September 2003 - Boost-users

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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BGL and reversing / moving edges
by joshrose 17 Dec '03

17 Dec '03

G'day, I was hoping someone might be able to tell me if they've run into any situations using BGL where they needed to move (or reverse (i.e. flip the source and target)) an edge within a graph implemented as an adjacency_list. I'm working on an implementation of an algorithm for max. weight bipartite matching ("the assignment problem"), and one of the assumptions in the algorithm is that non-matched edges are directed from one subgraph, A, to the other subgraph, B, and matched edges are directed the other way. Over the course of growing the matching, a simple way to add and remove edges from the candidate set is just to reverse the edge, thus the need for some way to reverse the edge within BGL. I don't think I can just remove and then re-add the edge in the other direction, primarily because doing so will (I believe) invalidate any edge_descriptors referring to that edge. In particular, there are property maps keeping track of the weight of edges, the predecessors of certain nodes, etc. that use edge descriptors as keys. I've spent a fair bit of time reading the documentation and looking through the implementation of adjacency_lists (incl. edge_list_impl), and I'm not really sure of a way to either move an edge directly within a graph, or even to create a new edge from another s.t. they have the same edge_descriptor (in general a bad thing, probably). Anyone have any thoughts on this? Thanks, -Josh

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travelling salesman for BGL ?
by Philippe Guglielmetti 13 Nov '03

13 Nov '03

I'm looking for a free "travelling salesman problem" solver. Does anyone know if something exists for the Boost Graph Library ? I found nothing in the book... Is anybody interested in porting existing code, for example http://www.math.princeton.edu/tsp/concorde.html on BGL ? -- Philippe Guglielmetti - www.dynabits.com

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Compile Boost.thread libraries has a static library (.lib) with msvc 6 ?
by Huck finn 01 Oct '03

01 Oct '03

Hi everyone, I'm a total newbie to boost, but I've got to developp a project that could use some of the powerful boost libraries, so I'm trying to make a move in that way... Ok, most of the boost libraries I can build in a static way and create (.lib) files with Microsoft Visual Studio 6.0 for my partners to use . But I am having a problem doing the same thing with the Boost.Thread libraries... First question : Is it possible to build this librairy in a (.lib) file with msvc 6.0? I'm getting tons of warnings concerning "dllexport" problems, but the (.lib) are still created. I was wondering if someone could help me understanding/fixing the warning problems : warning C4275: non dll-interface class 'boost::noncopyable' used as base for dll-interface class 'boost::detail::condition_impl' c:\wrk\common\boost-1.30.2\boost\noncopyable.hpp(22) : see declaration of 'noncopyable' warning C4273: 'thread::thread' : inconsistent dll linkage. dllexport assumed. I really need to avoid using .dll in this project, so builing this static library is very important to me... Thanks in advance, Simon _________________________________________________________________ MSN Search, le moteur de recherche qui pense comme vous ! http://fr.ca.search.msn.com/

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bind and Constructor invocation?
by Jeff Flinn 30 Sep '03

30 Sep '03

I don't see any way to use bind to directly construct an object, other than calling a function that returns an object. Or am I missing something? Like something similar to Spirit::Phoenix construct_<>? This would avoid manually creating these factory functions. -- Jeff Flinn Applied Dynamics, International

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BGL runtime crash with g++ -O2 optimizer.
by Franck.Caron＠infineon.com 29 Sep '03

29 Sep '03

Hi all, I have a problem while compiling BGL with gcc 3.1.1 on solaris7 with the -O2 optimizer option. All is ok with -g (debug) but -O2 produce a crash at runtime Here is a code that reproduce the problem : #include <boost/graph/adjacency_list.hpp> #include <boost/graph/properties.hpp> #include <iostream> #include <string> using namespace std; using namespace boost; struct VertexPropertyTag { typedef vertex_property_tag kind; }; typedef property<VertexPropertyTag,string> VertexProp; typedef adjacency_list<setS,vecS,bidirectionalS,VertexProp> Graph; int main(){ Graph graph; graph_traits<Graph>::vertex_descriptor v1 = add_vertex(string("s1"),graph); graph_traits<Graph>::vertex_descriptor v2 = add_vertex(string("s2"),graph); add_edge(v1,v2,graph); graph_traits<Graph>::edge_iterator eIt,eItEnd; tie(eIt,eItEnd) = edges(graph); for(;eIt != eItEnd;++eIt){ cout << "->" << *eIt << endl; } return 0; } With g++ -Wall -pedantic -fPIC -g -c -o solaris7/gcc3.1/Main.o Main.cc -I. -I/opt/boost_1.30.2 g++ -fPIC -o solaris7/gcc3.1/testbug.exe solaris7/gcc3.1/Main.o -L /opt/boost_1.30.2/libs/gcc3.1/release/single-thread -R -Wl,-Bdynamic Here is the result : shell> solaris7/gcc3.1/testbug.exe ->(0,1) It is OK With g++ -Wall -pedantic -fPIC -O2 -c -o solaris7/gcc3.1/Main.o Main.cc -I. -I/opt/boost_1.30.2 g++ -fPIC -o solaris7/gcc3.1/testbug.exe solaris7/gcc3.1/Main.o -L /opt/boost_1.30.2/libs/gcc3.1/release/single-thread -R -Wl,-Bdynamic Here is the result : shell> solaris7/gcc3.1/testbug.exe ->(0,1) ->(0,0) Bus error (core dumped) Does anybody already had this ? Is it a bug in my code, in BGL or in gcc ? Thanks for the help. Franck

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Re: [Boost-users] Trying to get boost threads working under visual .NET
by John Maddock 29 Sep '03

29 Sep '03

> I'm trying to get the Boost thread library working under Microsoft .Net, > here is what I've done and the problems I'm seeing. > > I am currnetly using the regex lib and the date/time classes, which are > working. I now want to start creating threads so I follow the given > example, and started to get linker errors for xtime_get and > boost::thread::sleep. So I look around, and do the bjam -sTOOLS=msvc in > the appropriate threads directory and get no errors. It still won't > link. > I notice that the only boost*.lib files in my vc7\lib dir were from > boost_regexp, so I copy 4 files boost_thread(d).dll/lib into that > directory. I then explicitely add boost_threadd.lib into the project's > link. Ok, so now my application compiles AND links, but it wants > boost_threadd.dll when it executes. So I copy boost_threadd.dll into the > projects Debug directory wehre the .exe compiles to. Now when I run it, I > get a dialog box saying the application failed because > "boost_regex_vc7_mdid.dll" can not be loaded! the regex stuff was working > FINE and I don't think I did anyhting to change it. > > So can someone shed some light on this for me, please ? Why does it now > want the boost_regex dll? Thanks for any input.. if I've missed some > crucial documentation somewhere, sorry. If you changed your project build options from using one of the static C runtimes to using the dll runtime then that would be the problem, define BOOST_REGEX_STATIC_LINK when building if you want to static link to boost.regex. John. --------------------------------- Want to chat instantly with your online friends? Get the FREE Yahoo!Messenger

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regex and stream processing
by John Maddock 29 Sep '03

