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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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