August 2007 - Boost-users - lists.boost.org

boost lambda 1.34.1 questions.
by chun ping wang 03 Aug '07

03 Aug '07

HI I have several questions. How do I delete a pointer to a bind type and how do i specify a return type. 2 examples: I want to transform this BOOST_FOREACH code into std::for_each using lambda. typedef std::pair<Foo*, Bar*> FooBar BOOST_FOREACH(FooBar fb , MapFooBar) { delete fb.second; } Foo* f = ... ; BOOST_FOREACH(FooBar fb, MapFooBar) { if (fb.second == o) return fb.first; } 2.) In this case is using BOOST_FOREACH better?

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[Important] Boost Subversion repository is now online
by Douglas Gregor 03 Aug '07

03 Aug '07

Hello all, The Boost Subversion repository is now back online. All of the files in CVS (including their histories) have been imported into the Subversion repository. CVS is still available for anonymous, read- only access for now, but will not be updated. The main Boost development branch is available via anonymous, read- only checkout at: http://svn.boost.org/svn/boost/trunk/ Or for developer read/write access at: https://svn.boost.org/svn/boost/trunk/ Information about accessing the Boost Subversion repository is available at: http://svn.boost.org/trac/boost/wiki/BoostSubversion Please report any problems to me to the main Boost list, and we will try to resolve them as quickly as possible. We still need help porting the regression-testing script over to use Subversion. See Trac ticket #1122: http://svn.boost.org/trac/boost/ticket/1122 Also, there is more documentation that will need to be updated within the Boost tree. - Doug Subversion tip: when you commit a change to Subversion that fixes ticket number NNN, include the text "Fixes #NNN" in your commit log. Trac will automatically close the ticket and cross-reference the commit with the ticket. See, for example, http://svn.boost.org/trac/ boost/changeset/38330

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Re: [Boost-users] boost::regex_match throws exception
by mildaiv＠centrum.cz 03 Aug '07

03 Aug '07

>mildaiv(a)centrum.cz wrote: >> I build boost::regex 1.34 using Borland BDS 2006. >> Simple regular expresions works fine, but I have problem with this >> regular expresion: >> ^[_a-zA-Z0-9-]+(\.[_a-zA-Z0-9-]+)*(a)[a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+)+$ >> if a try to match it with any string longer then 22 bytes, regex >> throws exception. >> After some investigations i simplified regular expresion to >> ^[10+]*@$ >> and it still throws exception >I can't reproduce with Boost-1.34: please post a complete self contained >test case. Also make sure that those \'s are double escaped if they're >embedded in code: >boost::regex >e("^[_a-zA-Z0-9-]+(\\.[_a-zA-Z0-9-]+)*(a)[a-zA-Z0-9-]+(\\.[a-zA-Z0-9-]+)+$"); This was the problem, everything now works fine. Thanks for your help. >Otherwise the expression does something rather different, and *will* get >pathological and throw an exception. >HTH, John.

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Packed resource files with iostreams & zlib filter
by gyrotech＠freakinabox.com 03 Aug '07

03 Aug '07

Hello all. I am trying to create a wrapper for a set of resources (mixed text, image, etc files) for use in an SDL-based application. I want to use iostreams and keep it as close to C++ as I can, but SDL uses some functions that load data from c-type file pointers or a location in memory using a void* and byte-count. Is it possible to define a method of file access using iostreams and a filter that will then let me create sub-streams of the data inside?? For instance - a zlib-compressed file called 'foobar.gz' that contains 'foo.txt' and 'bar.png'. I want to attach an iostream to foobar.gz then use functions to get the contents in different formats, e.g. stream<my_res_file> compressed_file( "foobar.gz" ); ifstream foo = compressed_file.getasfilestream( "foo.txt" ); // read stuff from foo foo.close(); char* img_data; unsigned long size; compressed_file.getasmembuffer( img_data, &size ); // read img_data and poke around with it delete[] img_data; I know the above is just for illustration, but I can't find any libs that do this sort of work. I am having some real problems now even at the design stage, for instance how to neatly pack multiple files into a single one. My packed-file headers always seem to go wrong and without fixed-length space for files names it gets even more painful :-) If this isn't the right place for this sort of question (I see it's far more conceptual than directly boost-related) then I apologise and will start hitting on some more generic forums and lists ;-) Thanks for your time, GT

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Location of html documention?
by Robert Ramey 03 Aug '07

