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warnings with boost::bind
by Hansi 31 Mar '09

31 Mar '09

Hello, I have a question. I use boost::bind with the following class: class B { int data; } class A { bool SetData(const B&){return true;}; } now when I make somewhere the following: A a; boost::bind<bool>(&A::SetData,&a); I get a warning 8>D:\boost\boost_1_34_1\boost/bind.hpp(1575) : warning C4180: qualifier applied to function type has no meaning; ignored 8> D:\boost\boost_1_34_1\boost/bind.hpp(1609) : see reference to class template instantiation 'boost::_bi::add_cref<Pm,I>' being compiled 8> with 8> [ 8> Pm=bool (__thiscall Microtec::Program::* )(const Microtec::TrackingInfo &), 8> I=1 8> ] 8> .\Program.cpp(2385) : see reference to class template instantiation 'boost::_bi::dm_result<Pm,A1>' being compiled 8> with 8> [ 8> Pm=bool (__thiscall Microtec::Program::* )(const Microtec::TrackingInfo &), 8> A1=bool 8> ] I think it is for the const reference. Is this a problem? Is there some way to avoid it (okay the way with pragma I know)? I use boost 1.34.1 and MSVC2005 Regards

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Cyclic includes when using smart pointers.
by Jared Lee Richardson 31 Mar '09

31 Mar '09

Hey, I'm having trouble with cyclic includes in a project I'm working on. This is my first attempt at a project that heavily uses boost, and specifically, smart pointers. I have the following situation, simplified down. Header file 1: class Test1 { vector<Test2Ptr> mTest2Objects; }; typedef boost::shared_ptr<Test1> Test1Ptr; Header file 2: class Test2 { vector<Test1Ptr> mTest1Objects; }; typedef boost::shared_ptr<Test2> Test2Ptr; Now normally I'd get around this easily by doing a forward declaration, but I can't do that with a smart pointer definition. How can I work around this? So far I have found ways to work around the above(Since that's not precisely what I'm doing), but when I start inlining functions it will become very difficult to work around. Obviously something is wrong with my include structure or how I am going about this, but I don't know what... Any help? Is there a way I can forward-declare smart pointers? How are complicated cyclic includes usually resolved, if forward declares aren't enough(i.e., inline files)? Thanks, Jared

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[concept check][mpl] (Conditional) Concept checking for functions
by Jesse Perla 31 Mar '09

31 Mar '09

One rough idea I had was that since I will always have boost::function declarations as the default type, I could try to see if the type F is compatible with the boost::function type? Could this be done in a simple metafunction similar to the following: template<class BoostF, class F> struct CheckFunctionCompatible { static void Check() { F f; BoostF fboost = f; //If this fails, then I am basically failing } }; But then if I instantiate, won't it also try to instantiate the constructor? template<class F> class { typedef CheckFunctionCompatible<boost::function<double (double)>, F> test_F_compatibility; }; Of course, this wouldn't work for detecting the signature of the function, but that is a 2nd order feature for me. Of course, this also assumes that F can be constructed with no parameters, but this also might be reasonable for me if there is no better solution. -Jesse

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TupleIt and zip_iterator
by Andreas Fabri 31 Mar '09

31 Mar '09

Was Anthony Williams TupleIt, mentioned in http://www.cpptalk.net/7-vt9657.html?postdays=0&postorder=asc&start=90 and distributed in http://groups.yahoo.com/group/boost/files/tupleit.zip) the precursor of the boost::zip_iterator? In contrast to the boost::zip_iterator an TupleIt iterator range can be sorted. What are the advantages of the zip_iterator, besides being in boost. andreas

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Re: [Boost-users] [wave]include not found
by Ein Held 31 Mar '09

31 Mar '09

Here we go: http://rapidshare.com/files/215649826/wave.zip.html or http://uploaded.to/?id=ndz0tn

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[Q] does map.erase destroy shared_ptr ?
by V S P 31 Mar '09

