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Variant class serialization
by Alexander Katasonov 01 Nov '04

01 Nov '04

It is possible to serialize variant template class using boost serialization library? I couldn't do it directly, like this boost::variant<int, int, int> var; std::ofstream ofs("./out.xml"); boost::archive::xml_oarchive oa(ofs); oa << boost::serialization::make_nvp("variant", var); ofs.close();

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Boost (Test) lib. in VS2003
by Kovarththanan Rajaratnam 01 Nov '04

01 Nov '04

Hello Im trying to get Boost (Test library) working with Visual Studio .Net 2003, but Im having trouble getting a simple test compiling. Ive followed the steps in "Getting started" guide and compiled and installed it. What changes do I have to make in VS2003 to get it working? -- Best Regards Kovarththanan Rajaratnam

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boost graph library bugs
by Qiaofeng Yang 31 Oct '04

31 Oct '04

Hi, Does anybody use boost graph library here? I have been using it for a while and found that there seem quite a few bugs in the library. For example, there are bugs in: 1. incremental_components functions 2. subgraph functions Does anybody have problems with boost graph library? Where to find listed bugs found in boost graph library? Thanks very much! Qiaofeng

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Re: [Boost-users] shared_ptr<> w/ Boost::Python
by John Meinel 30 Oct '04

30 Oct '04

> >>-----Original Message----- >>From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- >>bounces(a)lists.boost.org] On Behalf Of John Meinel >>Sent: Saturday, October 30, 2004 9:24 AM >>To: boost-users(a)lists.boost.org >>Subject: [Boost-users] shared_ptr<> w/ Boost::Python >> [...] > >>" No to_python (by-value) converter found for C++ type: class >>boost::shared_ptr<class mine> " >> >>I have a converter for "class mine". I actually thought that the >>lifetime managers were using a shared_ptr, so if I did it myself, it >>would just be transparent. > > > [Nat] We tell boost::python the smart pointer type we're using, like > this: > > class_<DrawableInterface, DrawablePtr, boost::noncopyable> > ("DrawableInterface", no_init) > ; > > where DrawablePtr is a typedef for the smart pointer type. > This does work, if done by itself. I can do: class_<mine, boost::shared_ptr<mine>, bases<parent> , boost::noncopyable>("mine", no_init) However, this class has virtual functions. And while not strictly required, I tried to follow the recommendation that you create wrappers for all the functions, so that you can sub-class the C++ object in python. So I already have a class of: class mine_w : public mine { public: PyObject *self; mine_w(PyObject *_self) : self(_self) {} virtual bool func1(int a) { return call_method<bool>("func1", a); } } So right now, by definition looks like: class_<mine, mine_w, boost::noncopyable>("mine", no_init); If I changing mine_w to shared_ptr<mine> allows it to work. But trying to do: class_<mine, boost::shared_ptr<mine_w>, bases<parent> , boost::noncopyable>("mine", no_init); Again complains about no to-python converter for the given type. And trying to supply both, with: class_<mine, boost::shared_ptr<mine>, mine_w, bases<parent> , boost::noncopyable>("mine", no_init); Complains that I have too many template arguments. Also, what about the (hypothetical) situation where I might return shared_ptr<mine> from one function, but auto_ptr<mine> from another? Also, another "bug". If I create a pure-virtual class, then I should set the no_init field. However, if I try to sub-class this object in Python, the C++ constructor cannot be called, and so I can't pass this object to C++ functions. I'm trying to create some opaque interface classes (callbacks, etc). Without a wrapping class, it won't compile without no_init, since it tries to compile a function that would generate one. With a wrapping class I don't need no_init, and if I put it, then I can't properly subclass my object. Are these just known problems, and people live with it, or has it just not really come up? John =:->

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shared_ptr<> w/ Boost::Python
by John Meinel 30 Oct '04