03 Aug '07

I've downloaded boost on my system and run tests which build the libraries. When I surf the documention on my local hard drive in to "type_traits" I'm redirected to the www.boost.org How do I get the html documentation on my hard drive. Perhaps it is produced by the normal install process - which I confess I didn't do - as running the tests builds the libraries I need. I looked for it there but I didn't see it. Robert Ramey

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[Boost.Thread] self deadlocking issue
by Cheng Lian 03 Aug '07

03 Aug '07

Hi, all I was debugging a buggy program which could be simplified as below: #include <boost/thread.hpp> using namespace boost; mutex m; void f() { mutex::scoped_lock lock( m ); } int main() { mutex::scoped_lock lock( m ); f(); return 0; } I think this would definitely self deadlock and the program should be waiting forever. And my Debian Linux box proved that true. But on my XP (with SP2) box, the program didn't dead lock and everything pass through! Seems that on Win32 platform, the mutex is recursive? I checked the code and only CRITICAL_SECTION related is found around the lock/unlock lines. But I think CRITICAL_SECTION itself is not recursive. Then why? Thanks for response. Cheers Cheng

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[serialization]Error occured when serializing pointer
by wei niu 03 Aug '07

03 Aug '07

My compiler is VC7.1.When compiling the demo.cpp,an runtime error occured. the output is below: original schedule 6:24 bob 0x003409F8 34?35'52.56" 134?2'78.3" 24th Street and 10th Avenue 0x00340A58 35?37'23.456" 133?5'54.12" State street and Cathedral Vista Lane 0x00340B08 35?36'15.456" 133?2'15.3" White House 9:57 bob 0x003409F8 34?35'52.56" 134?2' 78.3" 24th Street and 10th Avenue 0x00340A58 35?37'23.456" 133?5'54.12" State street and Cathedral Vista Lane 0x00340B08 35?36'15.456" 133?2'15.3" White House 11:2 alice 0x003409F8 34?35'52.56" 134?2'78.3" 24th Street and 10th Avenue 0x00340A58 35?37'23.456" 133?5'54.12" State street and Cathedral Vista Lane 0x00340B08 35?36'15.456" 133?2' 15.3" White House 7:17 ted 0x00340B48 35?34'48.789" 133?2'16.23" Lincoln Memorial 0x00340B08 35?36'15.456" 133?2'15.3" White House 0x00340A58 35?37'23.456" 133?5' 54.12" State street and Cathedral Vista Lane 9:38 ted 0x00340B48 35?34'48.789" 133?2'16.23" Lincoln Memorial 0x00340B08 35?36'15.456" 133?2'15.3" White House 0x00340A58 35?37' 23.456" 133?5'54.12" State street and Cathedral Vista Lane 11:47 alice 0x00340B48 35?34'48.789" 133?2'16.23" Lincoln Memorial 0x00340B08 35?36'15.456" 133?2'15.3" White House 0x00340A58 35?37'23.456" 133?5'54.12" State street and Cathedral Vista Lane This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. When debuging I found it cannot serialize the pointer.Why? Thanks. PS: boost's source code is hard for me,are there any good and easy ways of studying it?

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[Graph] How to initialize edge index map?
by Anton A. Patrushev 03 Aug '07