29 Sep '03

Message forwarded from Dave Gomboc: > We have a stream of text data (actually it is a chunked > response of a webserver, but it might be a file or > something...) The data size may be very large and we need to > do some find/replace in this stream using regular > expressions. It is not possible to load entire stream into > the memory. I'm not even hope that Regex++ could work with > such kind of streams, but maybe someone can suggest me a > solution to this problem? This is possible without much trouble _if_ the text strings you are trying to match will fit into main memory, even if all the data won't. Use a std::list as a buffer, so that deleting and inserting is inexpensive, and you don't have to perform copies and update iterators when reading in more input. Fill your (sliding window) buffer, then regex it, using the partial match feature whenever you have not already detected the end of the file. If a match occurs, any characters occuring before the match can be processed (serialized to disk, or whatever) and removed from the buffer. Repeat this looking for a match until you reach the end of current input. You'll either have "no match" or "partial match" at this point: remove non-matching characters (that could be all of them) at this point, then re-fill your buffer with more data and keep going. If you're just doing one substitution, that's fine, but if more, there are a few things to keep in mind. I have done over 60 distinct substitutions at a time on a stream of 0.1 gigabytes using this technique, and it works quite quickly. (I used a buffer that held about 1 million characters (2^20), but I also tested with buffers as small as 256 characters -- the strings I was matching were not large). Just read in data, process all the substitutions in order, write the data out and repeat. If you're doing multiple substitutions, you (of course) can't flush any data from memory until you've tried all the substitutions on the current region of interest. Also, for each later substituion, the current region of interest shrinks because you have to acknowledge partial matches from earlier subsitutions. For example, say that there is no partial match at the end of substituions 1 through 6 (there might have been full matches where substitution was performed, that's okay.) But substituion 7 has a partial match at the last five characters. Now, your region of interest for substitution 8 is five characters smaller, because you don't want to process those last five characters because substitution 7 might change them once you've read in more input. The order of your substituions is important if the outputs of some desired subsitutions overlap with the inputs of others. If you are not grokking my meaning, I can fish around for the source code. Perhaps it's easier to explain in code than in words, my code for the entire process is maybe 10 or 15 lines. An alternative is to try to do some streambuf hacking, but the above method was simpler and adequate for my purposes. Dave --------------------------------- Want to chat instantly with your online friends? Get the FREE Yahoo!Messenger

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regex problem
by John Maddock 29 Sep '03

29 Sep '03

> The last assert always fails, because regex::match insists on including the > space after the ":" in the second match result, which seems wrong to me. > I've tried giving various different combinations of flags to the regex ctor, > although from what I can tell from the documentation the default flags > should work. This is with VC7 and boost 1.30.2. For comparison, perl > (5.6.1) does not seem to have this problem, as the following script > illustrates: > > #!/usr/bin/perl > print "matches: <$1> <$2>\n" if ('foo: bar' =~ /([\w]+):[\s]*(.*)/); > > Is there any way to get the behavior I want? This is the difference between perl and POSIX leftmost-longest matching rules showing itself (the next release will default to perl rules and do what you want, but of course that doesn't help you now), basically non-marked sections are neither greedy nor non-greedy under POSIX rules, so regex finds the match it does because it makes $2 further to the left than the alternative (without effecting the overall match). You can get the effect you want by making your expression more "precise": "([\\w]+):[\\s]*([^\\s].*)" for example, John. --------------------------------- Want to chat instantly with your online friends? Get the FREE Yahoo!Messenger

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Re: Implementation of my first template class
by Zenaan Harkness 29 Sep '03

29 Sep '03

Take 3: /** * A class providing a combination of an input stream * and an input iterator. * I use for convenience when processing a part-ascii, * part-binary stream. */ template<typename charT, typename traits = std::char_traits<charT> > class basic_istringtraverser : public std::basic_istringstream<charT, traits> { public: basic_istringtraverser(std::basic_string<charT> s) : std::basic_istringstream<charT, traits>(s) {} charT operator*() {return (charT)(rdbuf()->sgetc());} basic_istringtraverser& operator++() { rdbuf()->sbumpc(); return *this; } }; /** Specialization for char type. */ typedef basic_istringtraverser<char> istringtraverser;

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RE: [Boost-users] Base Pointer member functions failure
by Mark Loew 29 Sep '03

29 Sep '03

Excellent thanks. I see exactly what I was missing. Thanks for the help. Mark Loew, MCSD, MCSE Application Development Consultant Sagestone Consulting www.sagestone.com Grand Rapids, MI 616-954-9556 x149 Microsoft Gold Certified Partner mloew(a)sagestone.com -----Original Message----- From: Douglas Gregor [mailto:gregod@cs.rpi.edu] Sent: Saturday, September 27, 2003 1:58 PM To: Boost Users mailing list Subject: Re: [Boost-users] Base Pointer member functions failure On Friday 26 September 2003 06:38 pm, Mark Loew wrote: > Alright I am now functioning in my code. > > Now the hard part. Can you explain to me what I am missing. The _1 > states to use the first paramter in the first position. > > Doug mentioned that there is an implicit 'this' argument. That was Peter :) > So the bind is creating a function object > template<class S, class T, class A> > With the constructor of > somefunc( S (T::*p)(A) ); // declaring the pointer to the function > > then the operator is > operator( T *p, A x ) > and calls the func Right, so the function object has two parameters, the first (which corresponds to the implicit 'this' parameter) is of type T* and the second is of type A. When using bind, think of member function pointers as having an operator() like this one, and try to forget the ugly member pointer syntax. > So in the bind I was thinking that > Boost::bind( Base::CheckFunc, x ) > > I wrongly assumed that the T value was the variable passed in by the > find_if and the second parameter was the x my second variable on my > func. With bind(), no parameter is special, including the implicit object parameter. If we have: g = boost::bind(f, _1, x) then g(y) maps to: f(y, x) in our case, 'f' is an adaptor around a member function pointer, which ends up calling: y->*CheckFunc(x) Doug _______________________________________________ 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] istream U istream_iterator -> traverser
by Zenaan Harkness 28 Sep '03

28 Sep '03

Further thought: has anyone ever written (made available) something like <vstream> for streaming into and out of vectors (similar to <sstream>). Or perhaps <cstream> - generic container streaming in/out, with specializations for vector, etc. - or has such a thing just never been needed by anybody before? tia zen

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Trying to get boost threads working under visual .NET
by Brian Bowles 28 Sep '03

28 Sep '03

I'm trying to get the Boost thread library working under Microsoft .Net, here is what I've done and the problems I'm seeing. I am currnetly using the regex lib and the date/time classes, which are working. I now want to start creating threads so I follow the given example, and started to get linker errors for xtime_get and boost::thread::sleep. So I look around, and do the bjam -sTOOLS=msvc in the appropriate threads directory and get no errors. It still won't link. I notice that the only boost*.lib files in my vc7\lib dir were from boost_regexp, so I copy 4 files boost_thread(d).dll/lib into that directory. I then explicitely add boost_threadd.lib into the project's link. Ok, so now my application compiles AND links, but it wants boost_threadd.dll when it executes. So I copy boost_threadd.dll into the projects Debug directory wehre the .exe compiles to. Now when I run it, I get a dialog box saying the application failed because "boost_regex_vc7_mdid.dll" can not be loaded! the regex stuff was working FINE and I don't think I did anyhting to change it. So can someone shed some light on this for me, please ? Why does it now want the boost_regex dll? Thanks for any input.. if I've missed some crucial documentation somewhere, sorry.

