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removing parallel edges in the Boost Graph Library?
by Nicholas Burlett 01 Apr '04

01 Apr '04

I am trying to use BGL to model a directed multigraph, but every time I try to remove just one of the edges (u,v), it removes all of the edges from u to v. My graph definition is: typedef adjacency_list<listS, listS, bidirectionalS, VertexProperty, EdgeProperty> graphdata; where VertexProperty and EdgeProperty are properties I've defined. Everything else seems to work: I have can add parallel edges, find the edge I want to remove based on the EdgeProperty, filter the graph for topological sorting, check for existing edges, etc. In the following, e is of type graph_traits<graphdata>::edge_descriptor, and g is the graph of type graphdata (defined above): std::cout << "about to remove edge\n"; DumpInfo(); remove_edge(e, g); std::cout << "removed edge\n"; DumpInfo(); Here is some sample output: about to remove edge vertex: 0 out-edges: in-edges: (1,0) (1,0) adjacent vertices: vertex: 1 out-edges: (1,0) (1,0) in-edges: adjacent vertices: 0 0 removed edge vertex: 0 out-edges: in-edges: adjacent vertices: vertex: 1 out-edges: in-edges: adjacent vertices: Note that there were two edges present before the call to remove_edge, but only one after. What am I doing wrong? I'm using version 1.31, if that helps. Thanks, Nicholas Burlett nrb23(a)cornell.edu

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Re: [boost] [BGL] forced client complexity
by Cromwell Enage 31 Mar '04

31 Mar '04

prs, On reflection, I've decided to cross-list my reply. > If one accepts the axiom that "a picture is worth a > thousand words," then it naturally follows that > discussion of graphs is always overly prolix. I recently had a chat with a fellow programmer and attempted to summarize, in semi-layman terms, how the core algorithms of my multi-state-mazes library work. They're pretty simple, but I couldn't do it without paper and pencil. > Sadly, the same reasoning is also applicable to > the code of graph libraries. If a "code-visualizing compiler IDE" existed that would give us "code pictures" (plus conform to the new C++ standard, not ICE, and so on), I'm pretty sure more of us would be using it for all programming projects, not just graph applications. :) But seriously, with graph theory containing several different problem domains (search, network, AI, etc.), a graph library attempting to be generic enough for use in all of them is necessarily complex. > Boost.Graph seems to expose and require an > unnecessarily large amount of complexity, > though. If by "exposure" you mean lots of source code, I'll take that complexity any day of the week and twice on Sundays. :) The library does have a rather steep learning curve, especially if you're somewhat unfamiliar with graph theory and/or template programming. > Whereas libraries like Spirit go to great lengths > to make hard things easy, BGL seems to try only to > make hard things possible. I haven't looked at the Spirit library yet, so I can't tell you how easy it may be to use it. Perhaps getting your hands on a copy of the Boost Graph Library book will help (I don't have one, so I'm not certain). > The amount of scaffolding required > to use BGL for even the simplest of projects > often dwarfs the code size of a naive, > yet functional, special-purpose implementation. Special-purpose implementation of a graph library? Or the project? BGL aims to be as generic as the STL, but whereas each STL container deals with essentially one type of element, a graph needs to contain two types: a vertex type and an edge type. Furthermore, while most STL algorithms confine themselves to handling just those STL container elements, most graph algorithms also need the properties of vertices and/or edges as input. BGL delegates some of the responsibility of property storage to the Boost Property Map Library. I'm just glad the developers kept the complexity down to its current level. > While I understand that the BGL is deeply entrenched > in boost culture, certain academic circles, and even > publications, I nonetheless suggest that BGL lacks > the ease of use necessary for widespread adoption. Having dwelt in the academic circle known as the University of Central Florida, and thus familiar with the theoretical uses of a graph library (plus I've studied some game development apps on the side), I'd like to learn more about how the Real World would want to use BGL. > Even knowing that ease-of-use is not a criterion > for acceptance into boost, looking at what is > required of the client to use the BGL always leaves > me feeling perplexed. Is there any particular reason > that a simplified interface is not made available? Again, I don't know a simple graph problem that requires a simplified graph interface. > Perhaps a container adapter could be packaged with > the library allowing a compromise of functionality > and flexibility for simplicity? I thought the boost::vector_as_graph class template served that purpose. Wrap it around a std::vector<EdgeList>, with EdgeList = std::list<unsigned int> (or an edge list container of your choice, so long as the value type is usable as an index in the vector), and you should be good to go. > If a graphing problem is trivial, shouldn't BGL > provide a trivial solution? Why are the simplest > useful examples several hundred lines of code? The examples don't seem that big and hard to understand. Of course, quite a few of them have #ifdefs that I could do without since I don't use the compilers in question, but I can live with them. > I apologize for all of my vague criticisms - my > intention is not to flame but rather to test the > waters. Your criticisms seem healthy, and I hope my responses are helpful. > It is difficult for me to assess whether the > simplicity I yearn for isn't present for stylistic > reasons or whether it would rather necessitate a > sacrifice of flexibility, functionality or > implementation clarity. Nor is it clear to me to > what extent these criteria can be compromised to > promote clarity of client code. For what it is > worth, the kind of ease-of-use I'm imagining might > look like: #include <less_than_10_graph_headers> ... digraph<some_node_type,some_edge_context_type> g; g << "vertex" << make_pair("vertex", "implicit_vertex"); g.add_edge("brother", "sister", "sibling"); if(g.find(make_pair("brother", "sister"))) related = true; > Could someone please elucidate on why it is > impossible/impractical/unnecessary/whatever for a > graph library to have such an interface? I believe the potential for ambiguity would hinder this syntax the most. In this case, you'd have to overload operator<< to input both edges and vertices, and what if some_node_type turned out to be std::pair? You couldn't pass in make_pair(vertex,vertex) as an edge then. The same goes for g.find(); is it supposed to find a vertex, an edge, or both? Also, it seems you want to be able to use non-built-in or custom types as vertex IDs. You'll have to build your own custom-type-to-vertex map and bind it to the graph; BGL won't do it for you, to retain its genericity. Incidentally, BGL favors free functions over member functions. The rationale for that can be found in the FAQ <http://www.boost.org/libs/graph/doc/faq.html>. > Should I accept that the BGL is not the magic bullet > graph library and move on, or can this kind of > simplicity be somehow found within? Yeah, no magic bullets here. It depends on the problem you are trying to solve. Cromwell Enage __________________________________ Do you Yahoo!? Yahoo! Finance Tax Center - File online. File on time. http://taxes.yahoo.com/filing.html