03 Aug '07

Hi, How to initialize edge index map? I tried following: typedef adjacency_list<vecS, vecS, directedS, Vertex, Edge> graph_t; graph_traits<graph_t>::edge_iterator ei, ei_end; graph_t graph(num_nodes); ...... adding edges ...... for(tie(ei, ei_end) = edges(graph); ei != ei_end; ++ei, ++index) put(edge_index, graph, *ei, index); But I always get a compilation error: /usr/include/boost/property_map.hpp: In function ‘void boost::put(const boost::put_get_helper<Reference, PropertyMap>&, K, const V&) [with PropertyMap = boost::adj_list_edge_property_map<boost::directed_tag, boost::detail::error_property_not_found, boost::detail::error_property_not_found&, unsigned int, boost::property<boost::edge_bundle_t, Edge, boost::no_property>, boost::edge_index_t>, Reference = boost::detail::error_property_not_found&, K = boost::detail::edge_desc_impl<boost::directed_tag, unsigned int>, V = int]’: /usr/include/boost/graph/detail/adjacency_list.hpp:1667: instantiated from ‘void boost::put(Property, boost::adj_list_helper<Config, Base>&, const Key&, const Value&) [with Config = boost::detail::adj_list_gen<boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, Vertex, Edge, boost::no_property, boost::listS>, boost::vecS, boost::vecS, boost::directedS, boost::property<boost::vertex_bundle_t, Vertex, boost::no_property>, boost::property<boost::edge_bundle_t, Edge, boost::no_property>, boost::no_property, boost::listS>::config, Base = boost::directed_graph_helper<boost::detail::adj_list_gen<boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, Vertex, Edge, boost::no_property, boost::listS>, boost::vecS, boost::vecS, boost::directedS, boost::property<boost::vertex_bundle_t, Vertex, boost::no_property>, boost::property<boost::edge_bundle_t, Edge, boost::no_property>, boost::no_property, boost::listS>::config>, Property = boost::edge_index_t, Key = boost::detail::edge_desc_impl<boost::directed_tag, unsigned int>, Value = int]’ shooting_star_boost_wrapper.cpp:266: instantiated from here /usr/include/boost/property_map.hpp:319: error: no match for ‘operator=’ in ‘((const boost::adj_list_edge_property_map<boost::directed_tag, boost::detail::error_property_not_found, boost::detail::error_property_not_found&, unsigned int, boost::property<boost::edge_bundle_t, Edge, boost::no_property>, boost::edge_index_t>*)((const boost::adj_list_edge_property_map<boost::directed_tag, boost::detail::error_property_not_found, boost::detail::error_property_not_found&, unsigned int, boost::property<boost::edge_bundle_t, Edge, boost::no_property>, boost::edge_index_t>&)((const boost::adj_list_edge_property_map<boost::directed_tag, boost::detail::error_property_not_found, boost::detail::error_property_not_found&, unsigned int, boost::property<boost::edge_bundle_t, Edge, boost::no_property>, boost::edge_index_t>*)(& pa))))->boost::adj_list_edge_property_map<Directed, Value, Ref, Vertex, Property, Tag>::operator[] [with Directed = boost::directed_tag, Value = boost::detail::error_property_not_found, Ref = boost::detail::error_property_not_found&, Vertex = unsigned int, Property = boost::property<boost::edge_bundle_t, Edge, boost::no_property>, Tag = boost::edge_index_t](k) = v’ /usr/include/boost/pending/detail/property.hpp:21: note: candidates are: boost::detail::error_property_not_found& boost::detail::error_property_not_found::operator=(const boost::detail::error_property_not_found&) I really can't get through all these template parameters :( Please, tell me how to initialize this map properly! Thanks, Anton.

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ScopeExit Review Announcement
by Jody Hagins 03 Aug '07

03 Aug '07

Alexander Nasonov's ScopeExit submission will be formally reviewed August 13 - August 22. The current submission has been uploaded to http://boost-consulting.com/vault/index.php?action=downloadfile&filename=sc… It's also available at http://tinyurl.com/2z6qg2 Online documentation is here http://194.6.223.221/~nasonov/scope_exit-0.04/libs/scope_exit/doc/html/inde…

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[Graph] problem with arguments of transitive closure algorithm ?
by Emmanuel Viaud 02 Aug '07

02 Aug '07

Hello. Using Boost 1.34.1 (with g++-3.4.2) and more specifically the Boost Graph library, I stumbled on a small problem with the transitive_closure algorithm. I saw in the documentation that I can get a map containing the mapping between the vertices of the original graph and the ones in the transitive closure graph (the orig_to_copy parameter). But every time I call the method, I get an empty map as a result. To sum up my code, I use the following data structures for the graph: typedef boost::adjacency_list < boost::vecS, boost::vecS, boost::directedS > graph_t; typedef boost::graph_traits < graph_t >::vertex_descriptor vertex_t; and the following one for the expected map: typedef std::map < vertex_t, vertex_t > ioMap_t; The graphs and map are declared the following way: graph_t myGraph; graph_t myTCGraph; ioMap_t ioMap; I used both versions of the algorithm: 1) using named parameters, I call: transitive_closure(myGraph, myTCGraph, orig_to_copy(ioMap)); 2) using "standard" parameters, I call: transitive_closure(myGraph, myTCGraph, ioMap, get(vertex_index, myGraph)); So, the main question is easy: Where did I write something wrong ? :-) A remark though. I see that the declaration in the case of "standard" parameters is the following : template <typename Graph, typename GraphTC, typename G_to_TC_VertexMap, typename VertexIndexMap> void transitive_closure(const Graph& g, GraphTC& tc, G_to_TC_VertexMap g_to_tc_map, VertexIndexMap index_map); So, if I understand everything (I'm far from speaking C++ fluently), this means that the g_to_tc_map parameter is passed by value. Shouldn't it be rather passed by reference (this would explain my problem as, when debugging my code, I saw that the map is correctly filled in the transitive_closure method but the caller gets back nothing at all) ? Hope I managed to be clear and thanks for your help. Best regards, Emmanuel

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