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RE: [Boost-users] Base Pointer member functions failure
by Mark Loew 27 Sep '03

27 Sep '03

Alright I am now functioning in my code. Now the hard part. Can you explain to me what I am missing. The _1 states to use the first paramter in the first position. Doug mentioned that there is an implicit 'this' argument. So the bind is creating a function object template<class S, class T, class A> With the constructor of somefunc( S (T::*p)(A) ); // declaring the pointer to the function then the operator is operator( T *p, A x ) and calls the func So in the bind I was thinking that Boost::bind( Base::CheckFunc, x ) I wrongly assumed that the T value was the variable passed in by the find_if and the second parameter was the x my second variable on my func. What am I missing. I just don't want my code to work I want to know why. Makes reusing the thing much easier. Mark Loew, MCSD, MCSE Application Development Consultant Sagestone Consulting www.sagestone.com Grand Rapids, MI 616-954-9556 x149 Microsoft Gold Certified Partner mloew(a)sagestone.com -----Original Message----- From: Peter Dimov [mailto:pdimov@mmltd.net] Sent: Friday, September 26, 2003 6:11 PM To: Boost Users mailing list Subject: Re: [Boost-users] Base Pointer member functions failure Mark Loew wrote: > Okay, > > Call me stupid but I can't get this to work > > class Base > { > virtual const bool CheckFunc(const value& val ) const { return > true; } } [...] > std::find_if( vecBase.begin(), vecBase.end(), > boost::bind(Base::CheckFunc, aVal ) ); Try boost::bind(&Base::CheckFunc, _1, aVal) instead. Remember that a member function has an implicit 'this' argument. _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Building boost threads with MinGW
by Jeremy Godfrey 27 Sep '03

27 Sep '03

Hi, When I build boost threads with bjam and MinGW, the resulting DLL is not dependent on mingwm10.dll like (as I understand things) all MinGW multithreaded binaries should be. This would indicate that the -mthreads compile/link option is not being used. Does anyone know how to fix this? Regards, Jeremy Godfrey --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com) Version: 6.0.520 / Virus Database: 318 - Release Date: 18/09/2003

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istream U istream_iterator -> traverser
by Zenaan Harkness 27 Sep '03

27 Sep '03

Sidestepping any ascii/binary issues for the moment, I am reading a part-binary, part-ascii file(s) and needing to process them (extract their data). I have need to read characters, as well as read in "binary" numbers, and print the whole lot out as ascii, with delimiters, etc (I use a mini-program/ format-string as a 'driver' to specify to my program how to process the input). I eventually realised (after converting my code back and fort between iterator style and istream style) that in fact I need both an istream and an input iterator (conveinence factor here). So firstly, I created both an istringstream, and an istream_iterator over that istringstream. Using either to .get or >> extract stuff from my string/stream would advance the underlying buffer, so things seem to work out well. I then decided to combine the two into a single class, which I can then "hide" implementation details or add functionality (eg. manipulators to specify byte-oirdering, endianness, etc), and still have one nice big interface of stream + iterator to get stuff from. My question is, why did this initial cut not compile: using namespace std; class istringtraverser : public istringstream, public istream_iterator<char> { public: istringtraverser(string s) : istringstream(s), istream_iterator<char>(*this) {} }; While this one DOES compile: using namespace std; class istringtraverser : public istringstream, public istream_iterator<char> { istringstream* miss; public: istringtraverser(string s) : istringstream(s), miss(this), istream_iterator<char>(*miss) {} }; And, how can I instantiate my traverser without it segfaulting? Eg., on my debian box, "istringtraverser st(some_string);" compiles but segfaults. Any insight appreciated, Zenaan PS I'm a Java programmer learning C++, finding out that C++ is more powerful/ featureful, yet some simple things (eg. uppercase a std::string, using std::transform with std::toupper) just do not work as expected. I can see why they now teach Java as a first language at Uni.

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Base Pointer member functions failure
by Mark Loew 26 Sep '03

26 Sep '03

Okay, Call me stupid but I can't get this to work class Base { virtual const bool CheckFunc(const value& val ) const { return true; } } class Derived1: public Base { } class Derived2: public Base { } // some where else in code Derived1 dev1; Derived2 dev2; vector<Base *> vecBase; vecBase.push_back( &dev1 ); vecBase.push_back( &dev2 ); value aVal; vec<Base *> std::find_if( vecBase.begin(), vecBase.end(), boost::bind( Base::CheckFunc, aVal ) ); I have tried a gazillion things a thought would work using mem_fun_ref and such. This ones get's me the closest I believe but I get a bunch of qualifier to funcation type has no meaning warnings. As well I get a condiation expression of type 'overloaded-function is illegal. I am using VS.Net 2003. Any ideas on what I am missing. As well can I get my cake and eat it to by making the CheckFunc virtual and have it resolve to the derived form? TIA Mark Loew, MCSD, MCSE Application Development Consultant Sagestone Consulting www.sagestone.com <http://www.sagestone.com/> Grand Rapids, MI 616-954-9556 x149 Microsoft Gold Certified Partner mloew(a)sagestone.com

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boost regex and match_partial
by Angus Leeming 26 Sep '03

26 Sep '03

I'm afraid I haven't got the hang of match_partial. Below is a little code with two functions that I think should produce identical results, but don't. In strip_commas_try1 I use: boost::regex const front("^( *[[],*)(.*)$"); regex_match(it, end, what, front); In strip_commas_try2 I use: boost::regex const front("^( *[[],*)"); regex_match(it, end, what, front, boost::match_partial); Why does this second case not result in what[0].matched ? Many thanks, Angus (This is with BOOST_VERSION 103002 and g++ (GCC) 3.2 20020903 (Red Hat Linux 8.0 3.2-7)). #include<iostream> #include<string> #include <boost/regex.hpp> using std::string; string const strip_commas_try1(string const & input) { string::const_iterator it = input.begin(); string::const_iterator end = input.end(); // Strip any commas that follow immediately after the '['. // "[,,,,foo..." -> "foo..." boost::regex const front("^( *[[],*)(.*)$"); boost::smatch what; regex_match(it, end, what, front); if (!what[0].matched) { std::cout << "Try 1 failed" << std::endl; return string(); } it = what[1].second; string const result = string(it, end); std::cout << "Try 1: " << result << std::endl; return result; } string const strip_commas_try2(string const & input) { string::const_iterator it = input.begin(); string::const_iterator end = input.end(); // Strip any commas that follow immediately after the '['. // "[,,,,foo..." -> "foo..." boost::regex const front("^( *[[],*)"); boost::smatch what; regex_match(it, end, what, front, boost::match_partial); if (!what[0].matched) { std::cout << "Try 2 failed" << '\n'; return string(); } it = what[1].second; string const result = string(it, end); std::cout << "Try 1: " << result << std::endl; return result; } int main() { string const input = "[,,,foo,,,,bar,,,gaz,,]"; std::cout << "Input: " << input << std::endl; strip_commas_try1(input); strip_commas_try2(input); return 0; }

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indirect_iterator_generator and std::distance ambiguity
by Jeff Flinn 24 Sep '03

