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Re: [Boost-users] Multiprecison: converting a complex class to a number<> backend
by John Maddock 30 Jun '16

30 Jun '16

On 29/06/2016 22:17, Christopher Kormanyos wrote: > > In my opinion, trying to adapt a complex number class to the backend > requirements of number might not be the best way to go. > > I would recommend writing an extended complex template class > that is intended to be instantiated for both user-defined types as well as > float, double and long double. > > The real and imag parts are template parameter types. They could be > of type mpfr_float because the template parameter type is > determined at compile-time when the class is instantiated. > > In the winter, I wrote an extended complex class and tested it extensively > with multiprecision and fixed point. There was also another candidate > implementation of extended complex a few years ago from another > developer, but it never got to review. > > I have not yet made my extended complex code available. > > I am not subscribed to the user's list. If the post gets to the > developer's > list, there is a good chance I will see it. I'm curious as to what you see as the stumbling block to providing a complex number backend to class number<> ? The main advantages are that the expression-template code and all operator overloads are "just there" already, what do you see as the drawbacks? Best, John.

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Multiprecison: converting a complex class to a number<> backend
by Daniel Brake 29 Jun '16

29 Jun '16

Hi Boost, I have implemented my own complex class wrapping around Boost.Multiprecision number<>, particularly mpfr_float. Now, I'd like to take the class I've written, and extend/convert it into a backend suitable for use in number<>. While I've read the documentation describing the requirements for a backend <http://www.boost.org/doc/libs/1_61_0/libs/multiprecision/doc/html/boost_mul…>, and think I understand what I need to do, I have found 0 examples in the wild. My current setup has a pair of files mpfr_complex.hpp, mpfr_complex.cpp describing something like (just what you'd expect, really) --------- class complex{ mpfr_float real_, imag_; public: // the *= family of operators, getters, setters, // some factory functions, etc }; //the free operators defined down here, along with pow, exp, etc. -------------- I think what I'd like to write is a new complex_backend.hpp file which implements the required functions for the complex wrapper around mpfr_float. In this file, I believe I implement the family of functions such as eval_multiply(b, a) in terms of the operators for my complex class. Is this right? In a related vein, with et_on for mpfr_float, I've started adding templated overloads for the complex operators and math function accepting expressions of reals, and I think this is going to get out of hand, so using number<> would conceivably save me a ton of time writing my own functions. It will also save me a ton of errors for hand-writing the expression templates for complexes, which appear to be ready to go from Boost.Multiprecision once I get a backend implemented. Again, my goal is expression templates for complexes with real and imaginary fields consisting of mpfr_floats, leveraging the number<> template, with et_on, and my own backend. Do you have any advice? Any references to any other custom backends? Daniel Brake University of Notre Dame Applied and Computational Mathematics and Statistics

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Boost interprocess mutex with shared memory
by Ashok Palaniswamy 28 Jun '16

28 Jun '16

Hi all, I want to implement boost interprocess mutex with shared memory. This mutex will protect the SMBUS access between multiple processes. In the entire source code, this mutex will be used across different the files. Please let me know if you have any sample programs available. Thanks, P.Ashok L&T Technology Services Ltd www.LntTechservices.com<http://www.lnttechservices.com/> This Email may contain confidential or privileged information for the intended recipient (s). If you are not the intended recipient, please do not use or disseminate the information, notify the sender and delete it from your system.