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Re: [BGL] forced client complexity
by Christopher D. Russell 31 Mar '04

31 Mar '04

A well written critique. I had to go look up the word "prolix" (i.e. verbose). In defense of BGL: I am no BGL expert despite having read the book several times and writing a complex client application that uses dozens of different graph types. I admit, it was some hard work getting going with BGL. However, this is because I didn't know C++ templates nearly as well as I thought I did. Certainly there's nothing in the library that would preclude anyone from writing simpler BGL-derived classes that offer solutions that are packaged to solve specific problems. Post specific problems and people will help. > It is difficult for me to assess whether the > simplicity I yearn for isn't present for stylistic > reasons or whether it would rather necessitate a > sacrifice of flexibility, functionality or > implementation clarity. Having become baseline proficient with BGL, I would disagree that it's overly complex. To me BGL is an elegant solution to a class of very complex problems that strikes a reasonable balance between complexity and flexibility. In my opinion, if you frequently use graphs BGL is well worth the investment required to learn how to use it. - Chris "Provisional Dissonance" <prosonance(a)yahoo.com> wrote in message news:20040331094800.93338.qmail@web60105.mail.yahoo.com... > If one accepts the axiom that "a picture is worth a > thousand words," then it naturally follows that > discussion of graphs is always overly prolix. Sadly, > the same reasoning is also applicable to the code of > graph libraries. Boost.Graph seems to expose and > require an unnecessarily large amount of complexity, > though. Whereas libraries like Spirit go to great > lengths to make hard things easy, BGL seems to try > only to make hard things possible. The amount of > scaffolding required to use BGL for even the simplest > of projects often dwarfs the code size of a naive, yet > functional, special-purpose implementation. > > While I understand that the BGL is deeply entrenched > in boost culture, certain academic circles, and even > publications, I nonetheless suggest that BGL lacks the > ease of use necessary for widespread adoption. Even > knowing that ease-of-use is not a criterion for > acceptance into boost, looking at what is required of > the client to use the BGL always leaves me feeling > perplexed. Is there any particular reason that a > simplified interface is not made available? Perhaps a > container adapter could be packaged with the library > allowing a compromise of functionality and flexibility > for simplicity? If a graphing problem is trivial, > shouldn't BGL provide a trivial solution? Why are the > simplest useful examples several hundred lines of > code? > > I apologize for all of my vague criticisms - my > intention is not to flame but rather to test the > waters. It is difficult for me to assess whether the > simplicity I yearn for isn't present for stylistic > reasons or whether it would rather necessitate a > sacrifice of flexibility, functionality or > implementation clarity. Nor is it clear to me to what > extent these criteria can be compromised to promote > clarity of client code. For what it is worth, the > kind of ease-of-use I'm imagining might look like: > > #include <less_than_10_graph_headers> > ... > digraph<some_node_type,some_edge_context_type> g; > g << "vertex" << make_pair("vertex", > "implicit_vertex"); > g.add_edge("brother", "sister", "sibling"); > if(g.find(make_pair("brother", "sister"))) > related = true; > > Could someone please elucidate on why it is > impossible/impractical/unnecessary/whatever for a > graph library to have such an interface? Should I > accept that the BGL is not the magic bullet graph > library and move on, or can this kind of simplicity be > somehow found within? > > Thanks in advance, > prs > > > __________________________________ > Do you Yahoo!? > Yahoo! Finance Tax Center - File online. File on time. > http://taxes.yahoo.com/filing.html > _______________________________________________ > Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost >

