January 2014 - Boost - lists.preview.boost.org

[offtopic] user-defined raw string literals
by Adam Wulkiewicz 01 Feb '14

01 Feb '14

Hi, I have some idea related to the usage of UDLs in Boost.Geometry library but the way I'd like to handle it is AFAIK not supported. A little introduction first. There are many text-based languages of defining data. One of them is WKT (http://en.wikipedia.org/wiki/Well-known_text) which allows to define vector data e.g. a polygon like this: |POLYGON((30 10, 40 40, 20 40, 10 20, 30 10))| So my thought was: why not use C++11 UDLs for this purpose? There are operators in the WKT language so I should probably use string literal, put WKT in it and be happy with it. The use case could look like this: |auto ||polygon = "POLYGON((30 10,40 40,20 40,10 20,30 10))|"_wkt; Ok so now the tricky part. It should be parsed in compile-time, the type of the geometry retrieved from the string literal and proper type returned (bg::polygon<> in this case). Unfortunately string literals can't be handled as raw literals, e.g. using the variadic-template version of operator"": template <char...> void operator "" () Why? Is there a reason for this? If we had the ability to use the compile-time version with string literals it would be possible to implement various compile-time parsers, not only for the mentioned WKT. So what do you think about it? Regards, Adam

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[docs][website] Can the docs on the website be xhtml + svg?
by John Maddock 01 Feb '14

01 Feb '14

I've been investigating getting better equations and graphs into the Math lib docs and one prerequisite seems to be serving up pages as XHTML rather than HTML: without that SVG's simply do not display correctly (or at all) in IE. The docbook xhtml generation seems to be working OK, but would the pages get served correctly on the current website? Thanks, John.

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[conversion] Need a help with MSVC failures
by Antony Polukhin 01 Feb '14

01 Feb '14

Hi, Some of the tests for Boost.LexicalCast fail on any MSVC compiler. Unfortunately currently I have no access to Windows. Could someone please investigate the failures and tell me were to search the bug? -- Best regards, Antony Polukhin

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[range] Can iterator_range also model Random Access Range?
by Mostafa 01 Feb '14

01 Feb '14

It seems that iterator_range can properly model any refinement of the Forward Range concept. Is that right? The reason I ask is that this is not very clear from the documentation, and I had to deduce this from both the iterator_range API and the Random Access Range concept definition. (See documentation at: range/reference/utilities/iterator_range.html) Thanks, Mostafa

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Range Adapters (map_keys, map_values) cause undefined behavior (segv, etc) when applied to R-Values, especially in the context of BOOST_FOREACH
by Igor Lubashev 01 Feb '14

01 Feb '14

Hi! I've filed a ticket (https://svn.boost.org/trac/boost/ticket/9578) for this issue two weeks ago, but I see no action there. Does anyone else think that this (see subj) is a problem? To spare the trouble of following the link, here is the essence of the problem, as I see it. (The ticket has a simple test case attached.) When applied to r-values (for example, maps returned by value from a function), adapters do not make a copy of the r-value but just capture a reference to it. This makes the returned range_iterator dangerous, if it is used after the r-value (the temporary) is destroyed. In particular, the following use causes undefined behavior on all compilers I'd tested on: g++ (4.1.2, 4.4.3, 4.6.3) and Visual Studio (15 [VC9], 16 [VC10]). BOOST_FOREACH(const string &s, return_map_by_value() | map_keys) ... Note that the following works fine (since BOOST_FOREACH takes care of differentiating between l-values and r-values and does the right thing to r-values): BOOST_FOREACH(const MapType::value_type &v, return_map_by_value()) ... It seems that boost::range::adapters need to do a similar thing to what BOOST_FOREACH is does to identify r-values and make a copy (which the compiler is likely to optimize away). Any comments are welcome! Thanks, - Igor

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Re: [boost] Participation in GSOC 2014
by Vineet Kumar, Indian Institute of Technology, BHU, Varanasi (INDIA) 31 Jan '14

31 Jan '14

Hello Everyone, I want to participate in GSOC 2014, and boost C++ is looking me the most appropriate place where I can contribute efficiently. So how to get started with boost C++ libraries ? I have an Idea of implementing a library in boost. So what I do then , concentrate on library or something else With Regards Vineet Kumar, Indian Institute of Technology, BHU

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GSoC
by Utsav Tiwary 31 Jan '14

31 Jan '14

My idea for GSoC involves implementation of advanced maths libraries for boost which involve the solving of boundary value problems using finite difference method. Language to be used is C. Are there any existing implementations ?

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boost::pool nextof method
by Gilbert Polo 31 Jan '14

31 Jan '14

I am currently learning how to use the boost pool library. However, I have a question regarding the nextof of method found in the class simple_segregated_storage.hpp. How does the increment of the void pointer work. How does it know how much to increment the void pointer by in order to get to the next chunk?

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[type_traits] type_traits for types with operator().
by Anton Bikineev 31 Jan '14

31 Jan '14

Hello. Recently I looked for type_traits for callable classes. It so strange, I didn't find such traits. Most likely, I just missed them or something like them. I actually don't know is there a real need for them. Anyway I tried to write such traits at least for practice and metaprogramming training. I tested them with gcc, clang and msvc2010. I would appreciate if you looked at the code. Here is the link<https://github.com/AntonBikineev/is_functional/> to my github repository. It's cool that they can see hidden generated operator() of lambdas closure type. Best regards, Anton.