24 Sep '03

I'm having problems compiling the code below with boost_1_30_2 and VC71 complaining about: ...\Microsoft Visual Studio .NET 2003\Vc7\include\xutility(489) : error C2665: 'std::_Distance2' : none of the 4 overloads can convert parameter 4 from type 'std::iterator_traits<_Iter>::iterator_category' with [ _Iter=CDictionary::tVarConstItr ] ... Replacing with std::distance( lBeg.base(), lItr.base() ) does compile and work properly. Am I missing something in the typedef of tVarConstItr that would allow direct usage? ---------------------------------------------------------- class CDictionary { ... class VarSpec { ... typedef boost::shared_ptr<VarSpec> tPtr; }; typedef VarSpec tVar; typedef tVar::tPtr tVarPtr; typedef std::vector<tVarPtr> tVars; typedef boost::indirect_iterator_generator < tVars::const_iterator , tVar , tVar& , tVar* , std::iterator_traits<tVars::const_iterator> ::iterator_category >::type tVarConstItr; typedef boost::indirect_iterator_generator < tVars::iterator , tVar , tVar& , tVar* , std::iterator_traits<tVars::iterator> ::iterator_category >::type tVarItr; tGroups Groups()const{ return mGroups; } tVarItr VarBegin() { return tVarItr ( mVars.begin() ); } tVarItr VarEnd () { return tVarItr ( mVars.end () ); } tVarConstItr VarBegin()const{ return tVarConstItr( mVars.begin() ); } tVarConstItr VarEnd ()const{ return tVarConstItr( mVars.end () ); } }; usage: ------ int CDictionaryEditorView::Idx( const TCHAR* aChrPtr, bool aExact )const { boost::function1<bool,const CDictionary::VarSpec&> lFindFnc; if( aExact ) { lFindFnc = boost::bind( std::equal_to<std::string>() , std::string(aChrPtr) , boost::bind( &CDictionary::VarSpec::Name, _1 ) ); } else { //... } CDictionary::tVarConstItr lBeg = mDctPtr->VarBegin(); CDictionary::tVarConstItr lEnd = mDctPtr->VarEnd (); CDictionary::tVarConstItr lItr = std::find_if( lBeg, lEnd, lFindFnc ); return (lItr!=lEnd)? std::distance( lBeg, lItr ) : -1; } -- Jeff Flinn Applied Dynamics, International

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[bgl] how to reverse a graphvizDigraph?
by Jeremie Leguay 24 Sep '03

24 Sep '03

Hi! I would like to reverse all the edges of a graphviz graph but the structure of this kind of graph doesn't seems to fit with the one use by the reverse_graph functionalities. Am I true or did I forget something? Here is the code that doesnt work: GraphvizDigraph g; read_graphviz("datas",g); typedef reverse_graph<GraphvizDigraph> ReverseGraphType; ReverseGraphType gr(g); print_graph(gr, get(vertex_index, gr)); //if I remove this line, it works! More generally, I would like to inverse the graph with keeping the same indexes on the vertices. Do you have ideas? best regards /Jeremie Leguay

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regex problem
by Scott McCaskill 24 Sep '03

24 Sep '03

I seem to be having some trouble with the regex library: #include <boost/regex.hpp> #include <cassert> #include <iostream> int main(int argc, char* argv[]) { using namespace boost; cmatch what; assert(regex_match("foo: bar", what, regex("([\\w]+):[\\s]*(.*)"))); assert(what.size() == 3); assert(what[1].matched); assert(what[2].matched); assert(std::string("foo") == std::string(what[1])); std::cout << std::string(what[2]) << "\n"; assert(std::string("bar") == std::string(what[2])); // fails return 0; } The last assert always fails, because regex::match insists on including the space after the ":" in the second match result, which seems wrong to me. I've tried giving various different combinations of flags to the regex ctor, although from what I can tell from the documentation the default flags should work. This is with VC7 and boost 1.30.2. For comparison, perl (5.6.1) does not seem to have this problem, as the following script illustrates: #!/usr/bin/perl print "matches: <$1> <$2>\n" if ('foo: bar' =~ /([\w]+):[\s]*(.*)/); Is there any way to get the behavior I want? Thanks, Scott McCaskill

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Regex and stream processing
by Yaroslav Govorunov 23 Sep '03

23 Sep '03

Hello everybody and especially Dr John Maddock :) ! First of all I wish to thank all developers for this amazing product. I come here to get an advice and here is my problem: We have a stream of text data (actually it is a chunked response of a webserver, but it might be a file or something...) The data size may be very large and we need to do some find/replace in this stream using regular expressions. It is not possible to load entire stream into the memory. I'm not even hope that Regex++ could work with such kind of streams, but maybe someone can suggest me a solution to this problem? With best regards, Yaroslav Govorunov, E-mail: slov(a)rsdn.ru http://www.rsdn.ru http://www.isapirewrite.com

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Preprocessor Library question
by Eric Robert 23 Sep '03