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boost::serialize 1.61 ticket #12141 not quite fixed for Visual Studio 15?
by Colin Humphries 27 Jun '16

27 Jun '16

After converting to boost 1.61 and Visual Studio 15 we now see a problem closely related to one reported in ticket #12141. Our XML archives now end with the following 2 lines: </boost_serialization> </boost_serialization> Could someone suggest a quick fix please? I think the problem must be in archive/impl/xml_woarchive_impl.ipp but I can't seem to grasp how the archive destructor emits the last line. Regards, Colin Humphries

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Backend of multi_index container
by Anaswara Nair 27 Jun '16

27 Jun '16

Hi, I was going through the documentation of boost::multi_index container. I would like to know what is in its back end. Something like B-Tree,B+tree,etc.? Actually I want to create a database(in the sense it contains millions of records), but need not be reusable at a later period of time. i.e, I am looking only for run-time persistent data. Once data is inserted to this, it will not be modified. And there will be a unique id for each record. I would also like to know whether multi_index is the best suited one for the implementation of my so called database.. Thankyou

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Re: [Boost-users] Backend of multi_index container
by anaswara 26 Jun '16

26 Jun '16

I have 7 fields in each record,two strings and five 64 bit integers. Of these,one of the integers is unique. I need to store all such records into the DB. In multi-index, I have a structure and this structure is being indexed by that integer value. If I have to similarly create a structure and store it as the value in LMDB, then what is its difference from multimap? I can do the same in multimap also. Then how does LMDB become a database. Sent from Samsung Mobile -------- Original message -------- From: degski <degski(a)gmail.com> Date: 24/06/2016 7:43 PM (GMT+05:30) To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Backend of multi_index container On 24 June 2016 at 15:51, Anaswara Nair <anaswara.nn(a)gmail.com> wrote: I have gone through LMDB. However AFAIK LMDB stores the data as a key-value pair. Yes, it's a key-value store. Though duplicate keys are allowed, I couldn't find any relation between these entries. I couldn't understand its use as a database as well. It's like std::(multi)map, maybe the wikipedia entry helps. Can you provide some help so that I can go deeper into this. In your original question, you refer to having one unique ID and some related data per record. Maybe you could expand a bit on what you would like to achieve. degski

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[Boost.PropertyTree] Application hangs (Boost 1.61)
by Andrew C 25 Jun '16

25 Jun '16

Hi! It seems to be a bug that this application hangs inside "erase" method: #include <boost/property_tree/ptree.hpp> int main() { boost::property_tree::ptree pt; pt.erase(pt.begin()); // enters infinite loop... } Compiled with Cygwin/GCC-5.4.0. Is it really a bug or my misuse? Thanks!

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CPack, CMake and Boost's shared libraries
by r＠primef.actor 25 Jun '16

25 Jun '16

What is the canonical cross-platform way to package boost shared libraries with CPack (and/or CMake)? On Windows, DLLs can be copied to the executable's folder and it will "just work". On OS X, one can use install_name_tool to set up a so-called rpath pointing to a relative location where the libraries reside, relative to the executable. On Ubuntu, one can similarly use ldd for setting up the correct pointers to where the libraries will reside relative to the executable. The question is then: is there some documentation on how to ship boost libraries along with your executable, in a cross-platform and canonical way, with CPack? Here's a question on stack overflow [1] that addresses the same problem, however the proposed solution of using set(CMAKE_EXE_LINKER_FLAGS "-Wl,-rpath='$ORIGIN'") in CMake does not seem cross-platform to me (MSVC won't recognize the command). Regards, Raoul [1]: http://stackoverflow.com/questions/26142948/packaging-c-program-using-boost…

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[Interprocess] Sharing FFMPEG Datatypes
by Loren Garavaglia 25 Jun '16

25 Jun '16

Hi All, I'm trying to figure out if it's possible using Boost to share FFMPEG data between 2 processes. What I'm trying to do is have one process read from a video stream and place the received packets in a buffer. The other process then reads from the buffer, decodes the packet, and does some analysis on the image. Unfortunately, due to some constraints I cannot take a multi-threaded approach to this problem. My data that I would like to share is as follows: struct FFMPEGData { AVFormatContext *pFormatCtx; AVCodecContext *pCodecCtx; AVCodec *pCodec; AVFrame *pFrame, dst; AVPacket *packet; AVPacket* pack = new AVPacket[packetNum]; struct SwsContext *convert_ctx; }; With "pack" being my buffer with a set size. I tried following the boost example here <http://www.boost.org/doc/libs/1_57_0/doc/html/interprocess/allocators_conta…> but it seems to be for a simpler form of complex data. All of the FFMPEG datatypes are structs themselves, so I wasn't sure what to do. My question is, is it even possible to share these kinds of datatypes between processes using Boost Interprocess and if so do I need to create allocators and containers for all of the data fields within these FFMPEG datatypes? Thanks, Loren

