February 2013 - Boost-users

Re: [Boost-users] [parallel graph] error building parallel BGL
by The Maschine 27 Feb '13

27 Feb '13

To be honest I thought that boost.build will include the link to MPI automatically. Isn't this suposed to include mpi?> ./b2 libs/graph_parallel/example Ill try to test it by hand. ThanksTasos

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Unable to build 1.53.0 Ubuntu Linux 10.04
by Michael Powell 27 Feb '13

27 Feb '13

Hello, I am running GCC 4.4.3 (default?) distributed with Ubuntu Linux 10.04 LTS. I would like to build the latest Boost to keep up with the language and library standards, because we'll need those on a project we're working on (obviously), but it seems that we'll need to upgrade the GCC tool chain in order to do this: plus it us necessary even helpful to have access to lambda functors, expressions, etc, access Boost Phoenix (for Spirit2), and so on. I've read how it's possible to upgrade the GCC tool chain, but it worries me for obvious reasons. Also, building is one thing, the front end tool chain. We'll be cross compiling to ArchLinux running on ARM. I've done some reading about this issue and it seems that this is more of a back end concern. In other words, as long as the thing builds, compiles and links with whatever tool chain, language standard, compiler, etc, the cross compile should go well. Specifically, I believe we're going with CodeBench, but if there are other cross compilers available, that would be helpful to know as well. Any wisdom approaching an issue like this? Regards, Michael

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[MSM] Unable to retrieve correct value of attribute of a state from within actions. (Possible Bug?)
by Deniz Bahadir 27 Feb '13

27 Feb '13

Hi everyone, Hi Christophe, Using Boost.MSM with eUML I tried to access the attribute of a state from within an action. However, the value is not what I expected when accessing the attribute of the state given as argument to the action. (It seems to be the default-parameter.) If I access the state directly (by name) and retrieve the value from it, it is set correctly as expected. Could it be that an action gets its arguments as copies? If so, I guess, the attributes of the copied arguments should be copied, too. This is the case for events. The attributes of an event given to the action seems to be set correctly. But the attributes of a state seem to be default-initialized. For clarification a simple example (this time tested and successfully compiled): #include <iostream> #define BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS #include <boost/msm/back/state_machine.hpp> #include <boost/msm/front/euml/euml.hpp> using namespace boost::msm::front::euml; namespace msm = boost::msm; namespace mpl = boost::mpl; using namespace std; namespace { // The attribute: BOOST_MSM_EUML_DECLARE_ATTRIBUTE(int, Number) BOOST_MSM_EUML_ATTRIBUTES((attributes_ << Number), NumberAttr) // An event containing the attribute: BOOST_MSM_EUML_EVENT_WITH_ATTRIBUTES(event1, NumberAttr) // Two states with attributes: BOOST_MSM_EUML_STATE((no_action, no_action, attributes_ << Number), state1) BOOST_MSM_EUML_STATE((no_action, no_action, attributes_ << Number), state2) // Entry-action which initializes the attributes: BOOST_MSM_EUML_ACTION(init_events_and_states) { template <class Evt, class Fsm, class State> void operator()(Evt const&, Fsm&, State&) { event1.get_attribute(Number) = 100; state1.get_attribute(Number) = 1; state2.get_attribute(Number) = 2; }; }; // Action that prints the Number-attributes of event and state. // NOTE: The state-Numbers differ! BOOST_MSM_EUML_ACTION(printNumber) { template <class Fsm, class Evt, class SourceState, class TargetState> void operator()(Evt const& evt, Fsm&, SourceState& source, TargetState& target) { std::cout << "In action \"printNumber\"." << "\n event1.Number == " << event1.get_attribute(Number) << "\n evt.Number == " << evt.get_attribute(Number) << "\n state1.Number == " << state1.get_attribute(Number) << "\n source.Number == " << source.get_attribute(Number) << "\n state2.Number == " << state2.get_attribute(Number) << "\n target.Number == " << target.get_attribute(Number) << std::endl; }; }; // The transition table: BOOST_MSM_EUML_TRANSITION_TABLE(( state1 + event1 / printNumber == state2 ), stt) // The FSM front-end and back-end: BOOST_MSM_EUML_DECLARE_STATE_MACHINE(( stt, init_ << state1, init_events_and_states ), FsmFrontend); typedef msm::back::state_machine<FsmFrontend> Fsm; void test() { Fsm fsm; // needed to start the highest-level FSM. // This initializes all attributes. fsm.start(); // emit event1 fsm.process_event(event1); } } // namespace int main() { test(); return 0; } // This prints the following (except "//") on the cmdline : // In action "printNumber". // event1.Number == 100 // evt.Number == 100 // state1.Number == 1 // source.Number == 0 // state2.Number == 2 // target.Number == 0 As you can see, the attribute-values of "event1" and "evt" are the same. However, the attribute-values of "state1" and "source" differ although they should be the same, too. (The same applies to "state2" and "target".) I tried this example with a custom type as attribute-type which prints each constructor-call and assignment-call and I realized, the copy-constructor was never called. If you want to try it yourself, just replace the declaration of the attribute in the above example with the following code: class MyInt { int val_; public: MyInt() : val_(50) { std::cout << "MyInt()" << std::endl; } MyInt(const MyInt& obj) : val_(obj.val_) { std::cout << "MyInt(const MyInt&) - val_=" << val_ << std::endl; } MyInt(const int& i) : val_(i) { std::cout << "MyInt(const int&) - val_=" << val_ << std::endl; } MyInt& operator=(const MyInt& obj) { val_ = obj.val_; std::cout << "op=(const MyInt&) - val_=" << val_ << std::endl; return *this; } MyInt& operator=(const int& i) { val_ = i; std::cout << "op=(const int&) - val_=" << val_ << std::endl; return *this; } }; // The attribute: BOOST_MSM_EUML_DECLARE_ATTRIBUTE(MyInt, Number) This looks like a bug, but I am not sure. Maybe I have to write my transition-table differently? Ciao, Deniz PS: I am using Boost 1.53.0 with GCC 4.7.2 (and C++11 support activated, most of the time.)