23 Sep '03

Hi, Maybe somebody can help me here. I'm just trying to understand what's going on with the FOR code. It goes something like this (I expanded the general include and stripped some code for clarity) : # define BOOST_PP_FOR BOOST_PP_CAT(BOOST_PP_FOR_, BOOST_PP_AUTO_REC(BOOST_PP_FOR_P, 256)) # # define BOOST_PP_FOR_P(n) BOOST_PP_CAT(BOOST_PP_FOR_CHECK_, BOOST_PP_FOR_ ## n(1, BOOST_PP_FOR_SR_P, BOOST_PP_FOR_SR_O, BOOST_PP_FOR_SR_M)) # # define BOOST_PP_FOR_SR_P(r, s) s # define BOOST_PP_FOR_SR_O(r, s) 0 # define BOOST_PP_FOR_SR_M(r, s) BOOST_PP_NIL # # define BOOST_PP_FOR_1(s, p, o, m) BOOST_PP_FOR_1_C(BOOST_PP_BOOL(p(2, s)), s, p, o, m) # define BOOST_PP_FOR_2(s, p, o, m) BOOST_PP_FOR_2_C(BOOST_PP_BOOL(p(3, s)), s, p, o, m) # define BOOST_PP_FOR_3(s, p, o, m) BOOST_PP_FOR_3_C(BOOST_PP_BOOL(p(4, s)), s, p, o, m) # define BOOST_PP_FOR_4(s, p, o, m) BOOST_PP_FOR_4_C(BOOST_PP_BOOL(p(5, s)), s, p, o, m) # define BOOST_PP_FOR_5(s, p, o, m) BOOST_PP_FOR_5_C(BOOST_PP_BOOL(p(6, s)), s, p, o, m) # # // # // EXTENDED include <boost/preprocessor/repetition/detail/for.hpp> # # define BOOST_PP_FOR_1(s, p, o, m) BOOST_PP_FOR_1_C(BOOST_PP_BOOL(p(2, s)), s, p, o, m) # define BOOST_PP_FOR_2(s, p, o, m) BOOST_PP_FOR_2_C(BOOST_PP_BOOL(p(3, s)), s, p, o, m) # define BOOST_PP_FOR_3(s, p, o, m) BOOST_PP_FOR_3_C(BOOST_PP_BOOL(p(4, s)), s, p, o, m) # define BOOST_PP_FOR_4(s, p, o, m) BOOST_PP_FOR_4_C(BOOST_PP_BOOL(p(5, s)), s, p, o, m) # define BOOST_PP_FOR_5(s, p, o, m) BOOST_PP_FOR_5_C(BOOST_PP_BOOL(p(6, s)), s, p, o, m) # # define BOOST_PP_FOR_1_C(c, s, p, o, m) BOOST_PP_IIF(c, m, BOOST_PP_TUPLE_EAT_2)(2, s) BOOST_PP_IIF(c, BOOST_PP_FOR_2, BOOST_PP_TUPLE_EAT_4)(BOOST_PP_EXPR_IIF(c, o)(2, s), p, o, m) # define BOOST_PP_FOR_2_C(c, s, p, o, m) BOOST_PP_IIF(c, m, BOOST_PP_TUPLE_EAT_2)(3, s) BOOST_PP_IIF(c, BOOST_PP_FOR_3, BOOST_PP_TUPLE_EAT_4)(BOOST_PP_EXPR_IIF(c, o)(3, s), p, o, m) # define BOOST_PP_FOR_3_C(c, s, p, o, m) BOOST_PP_IIF(c, m, BOOST_PP_TUPLE_EAT_2)(4, s) BOOST_PP_IIF(c, BOOST_PP_FOR_4, BOOST_PP_TUPLE_EAT_4)(BOOST_PP_EXPR_IIF(c, o)(4, s), p, o, m) # define BOOST_PP_FOR_4_C(c, s, p, o, m) BOOST_PP_IIF(c, m, BOOST_PP_TUPLE_EAT_2)(5, s) BOOST_PP_IIF(c, BOOST_PP_FOR_5, BOOST_PP_TUPLE_EAT_4)(BOOST_PP_EXPR_IIF(c, o)(5, s), p, o, m) # define BOOST_PP_FOR_5_C(c, s, p, o, m) BOOST_PP_IIF(c, m, BOOST_PP_TUPLE_EAT_2)(6, s) BOOST_PP_IIF(c, BOOST_PP_FOR_6, BOOST_PP_TUPLE_EAT_4)(BOOST_PP_EXPR_IIF(c, o)(6, s), p, o, m) # # define BOOST_PP_FOR_257(s, p, o, m) BOOST_PP_ERROR(0x0002) # # define BOOST_PP_FOR_CHECK_BOOST_PP_NIL 1 # # define BOOST_PP_FOR_CHECK_BOOST_PP_FOR_1(s, p, o, m) 0 # define BOOST_PP_FOR_CHECK_BOOST_PP_FOR_2(s, p, o, m) 0 # define BOOST_PP_FOR_CHECK_BOOST_PP_FOR_3(s, p, o, m) 0 # define BOOST_PP_FOR_CHECK_BOOST_PP_FOR_4(s, p, o, m) 0 # define BOOST_PP_FOR_CHECK_BOOST_PP_FOR_5(s, p, o, m) 0 Now, I'm trying to understand how it works. I don't understand why FOR isn't a shortcut for FOR_1. The only reason I see is the FOR_CHECK test but I can't seems to understand how it works. Anyone ? Eric Robert

1 0

regex compile problem with vc6 and stlport
by Sven Olsen 23 Sep '03

23 Sep '03

I am using MSVC6 (sp5) with STLport v4.5.3 and attempting to compile boost::regex v3.31, as far as I know these are the latest versions/updates. I dutifully followed the installation instructions, but `nmake -fvc6-stlport.mak` died with the error: ../src/cpp_regex_traits.cpp(662) : error C2660: 'isspace' function does not take 2 parameters By building the files in the IDE, I was able to figure out why the isspace error happens: there is a global scope isspace() defined in ctype.h. The isspace problem can be fixed by defining BOOST_REGEX_STD to be std:: (in other words, getting rid of the old STLport isspace workaround). But with that done, I now get a number of linking errors when I try to build the library using nmake (though I have been able to compile .dlls via the IDE). By manually adding stlport_vc6.lib to the list of linked libraries, I can get rid of all reported linking errors, but the dll's are still failing to compile. Has anyone else using STLport v4.5.3 and regex 3.31 (boost dist 1.30.2) gotten the library to compile under MSVC6? At this point I may try compiling the dlls by hand through the IDE, but it seems like there ought to be a way to get nmake working... Thanks, Sven PS- I should probably admit that this is my first time trying to compile regex using STLport, so it's quite possible that there is some silly little thing that I am doing wrong... I have tried setting the include and lib paths both manually and using the STLPORT_PATH environment variable (C:\STLport-4.5.3 in my case), and I get the same results either way.

3 4

Icompatibility between MS cl preprocessor and boost macro constructs
by m.doppler＠icoserve.com 22 Sep '03

22 Sep '03

Hi, the header files boost/iterator_adaptors.hpp and boost/regex/v3/instances.hpp contain macro constructs that are icompatible with the Microsoft compiler cl when using them in a source file, preprocessing the source to a another source file and afterwards compiling the preprocessed source file. For iterator_adaptors.hpp, cl version 13.00 is affected, for instances.hpp cl 13.00 and 13.10. The problem can be reproduced by compiling the following simple source file (test.cpp) in the base boost directory (boost-1.30.2): #include "boost/iterator_adaptors.hpp" #include "boost/regex.hpp" int main(void) { return 0; } The commandline to preprocess the file is: cl /TP /GX /EHsc /Zc:wchar_t /Zc:forScope /c /I. /P test.cpp The commandline to compile the previously preprocessed file is: cl /TP /GX /EHsc /Zc:wchar_t /Zc:forScope /c /I. test.i Note that when directly compiling the same test program using the following commandline the problem disappears: cl /TP /GX /EHsc /Zc:wchar_t /Zc:forScope /c /I. test.cpp One might expect that the last command line should produce the same result as the first two, but unfortunately this is not the case. I have attached a patch file that solves the icompatibility with the preprocessor by incorporating the following changes: - In instances.hpp the patch adds single spaces between the BOOST_DEFAULT_ALLOCATOR and the end of some template declarations. - In iterator_adaptors.hpp the conditional BOOST_WORKAROUND macros are refactored from inside the template declarations of indirect_iterator_generator and indirect_iterator_pair_generator to the front of them by duplicating the template struct definitions minus the BOOST_WORKAROUND code in the else branch of the conditional macro. In case you wonder why we need to preprocess the source file into a seperate file before compiling it: This is required to use distcc (http://distcc.samba.org) with Microsofts cl. Is there a chance this patch gets accepted for the next boost version? Michael --- michael doppler ----------------------------------- developer icoserve it gmbh innrain 98, 6020 innsbruck tel: +43 - 512 - 567622 - 250 fax: +43 - 512 - 567622 - 111 web: www.icoserve.com email: m.doppler(a)icoserve.com ---------------------------------------------------------------

