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Logical AND
by Mads M.P. 05 Aug '02

05 Aug '02

I've been looking for a parameter like "AND" when using regular expressions (from boost 1.28). I need a match on "a AND is" when searching a sentence like "This is a test". Is there a way to create such a search string by using regular expressions ? Regards Mads c(a)medit.dk

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Boost 1.28 Regex and VC6 link problem
by Edward Diener 04 Aug '02

04 Aug '02

Using Boost 1.28 and regex I get linker errors regarding raw_storage. I believe someone has brought this up before but I didn't save the previous answer. error LNK2001: unresolved external symbol "public: class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> __fastcall boost::re_detail::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::allocator(void)const " error LNK2001: unresolved external symbol "public: class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> __fastcall boost::re_detail::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::allocator(void)const " error LNK2001: unresolved external symbol "public: __thiscall boost::re_detail::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >(class re_detail::detail::allocator_adapter<char,class boost::detail::simple_alloc> const &)" error LNK2001: unresolved external symbol "public: __thiscall boost::re_detail::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >(class re_detail::detail::allocator_adapter<char,class boost::detail::simple_alloc> const &)" error LNK2001: unresolved external symbol "public: void * __fastcall boost::re_detail::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::insert(unsigned int,unsigned int)" error LNK2001: unresolved external symbol "public: void __fastcall boost::re_detail::raw_storage<class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::resize(unsigned int)" It seems to be related to these lines in instances.hpp template class re_detail::raw_storage< BOOST_DEFAULT_ALLOCATOR BOOST_REGEX_CHAR_T) >; template class BOOST_REGEX_DECL re_detail::raw_storage<BOOST_DEFAULT_ALLOCATOR(BOOST_REGEX_CHAR_T) >; Are these lines in error ? Should one or both of them be removed ? My guess is that the line with BOOST_REGEX_DECL needs to be removed.

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Problems with mpl::find and std library
by Tanton Gibbs 03 Aug '02

03 Aug '02

I had a problem with using mpl::find and the std::find at the same time. Basically, my compiler, Compaq C++ V6.5-026, notes an ambiguity in find.hpp between the find_if that it uses and the find_if in the STL. I changed the line that reads struct find : find_if< Sequence, same_as<T> > {}; to be struct find : mpl::find_if< Sequence, same_as<T> > {}; and it works fine. I'm not sure if this is a compiler bug or if we need to find other occurences like this one and fix them. Any help is appreciated. Tanton

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boost.python - from_python for obj.__class__
by Nikolay Mladenov 02 Aug '02

02 Aug '02

Hi, I have exported some classes to python with boost.python, and now I am wondering: Does any body know how can I convert obj.__class__ (of an exported object from C++) to a class specific value( for example typeid(corespondong_cpp_class) )? Thanks in advance, Nikolay

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bjam issue related to boost::python
by Srivatsan Raghavan 02 Aug '02

02 Aug '02

hi all , i created a c++ extension module using python which worked fine.. then i wanted to embed a call to PyRun_SimpleFile in another app, and the script i was calling is attempting to use my extension module but i was getting telling me that the interpreter wasn't initialized after much searching, research, and work with msvc's Dependency Walker i narrowed it down to the fact that boost_python_debug.dll is trying to link to the release version of python22.dll , whereas it should be linking to python22_d.dll (which unfortunately does not come with the python installer , that has to be compiled manually ) at any rate, how can the boost::python Jamfile be modified to try this check when it comes boost::python ? --vat ==.sig== Evil requires nothing more to win than that good men do nothing

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[BGL] Vertex removal without iterator invalidation?
by Erik Arner 01 Aug '02

01 Aug '02

Yet another question from the BGL newbie... I understand that performing remove_vertex() on graphs with vertexList=vecS will result in invalidated itarors and descriptors for the graph. However, some toy examples i made suggest that if I remove a vertex in such a graph, the vertex descriptors and vertex iterators for vertices with *lower* ID than the removed vertex remain valid after removal, while those for higher ID vertices are invalidated. Is this a true feature of a graph with Vertexlist=vecS, or is my observation a mere coincidence? Is it safe to write code that exploits this "feature"? If it indeed is a feature, I can construct a sorted list of vertices to remove, and remove the vertices in descending order in an easy fashion. If it is not a feature, any suggestions on how to perform this task i.e. removing a list of vertices while keeping the VertexList type vecS? Thanks, Erik