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Re: boost::variant's and > 10 supported types
by Aleksey Gurtovoy 31 Mar '04

31 Mar '04

Eric Friedman writes: > Preston A. Elder wrote: > > How do I support > 10 types in a variant without having support for > > make_variant_over (since I wish to still support Borland and MSVC 6/.NET > > (aka. 7, not 7.1), as well as gcc). > > To solve your problem under the current implementation, you need a > greater value for BOOST_MPL_LIMIT_LIST_SIZE. I'm unfortunately not > attuned enough to the MPL implementation to know what is involved in > attaining this; I've CCed this to Aleksey Gurtovoy (the MPL maintainer), > who may be able to help you. Just #define-ing BOOST_MPL_LIMIT_LIST_SIZE to something that is a multiple of 10 (e.g. 20) before including Boost headers should work. -- Aleksey Gurtovoy MetaCommunications Engineering

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Lambda question
by Anders Sundman 31 Mar '04

31 Mar '04

Hi all! I'm using the lambda library to compute the sum of squared differences, but I have encountered a puzzling problem. I would really appreciate if someone could explain it to me. This doesn't compile: std::inner_product(i1, i1+x, i2, 0.0, (_1 + _2), (_1*_1)(_1 - _2)); however, this does: std::inner_product(i1, i1+x, i2, 0.0, std::plus<double>(), (_1*_1)(_1 - _2)); The compiler message is very voluminous and hard to read. But I think this part might be of importance, the (double&, double) looks strange: /usr/include/c++/3.3/bits/stl_numeric.h:119: error: no match for call to `( boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambd a::arithmetic_action<boost::lambda::plus_action>, boost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::placeholder <1> >, boost::lambda::lambda_functor<boost::lambda::placeholder<2> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > >) (double&, double)' /usr/include/boost/lambda/detail/lambda_functors.hpp:142: error: candidates are: typename T::sig<boost::tuples::null_type>::type boost::lambda::lambda_functor<Base>::operator()() const [with T = boost::lambda::lambda_functor_base<boost::lambda::arithmetic_action<boost::la mbda::plus_action>, Many thanks in advance Anders Sundman

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Error building Boost_1_30_0
by Albert Gome 31 Mar '04

