October 2014 - Boost-users - lists.preview.boost.org

[Boost.TypeTraits] Which was the first Boost release that included make_signed?
by dariomt＠gmail.com 24 Oct '14

24 Oct '14

Looking at Boost.TypeTraits documentation it seems that boost/type_traits/ make_signed.hpp was added in version 1.35.0, but I can't find any reference to that change in the release notes. Which was the first Boost release that included make_signed?

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Pattern issue with boost::regex
by Tal Shnaiderman 24 Oct '14

24 Oct '14

Hi All, I have a question regarding boost::regex pattern recognition and groups I created the following code, in it i created a pattern and a string to match: 1 2 3 4 5 6 p = "((a b (f+\\.))d d(\\3))"; str="a b ffff.d dfff."; boost::regex pattern(p, boost::regex::icase&boost::regex::extended &~boost::regex::no_bk_refs); bool match = boost::regex_match(str, pattern); cout << str << ((match)?"-Pattern is legal":"-Pattern is illegal" )<< endl; Pattern is illegal I'm saw that my result is 'Pattern is illegal' because the group \\3 that refers to (f+\\.) isn't equal to it. if I change the input to str="a b ffff.d dffff."; The pattern is legal. In other words my original plan was to use the \\3 instead of writing the pattern; p = "((a b (f+\\.))d d(f+\\.))"; But I can see that in the original pattern it simply expect the same output to reappear Is there a way I can use the group naming not to copy the (f+\\.) group? Thanks, I hope my Q is clear since I'm new to the regex topic.

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cross compile boost for arm TRY2 (Possibly solved)
by John Davis 24 Oct '14

24 Oct '14

Hello Here is a more succient attempt at building boost with a cross compiler. It appears to work. I'm not certain if it works at this point though. Please take a look and comment. Here is the script: --------------------------------------------------------------- #!/bin/bash # edit /opt/xxx/yyy/boost/boost_1_51_0/tools/build/v2/user-config.jam to add the following line # using gcc : 4.3arm : arm-linux-gnueabi-g++ : <architecture>arm <target-os>linux ; # Later we modify path, make sure our path does not use the cross compiler at beginning export PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/opt/java6/bin:/opt/java6/db/bin:/opt/java6/jre/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl # In this stage, we are using the host compiler. # setup env variable for $BOOST_DIR # I'm not sure if this is being used, but set it just in case. export BOOST_ROOT=/opt/xxx/yyy/boost/boost_1_51_0 # this is run from $BOOST_DIR/tools/build/v2 aka /opt/xxx/yyy/boost/boost_1_51_0/tools/build/v2 # in this case, I do not think you invoke the cross compiler. I think at this point, you are building # code for the host development machine. ./bootstrap.sh --with-toolset=gcc # setup path so that gcc from cross compiler is first in the path # also specify cross_compiler env variable in case its used. # # this will find the cross compiler for those who dont use the prefix, ie. gcc export PATH=/opt/arm/usr/local/arm-linux-gnueabi/bin:$PATH # this will find the cross compiler for those who use the prefix, ie. arm-linux-gnueabi-gcc export PATH=/opt/arm/usr/local/bin:$PATH # this will set the cross compiler prefix for those who use it export CROSS_COMPILE=arm-linux-gnueabi- # build boost.build so that we can build boost or are we building boost at this point? # # WARNING!!! # Specify an install directory so that it doesn't put the results in /usr/local/bin. # Even if you dont specify install as an option to ./b2 it will attempt to copy files to /usr/bin # in the following step! # # /opt/xxx/boost is where we want results. Our code will this dir in order to use boost. # /opt/xxx/yyy/boost/boost_1_51_0 is the top of the boost src. We are building beneath there. ./b2 --toolset=gcc-4.3arm --prefix=/opt/xxx/boost # at this point, we have the cross compiler in our path first. We are good to go for building our code using boost # with the cross compiler. -------------------------- -- John F. Davis 6 Kandes Court Durham, NC 27713 919-888-8358 独树一帜

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[Log] record_ostream too restrictive due to non-copyability, non-assignability?
by Latimerius 23 Oct '14

23 Oct '14

Hello, I'm trying to migrate from an existing solution to Boost.Log. So far I've been able to emulate all important features of the existing library - except one. The existing library supported submitting a log message in multiple statements. This is useful when the message being composed has conditional parts, when a part of it is composed in a loop or even a different function, something like this: auto logmsg = log (Channel::CORE, Severity::DEBUG); logmsg << "unconditional part"; if (condition) logmsg << " conditional part"; for (auto element : container) logmsg << element; logging_subroutine (logmsg); logmsg << endmsg; To that end I extracted a structure from the manual_logging() function from the Boost.Log documentation to hold the state of the message being composed: struct log_msg_state { my_logger & logger; logging::record rec; logging::record_ostream strm; ... <constructor & destructor definition> ... }; Having done this, I can emulate most of the above example fairly easily by defining a bunch of operator<<() overloads for the log_msg_state. However, I've been struggling with record_ostream. It was a bit of a challenge even to initialise it in the constructor - we can't use the initialiser list as we have to make sure first that our logging::record is valid. On the other hand, in the ctor body when the check can be performed, it's too late as record_ostream has already been constructed already and as it turns out, you can't do much with a constructed instance - no usual stuff like if (rec) strm = logging::record_ostream (rec); works! Fortunately, I've been able to hack around it like this: if (rec) new (&strm) logging::record_ostream (rec); Not pretty but has been working well so far! However, I've failed to find a solution for returning my log_msg_state (and thus record_ostream) from a function. The non-copyability, non-assignability, non-moveability are always getting in the way. (Note also that I do NOT want to hold a pointer to record_ostream in my log_msg_state and allocate it dynamically - that would certainly make things easier but I don't want to penalise each and every log message with a dynamic allocation for no good reason.) Could someone please advise me how to get the functionality I need, a solution or a work-around at least? Thanks in advance pvl