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collection container
by Bohdan 01 Aug '02

01 Aug '02

Has boost any plans on creating container, that holds data by pointer, not by value? Rationale: It is impossible to use normally vector<...> for types that do not have copy constructor. Interface of vector< shared_ptr<...> > doesn't seems to be very convenient( for example with std::algorithms ). And most of all it is not good idea to show vector< shared_ptr<...> > interface to user of my lib, that wants to have container::iterator with normal behavior. AFAIK majority of existing libraries have/need such container ? As to me it is strange that neither stl nor boost have such class. I'm missing 'something' and there are important reasons for not doing this ?

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Creating groups of regular expressions
by cyndi_r2002 01 Aug '02

01 Aug '02

Hi, I have started using Regex++ and like it a lot but is there a way to use grouping constructs using Regex++ / any alternative that would provide the same functionality? Thanks, Cyndi

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Newbie link problem
by Lev Assinovsky 01 Aug '02

01 Aug '02

Hi all! I would like to do a very simple thing: link my main tst.cpp with the third party library $(MYDIR)/libfoo.a. The final command line should be: g++ -o tst tst.cpp -L$(MYDIR) -lfoo Currently I have in my Jamfile: exe tst : tst.cpp : <include>$(ADC_ROOT) <include>$(BOOST_ROOT) <include>"$(HOME)/inc" ; What must be added to provide linking with libfoo.a? (adding of variable LINKLIBS=$(MYDIR)/libfoo.a DOESN'T WORK) Thanks in advance! ---- Lev Assinovsky Aelita Software Corporation O&S Core Division, Programmer ICQ# 165072909 [Non-text portions of this message have been removed]

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boost working with CGAL ??
by Matthias Kronenberger 31 Jul '02

31 Jul '02

I want to use CGAL from http://www.cgal.org together with the boost library. I'm using MSVC 6.5 There seem to be some problems related to namespace issues. I'm getting the following kind of errors: d:\matthias\programmieren\cgal\include\cgal\number_utils.h(236): error C2955: 'is_integral': Fuer die Verwendung einer Vorlagenklasse ist eine Vorlagen-Argumentliste erforderlich d:\matthias\programmieren\boost\boost\type_traits\arithmetic_traits.hpp(38): Siehe Deklaration von 'is_integral'

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Cannot put .o File with Graph Code into .a File
by Adalbert Perbandt 30 Jul '02

30 Jul '02

Hi there, while trying to setup the BGL for use in my environment I'm facing a strange behavior when I try to put a C++ object file which contains instanciations of BGL templates into an object library. My environment: - Sun SPARC machine with Solaris 2.7 (SunOS 5.7) - gcc 2.95.2 The problem shows up when I try to put an .o file into a library file. I can reproduce the error with the file adjacency_list.cpp from the BGL's examples directory: $ pwd /home/perbandt/boost_1_28_0/libs/graph/example $ g++ --version 2.95.2 $ g++ -g -I../../../../boost_1_28_0 -c adjacency_list.cpp $ ls -l adjacency_list.o -rw-r--r-- 1 perbandt relman 3367052 Jul 19 18:40 adjacency_list.o $ which ar /usr/ccs/bin/ar $ ar rv libtest.a adjacency_list.o a - adjacency_list.o Bus error When I try a .a file with already one or more .o files in it I get a segmentation fault. With another file that contains instantiations of BGL templates the problem does appear only when it was compiled with the -g option given. Is this a known problem? Seems to me as if ar would have trouble handling the very long symbol names in the .o file. Or is something wrong with my environment? Thanks, Adalbert Perbandt.