31 Mar '04

Hi, I am build Boost_1_30_0 on HPUX11.11 using gcc 3.3.3. I m getting these errors. skipping Boost.Python library build due to missing or incorrect configuration couldn't find Python.h in "/usr/local/include/python2.2" . . . . . ...patience... ...found 2254 targets... ...updating 295 targets... gcc-C++-action libs/regex/build/bin/libboost_regex.a/gcc/debug/runtime-link-dynamic/c_regex_traits.o libs/regex/src/c_regex_traits.cpp: In static member function `static void boost::c_regex_traits<char>::update()': libs/regex/src/c_regex_traits.cpp:655: call of overloaded `getlocale(int)' is ambiguous /usr/include/locale.h:114: candidates are: locale_data* getlocale(int) libs/regex/src/c_regex_traits.cpp:62: const char* <unnamed>::getlocale(int) libs/regex/src/c_regex_traits.cpp:658: call of overloaded `getlocale(int)' is ambiguous /usr/include/locale.h:114: candidates are: locale_data* getlocale(int) libs/regex/src/c_regex_traits.cpp:62: const char* <unnamed>::getlocale(int) libs/regex/src/c_regex_traits.cpp:660: call of overloaded `getlocale(int)' is ambiguous /usr/include/locale.h:114: candidates are: locale_data* getlocale(int) libs/regex/src/c_regex_traits.cpp:62: const char* <unnamed>::getlocale(int) libs/regex/src/c_regex_traits.cpp:663: call of overloaded `getlocale(int)' is ambiguous /usr/include/locale.h:114: candidates are: locale_data* getlocale(int) libs/regex/src/c_regex_traits.cpp:62: const char* <unnamed>::getlocale(int) g++ -c -Wall -ftemplate-depth-100 -DBOOST_REGEX_NO_LIB=1 -DBOOST_REGEX_STATIC_LINK=1 -g -O0 -fno-inline -I"libs/regex/build" -I "/mnt/r7/apal3/lib/boost_1_30_0" -o "libs/regex/build/bin/libboost_regex.a/gcc/debug/runtime-link-dynamic/c_regex_traits.o" "libs/regex/build/../src/c_regex_traits.cpp" ...failed gcc-C++-action libs/regex/build/bin/libboost_regex.a/gcc/debug/runtime-link-dynamic/c_regex_traits.o... gcc-C++-action libs/regex/build/bin/libboost_regex.a/gcc/debug/runtime-link-dynamic/c_regex_traits_common.o gcc-C++-action libs/regex/build/bin/libboost_regex.a/gcc/debug/runtime-link-dynamic/cpp_regex_traits.o gcc-C++-action libs/regex/build/bin/libboost_regex.a/gcc/debug/runtime-link-dynamic/cregex.o gcc-C++-action libs/regex/build/bin/libboost_regex.a/gcc/debug/runtime-link-dynamic/fileiter.o gcc-C++-action libs/regex/build/bin/libboost_regex.a/gcc/debug/runtime-link-dynamic/posix_api.o gcc-C++-action libs/regex/build/bin/libboost_regex.a/gcc/debug/runtime-link-dynamic/regex.o gcc-C++-action libs/regex/build/bin/libboost_regex.a/gcc/debug/runtime-link-dynamic/regex_debug.o gcc-C++-action libs/regex/build/bin/libboost_regex.a/gcc/debug/runtime-link-dynamic/regex_synch.o gcc-C++-action libs/regex/build/bin/libboost_regex.a/gcc/debug/runtime-link-dynamic/w32_regex_traits.o . . . . . ...skipped <libs!regex!build/libboost_regex.a/gcc/debug/runtime-link-dynamic>libboost_regex_debug.a for lack of <libs!regex!build/libboost_regex.a/gcc/debug/runtime-link-dynamic>libboost_regex_debug.a(c_regex_traits.o)... ...skipped <!libs!regex!build!bin-stage>libboost_regex_debug.a for lack of <libs!regex!build/libboost_regex.a/gcc/debug/runtime-link-dynamic>libboost_regex_debug.a... gcc-C++-action libs/regex/build/bin/libboost_regex.a/gcc/release/runtime-link-dynamic/c_regex_traits.o libs/regex/src/c_regex_traits.cpp: In static member function `static void boost::c_regex_traits<char>::update()': libs/regex/src/c_regex_traits.cpp:655: call of overloaded `getlocale(int)' is ambiguous /usr/include/locale.h:114: candidates are: locale_data* getlocale(int) libs/regex/src/c_regex_traits.cpp:62: const char* <unnamed>::getlocale(int) libs/regex/src/c_regex_traits.cpp:658: call of overloaded `getlocale(int)' is ambiguous /usr/include/locale.h:114: candidates are: locale_data* getlocale(int) libs/regex/src/c_regex_traits.cpp:62: const char* <unnamed>::getlocale(int) libs/regex/src/c_regex_traits.cpp:660: call of overloaded `getlocale(int)' is ambiguous /usr/include/locale.h:114: candidates are: locale_data* getlocale(int) libs/regex/src/c_regex_traits.cpp:62: const char* <unnamed>::getlocale(int) libs/regex/src/c_regex_traits.cpp:663: call of overloaded `getlocale(int)' is ambiguous /usr/include/locale.h:114: candidates are: locale_data* getlocale(int) libs/regex/src/c_regex_traits.cpp:62: const char* <unnamed>::getlocale(int) g++ -c -Wall -ftemplate-depth-100 -DNDEBUG -DBOOST_REGEX_NO_LIB=1 -DBOOST_REGEX_STATIC_LINK=1 -O3 -finline-functions -Wno-inline -I"libs/regex/build" -I "/mnt/r7/apal3/lib/boost_1_30_0" -o "libs/regex/build/bin/libboost_regex.a/gcc/release/runtime-link-dynamic/c_regex_traits.o" "libs/regex/build/../src/c_regex_traits.cpp" ...failed gcc-C++-action libs/regex/build/bin/libboost_regex.a/gcc/release/runtime-link-dynamic/c_regex_traits.o... Does anybody know how to reolve this? Thnks Albert --------------------------------- Do you Yahoo!? Yahoo! Finance Tax Center - File online. File on time.