30 Oct '04

I realize this may not be the right list, but since I'm already subscribed... I've been using boost::python to wrap some C++ code for quite a while now, and I've been quite happy with it. However, I decided to get into boost more, and I've found that shared_ptr/shared_array are quite nice. So I've started changing my functions from returning a raw pointer to returning a shared_ptr. In the boost::python tutorial, they talk about when you return a raw reference or pointer, you need to wrap it to manage lifetime of the object. http://www.boost.org/libs/python/doc/tutorial/doc/call_policies.html In the beginning of that page, they talk about how smart pointers are better for defining the scope and lifetime of objects, but sometimes raw pointers are necessary. I've gotten pretty good about when to manage_new_object, or return_internal_reference, etc. However, now that I have changed my return functions to actually return a smart pointer, it doesn't seem like I should need to wrap the return value anymore. Only now, when I try to do a "get" it gives me the error: " No to_python (by-value) converter found for C++ type: class boost::shared_ptr<class mine> " I have a converter for "class mine". I actually thought that the lifetime managers were using a shared_ptr, so if I did it myself, it would just be transparent. Does anyone know what the proper way to export a shared_ptr into python is? I suppose I could define the shared_ptr<class mine>, and only expose the "get()" function. But that would certainly be less than optimal. (I also obviously cannot wrap my function in another function that returns get(), because that would cause the shared_ptr to have the wrong lifetime.) Thanks for any help, John =:->

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RE: [Boost-users] i am stuck since a week here: need help:scopingerrorwhen trying to make boost work with luabind
by Brian Braatz 30 Oct '04

30 Oct '04

> help:scopingerrorwhen trying to make boost work with luabind > > Rohit O chokhani writes: > > Hi, i am a rookie as far as boost is concerned and i > > am trying to make boost work but just cant...on the > > point of giving up on it...so please help asap.... > > > > i am trying to use a scripting language called lua > > with my c++ source code. FOr that I felt the need to > > use luabind library which is completely dependent on > > boost.(project specific reasons for selecting luabind) > > > > > > As a result i need to have boost on my system. For the > > past 3-4 days ever since i have been trying to make > > boost works i have been getting all sorts of > > compilation errors. > > mainly they are as follows: > > > > C:\Program Files\Microsoft Visual > > Studio\VC98\INCLUDE\memory(16) : error C2059: syntax > > error : 'string' > > C:\Program Files\Microsoft Visual > > Studio\VC98\INCLUDE\memory(17) : error C2091: function [Brian Braatz] " C:\Program Files\Microsoft Visual > > Studio\VC98\" This shows me you are using VC6. While you "can" do this, you are asking for more pain than anyone should be forced to have. (it is not very compliant and has lots of template quirks. AND you get pages (and pages and pages and pages) of template warnings on valid code (making debugging compile time issues much more difficult) My *strong* suggestion to you is you install at least Visual Studio .net 2003 which comes with the vc++ 7.1 compiler. If you cannot purchase this product, the command line compiler is available for free download from: http://msdn.microsoft.com/visualc/vctoolkit2003/ Hope this helps (been there, done that, got the tee-shirt :) )

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RE: [Boost-users] shared_ptr<> w/ Boost::Python
by Nat Goodspeed 30 Oct '04

30 Oct '04

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of John Meinel > Sent: Saturday, October 30, 2004 9:24 AM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] shared_ptr<> w/ Boost::Python > > In the boost::python tutorial, they talk about when you return a raw > reference or pointer, you need to wrap it to manage lifetime of the > object. > http://www.boost.org/libs/python/doc/tutorial/doc/call_policies.html > > In the beginning of that page, they talk about how smart pointers are > better for defining the scope and lifetime of objects, but sometimes raw > pointers are necessary. I've gotten pretty good about when to > manage_new_object, or return_internal_reference, etc. > > However, now that I have changed my return functions to actually return > a smart pointer, it doesn't seem like I should need to wrap the return > value anymore. Only now, when I try to do a "get" it gives me the error: > > " No to_python (by-value) converter found for C++ type: class > boost::shared_ptr<class mine> " > > I have a converter for "class mine". I actually thought that the > lifetime managers were using a shared_ptr, so if I did it myself, it > would just be transparent. [Nat] We tell boost::python the smart pointer type we're using, like this: class_<DrawableInterface, DrawablePtr, boost::noncopyable> ("DrawableInterface", no_init) ; where DrawablePtr is a typedef for the smart pointer type.

