September 2011 - Boost-users

graph documentation dead link
by Benjamin Sobotta 12 Sep '11

12 Sep '11

Hello, I'm currently reading about the graph library, more specifically about the shortest path problem with resource constraints, and found that the link to the paper Irnich, S.; Desaulniers, G. (2005): Shortest Path Problems with Resource Constraints in: Desaulniers, G.; Desrosiers, J.; Solomon, M. (eds.) (2005): Column Generation Springer, New York, pp. 33–65 is broken. I found a new link to the paper: http://logistik.bwl.uni-mainz.de/Dateien/or_2004-01.pdf Cheers, Ben PS: The link is in .../doc/libs/1_47_0/libs/graph/doc/r_c_shortest_paths.html under "Introduction and Problem Description"

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thread running many times
by Kraus Philipp 12 Sep '11

12 Sep '11

Hello, I create a thread group and run the group with join_all(). My code shows like: for(i=0; i < runs; ++i) { threadgoup.join_all(); do something with the results } So I run the thread group n times. Is this the correct way or can I call join_all only once on the group? Thanks PHil

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[asio] serial_port::async_read_some() with native COM ports on WIN32
by Running Razor 12 Sep '11

12 Sep '11

I use serial_port::async_read_some() to read data from serial interface on windows. Using virtual com ports (FTDI, SiLabs) everything wents as expected. But on native COM ports the completion handler is not called until the buffer (passed to async_read_some) is completely filled. I use "plain" communication without hardware handshake: ... typedef serial_port_base ser; mDevice.set_option( ser::baud_rate ( baud ) ); mDevice.set_option( ser::flow_control ( ser::flow_control::none ) ); mDevice.set_option( ser::parity ( ser::parity::none ) ); mDevice.set_option( ser::stop_bits ( ser::stop_bits::one ) ); mDevice.set_option( ser::character_size( 8 ) ); ... Do I miss something or is this a bug? tested on boost_1_38_0 and boost_1_46_1

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boost thread (non-blocking) communication
by Jack Bryan 11 Sep '11

11 Sep '11

Hi, I am trying to do data-exchange communication among boost::threads. Are there asynchronous (non-blocking) communication APIs in boost ? For example, non_block_send( receiver_address, data_buffer, data_volume, data_tag , send_status ); non_block_recv( sender_address, data_buffer, data_volume, data_tag , recv_status ); if (recv_status == TRUE) getData(data_buffer) ; else wait; Any help is really appreciated. Thanks

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Compile errors using boost 4.7.4 and Intel ICC x64 on Debian
by Bill Moo 11 Sep '11

11 Sep '11

Hello List. The attached file contains the errors I get when I attempt to compile my utilities library using Boost 1.47.0 with the Intel Compiler v12.1.0 on Debian Squeeze v6.0.2. (My IDE is Qt Creator v2.3.0 using v4.7.4 (x64) SDK) This is my first attempt at doing this under Linux as the utilities library (dll) compile as is in Windows. So I would appreciate your thoughts on this as I can't continue the migration of the other projects until I get this library working. Thank you. -- Bill

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dijkstra_shortest_paths between sets of nodes (between polygons on a grid)
by Stuck Developer 10 Sep '11

