November 2005 - Boost-users

matrix resize problem with version 1.31
by Ricardo Vázquez Martín 17 Nov '05

17 Nov '05

Hi all, I've been using the library in a computer with gcc 3.4.4 and boost 1.32 (in knoppix). I'm interested on uBLAS. The problem is that I need my code working in a different machine (robot) with gcc 3.4.1 in RH9. I've proved 1.30 (which generates a warning becouse gcc version is unknown) and 1.31 versions and there are problems when a matrix is resized. The values of the matrix are moved from their original positions. Also I have problems with zero_vector. Are there some difference between boost library versions? Could I do something to fix that problem?. Do I need to install gcc 3.4.4?. I've seen that gcc 3.4.4 is tested for uBLAS. Thanks in advance, -- Ricardo Vázquez Martín <rvmartin(a)uma.es> Departamento de Tecnología Electrónica Telf.: +34 952 13 2845/7222 E.T.S. Ing. de Telecomunicación FAX: +34 952 13 1447 Universidad de Málaga Campus de Teatinos 29071 Málaga - Spain

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Trouble building bjam
by Andrew Mellinger 17 Nov '05

17 Nov '05

Everyone, I apologize if this isn't the right forum for bjam issues, but I can't find a group specifically for bjam. If someone knows of one, please direct me that way. I have tried searching google, but haven't identified anything relevant. I am trying to build bjam on SunOS 5.8 using gcc 3.1 with the posix thread model. When I do a gcc-v I also get: Configured with: ../configure --with-as=/usr/ccs/bin/as --with-ld=/usr/ccs/bin/ld --disable-nls I don't know if any of that is relevant. When I run ./build.sh from the jam_src directory (either in boost source tree or a download of 3.1.11) I get the following output. ### ### Using 'gcc' toolset. ### rm -rf bootstrap mkdir bootstrap gcc -o bootstrap/jam0 command.c compile.c execnt.c execunix.c execvms.c expand.c filent.c fileos2.c fileunix.c filevms.c glob.c hash.c hdrmacro.c headers.c jam.c jambase.c jamgram.c lists.c make.c make1.c newstr.c option.c parse.c pathunix.c pathvms.c regexp.c rules.c scan.c search.c subst.c timestamp.c variable.c modules.c strings.c filesys.c builtins.c pwd.c class.c native.c modules/set.c modules/path.c modules/regex.c modules/property-set.c modules/sequence.c modules/order.c ./bootstrap/jam0 -f build.jam --toolset=gcc --toolset-root= clean ...found 1 target... ...updating 1 target... ...updated 1 target... ./bootstrap/jam0 -f build.jam --toolset=gcc --toolset-root= don't know how to make command.c don't know how to make compile.c don't know how to make expand.c don't know how to make glob.c don't know how to make hash.c don't know how to make hcache.c don't know how to make headers.c don't know how to make hdrmacro.c don't know how to make jam.c don't know how to make jambase.c don't know how to make jamgram.c don't know how to make lists.c don't know how to make make.c don't know how to make make1.c don't know how to make newstr.c don't know how to make option.c don't know how to make parse.c don't know how to make regexp.c don't know how to make rules.c don't know how to make scan.c don't know how to make search.c don't know how to make subst.c don't know how to make timestamp.c don't know how to make variable.c don't know how to make modules.c don't know how to make strings.c don't know how to make filesys.c don't know how to make builtins.c don't know how to make pwd.c don't know how to make class.c don't know how to make native.c don't know how to make modules/set.c don't know how to make modules/path.c don't know how to make modules/regex.c don't know how to make modules/property-set.c don't know how to make modules/sequence.c don't know how to make modules/order.c don't know how to make execunix.c don't know how to make fileunix.c don't know how to make pathunix.c ...found 43 targets... ...updating 1 target... ...can't find 40 targets... ...can't make 1 target... [MKDIR] bin.solarisx86 ...skipped bjam for lack of command.c... ...skipped 1 target... ...updated 1 target... So for some reason jam0 can't identify the source files. I'm not sure why, I have very little experience with the bjam boostrap process. Does anyone have any hints or can they point me to some other resources? Thanks for your time, -Andrew