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uBLAS bindings
by Daniel L Elliott 30 Oct '04

30 Oct '04

Hello, I would like to post this to uBLAS-users, but I am not yet a member. If anyone knows how to fix this, I would appreciate your help. I am working on adding identity matrices (and perhaps some others) to the gesv method of the LAPACK bindings. I have a couple questions about the code. In the template <typename MatrA, typename MatrB, typename IVec> inline int gesv (MatrA& a, IVec& ipiv, MatrB& b) method the static asserts are checking for the matrix types allowed within the gesv type? Instead of using gesv to invert a very large matrix (which would require us to create a very large identity matrix), would it be advisable to simply triangularize matrix A (maybe using LU) and use the uBLAS solver and an identity_matrix? Also, any overview of how the bindings and traits work would be very helpful! Thank you, Dan Elliott

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boost::function
by sboschi75-personal＠yahoo.it 30 Oct '04

30 Oct '04

Hallo, I would like to override operators for boost::function. Forexample I was thinking of an operator "-" : template <T> function<T> operator - (const function<T>& a) { // what do I write here in roder to return the symmetric function? } Thanks Stefano

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i am stuck since a week here: need help:scoping error when trying to make boost work with luabind
by Rohit O chokhani 30 Oct '04

30 Oct '04

Hi, i am a rookie as far as boost is concerned and i am trying to make boost work but just cant...on the point of giving up on it...so please help asap.... i am trying to use a scripting language called lua with my c++ source code. FOr that I felt the need to use luabind library which is completely dependent on boost.(project specific reasons for selecting luabind) As a result i need to have boost on my system. For the past 3-4 days ever since i have been trying to make boost works i have been getting all sorts of compilation errors. mainly they are as follows: C:\Program Files\Microsoft Visual Studio\VC98\INCLUDE\memory(16) : error C2059: syntax error : 'string' C:\Program Files\Microsoft Visual Studio\VC98\INCLUDE\memory(17) : error C2091: function returns function C:\Program Files\Microsoft Visual Studio\VC98\INCLUDE\memory(17) : error C2809: 'operator new' has no formal parameters C:\Program Files\Microsoft Visual Studio\VC98\INCLUDE\memory(20) : error C2954: template definitions cannot nest C:\BOOST2\BOOST\boost/mpl/aux_/integral_wrapper.hpp(88) : fatal error C1506: unrecoverable block scoping error Error executing cl.exe. i did find some solutions of the various forums of boost recommending to build the latest version from cvs in order to get rid of the scoping issue. however, that hasnt solved my case. could anyone kindly suggest some fixes, i would really appreciate it, thanks and regards, rohit __________________________________ Do you Yahoo!? Yahoo! Mail Address AutoComplete - You start. We finish. http://promotions.yahoo.com/new_mail

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RE: [Boost-users] Re: Boost work-in-progress list?
by Brian Braatz 29 Oct '04

29 Oct '04

> bounces(a)lists.boost.org] On Behalf Of Jeff Garland > > On Fri, 29 Oct 2004 11:10:11 -0600, Brian Braatz wrote > > That is an extremely good idea (putting up that Wiki). THANK YOU > > This point was discussed at the Boost/OOPSLA workshop held earlier in the > week. There was general agreement that we need to do a better job of > keeping > this list up to date and helping people find it. I'll be posting more > details > on the workshop results probably sometime next week. > > Jeff > > http://www.crystalclearsoftware.com/cgi- > bin/boost_wiki/wiki.pl?OOPSLA2004/Workshop > [Brian Braatz] Thanks Jeff. I missed the boost workshop as there were 2 tutorials given that my boss insisted I attend which conflicted. I will be very interested to read the notes from that workshop. ( I did stop by around 12:30 for Dave A's talk on Python, but noone was there- must have still been at lunch).. One question- What is the intended usage of the Wiki of things folks are working on for potential boost submission? I ask because I am preparing some info to send out to the list and basically in a spot where I will be one of those folks. (or maybe I should just wait patiently for your notes and all will be revealed ? :) )