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Trouble with constructors boost::graph::directed_graph from boost::adjacency_list in C++
by Matthias Beste 31 Jan '14

31 Jan '14

Dear Boost-Users, Related to: boost::graph::directed_graph I've trouble with the Constructors of above as a simple example shows: <<<<<<<<<<<<<<<<<<< using namespace boost; typedef directed_graph<> Directed_Graphtype; class Mywrapper { private: Directed_Graphtype g; public: Mywrapper() : g() {}; }; >>>>>>>>>>>>>>>>>> I got the following Error while compiling: <<<<<<<<<<<<<<<< HOME/svn_repos/collab_cntfet/trunk/STA_signalintegrity/circuitGraph.h|78| instanziiert von hier| /usr/include/boost/graph/directed_graph.hpp|96|Fehler: keine passende Funktion für Aufruf von »boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, boost::no_property>, boost::property<boost::edge_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>::adjacency_list(const boost::directed_graph<>&)«| /usr/include/boost/graph/directed_graph.hpp|96|Anmerkung: Kandidaten sind:| /usr/include/boost/graph/adjacency_list.hpp|451|Anmerkung: template<class EdgeIterator, class EdgePropertyIterator> boost::adjacency_list::adjacency_list(EdgeIterator, EdgeIterator, EdgePropertyIterator, boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>::vertices_size_type, boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>::edges_size_type, const GraphProperty&)| /usr/include/boost/graph/adjacency_list.hpp|443|Anmerkung: template<class EdgeIterator> boost::adjacency_list::adjacency_list(EdgeIterator, EdgeIterator, boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>::vertices_size_type, boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>::edges_size_type, const GraphProperty&)| /usr/include/boost/graph/adjacency_list.hpp|435|Anmerkung: boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>::adjacency_list(boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>::vertices_size_type, const GraphProperty&) [with OutEdgeListS = boost::listS, VertexListS = boost::listS, DirectedS = boost::bidirectionalS, VertexProperty = boost::property<boost::vertex_index_t, unsigned int, boost::no_property>, EdgeProperty = boost::property<boost::edge_index_t, unsigned int, boost::no_property>, GraphProperty = boost::no_property, EdgeListS = boost::listS, boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>::vertices_size_type = long unsigned int]| /usr/include/boost/graph/adjacency_list.hpp|435|Anmerkung: keine bekannte Umwandlung für Argument 1 von »const boost::directed_graph<>« nach »long unsigned int«| /usr/include/boost/graph/adjacency_list.hpp|418|Anmerkung: boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>::adjacency_list(const boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>&) [with OutEdgeListS = boost::listS, VertexListS = boost::listS, DirectedS = boost::bidirectionalS, VertexProperty = boost::property<boost::vertex_index_t, unsigned int, boost::no_property>, EdgeProperty = boost::property<boost::edge_index_t, unsigned int, boost::no_property>, GraphProperty = boost::no_property, EdgeListS = boost::listS, boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS> = boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, boost::no_property>, boost::property<b oost::edg e_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>]| /usr/include/boost/graph/adjacency_list.hpp|418|Anmerkung: keine bekannte Umwandlung für Argument 1 von »const boost::directed_graph<>« nach »const boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, boost::property<boost::vertex_index_t, unsigned int, boost::no_property>, boost::property<boost::edge_index_t, unsigned int, boost::no_property>, boost::no_property, boost::listS>&«| /usr/include/boost/graph/adjacency_list.hpp|414|Anmerkung: boost::adjacency_list<OutEdgeListS, VertexListS, DirectedS, VertexProperty, EdgeProperty, GraphProperty, EdgeListS>::adjacency_list(const GraphProperty&) [with OutEdgeListS = boost::listS, VertexListS = boost::listS, DirectedS = boost::bidirectionalS, VertexProperty = boost::property<boost::vertex_index_t, unsigned int, boost::no_property>, EdgeProperty = boost::property<boost::edge_index_t, unsigned int, boost::no_property>, GraphProperty = boost::no_property, EdgeListS = boost::listS]| /usr/include/boost/graph/adjacency_list.hpp|414|Anmerkung: keine bekannte Umwandlung für Argument 1 von »const boost::directed_graph<>« nach »const boost::no_property&«| ||=== Build finished: 11 errors, 0 warnings ===| >>>>>>>>>>>>>>>>>>>>>>>>>> I would really like to know, where the problem is with this templates. The default constructor exists of course for boost::directed_graph and boost::adjacency_list a.s.o. ... however the compiler don't like them. This is confusing. Can someone help me out? Kind Regards Matthias -- Dipl.-Ing. Matthias Beste Wissenschaftlicher Mitarbeiter Lehrstuhl für Dependable Nano Computing (CDNC) Institute für technische Informatik (ITEC) Karlsruhe Institute of Technology (KIT) Haid-und-Neu Str.7 (Bldg 07.21) 76131 Karlsruhe, Germany Phone: +49 721 608-45009; Fax: +49 721 608-43962 Email: matthias.beste(at)kit.edu <mailto:matthias.beste@kit.edu> web: http://cdnc.itec.kit.edu/

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