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RE: [Boost-Users] absolute beginner, trying to compile
by James Zappia 30 Jul '02

30 Jul '02

It should be /usr/include/boost Then you can do: #include <boost/whatever.h> /usr/include is the base directory. So how you have it now it would be: #include <boost_1_28_0/boost/whatever.h> And you definitely don't want to do that. Regards, James -----Original Message----- From: thomas strack [mailto:yg-boost-users@gmane.org] Sent: Tuesday, July 30, 2002 10:17 AM To: boost-users(a)yahoogroups.com Subject: [Boost-Users] absolute beginner, trying to compile hi there, unfortunately im not very experienced in c/c++. but i want to try out some functions from the boost libs. so i downloaded and extracted the files (1_28_0) to /usr/include/boost_1_28_0. i think i should be able to use most of the functions now(i hope i didnt misunderstand the doc). i want to use dir_it lib, but i cant compile the testfile coming along with boost. it includes <boost/directory.h> and g++ cant find this file. i dont know exactly how to use the -I and -l options. it would be great if someone could help me out. thx,tommi Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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absolute beginner, trying to compile
by thomas strack 30 Jul '02

30 Jul '02

hi there, unfortunately im not very experienced in c/c++. but i want to try out some functions from the boost libs. so i downloaded and extracted the files (1_28_0) to /usr/include/boost_1_28_0. i think i should be able to use most of the functions now(i hope i didnt misunderstand the doc). i want to use dir_it lib, but i cant compile the testfile coming along with boost. it includes <boost/directory.h> and g++ cant find this file. i dont know exactly how to use the -I and -l options. it would be great if someone could help me out. thx,tommi

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Boost.Lambda - Invoking functors stored in a vector
by Thomas Wenisch 30 Jul '02

30 Jul '02

Hi all, I am storing a set of functors to be invoked in a vector, like this: std::vector< boost::function<void> > functors; At a later time, I would like to invoke each of the functors in the vector. I am trying to do this using Boost.Lambda, to start learning about the Lambda library, but I can't figure out what to write. if I write: std::for_each(functors.begin(), functors.end(), _1); None of the functions are invoked. if I try: for_each(funtors.begin(), functors.end(), _1()); I get compile errors. I suspect this is because the lamda expression is being executed immediately instead of getting passed in to for_each. Everything works fine when I use a separate Invoker function in the usual fashion, like this: void Invoker( boost::function<void> functor) { functor(); } std::for_each(funtors.begin(), functors.end(), Invoker); How can I get the lambda library to invoke each function in the vector? More generally, if the functions were function<void, T>, how could I bind the T parameter in the lambda expression? Thanks for any help, Tom Wenisch Computer Architecture Lab Carnegie Mellon University

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Johnsons BGL implementation for undirected graphs correct?
by Jan de Ruiter 29 Jul '02

29 Jul '02

When I use the BGL johnsons_all_pairs_shortest_paths example (source below)on an undirected graph, some results are quite wrong. For example, the output shows that the distance between node 1 and 6 equals 36. The SP however (1-4-5-8-9-6) = 4+4+4+12+2 = 26. Is there something wrong with me or is the BGL implementation incorrect? Any ideas? Jan de Ruiter //Output 0 1 2 3 4 5 6 7 8 9 0 0 99 111 123 103 107 135 105 111 123 1 -99 0 12 24 4 8 36 6 12 24 2 -111 -12 0 12 -8 -4 24 -6 0 12 3 -123 -24 -12 0 -20 -16 12 -18 -12 0 4 -103 -4 8 20 0 4 32 2 8 20 5 -107 -8 4 16 -4 0 28 -2 4 16 6 -135 -36 -24 -12 -32 -28 0 -30 -24 -12 7 -105 -6 6 18 -2 2 30 0 6 18 8 -111 -12 0 12 -8 -4 24 -6 0 12 9 -123 -24 -12 0 -20 -16 12 -18 -12 0 ------------------------------------------------------------------------- //Source #include <boost/config.hpp> #include <fstream> #include <iostream> #include <vector> #include <iomanip> #include <boost/property_map.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/graphviz.hpp> #include <boost/graph/johnson_all_pairs_shortest.hpp> int main() { using namespace boost; typedef adjacency_list<vecS, vecS, undirectedS, no_property, property< edge_weight_t, int, property< edge_weight2_t, int > > > Graph; const int V = 10; typedef std::pair < int, int >Edge; Edge edge_array[] = { Edge(0,1), Edge(1,2), Edge(2,3), Edge(1,4), Edge(2,5), Edge(3,6), Edge(4,5), Edge(5,6), Edge(4,7), Edge(5,8), Edge(6,9), Edge(7,8), Edge(8,9) }; const std::size_t E = sizeof(edge_array) / sizeof(Edge); Graph g(edge_array, edge_array + E, V); property_map < Graph, edge_weight_t >::type w = get(edge_weight, g); int weights[] = { 99, 12, 12, 4, 99, 12, 4, 99, 2, 4, 2, 99, 12 }; int *wp = weights; graph_traits < Graph >::edge_iterator e, e_end; for (boost::tie(e, e_end) = edges(g); e != e_end; ++e) w[*e] = *wp++; std::vector < int >d(V, std::numeric_limits < int >::max()); int D[V][V]; johnson_all_pairs_shortest_paths(g, D, distance_map(&d[0])); std::cout << std::setw(5) <<" "; for (int k = 0; k < 10; ++k) std::cout << std::setw(5) << k ; std::cout << std::endl; for (int i = 0; i < 10; ++i) { std::cout <<std::setw(5) << i ; for (int j = 0; j < 10; ++j) { std::cout << std::setw(5) << D[i][j] ; } std::cout << std::endl; } return 0; }