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cross compile (ARM target)
by Josiah Bryan 29 Oct '04

29 Oct '04

Greets Boost users - I've just begun to play with boost for usage in a making my own GUI for my PDA (SimPAD), using AGG to render the widgets and Boost for the toolkit-type libraries (in place of the nice-but-GPLed Qt from trolltech). My question for you guys is this: 1) Is it possible to specify an abritray cross compiler for boost? - my build machine: Mandrake Linux 10.0 - cross compiler: gcc version 2.95.2 19991024 (release) - installed in /opt/Embedix/tools/bin/arm-linux-* 2) Is there already a predefined cross-compiler "target" for jam? Or maybe somebody understands what i need to do to get it crosscompiled, and can answer the question even if im not *asking* the right questions. :-) Any help is welcome.. Thanks! -- Josiah Bryan IT Coordinator Productive Concepts, Inc. jbryan(a)productiveconcepts.com (765) 964-6009, ext. 224

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RE: [Boost-users] gcc-3.4.1 and add_const
by Foster, Gareth 29 Oct '04

29 Oct '04

This randomly made me wonder ... if(const int * == int const *) Is that just a personal preference thing? Gaz -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Peter Dimov Sent: 26 October 2004 14:21 To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] gcc-3.4.1 and add_const Alexander Neubeck wrote: > Hi. > > I recognized a strange (wrong?) behaviour of gcc-3.4.1 (and > gcc-3.3.3). > When adding const to a type T and this type T is a reference, the > result is just T again (with reference, but witout const)! > Then I tested, if boost handles this case correctly, and it didn't. > The type of add_const< int & >::result is int & and not as expected > const int &. Your expectation was wrong. A "const" reference to int is not the same as a reference to a const int. [...] > My questions to you: > Can anybody verify this behaviour? > Is this behaviour intended? > If yes, WHY? Because that's how top-level const works. int * const != int const *, and int & const != int const &. > P.S: > It was quite difficult to check, which result-type the add_const > really created. First I used typeid( ... ).name(). But then I > recognized that int, int &, const int & produce ALL THE SAME name?!? Yes, that's how typeid works. _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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RE: [Boost-users] Re: Boost work-in-progress list?
by Brian Braatz 29 Oct '04

29 Oct '04

That is an extremely good idea (putting up that Wiki). THANK YOU > -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of Aleksey Gurtovoy > > "Libraries Under Construction" page on the Boost Wiki > (http://www.crystalclearsoftware.com/cgi- > bin/boost_wiki/wiki.pl?LibrariesUnderConstruction) > is supposed to serve the purpose, but it's not up-to-date at the moment. > > You might consider posting a request for an update on this to the > developers list. > > HTH, > -- > Aleksey Gurtovoy

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RE: [Boost-users] tcp/ip software
by Brian Braatz 29 Oct '04

29 Oct '04

You can also look at ACE http://www.cs.wustl.edu/~schmidt/ACE.html It is very powerful, and quite stable, but it does not use modern C++ techniques. > -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of Aaron W. LaFramboise > Sent: Monday, October 25, 2004 7:30 PM > To: boost-users(a)lists.boost.org > Cc: 0(a)main.gmane.org > Subject: Re: [Boost-users] tcp/ip software > > Greg Silverman wrote: > > Since Boost does not have a library for TCP/IP, I was wondering what OO > > interface to sockets is most popular with Boost users? > > Giallo <http://giallo.sourceforge.net> is a work-in-progress candidate > for a future Boost sockets library. > > Aaron W. LaFramboise > _______________________________________________

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RE: [Boost-users] uBLAS past, present, and future.
by Foster, Gareth 29 Oct '04