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unused parameter warning
by Kevin Molcard 23 Oct '14

23 Oct '14

Hi all, in some boost libraries I am using, there are compilation warnings complaining about unused parameter. For instance: boost/signals2/detail/auto_buffer.hpp:102:45: warning: unused parameter 'size' I'd like to get rid of the warnings. What is the best way to proceed? Should I send a merge request in github or something else? Thanks in advance Kevin

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using boost in cross compiler environment. intel host and arm target
by John Davis 22 Oct '14

22 Oct '14

Hello I have some code for arm which I would like to use with boost. The boost libraries I am interested in are not header only and thus require building. I have downloaded the boost tarfile and I have read the following two webpages relative but I am still confused. Here is a summary of the two urls and where I am confused. http://www.boost.org/doc/libs/1_56_0/more/getting_started/ This url has the following procedure which seems to use the host default compiler to build boost. Easy Method for Building and Installing Boost Binary Libraries. step 1: $ cd $BOOST_DIR step 2: $ ./bootstrap.sh --help step 3: $ ./bootstrap.sh --prefix=path/to/installation/prefix ( Other docs specify for this step: $ ./b2 --build-dir=/tmp/build-boost toolset=gcc stage (optional --build-type=complete) Also says that --stagedir=/path/to/install/special/stage/target/library/binaries I'm not certain what the stage components are or what the stage part is. ) $ ./b2 install “This will leave Boost binaries in the lib/ subdir of the installation prefix.” The only customization mentioned here is for where you want your results to be placed. step 4: Add path/to/installation to my $PATH environment variable. http://www.boost.org/doc/libs/1_51_0/doc/html/bbv2/tasks.html#bbv2.tasks.cr… The section is on common tasks for boost build, in particular in the section is task on cross compilation. Boost.Build supports cross compilation with gcc toolset. When using gcc, you first need to specify your cross compiler in user-config.jam for example: using gcc : arm : arm-none-linux-gnueabi-g++; This looks good, i'm thinking I need to edit a user-config.jam file. After that, if the host and target os are the same, for example linux, you can just repeat this compiler version to be used: b2 toolset=gcc-arm Regarding the user-config.jam file. These are the notes I took while reading: http://www.boost.org/doc/libs/1_51_0/doc/html/bbv2/overview.html#bbv2.overv… On startup, boost.build searches and reads two config files: site-config.jam and user-config.jam. Alternatively, the docs say you can edit the one at the top of the boost.build directory. In my case, I believe that would be $BOOST_DIR/tools/build/v2 directory rather than $BOOST_DIR. This directory has five .jam files: boost-build.jam, bootstrap.jam, build-system.jam, Jamroot.jam, site-config.jam and user-config.jam. Then I started thinking maybe editing this file will build boost.build for running on arm. I don't want to run boost.build on arm. I want it to use the cross compiler to build boost so that the libs will work with code that runs on arm. Summary, this is what I think I need to do. Please correct me where I am wrong. 1. using the tarfile I've downloaded, copy the $BOOST_DIR/tools/build/v2/user-config.jam file to my /home/davis directory. 2. edit the ~/user-config.jam file (I wish I could put this file in the $BOOST_DIR tree rather than my home dir) to use the cross compilers I have in my /opt/arm directory. 3. With the /opt/arm/ compiler directory in my path and in the $BOOST_DIR/tools/build/v2 directory issue the commands to build boost 3.a. $ ./bootstrap.sh --prefix=path/to/installation/prefix --with-toolset=gcc-arm 3.b this should add a b2 program in the path/to/installation/prefix dir. /path/to/installation/prefix will actually be /opt/arm/boot.build. This should have the boost build tool I build that runs on intel but is set to build boost for arm. 4. Change directory to $BOOST_DIR 4.a $ /path/to/installation/prefix/b2 --build-dir=/tmp/build-boost toolset=gcc-arm or literally /opt/arm/boot.build/bin?/b2 -build-dir=/tmp/build-boost toolset=gcc-arm 4.c $ /path/to/installtion/prefix/b2 install -- John F. Davis 6 Kandes Court Durham, NC 27713 919-888-8358 独树一帜