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[BGL] Detection of cycles in graphs
by Erik Arner 29 Jul '02

29 Jul '02

This is a repost - I sent it last friday but it hasn't shown up, so I'll try again: Is there an algorithm implemented in BGL that detects whether a directed graph contains cycles or not? If not, what would be the best way to implement such an algorithm? Thanks, Erik

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Pass through buffer
by Tom Howard 29 Jul '02

29 Jul '02

Hi, I'm wondering if someone can help me with the pass through buffer (basic_passthrubuf) that is part of more_io. >From what I can understand the pass though buffer passes 1 character at a time to (and from) the underlying stream buffer and I'm wondering what happens with flushes. In the code I'm working on (gzostreambuf which writes to an ostream) I need to know is overflow() is being called because there is no more room in the buffer I'm using or because of an explicit flush. In the later case I need to also flush the compression (Z_SYNC_FLUSH), but doing so all the time will degrade the compression performance plus increase the number of flushes to the underlying stream. This is particularly bad as the underlying stream in my case is a socket stream an the increased flushes breaks up the data into many small packets. Because of the software at the other end of the socket, data must be sent as one message unless it's over 8096 bytes. So basically I only want to flush the underlying stream if the gzostreambuf has been flushed (either by endl or flush). is this possible? My current workaround is to make sure the buffersize of my gzostreambuf is greater than or equal to the buffersize of the underlying stream, but I was hoping there was a neater solution and thats why I was looking at the pass through buffer. >From what I unbderstand, If I use the pass through buffer as part of my gzostreambuf, then flushing will not be passed to the underling streambuf at all. This means that data sent to the stream may be compressed, but result in no output for quite some time later and this sort of latency would be unacceptable in the software I'm working on (client-server multi-agent simulation). Cheers, Tom Howard

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regex_search matches correctly but memory holder contains wrong value
by Anibal Jodorcovsky 29 Jul '02

29 Jul '02

Hi all, I have a small problem when trying out a regex that works ok with both jakarta (java code) and Perl. However, in boost::regex I get an extra space that's very weird. This is the code: #include <iostream> #include <string> #include <boost/regex.hpp> main() { static const boost::regex infileRedirection( "\\[(.+?)\\s*=\\s*(.+?)\\]" ); const string input = "[IN_FILE_REDIRECTION = STARTS_3]"; boost::cmatch what; if ( boost::regex_search( input, what, infileRedirection, boost::regbase::perl ) ) { cerr << "Matched! == input is (" << input << ")" << endl; string mySection; mySection.assign( what[1].first, what[1].second ); string newSectionName; newSectionName.assign( what[2].first, what[2].second ); cerr << "mySection is: --" << mySection << "--" << endl; cerr << "newSection is: --" << newSectionName << "--" << endl; } else { cerr << "Didn't match" << endl; } return 0; } And this is the output: [anibal@anibal ControlFile]$ ./a.out Matched! == input is ([IN_FILE_REDIRECTION = STARTS_3]) mySection is: --IN_FILE_REDIRECTION-- newSection is: -- STARTS_3-- Please note the extra space in the newSection. That should be STARTS_3 and not " STARTS_3". Why is it taking that space if the space itself is not in the () expression? Any help greatly appreciated, -Anibal