29 Oct '04

Doesn't freshmeat/sourceforge give you that automatically somehow? I remember seeing some sort of league table of the most 'active' projects on one of the two sites, taking that figure is something that could be automated, and so wouldn't go out of date, it might be a good start? If the code isn't on freshmeat/sourceforge maybe the same thing could be setup on the server where boost source is stored? Thinking about it, you could probably list the number of hackers on each project too, that would be a useful statistic. And what about bugs? Maybe the number of bugs in the bugzilla database (if there is one) could be shown too, that would go some way to indicating stability. And if there is an issuezilla (like openoffice.org has) then that might say something about completeness? The severity rating of each bug would be useful too ... Using all this stuff in a clever way, you could really come up with a groovy stats page for each project perhaps. Hope these ideas are helpful! Gaz -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Aaron W. LaFramboise Sent: 28 October 2004 20:25 To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] uBLAS past, present, and future. Daniel L Elliott wrote: > I am trying to better understand the current status of the uBLAS library. > Below I have listed a few questions. Of course, any responses are > completely off the record. We just need to get a better idea of the > current state of uBLAS. Thank you, in advance, for any information you > provide. I don't have the answers to these questions, but to be honest, I wish that every library in Boost had answers to all of these questions up in front on the main page of their documentation. These are very important peices of information, and misunderstandings with regards to these issues in general has created a lot of problems in the past. Sometimes, it would just be nice to have an honest indication of project vitality. Aaron W. LaFramboise _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Can't compile regex algorithm examples with MSVC++ 6 SP5
by Arno Schäfer 28 Oct '04

28 Oct '04

Hi all, try to compile and run all the regex algoritm examples lead by all examples to the same error (s. below). Has somebody an idea, what kind of define is missing or wrong? I try it with MSVC++ 6 SP5 on Windows 2000. thanks for any help, regards Arno switch on BOOST_REGEX_DIAG Compiling... Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8804 for 80x86 Copyright (C) Microsoft Corp 1984-1998. All rights reserved. cl /MDd /W3 /Gm /GR /GX /ZI /Od /I "..\Basics" /I "..\Basics\boost\include\boost - 1_31" /D "WIN32" /D "_DEBUG" /D "_CONSOLE" /D "_MBCS" /Fo"Debug/" /Fd"Debug/" /F D /GZ /c LibraryTest.cpp LibraryTest.cpp Linking to lib file: libboost_regex-vc6-mt-gd-1_31.lib ..\basics\boost\include\boost-1_31\boost\regex\config.hpp(596) : warning C4003: not enough actual parameters for macro 'BOOST_DO_STRINGIZE' BOOST_REGEX_DECL set as: BOOST_REGEX_CALL set as: __cdecl BOOST_REGEX_CCALL set as: __cdecl Using Win32 locale in regex traits class Using Version 4 regex code ..\boost\include\boost-1_31\boost\regex\v4\regex_traits.hpp(955) : error C2039: 'mbstate_t' : is not a member of 'std' ..\basics\boost\include\boost-1_31\boost\regex\v4\char_regex_traits.hpp(34) : error C2504: 'regex_traits' : base class undefined ..\basics\boost\include\boost-1_31\boost\regex\v4\char_regex_traits.hpp (34) : see reference to class template instantiation 'deprecated::char_regex_traits_i<charT>' being compiled ..\basics\boost\include\boost-1_31\boost\regex\v4\char_regex_traits.hpp(34) : error C2143: syntax error : missing ',' before '<' ..\basics\boost\include\boost-1_31\boost\regex\v4\char_regex_traits.hpp (34) : see reference to class template instantiation 'deprecated::char_regex_traits_i<charT>' being compiled ..\basics\boost\include\boost-1_31\boost\regex\v4\char_regex_traits.hpp(34) : error C2059: syntax error : '<' ..\basics\boost\include\boost-1_31\boost\regex\v4\char_regex_traits.hpp (34) : see reference to class template instantiation 'deprecated::char_regex_traits_i<charT>' being compiled ..\basics\boost\include\boost-1_31\boost\regex\v4\char_regex_traits.hpp(75) : fatal error C1506: unrecoverable block scoping error Error executing cl.exe. LibraryTest.obj - 5 error(s), 1 warning(s)

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RE: [Boost-users] Re: tcp/ip software
by Foster, Gareth 28 Oct '04