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Boost + Android NDK r11 + Clang
by Robert Dailey 23 Jun '16

23 Jun '16

How can I cross-compile static boost libraries for Clang in Android NDK r11 (arm) along with LLVM C++ (static)? Thanks in advance for detailed instructions

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[iostreams] use of gzip_compressor with strings
by Boncek, John 23 Jun '16

23 Jun '16

I need to do some in-memory manipulation of strings, including compression to gzip format. I am new to the use of Boost and to the use of gzip. I found the following snippet on the Internet, compressing a std::string and producing a new std::string as output. This implies that gzip_compressor never produces a null byte in its output but the gzip_compressor documentation doesn't say that and my search of the underlying library zlib documentation doesn't say anything like that either. So is this a correct use? std::string compress(const std::string& data) { namespace bio = boost::iostreams; std::stringstream compressed; std::stringstream origin(data); bio::filtering_streambuf<bio::input> out; out.push(bio::gzip_compressor(bio::gzip_params(bio::gzip::best_compression))); out.push(origin); bio::copy(out, compressed); return compressed.str(); } Thanks, John Boncek

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[Context] Console output problem under Cygwin
by Andrew C 23 Jun '16

23 Jun '16

Hi! Boost.Context examples (libs\context\example\v2) behave strangely under Cygwin/GCC-5.4.0. The problem is that all of the example applications output nothing to console. For example, jump_void.exe just ends at first "std::cout" command in execution context without any crash. This is the command line arguments I use to build both Boost.Context library and examples: b2.exe variant=debug link=static cxxflags="-std=c++14 -Wall -pedantic -D_GNU_SOURCE" Does anyone else ever met such a problem? Could it be a compiler bug or Boost.Context defect? Note: Under MinGW/GCC-4.9.3 all works OK. Thanks!

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[polygon] get_trapezoids not reporting holes?
by David Thompson 22 Jun '16