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Please help make this boost::bind example compile
by Chris Stankevitz 27 Feb '13

27 Feb '13

Hello, In the code below, the last function, "GetFunctionThatReturnsRefX_2", does not compile. It is attempting to use boost::bind to produce a boost::function that takes a pointer to an object and returns one of the object's member variables by reference. If it is possible, would you modify it so that it does compile? Note 1: No problem when returning a copy as in "GetFunctionThatReturnsCopyX_2" Note 2: I employ a workaround in "GetFunctionThatReturnsRefX_1" that uses a helper "facade" function. I'm hoping to avoid this. Similarly I'm hoping to not have to add member function TCObject::GetX. Invoked with "g++ -c test.cpp" using gcc 4.6.3. Thank you, Chris #include <boost/bind.hpp> #include <boost/function.hpp> //------------------------------------ //------------------------------------ struct TCObject { int x; }; //------------------------------------ //------------------------------------ int GetCopyX(TCObject* pClass) { return pClass->x; } //------------------------------------ //------------------------------------ boost::function<int(TCObject*)> GetFunctionThatReturnsCopyX_1() { return boost::bind(GetCopyX, _1); } //------------------------------------ //------------------------------------ boost::function<int(TCObject*)> GetFunctionThatReturnsCopyX_2() { return boost::bind(&TCObject::x, _1); } //------------------------------------ //------------------------------------ int& GetRefX(TCObject* pClass) { return pClass->x; } //------------------------------------ //------------------------------------ boost::function<int&(TCObject*)> GetFunctionThatReturnsRefX_1() { return boost::bind(GetRefX, _1); } //------------------------------------ //------------------------------------ boost::function<int&(TCObject*)> GetFunctionThatReturnsRefX_2() { //return boost::ref(boost::bind(&TCObject::x, _1)); return boost::bind(&TCObject::x, _1); }

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Can boost help me organize/parse lots of binary data?
by Chris Stankevitz 27 Feb '13

27 Feb '13

I am receiving a "live" stream of binary data that represents the states of various objects. Sort of like this: Car Speed (m/s): float32 Temperature (deg): uint16 ... My real packets have hundreds of items in them. I will be decoding many of these "packets" and doing various things with them like printing their values to console, etc. My plan is just to make classes: class Car { public: void Decode(istream&); private: float speed; unsigned temperature ... }; But it will not be very extendable. Unfocused open-ended question: Does boost offer something that will help me with this? Thank you, Chris

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[heap] How to orderly traverse a priority queue and update a given element?
by Francisco Lopes 27 Feb '13