28 Oct '04

Sorry, I noticed after trawling further through my mail backlog that this had already been answered. -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Foster, Gareth Sent: 28 October 2004 09:41 To: 'boost-users(a)lists.boost.org' Subject: RE: [Boost-users] Re: tcp/ip software Is there a plan to get something like this into boost (just out of interest). -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Jeffrey Holle Sent: 25 October 2004 22:01 To: boost-users(a)lists.boost.org Subject: [Boost-users] Re: tcp/ip software I've used Rogue Wave's SourcePro Net product and found it clean and useful. In implementing a useful server, I also had to use their Threads product. Whatever you do, pay attention to boost.threads in implementing a TCP/IP using library! Greg Silverman wrote: > Since Boost does not have a library for TCP/IP, I was wondering what OO > interface to sockets is most popular with Boost users? > > Greg Silverman > Northrop Grumman > Sunnyvale, CA _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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RE: [Boost-users] Re: tcp/ip software
by Foster, Gareth 28 Oct '04

28 Oct '04

Is there a plan to get something like this into boost (just out of interest). -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Jeffrey Holle Sent: 25 October 2004 22:01 To: boost-users(a)lists.boost.org Subject: [Boost-users] Re: tcp/ip software I've used Rogue Wave's SourcePro Net product and found it clean and useful. In implementing a useful server, I also had to use their Threads product. Whatever you do, pay attention to boost.threads in implementing a TCP/IP using library! Greg Silverman wrote: > Since Boost does not have a library for TCP/IP, I was wondering what OO > interface to sockets is most popular with Boost users? > > Greg Silverman > Northrop Grumman > Sunnyvale, CA _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Boost work-in-progress list?
by Eric Ocean 27 Oct '04

27 Oct '04

Is there a comprehensive list available on up-and-coming-but-not-yet-a-part-of-Boost libraries? The ones I'm currently aware of are very interesting, and I'd like to evaluate any others. Regards, Eric Ocean

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About property maps and the Boost Graph module
by Ken Yasumoto-Nicolson 26 Oct '04

26 Oct '04

Hi folks, I've searched the archives and boost.org trying to find some help, but I still can't get my head around how the property maps are supposed to work. I'm pretty new to Boost, so I'm maybe not too familiar with the underlying concepts, etc, so forgive me if my question seems a little too basic! My problem is this: Given a directed graph with a single start and end point, I want for each node (vertex) to build a list of all the other nodes that can be reached from the current node. The algorithm is simple, I think: do a depth_first_search() and implement my code on dfs_visitor::finish_vector(). This skeleton I have done. However, the bit I can't get my head around is how to use property maps to collect the info. The key parts of my best effort so far are: struct statement_list_t { typedef boost::vertex_property_tag kind; }; typedef boost::property< statement_list_t, std::set<size_t> > StatementListProperty; typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::bidirectionalS, StatementListProperty, boost::no_property > ADJ_GRAPH; struct connection_detector : public boost::dfs_visitor<> { public: connection_detector() {} template <class Vertex, class Graph> void finish_vertex(Vertex u, const Graph& g) { /* for each child in out_edges( u, g ) current node set = union_of( current, child ) */ } } However, my questions are: 1. std::set<size_t> - is the size_t the best type to store a reference to a vector in? 2. In finish_vertex<> (or other places) how do I address the StatementListProperty value for a given vertex? 3. How would I use an Exterior Property Map instead? Thanks for any advice! Ken

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shared_ptr and shared_from_this
by Timothy Ritchey 26 Oct '04