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[BGL, Graph] listS and property maps
by Stephane Grabli 17 Nov '05

17 Nov '05

Hi, I'm new to the BGL and I'm trying to use the strong_components algorithm, defined this way: template <class Graph, class ComponentMap, class P, class T, class R> typename property_traits<ComponentMap>::value_type strong_components(Graph& g, ComponentMap comp, const bgl_named_params<P, T, R>& params = all defaults) with a graph defined like this: typedef adjacency_list<listS,listS,directedS> Graph; (in particular using listS for vertices storage). Does anyone know how I should declare the ComponentMap property map? I couldn't figure this out from the documentation and the examples I've seen all assume that a vecS type storage is used for vertices in the graph. Thanks! Stephane

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CVS silence:)
by Serge Skorokhodov 17 Nov '05

17 Nov '05

Hi, boost CVS has not changed for a few days. Should cvs update arguments be modified? TIA -- Serge

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[serialization] template point
by codeur＠altern.org 17 Nov '05

17 Nov '05

Hello I'm a new user of the serialization library and I didn't understand how I could serialize the following Map class : #include <vector> template<typename T> class Point { private: T x; T y; }; template<typename T> class Map { private: std::vector < Point<T> * > map; }; int main() { Map<double> m; /* double or float or int or user defined float/integer with infinite precision */ return 0; } Could somebody help me ? Thanks!

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[iostreams] WinRar cannot read zlib archive
by Christian Henning 16 Nov '05

16 Nov '05

Hi there I just have a simple question regarding the format of a zlib archive. Somehow WinRar cannot read the archive. If I use the simple example application provided in the zlib distribution WinRar is able to read it. This makes me wondering what difference is in the archive generated by boost::iostreams? Here is my example code which works fine. I using VC7.1 and Boost 1.33 #include <iostream> #define BOOST_IOSTREAMS_NO_LIB #include <boost/iostreams/device/file.hpp> #include <boost/iostreams/filtering_stream.hpp> #include <boost/iostreams/filter/zlib.hpp> namespace io = boost::iostreams; int _tmain(int argc, _TCHAR* argv[]) { { io::filtering_ostream out; out.push( io::zlib_compressor() ); out.push( io::file_sink( "hello.zip" )); out << "Hello boost::iostreams"; //close the file } io::filtering_istream in; in.push( io::zlib_decompressor() ); in.push( io::file_source( "hello.zip" )); std::string strMessage; std::getline( in, strMessage ); std::cout << strMessage << std::endl; return 0; } Besides the problem, seems that boost::iostream is an amazing lib and a huge contribution for the C++ community. Thanks, Christian

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[MPL] how do i validate a predicate template?
by Cory Nelson 16 Nov '05

16 Nov '05

Is there any way to validate a predicate (function, functor etc) template with MPL? ie, something like: BOOST_MPL_ASSERT((and_< is_function<Predicate>, equal_to<function_traits<Predicate>::arity, int_<1> >, is_same<function_traits<Predicate>::result_type, int >, is_same<function_traits<Predicate>::arg1_type, int > >)); -- Cory Nelson http://www.int64.org

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Re: [Boost-users] Inheritance
by james.jones＠firstinvestors.com 16 Nov '05

16 Nov '05

Hi Azam, Are you sure you want to inherit? Might it make sense to make a Boost graph object a private variable which you construct and then modify in your constructor? - James Jones Administrative Data Mgmt. (v)732-510-1806 375 Raritan Center Pkwy, Suite A (f)732-510-1855 Edison, NJ 08837 Visit us on the web at http://www.firstinvestors.com/ --- Original Message --- Date: Tue, 15 Nov 2005 18:53:15 -0800 From: "azam ." <boost80(a)gmail.com> Subject: [Boost-users] Inheritance To: boost-users(a)lists.boost.org Message-ID: <825e260c0511151853q4b0d599ek5a0d6d3daa28dec3(a)mail.gmail.com> Content-Type: text/plain; charset="iso-8859-1" Hi, I want to use Boost Graph Library via inheritance. Actually I want to define a graph which is an adjacency_list graph and is created in a special way. I thought of making it a derived class of adjacency_list and then define constructors to construct objects of this class. But my problem is how to (for example) set vertex properties in the constructor? Regularly if I want to add properties to vertices on a graph g, I use vertices(g) to get iterator of vertices and then I use this iterator, but what can I do in the constructor? I have no such graph object there and I can't use "this" reference too. Any help would be really appreciated. Thanks Azam

