October 2004 - Boost-users - lists.boost.org

boost::shared_ptr and stl algorithms
by Bill Eidson 15 Apr '05

15 Apr '05

std::vector< boost::shared_ptr<T> > TVec; I want to write a function object to run std::for_each. to do somework against members of T and accumulate results in functor. My attempts have failed in VC7 with memory errors in my operator() method. struct fo { bool operator()( boost::shared_ptr<T>& t ) { return true; } }; Thanks in advance bille

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Will libraries built on WinNT run on Win98? (MinGW)
by Reed Hedges 31 Mar '05

31 Mar '05

I know that Win98 is not really supported, but is there any chance that libraries (specifically thread and regex) that were build on WinNT using MinGW work on Win98 (in MinGW)? My guess is no, but has anyone tried it? thanks reed

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Bug in lexical_cast<> with doubles
by Leon Raj 29 Jan '05

29 Jan '05

I think I've found a bug in the boost::lexical_cast<> library (v1.31.0) on WinXP SP1, MSVC 6.0 (sp5) and MSVC.NET 2003. --- Start code snippet --- #include <boost/lexical_cast.hpp> #include <iostream> int main( int argc, char* argv[] ) { double dMax = = std::numeric_limits< double >::max(); // On a Win32 x86 system, dMax is now 1.7976931348623157e+308 // This is successful and strMax is "1.797693134862316e+308" std::string strMax = boost::lexical_cast< std::string >( dMax ); try { double newDMax = boost::lexical_cast< double >( strMax ); std::cout << "Successfuly" << std::endl; } catch ( boost::bad_lexical_cast& ) { std::cout << "Failed to cast" << std::endl; } // On a Win32 x86 system, this always fails, // because (I think) strMax overflows a double, // because 1.7976931348623157e+308 is *rounded UP* // to 1.797693134862316e+308, which cannot be // represented by a double } --- End code snippet --- ----------------------------------------------------- Leon Raj Senior Engineer Invetech Pty. Ltd. Phone: +61 3 9211 7000 (Switchboard) +61 3 9211 7938 (DDI) leon.raj(a)invetech.com.au IMPORTANT - This e-mail and any attachments may be confidential. Any retransmissions, dissemination or other use of these materials by persons or entities other than the intended recipient is prohibited. If received in error, please contact us and delete all copies. Before opening or using attachments, check them for viruses and defects. Our liability is limited to resupplying any affected attachments. [Any representations or opinions expressed in this e-mail are those of the individual sender, and not necessarily those of Vision Systems Limited].

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Format Library - Asterisk Support
by Barak Simon 01 Dec '04

01 Dec '04

Hi, I have noticed that the format library does not support at present the printf asterisk for providing dynamic width as an extra parameter. Unfortunately my users need to use this widely and I would really hate to revert back to a non-typesafe solution. a. Are there any plans to support it in near future? b. If not, is there an easy way to add that to parsing.hpp, parse_printf_directive method, parse_width & parse_precision sections? currently the asterisk is ignored, and the library throws an exception thinking it has an extra parameter. c. Is there any workaround I miss which may give me the same expected result of providing say "%*s, width, charPtr" ? (I have 'width' and a non-null-terminated char pointer and need to construct the correct string from them without doing unnecessary copying...) Many thanks, Barak ________________________ Barak Simon GED IT Core Platform Deutsche Bank 190 George St. Sydney, 2000 Phone +61 2 925 85070 Fax +61 2 925 95050 -- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.

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MPL Library
by Edward Diener 18 Nov '04

18 Nov '04

I have bit the bullet and am attempting to get my head around the MPL library. I realize there is a book out by Messieurs Abrahams and Gurtovoy, I believe, but I thought I would tackle the boost documentation first. A few questions: 1) Is the documentation up to date ? 2) There are three separate documents to study, it seems, all giving information about the MPL library, a white paper circa 2002, a reference, and a mini-tutorial. Is the information in these in sync with each other ? The reason I ask is that the white paper/mini-tutorial mentions if_<> and apply_if<> but the reference does not mention them at all.Are they just understood intrinsic metafunctions that need no reference, or what ? If the former, are there more of these intrinsic metafunctions and, if co, what are they and what do they do ? 3) A number of the topics in the reference documentation mentioned in generalized overviews of the various sections have no specific links. Does this mean that they were never implemented ? Seems dubious in a number of cases. I would seriously like to figure out how MPL works and play around with it, but I feel stymied with what is in the boost docs.

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Boost::Regex - bug work-around...?
by Michael Starling 02 Nov '04

02 Nov '04

Hi there... I've been trying to implement some routines using the Boost library, primarily with the excellent RegEx library. Everything was working well enough in small tests, but when I tried running the routines on many patterns, my program would crash (it performs various pattern matching and search-and-replaces in multiple text files). I was able to determine that the crashes came on the calls to regex-related functions (though it tended to be a little unpredictable as to when, depending on the set of files I gave it). I tried changing my project settings (I use VC6, btw) to link with "debug" libraries instead of the standard ones (eg. "Debug Multithreaded"), and ran the program again, and everything worked perfectly. Unfortunately... I don't want to have my program running with all-debug libraries for performance and size reasons. However, is it possible to have my link-settings set to use standard libraries as before, but for the stuff that uses the regex library, to use a debug ".lib" file? Or... in the 'bjam' process, is it possible to say something to the effect of "when compiling the regex libraries, turn off compiler optimizations", so I can get a standard library that should work...? Hopefully that'll make sense... :P Thanks for your time, Mike.

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uBLAS past, present, and future.
by Daniel L Elliott 02 Nov '04

02 Nov '04

Hello, 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. - What is the history of uBLAS? What is the eventual goal? - What is the current status of uBLAS? How complete is it currently? Anything left unimplemented (Sparse stuff)? Should a project which relies upon uBLAS heavily *expect* to encounter bugs within uBLAS? - Is uBLAS expected to become a part of the C++ standard? - What advantages/disadvantages do you feel uBLAS has when compared to FORTRAN. Could it replace FORTRAN? Thank you to everyone for your time and effort on all BOOST libraries and for your answers. Sincerely, Dan Elliott

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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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