22 Jun '16

Hi all, I am having trouble with boost::polygon: when get_trapezoids is called on a polygon_set_data containing a polygon_with_holes_data, it returns trapezoids covering the outer loop but that cover the hole (i.e., the hole is being ignored). A small example is below to demonstrate. I've tried with boost 1.60, 1.55, and 1.50. Am I doing something wrong? Thanks, David #include "boost/polygon/polygon.hpp" #include <vector> namespace poly = boost::polygon; typedef long long Coord; typedef poly::point_data<Coord> Point; Coord outerPts[] = { -37205784000000LL, -22528321200000LL, -20252740200000LL, -40391736000000LL, 19228717200000LL, -39708900000000LL, 37774737000000LL, 32882157000000LL, -37205784000000LL, -22528321200000LL, }; Coord innerPts[] = { -8808676800000LL, -4351000500000LL, 29799924000000LL, 21288613500000LL, 8185023000000LL, -10611816600000LL, -8808676800000LL, -4351000500000LL, }; template<typename T> void liftPt(double x[2], const T& pt, double sf) { x[0] = sf * pt.x(); x[1] = sf * pt.y(); } template<typename T> void print_polyarray(const std::string& msg, T& parr, double scale, double iscale) { std::cout << msg << " has " << parr.size() << " polygons\n"; std::vector<poly::polygon_data<Coord> >::const_iterator pit; int pp = 0; for (pit = parr.begin(); pit != parr.end(); ++pit, ++pp) { poly::polygon_data<Coord>::iterator_type pcit; std::cout << " Polygon " << pp << " has " << pit->size() << " points\n"; double p0[2]; for (pcit = poly::begin_points(*pit); pcit != poly::end_points(*pit); ++pcit) { liftPt(p0, *pcit, iscale); std::cout << " " << p0[0] << " " << p0[1] << "\n"; } std::cout << "--\n"; } } int main() { const double scale = 2.31e13; const double iscale = 1./2.31e13; poly::polygon_with_holes_data<Coord> pface; std::vector<poly::polygon_data<Coord> > holes; poly::polygon_data<Coord> loop; std::vector<Point> polypts1; for (unsigned ii = 0; ii < sizeof(outerPts)/sizeof(outerPts[0])/2; ++ii) { polypts1.push_back(Point(outerPts[2*ii], outerPts[2*ii + 1])); } pface.set(polypts1.begin(), polypts1.end()); std::vector<Point> polypts2; for (unsigned ii = 0; ii < sizeof(innerPts)/sizeof(innerPts[0])/2; ++ii) { polypts2.push_back(Point(innerPts[2*ii], innerPts[2*ii + 1])); } loop.set(polypts2.rbegin(), polypts2.rend()); holes.push_back(loop); pface.set_holes(holes.begin(), holes.end()); Point holecenter( 9725423400000LL, 2108598800000LL); Point nonholepnt(37774730000000LL, 32882150000000LL); // ^^ Compare to 37774737000000LL, 32882157000000LL, which is a vertex in outerPts. std::cout << "Polygon has " << pface.size() << " vertices and " << pface.size_holes() << " holes\n"; std::cout << "Winding is " << (poly::winding(pface) == poly::CLOCKWISE ? "cw" : "ccw") << "\n"; std::cout << "Contains hole center? " << (poly::contains(pface, holecenter) ? "Y" : "N") << "\n"; std::cout << "Contains point it should? " << (poly::contains(pface, nonholepnt) ? "Y" : "N") << "\n"; // The above demonstrates that pface appears to be a valid polygon with a hole. // However, now when we ask for trapezoids, no hole is provided: // Add pface to polys so we can get trapezoids: poly::polygon_set_data<Coord> polys; std::vector<poly::polygon_data<Coord> > parr; polys.insert(pface); polys.get(parr); // This prints that parr (and thus polys) contains 0 polygons, which seems wrong: print_polyarray("Original polygon set", parr, scale, iscale); polys.get_trapezoids(parr); // This prints 2 polygons that form only the outer boundary, which seems wrong: print_polyarray("Tessellation ", parr, scale, iscale); return 0; }

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[boost] Checking interest in stacktrace library
by Antony Polukhin 22 Jun '16

22 Jun '16

Hi, I've got some prototype for getting stack traces: https://github.com/apolukhin/stacktrace It's design is based on the idea that class for stacktrace must be fully noexcept, without dynamic allocations in constructors and as simple as possible. Is there interest in it? What functionality would you like to have in it? -- Best regards, Antony Polukhin

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Coroutine jump_fcontext crash (Boost 1.61)
by Jason Mancini 22 Jun '16

22 Jun '16

Hello, Starting with Boost 1.61, if -DBOOST_USE_VALGRIND=1 is set, then the Coroutine sample from boost docs crashes on first stack switch. Is this a known issue? (We're using GCC 6.1 on 64-bit Linux.) Not posting a code sample, it's literally the exact one from the Coroutine web page. Compile with the define, then run. We have Valgrind 3.10.1 installed. [Curiously, the Context code sample runs fine.] I am suspecting a missing snippet on the Coroutine side that affects stack_context structure size. Thanks! Jason # gdb ./a.out ... SIGSEGV, Segmentation fault. (gdb) bt #0 0x00002aaaaaab3ec0 in jump_fcontext () from .../lib/libboost_context.so.1.61.0 (gdb)

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Re: [Boost-users] Suggestion for boost::dll:import_alias<>() or boost::dll::import<>()
by Leo Carreon 19 Jun '16