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boost::variant's and > 10 supported types
by Preston A. Elder 31 Mar '04

31 Mar '04

Hi, How do I support > 10 types in a variant without having support for make_variant_over (since I wish to still support Borland and MSVC 6/.NET (aka. 7, not 7.1), as well as gcc). To be precise, I need 18 types to be supported. -- PreZ Founder The Neuromancy Society http://www.neuromancy.net

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boost::filesystem::exists() & GetfileAttributesA
by Sebastian Orfino 31 Mar '04

31 Mar '04

Hi, I am experiencig a problem with exists() and its Windows implementation with GetFileAttributes API. I am using exists() prior to the scan of a directory to see if it exists; the fact is that on W2K (just tested it on that OS) after a day or two GetFileAttributesA() returns INVALID_FILE_ATTRIBUTES but the path does exists (it is a UNC-style path). After a restart of the app, all works fine. So, should I use exists() this way ? I don't know why not. Or just use directory_iterator and scan the hot-folder right away catching any exceptions ?. I don't want to iterate over a direcotry that doesn't exists if I could knew that in advance; besides, I don't know if that will work anyway. Does anyone know somthing about this GetFileAttributesA/boost::exists() behavior ? Thanks in advance, Sebastian.

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vc7.1-stlport
by GoochRules! 31 Mar '04

31 Mar '04

Greetings, I am attempting to build boost using "-sTools=vc7.1-stlport". I have copied the STLport libaries to C:\src\lib. The STLport headers are in c:\src\include\stlport. I extracted the STLport archive to c:\src\STLport-4.6.1. I have tried STLPORT_PATH=c:\src, c:\src\lib, c:\src\include, and c:\src\include\stlport with STLPORT_VERSION unset, and set to 4.6.1, as well as both unset. Boost succeeds in building, yet does not link against the STLport libraries (as reported by depends.exe), but rather to MSVCP71.DLL and MSVCP71.DLL (the C++ and C runtime libraries provided by vc7.1 I presume). I have ensured that c:\src\lib is first in %LIB% and c:\src\include\stlport;c:\src\include; is first in %INCLUDE% Any suggestions for what my STLport setup should look like are appreciated, as well as pointers on getting boost to link against the STLport libraries. --Matthew Peltzer

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Boost Python on Mac OS X
by James Mastro 31 Mar '04

31 Mar '04

Hello all, I'm trying to use Boost Python on Mac OS X 10.3. I'm following along with what is at http://www.boost.org/libs/python/doc/tutorial/doc/ building_hello_world.html. After using bjam like this: bjam -sTOOLS=darwin the following are built: libboost_python.dylib hello.so This seems to be correct. I'm not totally sure where they are supposed to go, so I put them in next to Python in the Python framework so Python could find them to import. It found them, but an "import hello" in Python resulted in: ImportError: Failure linking new module: ../../../../bin/boost/libs/python/build/libboost_python.dylib/darwin/ debug/shared-linkable-true/libboost_python.dylib: dyld: /Applications/MacPython-2.3/PythonIDE.app/Contents/MacOS/PythonIDE can't open library: ../../../../bin/boost/libs/python/build/libboost_python.dylib/darwin/ debug/shared-linkable-true/libboost_python.dylib (No such file or directory, errno = 2) Before putting the 2 libs in, "import hello" found nothing. So I assume Python is finding the hello module now, but not liking it. Can anyone show me where I've gone wrong? Many thanks. -jim

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Installing pyste
by Yannick Patois 31 Mar '04

31 Mar '04

Hi, When running "bjam install" from top-level directory, even with PYTHON_ROOT set correctly, it only creates shared libs but doesnt build and install pyste. What should be done to install it properly ? I finally went to libs/python/pyste/install and executed: python setup.py install I would expect this to be wrapped in some top-level command. Did I miss something in the doc ? Thanks, Yannick

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Compilation problems on Linux
by mayankg＠iiitb.ac.in 31 Mar '04

31 Mar '04

Hi, We are trying to use the libboost_python.so library in Linux with our project. When we try to compile the C++ file of our project having all the boost interfaces, we get the following compilation error only on Linux. Although on Windows it works fine. We are using the Python 2.2.3 and Boost 1.30.2 versions. /usr/include/boost/python/converter/as_to_python_function.hpp:28: sorry, unimplemented: ` method_call_expr' not supported by dump_expr /usr/include/boost/python/converter/as_to_python_function.hpp:28: sorry, unimplemented: ` method_call_expr' not supported by dump_expr /usr/include/boost/python/converter/as_to_python_function.hpp:28: sorry, unimplemented: ` method_call_expr' not supported by dump_expr /usr/include/boost/python/converter/as_to_python_function.hpp:28: sorry, unimplemented: ` method_call_expr' not supported by dump_expr Please help, Regards, Mayank