31 Mar '09

Hello, I am storing database streams as associated string tag as std::map< std::string, boost::shared_ptr<otl_stream> > once in a while I need to remove a stream based on the tag, so I do //find stream based on tag //close stream s->close //call map.erase can I expect that once I call map erase the destructor of the stream will get called? (for some reason I do not see my trace statement of the destructor, but the stream destruction are unfamiliar code to me.. so I may be just doing something wrong). thank you, Vlad -- V S P toreason(a)fastmail.fm -- http://www.fastmail.fm - Faster than the air-speed velocity of an unladen european swallow

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Returning a shared_ptr or raw pointer from a template function
by Ryan McConnehey 31 Mar '09

31 Mar '09

I want to allow the user to specify if a function returns a raw pointer or a shared_ptr from a creation type function. The code I've started with is as follows: class Track{}; class Tm{}; template <class R, class T> R create(void) { R temp(new T()); return temp; } This allows to the user to call the function like: Tm* tm3 = create<Tm*, Tm>(); boost::shared_ptr<Tm> tm4 = create<boost::shared_ptr<Tm>, Tm>(); I would like to have a class that has this create function and upon creation of the class specify if the create function returns a raw pointer or shared_ptr. template <class U> //The U specifies is the create function returns a raw or shared pointer class Rdi { template <class S> U create(void) { U temp(new S()); return temp; } }; How would I modify this class to allow the user to make the following calls? Rdi<boost::shared_ptr> fun1; Tm* tm3 = fun1.create<Tm>(); Rdi<raw Pointer???> fun2; boost::shared_ptr<Tm> tm4 = fun2.create<Tm>(); Any help would be appreciated. Ryan

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[wave]include not found
by Ein Held 31 Mar '09

31 Mar '09

Hello According to the wave documentation, the include folder functions of the context object work "are modelled after the command line behaviour implemented by the popular gcc compiler." Unfortunately this is wrong. By default gcc 4.x -Is' folders (when not used with -I-) are searched for "...." and <...> include files. Wave does not do so. Anyway, I am searching for a solution for this problem: Lets say I got a file named dub.cpp that I am parsing with wave and that looks like that: #include <foo/bar.hpp> int main{} bar.hpp looks like this: #include "test.hpp" extern int a; test.hpp is just an empty file in the same folder as bar.hpp I added the parent folder of foo to the wave context object via add_sysinclude_path . Unfortunately wave does not find the file test.hpp (exception - "error - could not find include file"). I tried nearly all possible combinations of add_include_path, add_sysinclude_path, set_sysinclude_delimiter - but I have not succeeded. This simple sample is still failing.. gcc -c -I"/foo/parent/folder" dub.cpp works fine though. Whats wrong?

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Completely Perplexed Noob to BGL: Reachability Question
by Roshan Rammohan 31 Mar '09

31 Mar '09

Hi all, Although I was attracted to BGL since I have to use a lot of graph algorithms for my work, and I have managed to read through as much online documentation as possible, generic programming is still very mysterious to me. All I need to do is compute reachability from vertex B to vertex A before I add the edge A->B to a graph (directed and acyclic) so that I can maintain its acyclic property. I do not want to add the edge, discover a cycle and then remove it. I saw a very closely related example here. (thanks to Steven Watanabe) http://lists.boost.org/boost-users/2009/03/46396.php That was helpful, but I'm still not able to adapt this to my need mainly because I find the syntax and concepts of generic programming extremely confusing. I am not sure how I can pass an extra parameter into a BFSVisitor which the member function discover_vertex can use. Does discover_vertex have to have only a vertex_descriptor and a Graph? I want to pass another constant vertex to it so I can return on equality. I need to initiate a BFS from vertex B, (and not continue with new trees once the tree with B as root is finished) . On discovering vertex A in this search I need to return true, false for all other cases. Pretty simple, and I am hoping someone would write a code snippet for me that will solve the problem and also provide me with the baby step I need to wrap my head around this Visitor concept. Thanks in advance. - Roshan Rammohan PhD Candidate, A.I. lab, Dept of C.S., Univ. of New Mexico, USA

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[statechart] state behaviour
by liquid 30 Mar '09

30 Mar '09

Hi, two questions about states in statechart: 1. How (if possible) to implement this: a state upon an event generates an event and transits to another state? 2. Can a state have private nondestroyable memory? Regards liquid

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