January 2005 - Boost - lists.boost.org

BIL and boost::any
by christopher diggins 03 Feb '05

03 Feb '05

Hello all, I just realized that an empty BIL interface, BOOST_IDL_BEGIN(IAnything) BOOST_IDL_EMPTY(IAnything) has some common ground with: boost::any Where boost::any stores a copy of a value of practical any type for later extraction, IAnything can point to just about anything. void BoostAnyTest() { int x = 5; boost::any a = x; TEST(any_cast<int>(a) == 5); } void AnythingTest() { int x = 5; IAnything a = x; TEST(extract<int>(a) == 5); } void ObjectTests() { BoostAnyTest(); AnythingTest(); } I just thought this could lead to some kind of connection between the libraries. It might be nice to see this in the boost::any namespace, i.e. a boost::any::any_ref. Christopher Diggins Object Oriented Template Library (OOTL) http://www.ootl.org

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New Library?
by John Eddy 03 Feb '05

03 Feb '05

Would anyone be interested in a library for doing logging? I've written one for my own purposes and thought others might find it useful. It will store log entries at various levels (FATAL, SHOUT, ERROR, WARN, INFO, DEBUG, DETAIL). There is a default level and the level can be customized for entries by individual instances of any type and for entries by any types as a whole. I'll be glad to provide more information if anyone is interested. John

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Dimensional Analysis
by Sérgio Vale e Pace 02 Feb '05

02 Feb '05

Is the dimensional analisys code shown in the MPL tutorial, part of the mpl library ? Or any other boost library ?

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Help needed with BGL & multi_index_container
by Me here 02 Feb '05

02 Feb '05

Hi there, I need an advanced container which allows me to access my data over number of different indices. That is exactly what for boost::multi_index_container was made. But, my data items also have relationships with other data in the same container, which could be represented as directed graph. So, I have made a custom container, which aggregates multi_index_container (MIC) to store data items and a graph (BGL) to store relationships. To allow switching from MIC to walk over relationships, as an additional field of my item in MIC I store BGL vertex; as vertex property in graph I store the key of unique index in MIC. So, MIC and BGL refer to each other. But, it is difficult to have those two containers in sync. So, I made another attempt to have MIC as customized vertex storage. I succeed two write the code for it (see it below). It also compiles and links :-). Unfortunately, I can not add neither vertices not edges. If I try to add vertex as in commeted code below, an error errors that there is no convertion from vertex property to vertex descriptor (error message is below). What's wrong? My another question is: how can I get access to my MIC stored in graph? I would like to use its indices. Best wishes, Alexander --------- sample code ----------- #include <iostream> #include <boost/multi_index_container.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/graph/adjacency_list.hpp> using namespace boost; using namespace boost::multi_index; using namespace std; struct MICSelector {}; struct Item { Item(int _a=0, int _b=0, int _c=0) : a(_a), b(_b), c(_c) {} int a,b,c; }; struct ItemHolder { ItemHolder(int id=0, const Item item=Item()) : m_ID(id), m_item(item) {} int m_ID; Item m_item; }; struct ItemHolderKey { typedef int result_type; int operator()(const ItemHolder& v) const { return v.m_ID; } }; template<class ValueType> struct MICWrapper { typedef multi_index_container < ValueType, indexed_by < ordered_unique< ItemHolderKey > > > type; }; namespace boost { // the specialization for your selector template<class ValueType> struct container_gen<MICSelector, ValueType> { typedef typename MICWrapper<ValueType>::type type; }; template <> struct parallel_edge_traits<MICSelector> { typedef allow_parallel_edge_tag type; }; }; typedef adjacency_list < listS, MICSelector, bidirectionalS, ItemHolder > MG; int tmain(int argc, char* argv[]) { MG mg; /* ItemHolder IH( 1, Item(1) ); add_vertex( &IH, mg ); // add_edge( // ItemHolder( 1, Item(1) ), // ItemHolder( 2, Item(2) ), // mg ); */ cout << typeid( boost::graph_traits<MG>::vertex_descriptor ).name(); return 0; } --------- sample code ----------- ----------- error message ------------- Compiling... MIC_BGL.cpp c:\test\MIC_BGL.cpp(87) : error C2664: 'boost::add_vertex' : cannot convert parameter 1 from 'ItemHolder *__w64 ' to 'const boost::detail::adj_list_gen<Graph,VertexListS,OutEdgeListS,DirectedS,VertexProperty,EdgeProperty,GraphProperty,EdgeListS>::config::vertex_property_type &' with [ Graph=boost::adjacency_list<boost::listS,MICSelector,boost::bidirectionalS,ItemHolder>, VertexListS=MICSelector, OutEdgeListS=boost::listS, DirectedS=boost::bidirectionalS, VertexProperty=boost::detail::retag_property_list<boost::vertex_bundle_t,ItemHolder>::type, EdgeProperty=boost::detail::retag_property_list<boost::edge_bundle_t,boost::no_property>::type, GraphProperty=boost::no_property, EdgeListS=boost::listS ] Reason: cannot convert from 'ItemHolder *__w64 ' to 'const boost::detail::adj_list_gen<Graph,VertexListS,OutEdgeListS,DirectedS,VertexProperty,EdgeProperty,GraphProperty,EdgeListS>::config::vertex_property_type' with [ Graph=boost::adjacency_list<boost::listS,MICSelector,boost::bidirectionalS,ItemHolder>, VertexListS=MICSelector, OutEdgeListS=boost::listS, DirectedS=boost::bidirectionalS, VertexProperty=boost::detail::retag_property_list<boost::vertex_bundle_t,ItemHolder>::type, EdgeProperty=boost::detail::retag_property_list<boost::edge_bundle_t,boost::no_property>::type, GraphProperty=boost::no_property, EdgeListS=boost::listS ] No constructor could take the source type, or constructor overload resolution was ambiguous ----------- error message ------------- __________________________________ Do you Yahoo!? Yahoo! Mail - Find what you need with new enhanced search. http://info.mail.yahoo.com/mail_250