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Location and namespace of a boost library (say, iterators)
by Deane Yang 31 Mar '04

31 Mar '04

I'm sorry if I'm being dumb about this, but I've run into the following difficulty a couple of times with boost libraries. I've decided to try using the new boost iterator library. Based on the documentation, I think I want to use iterator_adaptor. But scanning through the documentation, I don't immediately see - what namespace iterator_adaptor lives in. I assume it's just boost, but it probably doesn't hurt to mention this explicitly, since some boost libraries use sub-namespaces. - what header file to include. I couldn't find this in the documentation. I can figure all of this out, but it is helpful to have it specified in the documentation.

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Installing Boost 1_30_0 on HPUX
by Albert Gome 31 Mar '04

31 Mar '04

Hi, I am new to BOOST and i like to install that on HPUX11.11. I have downloaded BOOST_1_30_0 and have gcc installed on HPUX. What is the efficient way of installing it. ie the parameters with the bjam. Thanks Albert __________________________________ Do you Yahoo!? Yahoo! Finance Tax Center - File online. File on time. http://taxes.yahoo.com/filing.html

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[BGL] Finding out what properties exist in a graph?
by Steve Juranich 30 Mar '04

30 Mar '04

Is there an easy way to find out all of, for instance, the vertex properties associated with a graph? What I'm looking for is something like the following: <pseduocode> vector<properties> my_vertex_properties; property_iterator pi, last; for(tie(pi, last) = vertex_property_list(Graph); pi != last; ++pi) my_vertex_properties.push_back(*pi); </pseudocode> How about it? Does anything like this exist or am I just daydreaming again? Thanks. -- Stephen W. Juranich Science Applications Intl. Corp. (SAIC) (520) 570-7706

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Serialization library
by Steve Folly 30 Mar '04

30 Mar '04

Hi, I'm looking using the Robert Ramey's serialization library for our own projects and would like to know it's current status. Obviously, it's not in 1.31.0, so what are the plans for it's future inclusion? Thanks. Steve.

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graph, dfs search
by Peter Aronsson 30 Mar '04

30 Mar '04

Hi. I am having a problem with depth_first_search. The thing I do different is that I do not put any info in a property map and I do not want to bother myself with colormaps etc. The application code does: Graph g; pass2_visitor vis; depth_first_search(g,boost::visitor(vis)); But I get a compilation error, saying that it can not find a suitable operator+ in the property_map... See attached files for complete example. Grateful for all help! (I am running from HEAD on sourceforge cvs ) Regards Peter Aronsson -- _________________________________________________________________ / Peter Aronsson, Phd Student at PELAB (Programming Environments \ | Laboratory ) Department for Computer & Information Science | | Linköping University, Sweden | |=================================================================| | petar(a)ida.liu.se , phone +46 (0)13-28 1737 Room 3B:490 | \_________________________________________________________________/ #include "tg.hpp" int main() { TaskGraph g; pass2_visitor vis; depth_first_search(g,boost::visitor(vis)); } #ifndef _TASKGRAPH_H #define _TASKGRAPH_H #include <boost/config.hpp> #include <iostream> // for std::cout #include <utility> // for std::pair #include <algorithm> // for std::for_each #include <boost/utility.hpp> // for boost::tie #include <boost/graph/graph_traits.hpp> // for boost::graph_traits #include <boost/graph/adjacency_list.hpp> #include <boost/graph/adjacency_iterator.hpp> #include <boost/graph/graphviz.hpp> #include <boost/graph/depth_first_search.hpp> //Task graph types using namespace std; using boost::tie; struct vertex_execcost_t { typedef boost::vertex_property_tag kind; }; struct vertex_unique_id_t { typedef boost::vertex_property_tag kind; }; struct edge_result_set_t { typedef boost::edge_property_tag kind; }; typedef boost::property<boost::vertex_name_t,string, boost::property<vertex_execcost_t,float, boost::property<vertex_unique_id_t, int > > > VertexProperty; typedef boost::property<boost::edge_weight_t, int > EdgeProperty; typedef boost::adjacency_list<boost::listS, boost::listS, boost::bidirectionalS, VertexProperty, EdgeProperty> TaskGraph; typedef boost::graph_traits<TaskGraph>::vertex_descriptor VertexID; class pass2_visitor : public boost::default_dfs_visitor { public: pass2_visitor(/* initialize containers to store stuff in*/) { }; template <typename Vertex, typename Graph> void discover_vertex(Vertex u, const Graph & g) const { // Do some stuff }; }; #endif