27 Feb '13

I'm looking for a good data structure that can *maintain* its elements sorted. Currently I'm trying Boost.Heap<http://www.boost.org/doc/libs/1_53_0/doc/html/heap.html> . I frequently need to orderly traverse the data structure, find a element based on some property and update its priority when it matches. Boost.Heap priority queues provide ordered and non-ordered iterators. Element updates occurs through a element handle, a handle can be obtained from a ordinary non-ordered iterator, but not directly from a ordered one as in the following example: #include <iostream>#include <algorithm>#include <boost/heap/fibonacci_heap.hpp> using namespace boost::heap; int main(){ fibonacci_heap<int> fib_heap; fib_heap.push(1); fib_heap.push(2); fib_heap.push(3); for(auto i = fib_heap.ordered_begin(); i != fib_heap.ordered_end(); ++i) { auto h = fibonacci_heap<int>::s_handle_from_iterator(i); if(*h == 3) { fib_heap.increase(h, *h + 2); break; } } std::for_each(fib_heap.ordered_begin(), fib_heap.ordered_end(), [](const int &e) { std::cout << e << std::endl; });} How can I orderly traverse the queue and update an element in the traversal? Note that I leave traversal after the update. (Suggestions of alternative libraries for such purpose are welcome)

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Errors compiling for Linux Ubuntu
by Michael Powell 26 Feb '13

26 Feb '13

Hello, Unless my compiler tool chain is off, I am just getting a ton of errors compiling Boost 1.53.0 for Linux Ubuntu. Ultimately, we'll want to cross-compile down to Arch Linux / ARM as well if it makes a difference (and it will). Errors saying failed updating 57 targets, skipped 10150 targets. I am building with all libraries and setting my prefix to /opt/boost_1_53_0. Then I run the ./b2 install. I am basically following the Linux instructions, but apparently, what am I missing? Thank you. Regards, Michael

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Boost.MSM cc1plus.exe:: error: out of memory allocating 65532
by RaRi 26 Feb '13

26 Feb '13

Hi all, I'm using boost.msm from the boost 1.53.0 library. I have together 8 submachines and almost 50 states distributed between the differente submachines. The number of events is 44. Unfortunately I got the following compilation error: * cc1plus.exe:: error: out of memory allocating 65532* First of all I have observed the memory allocation while the compilation phase: It exceeded 2Gm memory and than I've received that error. So, my solution was to switch to an 64 bit system with 8 GB memory. But to hell, I still got this error. My system environment is configured as follows: Operating system : Windows 7 64-Bit MinGW32, gcc v.4.72 Is this an gcc bug or do I have to extend to 16 GB? But I don't think so, as the failue is always reported after almost 2 Gb memory allocation while the compilation phase... Thank you for your help in advance, BR, Rafael -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-MSM-cc1plus-exe-error-out-of-memor… Sent from the Boost - Users mailing list archive at Nabble.com.

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[units] Creating a velocity unit
by Ryan 26 Feb '13

26 Feb '13

Boost Community, I'm trying to create a custom velocity unit. I would like to create a unit that is in nautical miles per hour to represent my speed value. If I use pound_force.hpp as an example of units with more than one dimension I can create the following. BOOST_UNITS_DEFINE_BASE_UNIT_WITH_CONVERSIONS(metric, nautical_mile_per_hour, "nautical mile per hour", "nmi h^-1", factor, si::velocity, ???); If this is the right track, what id would I use and how do I know that it is unique? This seems forced. I would rather define this unit in terms of meters per second. Nautical miles is already in terms of meters and hours is also defined as a scale of seconds. Can I somehow use these two already defined units to create the new unit? How would I do this? Ryan

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[PBGL] distributed property map problem
by bminano 26 Feb '13

26 Feb '13

Hello, I am having a problem trying to initialize the distributed property map in parallel code. I get a memory access violation when running this part of code: BGL_FORALL_EDGES(e, g, Graph) { remote_key k(rank, index); put(values, k, 0.1); index++; } I followed the distributed_property_map_test, but I cannot figure where is the problem. It fails at the first edge. The distributed map is defined as follows: typedef boost::parallel::distributed_property_map<mpi_process_group, remote_key_to_global, EdgeIndexMap> ValueMap; ValueMap values(g.process_group(), remote_key_to_global(), eindex); values.set_reduce(rank_accumulate_reducer<double>()); Where eindex is a local map with the local indices of the edges. Please, could someone help me? -- View this message in context: http://boost.2283326.n4.nabble.com/PBGL-distributed-property-map-problem-tp… Sent from the Boost - Users mailing list archive at Nabble.com.

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