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Collections of shared_ptr<Base> and shared_ptr<Derived>
by Keith Weintraub 16 Nov '05

16 Nov '05

Folks, What is the best way to pass a std::vector<boost::shared_ptr<Derived> > to a function that expects a std::vector<boost::shared_ptr<Base> >? Can I use a cast or should I create a new std::vector<boost::shared_ptr<Base> > by iterating over the std::vector<boost::shared_ptr<Derived> >? Here is some sample code. What f is doing is not important it is just an example: class A { // This class is from a library I have no control over. public: virtual string getName() { return string("A");} }; class B : public A { // I need to create B from A to have extra functionality public: virtual string getName() { return string("B");} virtual string getLongName() { return string("This is B");} }; void f(std::vector<boost::shared_ptr<A> > &v) { // This function is from a library that I have no control over. for(int i = 0; i < v.size(); i++) cout << v[i]->getName(); } int main(char *argv, int arc) { std::vector<boost::shared_ptr<B> > bvec(10); boost::shared_ptr<B> bPtr(new B); bvec[0] = bPtr; f(bvec); // This should not compile. <------------------------- } The last line (with the arrow) won't compile because std::vector<boost::shared_ptr<B> > cannot be converted to std::vector<boost::shared_ptr<A> >.

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Boost.Iostreams - Filtering Stream questions (flushing, interactive input)
by Michael Rickert 16 Nov '05

16 Nov '05

I've been trying to use Boost.Iostreams, with mixed success. I've got a few more stumbling blocks that hopefully I can get some help with :-). First, I have a socket class, which I've used Boost.Iostreams to create a nice interface for. Quick details: class winsock_device { typedef boost::iostreams::bidirectional_device_tag category; //..implementation.. }; class winsock_socket { typedef winsock_device stream_device_type; typedef boost::iostreams::stream_buffer< stream_device_type > stream_buffer_type; typedef std::iostream stream_type; stream_device_type m_stream_device; stream_buffer_type m_stream_buffer; stream_type m_stream; public: winsock_socket( SOCKET raw_socket ) : m_stream_device( raw_socket ) , m_stream_buffer( m_stream_device ) , m_stream( & m_stream_buffer ) {} stream_type & stream() { return m_stream; } //..more implementation.. }; The implementation seems to work, tests show it to be working fine for input and output (with output needing to be flushed). Only problem is that the newlines are mismatched - a simple telnet chat client gets supurflous \r characters using std::getline, so I decided to wrap around the stream using a boost::iostreams::filtering_stream< boost::iostreams::bidirectional >, which is where things fall apart. I took my simple example, and replaced: std::iostream & ios = socket->stream(); with: namespace bios = boost::iostreams; bios::filtering_stream< bios::bidirectional > ios; ios.push( socket->stream() ); both with the same testing code: std::string nickname; ios << "Welcome, user - please enter a nickname:\n" << std::flush; socket->stream().flush(); std::getline( ios , nickname ); ios << "Welcome, " << nickname << "\n"; ios << "*** actual chatting not yet implemented ***\n"; ios << "Disconnecting you now, bye " << nickname << " !!!\n" << std::flush; socket->stream().flush(); This failed to work at all at first, eventually I figured out I needed to flush first the ios stream, and then the underlying socket->stream. This brings me to: question 1: Is there a workaround to allow an ending stream of (std::iostream &) to be flushed automatically by flushing filtering_stream? Even with no filters installed, however, the program freezes (until I shut down the telnet client) when I attempt to read a line from the stream, even after entering multiple newlines - I'm not exactly sure what's happening here. This brings me to: question 2: How can I get the input moving through my stream? Do I need to start a seperate thread to constantly flush() the stream that the main thread is blocked on i/o for? Thanks, -Mike

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