2 1

boost::TokenizerFunction
by Zenaan Harkness 21 Sep '03

21 Sep '03

TokenizerFunction "Expression Semantics" table (documentation - eg. on debian: /usr/share/doc/libboost-doc/HTML/libs/tokenizer/index.htm), states that "tok is constructed", as part of "Precondition". However I note two things: 1: on looking at the source code for the provided example functions, each constructs a Token as it's first (or second) line of code in the call to operator(). 2: the "Semantics" says "The return value [bool] indicates whether a new token was found in the sequence". If there is no token available (eg. we are already at end of stream(/string) and will return false) why waste effort constructing storage for a token? Why does the doco say that the token must be constructed as a precondition? Is the code wrong, or the doco - ie. should my custom function construct a new (empty) token, or follow doco and have user construct one? It would seem potentially more efficient for the user to construct one, as they may be reused. I am trying to use (my own custom) function directly, in a for loop. Why would I use tokenizer class to wrap it? There is no example on using a function directly, thus these string of questions which I would like some answers on. The documentation for TokenizerFunction doesn't seem to have a proper doxygen-like api description - at least not on my local debian installation. So I have to revert to the source. As I'm a newbie, it is requiring quite a bit of going back and forth to try and figure it all out - eg., should I use a tokenizer (container), token_iterator, or just for-loop on a specific (custom) tokenizer function?? Finally, as I've been trying to figure out how to write my own TokenizerFunction. Delving into the code for the example TFs has eventually led me there, but a simpler example in the documentation would be very useful for other newbies, I'm sure. - I know, I should post the code. Well, I'm not done yet, and I'm implementing a function I need specifically, as opposed to just for learning or doco, but perhaps later in the week I can send something along if no one beats me to it. Once I understand it all a bit better. Simple one-hit functions can be a good way to learn how to code what you need (ie. not templatized). A progression from a one-hit to a templatized version would be ideal for learning. TIA Zen -- Mr Zenaan Harkness Phone +61 (0)412 166 990 Please respect the confidentiality of this email.

1 0

Q: exceptions and -fPIC
by Andrey Nechypurenko 19 Sep '03

19 Sep '03

Hi, I am on the following platform: Linux 2.6.0-test5 #11 Wed Sep 10 20:28:31 CEST 2003 i686 unknown Reading specs from /usr/lib/gcc-lib/i386-slackware-linux/3.2.2/specs Configured with: ../gcc-3.2.2/configure --prefix=/usr --enable-shared --enable-threads=posix --enable-__cxa_atexit --disable-checking --with-gnu-ld --verbose --target=i386-slackware-linux --host=i386-slackware-linux Thread model: posix gcc version 3.2.2 Boost version 1.30.2 compiled with: bjam "-sTOOLS=gcc" I have a question regarding the following boost::filesystem use case: try { for(fs::directory_iterator dir_itr(full_path); dir_itr != end_iter; ++dir_itr ) { // use dir_itr } } catch(const std::exception &ex) { std::cout << ex.what() << std::endl; } In case of full_path pointed to the directory without read permissions the corresponding exception is thrown and catched in the catch block. My problem is that if I compile my application with -fPIC option, I am unable to catch the exception anymore and the program is simply aborted. I need to use -fPIC because of other library which has own build system and if I follow suggested guidlines for Makefile, I get -fPIC automatically. I would verry appreciate if somebody could tell me are there any ways to make the code mentioned above work when it is compiled with -fPIC? Should I recompile boost with -fPIC? If yes, what is the right place to set this parameter? BTW how it is supposed to write a shared library which includes boost code? As I understand, than my code must be compiled with -fPIC... Thanks, Andrey. P.S. Here is example I am using and the makefile: // ttt.cpp #include <iostream> #include <boost/filesystem/operations.hpp> #include <boost/filesystem/path.hpp> namespace fs = boost::filesystem; int main(int argc, char **argv) { try { fs::path full_path = fs::system_complete(fs::path(argv[1], fs::native)); fs::directory_iterator end_iter; for(fs::directory_iterator dir_itr(full_path); dir_itr != end_iter; ++dir_itr ) { std::cout << dir_itr->leaf() << std::endl; } } catch(const std::exception &ex) { std::cout << ex.what() << std::endl; } return 0; } Makefile: CPPFLAGS := -I/usr/local/src/boost LDFLAGS := -L/usr/local/src/boost/libs/filesystem/build/bin/libboost_filesystem.a/gcc/debug/runtime-link-dynamic/ LIBS := $(LIBS) -lboost_filesystem ttt: ttt.cpp c++ $(CPPFLAGS) -g -ftemplate-depth-128 -fPIC -Wall $(LDFLAGS) -o $@ ttt.cpp $(LIBS) __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com

1 0

Spirit library - Problem with the copy constructor of the class rule<> ?
by fritz.birnbacher＠t-online.de 18 Sep '03

18 Sep '03

Hello, I am new in using boost and I played a little bit with the spirit library. I tried following code using MSVC 7.1 and boost 1.30.2 #include"stdafx.h" #include<spirit.hpp> using namespace boost::spirit; rule<> GetRule() { rule<> r = anychar_p; return r; } void Parse1() { char s[] = "ABCD"; parse(s, GetRule()); } void Parse2() { rule<> r = anychar_p; char s[] = "ABCD"; parse(s,r); } int _tmain() { Parse1(); return 0; } Parse1() throws an exception (access violation) Parse2() works correct. Is it a compiler problem or a problem in spirit or my problem ? Thanks

2 1

may it change ?
by maxch 17 Sep '03

17 Sep '03

Hi All, I am a new user of Boost. but when I look the source of Boost, I found that almost all the implementations is put in head files together, not as usual to put into CPP file. I know, it must be intended, however, could it possible to move the implementations into cpp file in future? Sorry if this question has been posted. Thanks!

2 2

Boost.Python - implementing slicing on extension container class
by Steve Horne 16 Sep '03

16 Sep '03

I'm currently writing a set of container classes using Boost.Python to wrap an existing C++ library. Progress has been very good - not even two days and I've wrapped all the existing C++ methods (at least 100). But of course a library designed for C++ is not a library designed for Python. Job 2 is to make it more Pythonic. The current problem is implementing slicing in the __getitem__, __setitem__ and __delitem__ methods. These are already working with single keys. To handle slicing, I need to identify in the key object is a slice object. This is the sticking point right now. I can access the type of the object using p.attr ("__class__") - but how do I get access to the slice type object from __builtins__ in order to compare? I could probably use a workaround such as extracting and checking a string representation from p.attr ("__class__").str (), but it seems to me that the ability to import symbols from another module (whether __builtins__ or some other Python or extension module). This could reduce to the ability to convert a PyObject* to an object instance - even more useful for using any C API functions that don't have a Boost.Python wrapper - but there seems to be no obvious way to do this. In addition, my containers are currently declared as follows... class_<classname, boost::noncopyable>("classname") ... ; The boost::noncopyable is there because the containers don't have copy constructors due to certain issues using the library in C++. Therefore, I'd like to better understand the implications of this. For instance, in Python the copy constructor is often used to make copy the entire container (as opposed to just rebinding names). Presumably Boost.Python supports this using the C++ classes copy constructor. This raises the questions... 1. How can I create an object to return to Python, containing an instance of the C++ container, without removing boost::noncopyable? (I need to do this to implement slicing too) This, I think, is roughly what is done in the Inheritance section of the tutorial so I probably need something like the 'factory' function. So, to reduce it to a simple copy-function example, the following should be about right... Base* container::make_copy () { container *temp = new container (); temp->do_copy (*this); return temp; } ... .def("make_copy", container::make_copy, return_value_policy<manage_new_object>()) I think this should be right, but confidence is low. 2. How can I support the Python copy constructor without having a C++ copy constructor. I'm using boost-1.30.2 with Python 2.2.3 and Visual Studio 7. Any advice would be appreciated. Thanks.