19 Jun '16

Sorry, I figured out how to use the search capability. I was misinformed because the documentation did not include the possible values for boost::dll::load_mode which I discovered by needing to have a look in the source code. From: Leo Carreon Sent: Sunday, June 19, 2016 1:40 PM To: Boost Users Mailing List Subject: Suggestion for boost::dll:import_alias<>() or boost::dll::import<>() Hi, I have been experimenting with the Boost.DLL library and I have discovered that the “lib” argument of either boost::dll::import_alias<>() or boost::dll::import<>() functions require the full path to the shared library to load. If I’m not mistaken, this functions use either the POSIX dlopen() function or the Windows LoadLibrary() function. These platform specific functions are capable of searching a list of paths if a non-qualified shared library name is given. My suggestion is to use this search capability for non-qualified shared library names. Kind regards, Leo Carreon

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Suggestion for boost::dll:import_alias<>() or boost::dll::import<>()
by Leo Carreon 19 Jun '16

19 Jun '16

Hi, I have been experimenting with the Boost.DLL library and I have discovered that the “lib” argument of either boost::dll::import_alias<>() or boost::dll::import<>() functions require the full path to the shared library to load. If I’m not mistaken, this functions use either the POSIX dlopen() function or the Windows LoadLibrary() function. These platform specific functions are capable of searching a list of paths if a non-qualified shared library name is given. My suggestion is to use this search capability for non-qualified shared library names. Kind regards, Leo Carreon

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is parallel-bgl active?
by Salvador Aguiñaga 17 Jun '16

17 Jun '16

Installing on a local 2 core system on a cluster ends in errors Installing on small system I want to use for temporary development, I get the following error. > > >parallel-bgl-0.7.0/boost/property_map/property_map.hpp:16:37: fatal > error: boost/pending/cstddef.hpp: No such file or directory > compilation terminated > > I've configured the system: > >"sudo apt-get install build-essential" > > And successfully installed the openmpi: "openmpi-1.10.2.tar.bz2" > > But when I get to: > /parallel-bgl-0.7.0/build/cmake .. > > I can't find a good solution online to this cstddef.hpp error. > > Any suggestions? > > > My system: uname -a > > Linux atomix 4.2.0-16-generic #19-Ubuntu SMP Thu Oct 8 14:46:51 UTC 2015 > i686 i686 i686 GNU/Linux >

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Re: [Boost-users] boost bind, issue moving from 1.57 to 1.60
by Jason Mancini 17 Jun '16

17 Jun '16

We worked around this failure by changing: Func = boost::bind(Func, _1) && boost::bind(&Boom::Oops, _1); to Func = boost::bind(AND, Func, &Boom::Oops, _1); // custom AND function Not sure why it used to work, or why it still works with raw pointers, but not shared_ptr. The actual change happens from 1.59 (working) to 1.60 (changed behavior). Jason

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Undefined Reference to 'boost::system::generic_category()'
by Blair Climenhaga 16 Jun '16

16 Jun '16

Hello everyone, I have been attempting to install OpenFOAM however the boost library has been giving me trouble, most recently reading out these error during OpenFOAM installation. undefined reference to `boost::system::generic_category()' undefined reference to `boost::system::system_category()' undefined reference to `boost::detail::set_tss_data(void const*, boost::shared_ptr<boost::detail::tss_cleanup_function>, void*, bool)' undefined reference to `boost::detail::get_tss_data(void const*)' If anyone has ever encountered this problem before, or has a hypothesis on how to solve I would be eager to hear your advice. I should mention that this error has persisted across multiple attempts at boost installs (1.48.0,1.52, and 1.61.0) as well as an update of my system from Ubuntu 12.04 to 14.04. Thank you everyone for your time in reading this and for any advice you may give. All the best, Blair Climenhaga

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[xint] Ptoblems with compiling
by Андрей Серебро 16 Jun '16

