char_traits<char> >::char_type’ Contradiction? Am I missing anything? Chris

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boost serialization help
by ohad barta 04 Sep '11

04 Sep '11

Hi My name is Ohad, and I work for the Technion institution, Israel. We are currently working on a research that involves programming in C++, and for that project we are using the serialization module of Boost. I'm not sure if this is the place to ask for help with boost. If not, Could you please direct me to the right address? my problems: 1) does the following supposed to work? : I have a : class saving helper{ boost::archive::binary_archive* ar; } and: class Y { X* first vector <Y*> second } and I try to save Y with the saving helper: for each level of Y object I initialize a saving helper, directly call a function that does *ar & * first (the function name isnt serialize\save) for each Y* on the next level I create a new saving helper object with a new pointer, initiallized the same: saving_helper::saving_helper(saving_helper* to_copy){ this->ar = to_copy->ar;} and continue saving the very same object (another level) with the new saving helper (the load is standard - via a regualr load function) I know that this is not the standard way to use boost, but I dont have much choice. 2) When trying to use the above method with text archive, I always get a streaming error, but If I use a binary archive than the streaming error vanished and instead I start to read the file from its middle (i.e. read the forth number instead of the first, reading the fifth bumber instead the second,etc). increasing the file length by adding to it 3 redundent numbers solved those two problems, and yet Im looking for a more stable solution, so help will be apprecialted. 3) boost tracking: where should I put the BOOST_CLASS_TRACKING macro? I currently use: boost 1.47.0 visual studio 2010 OS windows 7 Thanks in advance Ohad

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Subclassing "position_iterator"
by Alexander Feldman 04 Sep '11

04 Sep '11

Hi, I have the following question. I want to subclass/implement a new position_iterator that recognizes lines such as: #line 11 "electrical.lcl" and updates accordingly its location. My question is how to do that in the most elegant manner. Shall I copy/paste "position_iterator.hpp" and hack the increment() method? Would you, guys, use a Qi parser to recognize these lines? Maybe there is a better way... Thanks, -- Alex

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