2 4

Web page errors
by Reed Hedges 16 Sep '03

16 Sep '03

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Looks like I just found the *real* list :) The web page (http://boost.org/more/mailing_lists.htm#users) still links to the Yahoo page, and seems to have some other problems (some repeated text below the horizontal line). Would it be possible to fix that soon so as not to confuse others like me too much? thanks reed - -- Reed Hedges reed(a)zerohour.net http://zerohour.net/~reed -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (Darwin) iD8DBQE/ZHFjFK83gN8ItOQRApIQAJ9Mav7GFLBokSwHBb5s+3jzGF/UuwCeMkq7 FN80pQo0c7osCwWm0mNFEsk= =sLUi -----END PGP SIGNATURE-----

2 1

building Jam and Boost on Solaris
by banibrata dutta 16 Sep '03

16 Sep '03

hi, is it possible to build Jam and Boost on Solaris. going thru the Boost.Jam documentation, for building Jam from scratch, i figured that the latest Jam tarball, doesn't seem to have a Makefile. in that case how do i build Jam, and how do i build Boost? any help would be appreciated. thanks, bdutta. _________________________________________________________________ Interact with peers. Learn from experts. http://server1.msn.co.in/sp03/teched/index.asp Be tech-empowered!

3 2

Bug in boost::format with 0 valued integer
by Simon Clift 15 Sep '03

15 Sep '03

Hi folks, There appears to be a bug in boost::format, an unitialized value problem spotted when I was using valgrind on a program of mine. The following test code illustrates the (admittedly minor?) problem: #include <boost/format.hpp> #include <iostream> using namespace std; int main() { int dummy = 5; cout << boost::format( "%05d" ) % dummy << endl; dummy = 0; cout << boost::format( "%05d" ) % dummy << endl; }; I compiled this with -g and when run with valgrind it seems that the put_last function in feed_args.hpp sends an uninitialized value into the standard library <<(int) operator when the integer to be printed is 0 and leading zeros are specified. Valgrind reports (clipped for size) on the second ::format call (but not the first) of the test code: ==28879== Conditional jump or move depends on uninitialised value(s) ==28879== at 0x40289470: (within /usr/lib/libstdc++.so.5.0.3) ... ==28879== by 0x4028F36B: std::ostream::operator<<(int) (in /usr/lib/libstdc++.so.5.0.3) ==28879== by 0x804CF8D: void boost::io::detail::(anonymous namespace)::put_last<char, std::char_traits<char>, int>(std::basic_ostream<char, std::char_traits<char> >&, int&) (feed_args.hpp:114) ==28879== by 0x804C9A2: _ZN5boost2io6detail31_GLOBAL__N_test00Fill.cppfx7Zjb3putIcSt11char_traitsIcERiEEvT1_RKNS1_11format_itemIT_T0_EERSbIS9_SA_SaIS9_EERSt19basic_ostringstreamIS9_SA_SE_E (feed_args.hpp:176) ==28879== by 0x804BF44: void boost::io::detail::distribute<char, std::char_traits<char>, int&>(boost::basic_format<char, std::char_traits<char> >&, int&) (feed_args.hpp:237) ==28879== by 0x804ABB6: _ZN5boost2io6detail4feedIcSt11char_traitsIcERiEERNS_12basic_formatIT_T0_EESA_T1_ (feed_args.hpp:246) ==28879== by 0x804A14B: boost::basic_format<char, std::char_traits<char> >& boost::basic_format<char, std::char_traits<char> >::operator%<int>(int&) (format_class.hpp:69) ... Hope this helps. Otherwise I'm enjoying using boost! Best regards --- Simon -- Simon Clift E-mail: ssclift at math dot uwaterloo dot ca Ph.D. Student Scientific Computation Group University of Waterloo Waterloo, Ontario, Canada N2L 3G1

2 2

re: copy_if
by Witz 15 Sep '03

15 Sep '03

> > template<class II, class OI, class PRED> > > std::pair<II,OI> copy_if(II ibegin, II iend, OI obegin, OI oend, > > PRED p) > > { > > for(; ibegin != iend; ++ibegin) > > { > > if(p(*ibegin)) > > { > > *obegin = *ibegin; > > if(++obegin == oend) > > break; > > } > > } > > return std::make_pair(ibegin, obegin); > > } > > > > This should check whether obegin == end before copying, in case obegin > == oend initially. I don't know whether it should stop as soon as it > finds obegin == oend or wait until it knows there's another item to be > copied. The former behaviour saves a little time in the case that no > more items are wanted once the output buffer is full. The latter > behaviour avoids the occasional need for another pass that copies > nothing, if copy_if is called repeatedly to fill an output buffer which > is then flushed. > Ben. I've tended to rely on the common sense of the user (after all i cannot detect other possible errors such as 'oend < obegin') but i suppose the following addition at the start would seem sensible: ASSERT(obegin != oend); As for your second point - the amount of time saved by 'the former behaviour' depends on how expensive the predicate is and how many times it will be called if no more satisfactory items are available. As the entries in the output buffer are overwritten as and when required there is no need in any general sense to clear it between calls and this surely obviates any advantage your proposed approach may have. Witz

1 0

Re: Boost.Python - implementing slicing on extension container class
by Steve Horne 15 Sep '03

15 Sep '03

I have solved the issues I was having from my previous email. The cause of my problem was mainly that the information I needed was in the 'Embedding' section of the Boost.Python tutorial - I am not doing embedding so it did not occur to me to look there.

1 0

How do I browse the current 'boost-users' list?
by Andrew Bache 15 Sep '03

15 Sep '03

Is it possible to browse items on this list? I posted this via email having got to this page ... http://lists.boost.org/mailman/listinfo.cgi/boost-users What is not immediatly obvious (to me) is how I browse the current status of the list. Is there a URL that displays headers of the most recent posts? Can someone please point me at it? (There is a URL on the above page for an archive). Email reply please - for obvious reasons. Thanks Andy

2 1

RE: [Boost-users] Re: copy_if
by Ben Hutchings 15 Sep '03

15 Sep '03

Witz <witz(a)nildram.co.uk> wrote: > You can find an implementation of copy_if in Boost Wiki here: > > http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl > ?STLAlgorithmExtensions > > An extension that i find useful is the following: > > template<class II, class OI, class PRED> > std::pair<II,OI> copy_if(II ibegin, II iend, OI obegin, OI oend, > PRED p) > { > for(; ibegin != iend; ++ibegin) > { > if(p(*ibegin)) > { > *obegin = *ibegin; > if(++obegin == oend) > break; > } > } > return std::make_pair(ibegin, obegin); > } > > Here we have a finite sized sink. Items are copied from the source if > they satisfy the condition and if there is room left in the sink. The > positions reached are returned on termination of the algorithm. This should check whether obegin == end before copying, in case obegin == oend initially. I don't know whether it should stop as soon as it finds obegin == oend or wait until it knows there's another item to be copied. The former behaviour saves a little time in the case that no more items are wanted once the output buffer is full. The latter behaviour avoids the occasional need for another pass that copies nothing, if copy_if is called repeatedly to fill an output buffer which is then flushed. Ben.

1 0

BGL: finding all minimum cut sets
by Trevon Fuller 14 Sep '03

14 Sep '03

Does anyone know how to find all of the minimum size cut sets of a graph (if more than 1 exists) using the BOOST graph library? The example in the BGL book just finds 1 minimum cut set (p. 106ff.).