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Flyweight: wrapping shared_ptr
by Akim Demaille 22 Oct '14

22 Oct '14

Hi all, I'd like to add hash-consing on top of my hiearchy-based AST implementation, which uses shared_ptr (I'm in C++11) to guarantee value semantics (the pointee is const). Below is a tiny version that would help me see if using Boost.Flyweight is adequate. It works, but it is not transparent, because I have to explicitly call '.get()' on my flyweights to deference to the pointers. So for instance my code reads: size_t hash() const { size_t res = 0; hash_combine(res, boost::hash_value(op)); hash_combine(res, l.get()->hash()); hash_combine(res, r.get()->hash()); return res; } where I expect to have l->hash(), not l.get()->hash(). I have tried deriving from flyweight to add an operator->, but it fails horribly. I realize that it is suboptimal to use flyweight on top of shared_ptr, as I get two reference counters. Yet this change is less invasive than migrating my AST hierarchy to using variants as is done in the example of the documentation. What would be the right approach? Thanks a lot.

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Problem with bundled BGL properties
by alev mutlu 21 Oct '14

21 Oct '14

Hi all, I am new to BGL and the followings are snippets from my code. When I compile my code I get the following error. Any suggestions, error: no match for ‘operator=’ in ‘city_name.boost::vec_adj_list_vertex_property_map<Graph, GraphPtr, ValueType, Reference, Tag>::operator[] [with Graph = boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, relation, boost::property<boost::edge_name_t, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::no_property>, boost::no_property, boost::listS>, GraphPtr = boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, relation, boost::property<boost::edge_name_t, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::no_property>, boost::no_property, boost::listS>*, ValueType = boost::detail::error_property_not_found, Reference = boost::detail::error_property_not_found&, Tag = boost::vertex_name_t](v1) = r’ /home1/mutlu/boost/include/boost-1_37/boost/pending/detail/property.hpp:21: note: candidates are: boost::detail::error_property_not_found& boost::detail::error_property_not_found::operator=(const boost::detail::error_property_not_found&) struct argument{ int is_variable; string value; }; struct relation{ string relation_name; vector<argument> arguments; }; typedef property<edge_name_t, std::string> EdgeNameProperty; typedef adjacency_list<vecS, vecS, directedS, relation, EdgeNameProperty> Graph; int main(){ Graph g; property_map<Graph, vertex_name_t>::type city_name = get(vertex_name, g); property_map<Graph, edge_name_t>::type edge_value = get(edge_name, g); typedef graph_traits<Graph>::vertex_descriptor Vertex; typedef graph_traits<Graph>::edge_descriptor Edge; Vertex v1; v1 = add_vertex(g); city_name[v1]= r; } error: no match for ‘operator=’ in ‘city_name.boost::vec_adj_list_vertex_property_map<Graph, GraphPtr, ValueType, Reference, Tag>::operator[] [with Graph = boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, relation, boost::property<boost::edge_name_t, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::no_property>, boost::no_property, boost::listS>, GraphPtr = boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, relation, boost::property<boost::edge_name_t, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, boost::no_property>, boost::no_property, boost::listS>*, ValueType = boost::detail::error_property_not_found, Reference = boost::detail::error_property_not_found&, Tag = boost::vertex_name_t](v1) = r’ /home1/mutlu/boost/include/boost-1_37/boost/pending/detail/property.hpp:21: note: candidates are: boost::detail::error_property_not_found& boost::detail::error_property_not_found::operator=(const boost::detail::error_property_not_found&)

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1.57.0 beta 1 release candidates available for testing
by Marshall Clow 21 Oct '14

21 Oct '14

Release candidate files for 1.57.0 beta 1 are available at http://boost.cowic.de/rc/ As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. This helps ensure the candidates build OK before we push them out to SourceForge. The files (and associated md5s) are: MD5 (boost_1_57_0_b1_rc1.7z) = 8633fbf5ebb7eaabcb0f309c14646ae3 MD5 (boost_1_57_0_b1_rc1.tar.bz2) = 8e76f98146793f0fbd2492a9151c405b MD5 (boost_1_57_0_b1_rc1.tar.gz) = d41ff3ffb36ac84ff5bf34f799308907 MD5 (boost_1_57_0_b1_rc1.zip) = 8a844dc36284247b2e936f2120e118b2 Thanks! -- The release managers

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1.57.0 beta 1 is now available
by Marshall Clow 20 Oct '14

20 Oct '14

Boost release 1.57.0 beta 1 is now available from SourceForge See http://sourceforge.net/projects/boost/files/boost-binaries/1.57.0.beta.1/ This release contains no new libraries. For details of what's in the release, see http://www.boost.org/users/history/version_1_57_0.html. Note that the links to files on this web page are for the final release - use the SourceForge link above to get the beta files. Please download the beta, give it a try, and report any problems you encounter. Thanks, -- The Boost Release Team P.S. There are a couple of known problems with this beta: * There are problems building with MSVC 8.0 * There are some problems with range/detail/any_iterator.hpp. These will be fixed before the release.

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