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CVS import gotcha - beware!
by Steve Folly 29 Mar '04

29 Mar '04

Hi, Most of you are probably aware of this, but I just thought I'd share my experience with trying to import the new version of boost into our CVS repository using 'cvs import': It wasn't recognising new folders - e.g. boost/spirit/core and all it's contents. I was puzzling it for a while until I realised the import output was showing 'I' next to boost/spirit/core. Aha - it's ignored. DOH! Well, core files are ignored, aren't they! To all those who have been long suffering with this : don't forget to include '-I !' in the command to include all files!! I'll be happy if it helps at least one person! :) -- Regards, Steve.

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RE: [Boost-users] Defining less on member variables/functions
by Chris Jurney 29 Mar '04

29 Mar '04

In this case, I could have used pair's operator<, but if I have a class by value as the second item of the pair that doesn't have a meaningful operator<, I want to ignore it in the sort. Thanks for all the help, guys. Chris -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Victor A. Wagner Jr. Sent: Friday, March 26, 2004 8:40 AM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Defining less on member variables/functions why do you want to sort ONLY on the 1st element of the pair? At Thursday 2004-03-25 11:34, you wrote: >content-class: urn:content-classes:message >Content-Type: multipart/alternative; > boundary="----_=_NextPart_001_01C41297.D800D40A" > >I've had this same pattern come up 4 or 5 times now, and each time I've >been unable to find a stl + boost solution that allowed me to do what I >want without writing my own less function. Basically, I want something >that will let me do a sort, or define a map on structs or pairs without >writing a less that compares the member variable or ..first. My last attempt: > >vector<pair<float, float>> myVector >std::sort(myVector.begin(), myVector.end(), _1.first < _2.first); > >No such luck. It looks like I can do operator * and & on lambda objects, >but not access members through them. Is there anything in boost, stl, or >elsewhere that lets me not write this: > >class myLess >{ > bool operator() (pair<float, float> a, pair<float, float>b) > {return a.first < b.first;} >} > >Thanks for any help, >Chris > > >_______________________________________________ >Boost-users mailing list >Boost-users(a)lists.boost.org >http://lists.boost.org/mailman/listinfo.cgi/boost-users Victor A. Wagner Jr. http://rudbek.com The five most dangerous words in the English language: "There oughta be a law" _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Microsoft Managed C++
by Roger Wilco 29 Mar '04

29 Mar '04

I have a somewhat large (~100K lines) C++ server application. It uses Boost (lots of smart pointer use, thread use, regex), Xerces XML libraries, some MFC for GUI, and ADO for database access. I tried to build a test build of my application using Microsoft's Managed C++. I got all my code to compile, but I can't link to either Boost or Xerces XML. Is this possible? Has anyone done this? If I ultimately go the .NET route, I would replace Boost and Xerces with functionality provided by the native .NET runtime libraries. However, that would be a massive time consuming undertaking. At this point, I just want to dip my toes in the water and observe pros/cons of .NET, and have the option of migrating to .NET piecemeal. I have solid experience with C# and Java and I am extremely experienced with C++ (10 years). My main problems with C++ are: - Compile times. On my 2.8GHz dev system, a rebuild takes ~20 minutes and even a build after making a minor change takes 45 seconds. It's amazing how VC++ build speeds really have remained so stagnant despite increases in hardware speed. I realize VC++ is the slower of the IDEs for build times. - Debugging memory corruption or thread concurrency issues. This is much easier in Java/C# and the tools for assisting are much easier to use. I spent many days trying tools such as Purify for C++ and couldn't produce any fruitful results. - Diagnosing memory usage. My server application uses lots of memory. After running for several hours under production conditions it will reach around 400MB-1.3GB depending on the tasks its doing. I'd like to get a general overview of where this memory is being used. I don't suspect blatant memory leaks (new with no delete) but instead runaway caches or legitimate usage. These issues are of course still present in C#/Java but the diagnostic tools to address these issues seem to be much better. I haven't found any usable C++ tool for this issue and I rely on manually logging data points and manually trying to infer an idea of what is happening. - Java/C# is overall a better (easier/faster to develop/maintain) development platform for this type of server application work. However, I will happily stick with C++ if I can resolve these other issues. And I am of course, concerned about any performance hit when migrating to Java/C#. We max out CPU and RAM use, so these factors aren't important. I couldn't take more than a 25% drop in efficiency. Any other suggestions on my situation?