10 Sep '11

This ought to be a classic problem but I haven't found a solution yet... Conceputally, I'm trying to find the shortest paths between all polygons within a maximum weighted distance over a grid of friction weights (as well as the total weighted distance of each of these shortest paths). The grid with all the weights (a "friction" value representing the weight to move over that particular grid cell) is currently used to create a network with one vertex per grid cell and edges to its immediate eight neighbours (in the cardinal and diagonal directions). The weight of each edge is calculated to the average weight of the vertex and its neigbours in the four cardinal directions and multiplied by sqrt(2) in the diagonal directions to compensate for the longer euclidean distance. Conceptually again, on this grid, there are a bunch of polygons. These are then made up ofcontiguous groups of vertices. Each polygon could thus be considered a set (or a component) of vertices with a unique id for each polygon. The problem now is to find the shortest path over the weighted grid between the edges of all polygons within a maximum weighted distance from each other. NOTE that the shortest path between two polygons should be able to pass through the weighted grid cells of other polygons along the way when these other polygons are not considered being source or target "vertex sets". I first tried to solve this by looping through all of the polygons and finding the shortest path between some representative vertex (e.g. the centroid grid cell) inside a source polygon to a representative vertex within each possible target polygon. I did this by setting all of the grid cell weights to zero within each of the two polygons, running the dijkstra_shortest_paths between their representative vertices and then resetting the weights within these two polygons before solving it for another pair of polygons. This actually works but the search goes bezerk within the polygons where all the edges have a cost of zero, and if these polygons are big enough, I run out of memory (I guess the shortest path becomes too long...). I'm thinking this should be possible to solve by instead initializing all of the vertices within each source polygon to "discovered" (i.e. black) somehow and initializing the priority queue and the cost in some corresponding manner. I just don't know how. Then there is the question of knowing when the shortest path to the target polygon has been reached... And thirdly if it would be possible to stop the search when a maximum weighted distance has been reached. Any smart solutions to this problem?

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Re: [Boost-users] [bind] Dereferencing placeholder argument
by Ivan Le Lann 09 Sep '11

09 Sep '11

----- "Szymon Gatner" <szymon.gatner(a)gmail.com> a écrit : > 2011/9/9 Nat Linden <nat(a)lindenlab.com>: > > On Fri, Sep 9, 2011 at 10:04 AM, Ivan Le Lann <ivan.lelann(a)free.fr> > wrote: > > >> Have you tried *_1 ? > > > > I think that works with boost::lambda::bind and boost::lambda::_1 > > (also, presumably, the corresponding constructs in Phoenix) but not > > with plain boost::bind. > > Indeed I tried that - getting invalid indirection error. Some time ago I offered a patch to add arithmetical operator support to Boost.Bind and was answered : Use Lambda or Phoenix. If you want to tweak Boost.Bind, which I would not encourage, maybe this could help : http://boost.2283326.n4.nabble.com/Bind-Function-arithmetic-sample-impl-ins… As said, it is for arithmetical operators but might be adapted to your need. Regards, Ivan

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Re: [Boost-users] [bind] Dereferencing placeholder argument
by Ivan Le Lann 09 Sep '11

09 Sep '11

----- "Szymon Gatner" <szymon.gatner(a)gmail.com> a écrit : > Hi, > > Is there a way of automatic placeholder argument dereferencing when > using bind()? I mean: > > struct SomePredicate > { > bool operator()(int num, const Foo& foo) const > { > return SomeTestOnFoo(num, foo); > } > } > > std::vector<Foo*> foos; > > // line below gives compilation error because second argument passed > // to functor is Foo* and not Foo. > > std::for_each(foos.begin(), foos.end(), bind(SomePredicate(), 123, > _1); >From http://www.boost.org/doc/libs/1_47_0/doc/html/lambda/le_in_details.html#id2… (section "Sizeof and typeid") for_each(a.begin(), a.end(), cout << bind(&type_info::name, ll_typeid(*_1))); Have you tried *_1 ? Regards, Ivan

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memory lost using cyclic pointers (shared_ptr)
by Peng Yu 09 Sep '11