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[mpl]mpl::plus and non Integral Constants
by Andy Little 02 Feb '05

02 Feb '05

Reading the mpl documentation it states that boost::mpl::plus is expected to be specialised for non Integral Constants. Therefore should the following work ?: typedef boost::mpl::plus<int,int>::type int_plus_int_type; // eg int presumably OTOH it could be said that: mpl::plus<int_<1>, int_<1> >::type and mpl::plus<int,int>::type are conceptually different and that therefore mpl::plus<int,int> should be(remain) invalid. Any thoughts? regards Andy Little

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Reminder: Boost Logo Contest
by Joel de Guzman 02 Feb '05

02 Feb '05

Hi Y'all, This is to remind you about the ongoing Boost Logo Contest: http://www.boost.org/more/logo_contest.htm Entries will be accepted on or before February 15, 2005. Please email all entries to me (djowel at gmail dot com). I've posted the entries submitted so far in the page above. I decided not to continue with the wiki page because of problems and difficulties with it. Some things to note: 1) I'm limiting the image size to a width of 320 pix. This is for the sake of uniformity. Images that were rescaled to fit this limit might look jagged. If you are not satisfied, please re-submit. 2) Most entries have a title (italics). To those who wish to have a title (optional), please email me. This is optional because each entry has a corresponding number anyway. 3) Some entries have an annotation relating to the artwork. This is also optional but it might help if you annotate your work. Cheers, -- Joel de Guzman http://www.boost-consulting.com http://spirit.sf.net

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[type_traits][documentation]no <A name="example"></A>
by Larry Evans 01 Feb '05

01 Feb '05

http://cvs.sourceforge.net/viewcvs.py/boost/boost/libs/type_traits/index.ht… Contains: <H2>Example code</H2> But it should have: <H2><A name="example"></A>Example code</H2> in order for TOC at top to work.

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[iostreams] [regression] iostreams added to CVS
by Jonathan Turkanis 01 Feb '05

01 Feb '05

Dear all, The iostreams library has been added to CVS. I've also added a line to boost-root/status/Jamfile. Is this enough to have the library included in the regression tests, or is something more required? Jonathan

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lexical_cast: Needing to work for MSVC 6 (and similar)?
by Terje Slettebø 01 Feb '05

01 Feb '05

Hi. When testing it, I've found that the CVS version of lexical_cast apparently doesn't work for MSVC 6 (at least with my setup). I get the following errors when running the unit test: boost/lexical_cast.hpp(178) : error C2059: syntax error : '<' boost/lexical_cast.hpp(180) : see reference to class template instantiation 'boost::detail::lexical_stream<Target,Source>' being compiled boost/lexical_cast.hpp(178) : error C2238: unexpected token(s) preceding ';' boost/lexical_cast.hpp(180) : see reference to class template instantiation 'boost::detail::lexical_stream<Target,Source>' being compiled boost/test/utils/basic_cstring/bcs_char_traits.hpp(120) : error C2143: syntax error : missing ',' before '<' boost/test/utils/basic_cstring/bcs_char_traits.hpp(120) : error C2059: syntax error : '<' boost/test/utils/basic_cstring/bcs_char_traits.hpp(120) : fatal error C1903: unable to recover from previous error(s); stopping compilation I also see that the current regression test doesn't include MSVC 6 (http://www.meta-comm.com/engineering/boost-regression/developer/conversion. html). Because of this, Kevlin Henney and I was wondering whether or not MSVC 6 support for this component (and components in Boost in general) is no longer demanded, or in general, what the required conformance level is? If MSVC 6 support is still needed, I guess the above problems should be fixed. It seems to crash out in Boost.Test, as well. I see there are a few other failures in the regression test for more conformant compilers, though, and I'll look into these. Regards, Terje

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g++ 4.0 and typeof/operator overloading based metaprogramming
by Daniel James 01 Feb '05

01 Feb '05

Hello everyone, I've been trying out a pre-release of g++ 4.0, and its typeof now works a lot better than the older versions. This allows it to be used for metaprogramming. As an example, I've attached a compile time factorial implemented mainly using operator overloads (it's not commented at all, but should be pretty easy to understand for most people on this list). I think it would be possible to write a metaprogramming library which would have much nicer syntax (borrowing techniques from lamba & phoenix), and integrate well with mpl. I suppose that since such a library would only work on gcc for now (or do any other compilers have a good enough typeof?), it might not be appropriate for boost, but I thought this might be of interest here anyway. Daniel

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