September 2009 - Boost-users

Re: [Boost-users] Usingboost::serializationinreal-timewithoutallocating memory
by Brian Wood 22 Sep '09

22 Sep '09

Stefan Strasser writes: > that's the same approach. > code seems to be written by an external code generator instead of a c++ > compiler, but there is no difference beyond that, is there? > .NET for example implements serialization based on its reflection mechanism. > it iterates at runtime through the (reflected) fields of a class and extracts > the data. > I don't think an external code generator is "cleaner". I don't claim that an external code generator is cleaner, but that the Ebenezer approach is cleaner, since it (usually) writes marshalling functions at build time. C++ compilers should have been able to do that for 10 years now, but for whatever reason that isn't being developed. Regards, Brian Wood http://webEbenezer.net <http://webebenezer.net/> "Then Samuel took a rock and set it up between Mizpah and Shen. He named it Ebenezer [Rock of Help] and said, 'Until now the L-RD has helped us.'"

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Re: [Boost-users] Usingboost::serializationinreal-timewithoutallocating memory
by Brian Wood 22 Sep '09

22 Sep '09

Stefan Strasser writes: > sure, it's the best serialization solution I know and the template > technique trumps any reflection based solution (even if c++ had > reflection). In what way? The "Usage" section of this page, http://webEbenezer.net/comparison.html<http://webebenezer.net/comparison.html>, gives an example of how it's possible to produce a cleaner solution than that afforded by the Boost Serialization library. The Ebenezer approach to the bus_stop example is twelve lines less than the Boost Serialization approach. Regards, Brian Wood www.webEbenezer.net <http://www.webebenezer.net/> "Then Samuel took a rock and set it up between Mizpah and Shen. He named it Ebenezer [Rock of Help] and said, 'Until now the L-RD has helped us.'"

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boost::proto user guide - compile error creating a lazy function
by Tom Babbin 21 Sep '09

21 Sep '09

Hi, I am going through proto user guide. I am getting compiling error for the following piece code (it's pretty much copy and pasted from the guide). I used 1.40 and gcc. #include <iostream> #include <boost/mpl/int.hpp> #include <boost/proto/core.hpp> #include <boost/proto/context.hpp> #include <boost/proto/debug.hpp> #include <cmath> #include <vector> namespace proto = boost::proto; template<int I> struct placeholder {}; // Define some placeholders proto::terminal< placeholder< 1 > >::type const _1 = {{}}; proto::terminal< placeholder< 2 > >::type const _2 = {{}}; struct calculator_context : proto::callable_context< calculator_context const > { // Values to replace the placeholders std::vector<double> args; // Define the result type of the calculator. // (This makes the calculator_context "callable".) typedef double result_type; // Handle the placeholders: template<int I> double operator()(proto::tag::terminal, placeholder) const { return this->args[I]; } }; // Define a pow_fun function object template<int Exp> struct pow_fun { typedef double result_type; double operator()(double d) const { return std::pow(d, Exp); } }; // Define a lazy pow() function for the calculator DSEL. // Can be used as: pow< 2 >(_1) template<int Exp, typename Arg> typename proto::function< typename proto::terminal<pow_fun<Exp> >::type , Arg const & >::type pow1(Arg const &arg) { typedef typename proto::function< typename proto::terminal<pow_fun<Exp> >::type , Arg const & >::type result_type; result_type result = {{{}}, arg}; return result; } int main() { calculator_context ctx; ctx.args.push_back(3); std::cout << boost::proto::eval( pow1<2>( _1 ), ctx ); return 0; } The error says: calc2.cpp: In function 'int main()': calc2.cpp:116: error: no matching function for call to 'eval(boost::proto::exprns_::expr<boost::proto::tag::function, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<pow_fun<2> >, 0l>, const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<placeholder<1> >, 0l>&>, 2l>, calculator_context&)' /auto/cigprod/spg/lx86_64/opt/boost_1_40_0/boost/proto/eval.hpp:91: note: candidates are: typename boost::proto::result_of::eval<Expr, Context>::type boost::proto::eval(Expr&, Context&) [with Expr = boost::proto::exprns_::expr<boost::proto::tag::function, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<pow_fun<2> >, 0l>, const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<placeholder<1> >, 0l>&>, 2l>, Context = calculator_context] /auto/cigprod/spg/lx86_64/opt/boost_1_40_0/boost/proto/eval.hpp:100: note: typename boost::proto::result_of::eval<Expr, Context>::type boost::proto::eval(Expr&, const Context&) [with Expr = boost::proto::exprns_::expr<boost::proto::tag::function, boost::proto::argsns_::list2<boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<pow_fun<2> >, 0l>, const boost::proto::exprns_::expr<boost::proto::tag::terminal, boost::proto::argsns_::term<placeholder<1> >, 0l>&>, 2l>, Context = calculator_context] Thanks. -- View this message in context: http://www.nabble.com/boost%3A%3Aproto-user-guide---compile-error-creating-… Sent from the Boost - Users mailing list archive at Nabble.com.