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SQLite
by Witz 28 Mar '04

28 Mar '04

I don't know if this is the forum for bringing this up but ... I was wondering if anyone thinks SQLite might make a good addition to Boost - www.sqlite.org - if the author would agree to it. Ian Whittley

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boost::format with non-standard string class
by Scott Lamb 27 Mar '04

27 Mar '04

Hi, I'm not real happy with std::string, largely because it seems poorly suited to UTF-8. I'm happier with other classes such as Glib::ustring. [1,2] Is it possible to use boost::format with such a class? I'd previously thought that boost as a whole expected you to use std::string, but the recent discussion of boost::regex + Glib::ustring gave me some hope. It seems the requirements for boost::regex are more simple - a bidirectional, read-only character (not byte) iterator. That should be easy enough to provide for any UTF-8 string class. I do see explicit mention of std::basic_string in the boost::format headers, but I thought I'd ask anyway. (I likely will find or make another class to avoid pulling in all of glib. But it would be similar to Glib::ustring.) [1] - more in-depth discussion of Glib::ustring vs. std::string at <http://www.gtkmm.org/gtkmm2/docs/reference/html/ classGlib_1_1ustring.html#_details> [2] - additional reasons for disliking std::string at <http://www.sgi.com/tech/stl/string_discussion.html> Thanks, Scott

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boost/graph/push_relabel_max_flow::is_flow() bug?
by Arun Bhalla 27 Mar '04

27 Mar '04

Hi, I'm not really a user of Boost, but I've been referring to the Boost Graph Library code for another project. In particular, I've been looking at push_relabel_max_flow.hpp. I was writing a unit test which followed the same ideas of the is_flow() test, and it was failing on what should be a flow network with a valid maximum flow. The code in question: // a is an edge_descriptor if (capacity[a] > 0) if ((residual_capacity[a] + residual_capacity[reverse_edge[a]] != capacity[a]) || (residual_capacity[a] < 0) || (residual_capacity[reverse_edge[a]] < 0)) return false; I contend the test should actually be: // a is an edge_descriptor if (capacity[a] > 0) if ((residual_capacity[a] + residual_capacity[reverse_edge[a]] ! != capacity[a] + capacity[reverse_edge[a]]) || (residual_capacity[a] < 0) || (residual_capacity[reverse_edge[a]] < 0)) return false; I refer to an example network in CLR (1st ed.), p.589. There are several vertices, but I focus on vertices v1 and v2. In this graph, we have capacities c(v1,v2) = 10 c(v2,v1) = 4 and residual capacities cf(v1,v2) = 11 cf(v2,v1) = 3 With the above (original) test, it would fail because 11 + 3 (the sum of residual capacities) != the capacity of either edge. This would hold true if the sum of residual capacities were compared with the sum of capacities. Ordinarily this test would work if reverse_edge[a] has a capacity of 0, which would be the case if the edge (a) is in the flow network, but its reverse is not. I'm not a graph theory expert, though, so I defer to anyone who is. :) Thanks, Arun

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Defining less on member variables/functions
by Chris Jurney 26 Mar '04

26 Mar '04

I've had this same pattern come up 4 or 5 times now, and each time I've been unable to find a stl + boost solution that allowed me to do what I want without writing my own less function. Basically, I want something that will let me do a sort, or define a map on structs or pairs without writing a less that compares the member variable or .first. My last attempt: vector<pair<float, float>> myVector std::sort(myVector.begin(), myVector.end(), _1.first < _2.first); No such luck. It looks like I can do operator * and & on lambda objects, but not access members through them. Is there anything in boost, stl, or elsewhere that lets me not write this: class myLess { bool operator() (pair<float, float> a, pair<float, float>b) {return a.first < b.first;} } Thanks for any help, Chris

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Re: [Boost-users] MAC OS X installation of boost libs
by Michael Short 26 Mar '04

26 Mar '04

Hello I am using MAC OS X 10.3.3. First I done find the bjam tool? Second when I build the bjam tool myself I get the following error. Jamfile:71: in module scope rule unless unknown in module. I think if you could please just give me a quick step by step of what you did to setup the libs with the correct directorys you used then that would probably fix the problems. I did try following the instructions on the page you stated but just did not help. thanks Michael On Tuesday, March 23, 2004, at 09:25PM, James Mastro <jmastro(a)rochester.rr.com> wrote: >On Mar 22, 2004, at 5:12 PM, Michael Short wrote: > >> The only problem is that I am having problems installing and building >> the libs on my MAC OS X system. > >What kind of problems? What version of OS X? I built boost 1.31.0 on >OS X 10.3.2. I think the regex library gave me some problems, but I >believe everything else built OK. > >I just followed the directions here: > >http://www.boost.org/more/getting_started.html > >-jim > > >

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