09 Sep '11

Hi, I think that it is expected that shared_ptr cannot handle points that have cyclic references. In the following example, "a" points to "b" and "b" points to "a". There is a memory leak. I then modified it to remove the dependence using bare pointers, then the leak is resolved. But this is not a very satisfactory solution, as the programmer has to know whether to use bare point or shared_ptr. For very complexity program, it may not be possible to figure out it correctly. Does anybody know what is the best strategy for handing cyclic pointers? ~/linux/test/cpp/library/std/tr1/shared_ptr/loop$ cat main.cpp #include <tr1/memory> #include <iostream> struct B; struct A { std::tr1::shared_ptr<B> p; void print() { std::cout << "A" << std::endl; } }; struct B { std::tr1::shared_ptr<A> p; void print() { std::cout << "B" << std::endl; } }; int main () { std::tr1::shared_ptr<A> a(new A); std::tr1::shared_ptr<B> b(new B); a->p=b; b->p=a; a->p->print(); b->p->print(); } ~/linux/test/cpp/library/std/tr1/shared_ptr/loop$ valgrind ./main.exe ==75090== Memcheck, a memory error detector ==75090== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al. ==75090== Using Valgrind-3.6.1 and LibVEX; rerun with -h for copyright info ==75090== Command: ./main.exe ==75090== --75090-- ./main.exe: --75090-- dSYM directory is missing; consider using --dsymutil=yes B A ==75090== ==75090== HEAP SUMMARY: ==75090== in use at exit: 4,280 bytes in 6 blocks ==75090== total heap usage: 6 allocs, 0 frees, 4,280 bytes allocated ==75090== ==75090== LEAK SUMMARY: ==75090== definitely lost: 16 bytes in 1 blocks ==75090== indirectly lost: 80 bytes in 3 blocks ==75090== possibly lost: 0 bytes in 0 blocks ==75090== still reachable: 4,184 bytes in 2 blocks ==75090== suppressed: 0 bytes in 0 blocks ==75090== Rerun with --leak-check=full to see details of leaked memory ==75090== ==75090== For counts of detected and suppressed errors, rerun with: -v ==75090== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) #removing cyclic reference by using bare pointer. ~/linux/test/cpp/library/std/tr1/shared_ptr/loop$ cat main.cpp #include <tr1/memory> #include <iostream> struct B; struct A { std::tr1::shared_ptr<B> p; void print() { std::cout << "A" << std::endl; } }; struct B { std::tr1::shared_ptr<A> p; void print() { std::cout << "B" << std::endl; } }; int main () { std::tr1::shared_ptr<A> a(new A); std::tr1::shared_ptr<B> b(new B); a->p=b; b->p=a; a->p->print(); b->p->print(); } ~/linux/test/cpp/library/std/tr1/shared_ptr/loop$ vim main.cpp ~/linux/test/cpp/library/std/tr1/shared_ptr/loop$ make g++ -o main.exe main.cpp ~/linux/test/cpp/library/std/tr1/shared_ptr/loop$ valgrind main.exe valgrind: main.exe: command not found ~/linux/test/cpp/library/std/tr1/shared_ptr/loop$ valgrind ./main.exe ==75167== Memcheck, a memory error detector ==75167== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al. ==75167== Using Valgrind-3.6.1 and LibVEX; rerun with -h for copyright info ==75167== Command: ./main.exe ==75167== --75167-- ./main.exe: --75167-- dSYM directory is missing; consider using --dsymutil=yes B A ==75167== ==75167== HEAP SUMMARY: ==75167== in use at exit: 4,184 bytes in 2 blocks ==75167== total heap usage: 6 allocs, 4 frees, 4,272 bytes allocated ==75167== ==75167== LEAK SUMMARY: ==75167== definitely lost: 0 bytes in 0 blocks ==75167== indirectly lost: 0 bytes in 0 blocks ==75167== possibly lost: 0 bytes in 0 blocks ==75167== still reachable: 4,184 bytes in 2 blocks ==75167== suppressed: 0 bytes in 0 blocks ==75167== Rerun with --leak-check=full to see details of leaked memory ==75167== ==75167== For counts of detected and suppressed errors, rerun with: -v ==75167== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) -- Regards, Peng

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[bind] Dereferencing placeholder argument
by Szymon Gatner 09 Sep '11

09 Sep '11

Hi, Is there a way of automatic placeholder argument dereferencing when using bind()? I mean: struct SomePredicate { bool operator()(int num, const Foo& foo) const { return SomeTestOnFoo(num, foo); } } std::vector<Foo*> foos; // line below gives compilation error because second argument passed // to functor is Foo* and not Foo. std::for_each(foos.begin(), foos.end(), bind(SomePredicate(), 123, _1); I don't want to use indirect() adaptor from boost.range because I want final output range to still have Foo* as value_type so that it can still be copied to another std::vector<Foo*> etc. So: is there a way of telling bind() that is should dereference a placeholder argument before passing it to underlying bound functor? Regards, Simon -- Szymon Gatner The Lordz Games Studio www.thelordzgamesstudio.com

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