1 0

Cygwin: Building a static libboost_thread
by Reed Hedges 14 Sep '03

14 Sep '03

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hello, I have tried every combination of BUILD parameters but I can't seem to get a static libboost_thread.a on gcc/Cygwin (in "no cygwin" mode: TOOLS=gcc-nocygwin). Is it possible? I am using 1.30.2, IIRC. (If on the other hand someone knows how to get DevC++ (with msys gcc) to link against the shared library that would be helpful too) thanks reed - -- Reed Hedges reed(a)zerohour.net http://zerohour.net/~reed -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (Darwin) iD8DBQE/ZHFRFK83gN8ItOQRArZRAJ9M6ohiYEoPqIjXurvdJrx07YJ4TACfcHRg 5d3XguoTJNDWGgSId/zKcEY= =t/LR -----END PGP SIGNATURE-----

1 0

Test
by Victor A. Wagner, Jr. 13 Sep '03

13 Sep '03

I haven't received anything in over a week, this is just a test of the address, please ignore. Victor A. Wagner Jr. http://rudbek.com The five most dangerous words in the English language: "There oughta be a law"

1 1

Re: copy_if
by Witz 13 Sep '03

13 Sep '03

You can find an implementation of copy_if in Boost Wiki here: http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl?STLAlgorithm… An extension that i find useful is the following: template<class II, class OI, class PRED> std::pair<II,OI> copy_if(II ibegin, II iend, OI obegin, OI oend, PRED p) { for(; ibegin != iend; ++ibegin) { if(p(*ibegin)) { *obegin = *ibegin; if(++obegin == oend) break; } } return std::make_pair(ibegin, obegin); } Here we have a finite sized sink. Items are copied from the source if they satisfy the condition and if there is room left in the sink. The positions reached are returned on termination of the algorithm. Witz

2 1

Documentation links don't
by ygor＠comcast.net 13 Sep '03

13 Sep '03

The links for PDF/HTML documentation do not work. Thanks.

4 4

RE: [Boost-users] Re: tupl::get bag
by Ben Hutchings 12 Sep '03

12 Sep '03

nagual <nagual(a)promsoft.ru> wrote: <snip> > I correct line 12 & 13: > > tie(i1, i2, i3, c1, c2, c3).template get<num>() = t; > cout<<tie(i1, i2, i3, c1, c2, c3).template get<num>()<<endl; > > g++ (GCC) v 3.2.2 now compile ok. > > But cl (MSVC) v 13.00.9466 output not change. ;-c The problem there must be something else. VC++ 7.1 accepts the code with or without "template".

1 0

copy_if
by Mr Zenaan Harkness 12 Sep '03

12 Sep '03

Does boost have an implementation of copy_if that I can't find yet? Just wondering, because it is an algorithm that, according to both stroustrup and o'rielly, should have been part of the standard but was essentially accidentally forgotten. Surely this (and possibly other necessary additions) would be part of an boost algorithm library, even if only one or two functions... I need copy_if, both these books I have say it's one of "the first generic algorithm that most programmers will probably write", so where is it? ??? (Yes, I can type it in, but boost is supposed to fill in the blanks, yes?) tia zen

1 0

boost::char_separator enhancement (or, how do I do it myself)
by Mr Zenaan Harkness 12 Sep '03

12 Sep '03

I'm teaching myself C++, and want to tokenize my stream, using boost::tokenizer. I want to be able to optionally tokenize with or without including the delimiter character - this is supported. However: the delimiter character, if included, becomes its own token. I want an option to have the delimiter character be part of the previous token (which is what makes sense for the processing I am doing on my files). ??? ta zen

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Boost's pool implementation
by Thomas Harning 11 Sep '03

11 Sep '03

First off, I think the Boost pool is a great tool and for me has been one of the most useful of Boost's libraries. I have run into a problem however, due to the pool's usage of "malloc" and "free" as the names of functions. The problem is that I want to debug memory usage in my program and catch memory leaks, but using the leak detection in Visual Studio 7.1 for the CRT creates a macro for malloc and free, which conflicts with the pool's malloc and free and makes a general mess. Is there any better memory debug library/tools out there that are free and can get the line/file that the memory allocation occurred and the size perhaps and possibly a portion of the contained data as a character string? Perhaps I could write up a patch to rename the malloc and free from the boost pool [though I see that would be quite a pain to the existing users of boost's pool since code would have to be rewritten with whatever function is added]. Thanks. Thomas Harning Jr.

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boost::pool base class new override
by Rodrigo Serafim 11 Sep '03

11 Sep '03

hi first question: where on earth was boost while I was doing my last year project? just thinking of the amount of trouble I could have saved if I knew about it... makes me bang my head against several walls ;) Well, I starter looking towards memory managment with other eyes after 90% of my bugs being directly originated form it. So after looking on the boost memory library a question popped: how can I use smart pointers and pool toguether. In particular intrusive pointers and/or pool, being the "and/or" essencial. If i have class C all made and ready and now I want it work with smart pointers i just have to make a base class RefCount, use multiple inheritance to contruct C_RC and i can have both things. Problem is, now i want to use it in pool too, but my base class RefCount calls delete. My solution; make yet another base class Poolable and override new and delete there. Well to my surprise it worked but only in very special cases. I have to use pool<> and cant use object_pool<C_RC_P> it crashes. Also it only works in MSVC6 in Release, in Debug it crashes. In a nutshell, my questions: - Is object_pool->malloc / free diferent in semantics from pool->malloc / free ? - I dont mind using pool<> but doing pool<>(sizeof(C_RC_P)) isnt that typesafe, can I make it? - Why does it crash in debug ? I send the code in attatchement. sorry abount the lengthy mail, too many question, too little time Thanks, Rodrigo Serafim

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RE: [Boost-users] tupl::get bag
by Ben Hutchings 11 Sep '03

11 Sep '03

nagual <nagual(a)promsoft.ru> wrote: > I write example code for tuples::tuple::get use tuples::tie. > If compile icl (Intel C++) v 7.1 or bcc32 (Borland) v 5.6.4 all ok, > but if compile g++ (GCC) v 3.2.2 or cl (MSVC) v 13.00.9466 - > i have eror. > ;-c > I need to use it in MSVC. > Help me! <snip> Older compilers performed only minimal parsing of templates before they were instantiated, but the standard says they must do more parsing. This requires that you tell them which dependent names (names of things that depend on a template parameter) are being used as type or template names. You need to put the keyword "template" in front of "get<num>" so that the compiler can parse it correctly. Ben.

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2D Shared Array
by Kevin J. Menard, Jr. 11 Sep '03

11 Sep '03

Hi, Is it possible to build a shared_array of shared_arrays? I would imagine there must be away, but I haven't been so successful at my attempts to find it :-/ I'm working on converting an existing project over to the boost smart pointer library. We've been using dynamically allocated 2D arrays to hold points in a matrix, and would like to take advantage of the automatic clean-up that the boost smart pointers can provide. That's why I would like to make a shared_array of shared_arrays of some data type. Any help would be appreciated. And if I'm approaching this all wrong, please let me know. I'm open to suggestions for other ideas, so long as the individual points can still be referenced in the form of: point[row][col]. Thanks, Kevin

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