16 Jun '16

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[Log] Get the streams in a text_ostream_backend derived class
by Florian Lindner 16 Jun '16

16 Jun '16

Hello, I have class StreamBackend : public boost::log::sinks::text_ostream_backend and manually instantiate the backend and add a stream boost::shared_ptr<StreamBackend> backend = boost::make_shared<StreamBackend>(); backend->add_stream(boost::shared_ptr<std::ostream>(new std::ofstream(some file name))); using sink_t = boost::log::sinks::synchronous_sink<StreamBackend>; boost::shared_ptr<sink_t> sink(new sink_t(backend)); sink->set_formatter(config.second.format); sink->set_filter(config.second.filter); boost::log::core::get()->add_sink(sink); All I want is to overwrite the consume function in the derived class. Since I want to retain the original functionality as far as possible, I would like to work on the streams added add_streams. Problem is that the m_pImpl->m_Streams vector in the implementation is private and there is no method to get the added streams. What is the best way to go here? Thanks, Florian

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boost bind, issue moving from 1.57 to 1.60
by Jason Mancini 16 Jun '16

16 Jun '16

Hello, The following minimized program works under 1.57 but no longer under 1.60, as the second bind results in calling of a member function with nullptr at run-time. Is the code mal-formed? Is it a boost bind bug? It still works fine with raw pointers, but no longer works correctly with boost::shared_ptr. Same result with gcc 4.8.1 and gcc 6.1.0 on Linux. Thanks, Jason ------------------- #include <stdio.h> #include <boost/shared_ptr.hpp> #include <boost/make_shared.hpp> #include <boost/bind.hpp> #include <boost/function.hpp> struct Boom { bool Oops() const { printf("Boom::Oops @ %p\n", this); return true; } }; int main() { boost::shared_ptr<const Boom> obj = boost::make_shared<Boom>(); using tMatcher = boost::function<bool(boost::shared_ptr<const Boom>)>; tMatcher Func = boost::bind(&Boom::Oops, _1); Func = boost::bind(Func, _1) && boost::bind(&Boom::Oops, _1); Func(obj); } ------------------- Expected output: Boom::Oops @ 0x11f6d79 Boom::Oops @ 0x11f6d79 Actual output: Boom::Oops @ 0x11f6d79 Boom::Oops @ (nil) -------------------

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Handling process termination
by Shaginesh P.K.(NeSTIT) 12 Jun '16

12 Jun '16

Hi All, I am using boost library for logger. Seems pretty good. Am using boost with asynchronous sink. Hence require a close down of sink explicitly. But this is not possible when process crashes. Do boost have any mechanism for the same (Like handling the signals of OS and like stack dumps)? What does boost prefer for unexpected termination of process where the logs will go out uncollected? Could you please help me out of this? Thanks and Regards Shaginesh PK ________________________________ Confidentiality Statement / Disclaimer : This message and any attachments is intended for the sole use of the intended recipient. It may contain confidential information. Any unauthorized use, dissemination or modification is strictly prohibited. If you are not the intended recipient, please notify the sender immediately then delete it from all your systems, and do not copy, use or print. Internet communications are not secure and it is the responsibility of the recipient to make sure that it is virus/malicious code exempt. The company/sender cannot be responsible for any unauthorized alterations or modifications made to the contents. If you require any form of confirmation of the contents, please contact the company/sender. The company/sender is not liable for any errors or omissions in the content of this message. ________________________________

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Re: [Boost-users] Another query on Boost DLL Library
by Leo Carreon 11 Jun '16

11 Jun '16

Please ignore this question, I found out the answer with a bit more understanding of the example. From: Leo Carreon Sent: Thursday, June 09, 2016 2:07 PM To: Boost Users Mailing List Subject: Another query on Boost DLL Library Hi, When using the factory method when creating a plugin, is it possible to pass an argument to the factory method? If yes, how? Kinds regards, Leo

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