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Compilation problem
by Sergey Belovolov 29 Jul '02

29 Jul '02

gcc version 2.95.3 20010315 (release). It came with OS (SunOS 5.8 x86). After when I compiled & installed bjam I came into boost root dir and give (as it suggessted in docs): bjam "-sTOOLS=gcc". It builds 3 library: libboost_regex.a, libboost_regex.so, libboost_thread.a (while bjam builds library libboost_thread.a it throws messages: " g++: unrecognized option '-pthreads' "). Then I copy them into some dir that included in LD_LIBRARY_PATH environment varyable and copy dir boost to /usr/include. Then I create file with contents: #include <boost/thread/mutex.hpp> main() { return 0; } and compile it with: g++ test.cpp. Results: In file included from /opt/sfw/lib/gcc-lib/i386-pc-solaris2.8/2.95.3/../../../../include/g++-3/uti lity:31, from /usr/include/boost/config/select_stdlib_config.hpp:18, from /usr/include/boost/config.hpp:40, from /usr/include/boost/thread/mutex.hpp:15, from test.cpp:1: /opt/sfw/lib/gcc-lib/i386-pc-solaris2.8/2.95.3/../../../../include/g++-3/stl _relops.h: In function `bool rel_ops::operator !=(const _Tp &, const _Tp &)': /opt/sfw/lib/gcc-lib/i386-pc-solaris2.8/2.95.3/../../../../include/g++-3/stl _relops.h:37: template with C linkage /opt/sfw/lib/gcc-lib/i386-pc-solaris2.8/2.95.3/../../../../include/g++-3/stl _relops.h: In function `bool rel_ops::operator >(const _Tp &, const _Tp &)': /opt/sfw/lib/gcc-lib/i386-pc-solaris2.8/2.95.3/../../../../include/g++-3/stl _relops.h:42: template with C linkage /opt/sfw/lib/gcc-lib/i386-pc-solaris2.8/2.95.3/../../../../include/g++-3/stl _relops.h: In function `bool rel_ops::operator <=(const _Tp &, const _Tp &)': /opt/sfw/lib/gcc-lib/i386-pc-solaris2.8/2.95.3/../../../../include/g++-3/stl _relops.h:47: template with C linkage /opt/sfw/lib/gcc-lib/i386-pc-solaris2.8/2.95.3/../../../../include/g++-3/stl _relops.h: In function `bool rel_ops::operator >=(const _Tp &, const _Tp &)': /opt/sfw/lib/gcc-lib/i386-pc-solaris2.8/2.95.3/../../../../include/g++-3/stl _relops.h:52: template with C linkage and so on and so on... What's wrong? Why it says that STL templates use C linkage? Thanks for help in advance. Sergey Belovolov. b_sv(a)mail.ru SBelovolov(a)algorithm.aelita.com

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Installation problems
by fauzia_sharmeen 28 Jul '02

28 Jul '02

Hi, After downloading and unzipping the Regex library with the -d option, I ran nmake -fvc6.mak on the command prompt.However, I am getting an error message saying "Variable MSVCDIR not set". I checked the VcVars32.bat file to verify that the variable MSVCDIR has been set properly. Any ideas/suggestions about what I am doing wrong would be most appreciated. Thanks, Fauzia

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Iterator problem with adjacent_vertices
by EJ van Eijk 28 Jul '02

28 Jul '02

Hello, I'm currently implementing some algorithms for drawing graphs, using boost::graph. PropertyMaps e.a. are working like a charm, but for my algorithm I need to find the adjacent vertices. Now I've become stuck on the following: typedef boost::adjacency_list < boost::mapS, boost::vecS, boost::undirectedS, VertexProperty, EdgeProperty> Graph; typedef boost::graph_traits<Graph>::vertex_descriptor Vertex; class functor { ... void operator()(Vertex& v) { ... }; }; for_each(adjacent_vertices(u,g).first, adjacent_vertices(u,g).second, functor<Graph>(g)); complains about foo.cc:30: initialization of non-const reference type `Vertex &' foo.cc:30: from rvalue of type `unsigned int' But, when using vertices(g) instead of adjacent_vertices(v,g), the code compiles, and applies functor to each vertex. What am I missing? The documentation is quite thorough, but I'm lost at the moment... EJ