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[graph] : newbie question on brandes_betweenness_centrality
by Matthew Walker 21 Sep '09

21 Sep '09

Hi, I am very much a newbie at this and would greatly appreciate some help on how I could get the brandes_betweenness_centrality function to work for me. I have the following code that compiles without error, but seg faults when I run it: #include <map> #include <boost/graph/graph_traits.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/graph_utility.hpp> #include <boost/graph/betweenness_centrality.hpp> #include <boost/graph/exterior_property.hpp> int main() { ... // I am reading a network from a file and storing it into lEdges and lNumVertices typedef adjacency_list<vecS, vecS, undirectedS > Graph; Graph g(lEdges.begin(), lEdges.end(), lNumVertices); typedef boost::exterior_vertex_property<Graph, float> BetweennessProperty; typedef BetweennessProperty::map_type BetweennessMap; BetweennessMap lMap; brandes_betweenness_centrality(g, lMap); } If I could get this to work, I then have aspirations that the helper function central_point_dominance(g, lMap) might give me the betweenness centralization measure that I'm after. Thanks in advance for your help! Matthew

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Hierarchical enumeration?
by Archie14 21 Sep '09

21 Sep '09

Does boost (or any other lib in C++) have facility to support smth that resembles hierarchical enumeration? I would like to have something like the following: enum Hierarchy { Store::Clothing = 1 Store::Electronics, Building::Residential, Building::Commercial } ... Hierarchy h = Hierarchy::Building::Commercial; ... if (h == Hierarchy::Store) { if (h == Hierarchy::Store::Clothing) std::cout<<"clothing"; } ...

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ASIO newbie: Passing parameters from a TCP client to a server
by Ramon F Herrera 21 Sep '09

21 Sep '09

Hello all, I have studying the ASIO examples, and experimenting with them. Still, I could benefit from the guidance of experienced programmers. This is my first client-server set of apps. I need the client to pass a few arguments to the server, lets say four. Should I pass them in 4 different lines? Being synchronous I suppose the client blocks until the server performs a read? (that seems to be what I am seeing now). I heard that there are ways to attach the debugger (gdb) to a server process when it starts? (that feat seems to be major wizardry). Sample code would be very appreciated. TIA, -Ramon

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[fusion] transform a heterogeneous vector
by Jean-Louis Leroy 20 Sep '09

20 Sep '09

In the example from the documentation : struct triple { typedef int result_type; int operator()(int t) const { return t * 3; }; }; ... assert(transform(make_vector(1,2,3), triple()) == make_vector(3,6,9)); ...all the elements have the same type. How can it work with heterogeneous vectors ? What would be typedef'ed to result_type ? Jean-Louis

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Can Regex callback function arguments be modified?
by Ramon F Herrera 20 Sep '09

20 Sep '09

I am having some trouble with the Regex callback architecture. Fist of all for, for a variable number of matches, the only way to code is with a callback function and for_each iterator, correct? To make it more interesting, I have a callback calling another callback. This could obviously go deeper and deeper. Due to the inflexibility (perhaps by me perceived?) of the callback architecture, I am forced to use a lot of global variables. To be fair, this is highly manageable within my current application, but I am concerned that this "implicit number and types of parameters" restriction may become a stumbling block in future code. At this stage, what I am trying to determine whether I should base my program(s) on (from simplest to more complex): - Regex - eXpressive - Spirit So far, I prefer Regex because it is much more stable than Spirit. The latter seems to have great potential, but when when I find that I am unable to even build the test examples properly, and the specs vary from one version to the next, I conclude that it is best to allow the good people of Spirit ("spirited people"? :-) time to deliver a more polished product. Don't know anything about eXpressive yet. Regards, -Ramon

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[Test] How to treat memory leaks as errors?
by Василий Старостин 19 Sep '09

19 Sep '09

Hi! I use Boost.Test as testing facility and get "memory leak detected" messages every time this happens. And this is good. However, Boost.Test doesn't return non-zero error code when leaks detected (as it does this when tests fail). How can I make my testing program to return non-zero error code if memory leaked? WBR, Vasily

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How to find Boost 1.40.0 with cmake 2.6?
by Ingolf Steinbach 19 Sep '09

19 Sep '09

Hi, maybe this is a bit off-topic as it is probably a cmake problem, but it could turn out that the correct solution also involves suitable invocation of bjam. As there seems to be no Windows/VC9.0 installer for Boost 1.40.0 (yet), I have built and installed the libraries myself as follows: ...\boost_1_40_0> bootstrap ...\boost_1_40_0> .\bjam --prefix=C:\Programme\boost\boost_1_40_0 ...\boost_1_40_0> .\bjam --prefix=C:\Programme\boost\boost_1_40_0 install Now, there is the following tree in C:\Programme\boost: C:\Programme\boost +-boost_1_40_0 +-include | +-boost-1_40 | +-boost | +.... +-lib +-libboost....-vc90-mt-1_40.lib +-... What is the correct way to teach the FindBoost module in cmake where to search for the boost installation? I have found that I need to at least set(Boost_ADDITIONAL_VERSIONS "1.40" "1.40.0") However, cmake does not yet find Boost. According to the debugging output of the module, the situation seems to improve slightly when I additionally specify set(BOOST_ROOT C:/Programme/boost) Now, cmake reports "Boost version: 1.40.0" but does not find any libraries. Would I have to supply different options to bjam in order to find the libraries? Is it possible to avoid having to specify BOOST_ROOT in the CMakeLists.txt file? TIA for your support! Ingolf

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