26 Oct '04

I have an interpreter that uses a visitor pattern while performing a reduction of the program tree. As part of the visitor pattern, each class that can be a node in the tree must respond to: virtual void accept(Visitor& v); where each node then implements by calling visitor with itself using the proper type. The function calls in visitor are like: void visit(shared_ptr<Node> node); void visit(shared_ptr<Type> node); etc. (where Type is a descendant of node BTW). Normally with the visitor pattern (GOF style in this case), the implementation of accept is simply: void Node::accept(Visitor &v) { v.visit(this); } I've tried adding enable_shared_from_this<...> as a superclass of my nodes, and returning shared_from_this(), which works in some cases, but in others just seems to hang. These occur in classes that are a little more complex. For example, I have a TypeTemplate<T> class that wraps to underlying types TypeTemplate<int>, TypeTemplate<float>, TypeTemplate<etc>. I've tried adding enable_shared_from_this<TypeTemplate<T> >, and then having an implmentation void TypeTemplate<T>::accept(Visitor &v) { v.visit(enable_shared_from_this<TypeTemplate<T> >::shared_from_this()); } but it just hangs on both vc7.1 on windows and Xcode on OS X. (I had to add the extra scoping because I got complaints that "shared_from_this() was ambiguous in multiple inheritance.") I read in some past postings that the shared_from_this template doesn't work so well for complex class hierarchies, and I am wondering if I am running into that. I was thinking of putting my own internal_weak_ptr into the classes, but was confused by some of the examples I have seen. Most of them seem to reference a static function create() which instantiates the weak_ptr, and returns a shared_ptr<X>. When I consider my situation: shared_ptr<Node> aNode(new Node(...)); Visitor v; aNode->accept(v); How does the accept implementation return a shared_ptr that is linked with aNode? I've looked through the enable_shared_from_this implementation, and can't figure out how it is supposed to work. even if I return shared_from_this(), I'm not sure now that is linked to aNode. Does everything have to go through a factory like create()? Sorry for the long rambling e-mail. I hope it makes sense what I am trying to do. Cheers, tim

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"nested" spirit grammars and semantic actions
by Tim Robertson 26 Oct '04

26 Oct '04

Hi, I'm looking for advice on ways to "nest" spirit grammars that use semantic actions. In the past, I have written a spirit grammar that parses 2-dimensional array data from a file, and puts the data into an array object of my choosing. To do this, the grammar defines a new functor (array_insert) and calls the functor whenever a new array element is parsed. The functor puts the element into a reference to the destination object, held within the grammar: struct array_grammar { array_grammar(MyMatrix & m) : _inserter(m) {} struct array_inserter { array_inserter(MyMatrix & m) : _m(m) {} // operator() defined here... MyMatrix & _m; } // ...the usual grammar components... array_inserter _inserter; }; This works, as expected. However, I now have to write a parser for a file containing a collection of 2D arrays, where each array is delimited by tags (say, "BEGIN" and "END"). I would like to push each array into a std::vector of MyMatrix objects. Thus, it would be nice if I could re-use the array_grammar, and write a grammar which uses it to parse each array in the larger file: struct multi_array_grammar { multi_array_grammar(std::vector<MyMatrix> & v) : _inserter(v) {} struct array_inserter { array_inserter(std::vector<MyMatrix> & v) : _v(v) {} // ... operator(), etc. std::vector<MyMatrix> & _v; }; template <typename ScannerT> struct definition { definition(multi_array_grammar const & self) { array_begin = str_p("BEGIN"); array_end = str_p("END"); // Problem: how to create array_grammar with correct reference? array_grammar array(???); r = array_begin >> +array >> array_end; } }; array_inserter _inserter; }; The problem is that I can't figure out how to instantiate an array_grammar (which requires a reference to the current MyMatrix object) in order to parse the individual arrays. I have solved this problem by creating a functor in multi_array_grammar which calls the parse function for array_grammar directly, but this seems ugly to me. Do any of you have a better way? -Tim

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[FSM] Saving/Restoring the state_machine
by spooky＠go.ro 25 Oct '04

25 Oct '04

Is it possible to save the current state of the state machine to a stream or by means of boost::serialize? Details: I am building a state machine using boost::fsm that is trying to follow the activity of items in a processing pipeline. I am trying to implement a procedure that allows the software to be turned off and on again without loosing the information about the current state. Naturally, I want to have a timer and, at some interval I checkpoint the state machine and save the binary representation to a file. The contents of the file are used during application startup to restore the state machine. Can I achieve this functionality with boost::fsm? Best regards, Emil Mieilica

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tcp/ip software
by Greg Silverman 25 Oct '04

25 Oct '04

Since Boost does not have a library for TCP/IP, I was wondering what OO interface to sockets is most popular with Boost users? Greg Silverman Northrop Grumman Sunnyvale, CA

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