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Re: [Boost-Users] XML
by dick.bridges＠tais.com 26 Jul '02

26 Jul '02

What you say is true. In fact, it's *STILL* true. In the meantime, Xerces has released version 1.7.0 and, most recently, version 2.0. I've been following the Xalan mail lists and comments from some of the developers suggest that co-ordination between the two groups could be better. This "thread" probably belongs on xalan-c-users(a)xml.apache.org. Mail me direct to continue. Albrecht Fritzsche <albrecht.fritzsche@tisc To: Boost-Users(a)yahoogroups.com ali-dsl.de> cc: Subject: Re: [Boost-Users] XML 07/26/2002 11:33 AM Please respond to Boost-Users dick.bridges(a)tais.com wrote: > Unfortunately, the Xerces and Xalan projects don't appear to > be all that well co-ordinated. Makes it difficult to stay both > current and compatible. Huh - why do you think that? Simply reading the FAQ gives me "The Xalan-C++ release notes includes information about the Xerces-C++ release with which the Xalan-C++ release has been coordinated and tested." and even the Readme says "Xalan-C++ version 1.3 has been tested with Xerces-C++ version 1.6.0. Each Xalan-C++ version 1.3 download includes the Xerces-C++ distribution for the specified platform." Curious Ali Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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RE: [Boost-Users] XML
by dick.bridges＠tais.com 26 Jul '02

26 Jul '02

Xerces is ok for xml+namespaces but if you want to use additional facilities (e.g., XPath, XSLT, etc.) you'll have to go to other packages like Xalan. Unfortunately, the Xerces and Xalan projects don't appear to be all that well co-ordinated. Makes it difficult to stay both current and compatible. It sure would be nice to have a "boost-level" C++ library for xml but I'm not sure we could sell the idea that it should be "part of" C++. Hope I'm wrong. schalk_cronje@na i.com To: Boost-Users(a)yahoogroups.com cc: 07/26/2002 10:14 Subject: RE: [Boost-Users] XML AM Please respond to Boost-Users > I'm writing an XML based project right now. I haven't been > able to find > any good, open source XML parser to incorporate into my > application, so I What's wrong with Xerces? Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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RE: [Boost-Users] Re: [boost] Iterator Adaptor Poll
by Mark Storer 26 Jul '02

26 Jul '02

May i recommend providing both the "hello world" grade example, and something more real-world... like that path token iterator you mentioned? --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard;

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Re: [boost] Iterator Adaptor Poll
by David Abrahams 26 Jul '02

26 Jul '02

From: "Toon Knapen" <toon.knapen(a)si-lab.org> > > Sure, I'm all for toys, as in "this doesn't really do everything I'd want > > from a real example, but it shows me how the system works". The problem I > > have with ia_experiment.cpp is that my first reaction was "why would anyone > > want an "iterator" which does *that*?" The fact that it iterates over only > > two elements and stores its value internally is pretty weird. I think most > > people who have only seen the standard iterators would have a hard time > > imagining that this is also an iterator. Though technically, it is an > > iterator, it's so different in nature from most iterators that it seems > > like it would be completely foreign. > > > > What about a singly-linked-list iterator example? Wouldn't that show > > everything you're illustrating, but more transparently? > > Why not some kind of rotation iterator. The advantage of this example is that > there's a std::rotate in the STL which modifies the container whereas the > rotation_iterator_adaptor can give you the same result but withouth modifying > the containers. AFAICT this is a strong argument in favour of the IA. That's neat, but we already have the permutation adaptor, and I don't think it's really a simple enough example. Beman's example just makes a simple iterator, not an adaptor, and I think that's an important feature for a "hello, world"-type introduction. -Dave ----------------------------------------------------------- David Abrahams * Boost Consulting dave(a)boost-consulting.com * http://www.boost-consulting.com

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