August 2008 - Boost-users - lists.preview.boost.org

[Boost.Regex] regex_basic subpatterns iterators
by Mickael Wolff 19 Aug '08

19 Aug '08

Hi, I would like know if they are some method I missed to point parenthesis expression in basic_regex. For example, I would like to write something like this : === 8< === std::pair<std::string::iterator, std::string::iterator> mark ; boost::regex re("(\w+)") ; if(re.mark_count() == 2) { first_mark.first = re.marks[1].begin() ; first_mark.second = re.marks[1].end() ; } === 8< === My current solution is to do a regex on the regex, but I guess boost::regex did the work yet. Greetings, Mickaël. PS.: please apologize my english, I'm French. -- Mickaël Wolff aka Lupus Michaelis Racine <http://lupusmic.org> Blog <http://blog.lupusmic.org>

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Boost.Regex 1.36.0 fails to compile with VS2005 compiler
by Peter Klotz 19 Aug '08

19 Aug '08

Boost.Regex 1.36.0 does not compile due to a compiler specific workaround in files libs\regex\src\usinstances.cpp and libs\regex\src\wc_regex_traits.cpp. The attached patch fixes the problem but will (likely) break linking for others. I use bjam 3.1.13 and obtain this error message: ...patience... ...found 1793 targets... ...updating 618 targets... compile-c-c++ bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\wc_regex_traits.obj wc_regex_traits.cpp libs\regex\src\..\src\wc_regex_traits.cpp(53) : error C2375: 'std::allocator<_Ty>::allocator' : redefinition; different linkage with [ _Ty=unsigned short ] xmemory(120) : see declaration of 'std::allocator<_Ty>::allocator' with [ _Ty=unsigned short ] libs\regex\src\..\src\wc_regex_traits.cpp(53) : error C3190: 'std::allocator<_Ty>::allocator(void) throw()' with the pro vided template arguments is not the explicit instantiation of any member function of 'std::allocator<_Ty>' with [ _Ty=unsigned short ] cl /Zm800 -nologo @"bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\wc_regex_traits.obj.rsp" ...failed compile-c-c++ bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\wc_regex_traits.obj... ...failed updating 1 target... My bjam command line: bjam -q -sNO_COMPRESSION=1 --build-type=complete --without-graph --without-math --without-mpi --without-python --without-serialization --without-signals --without-wave --toolset=msvc-8.0 Regards, Peter. Peter Klotz Software Engineer Phone: +43 (0) 50 8648-4100 Fax: +43 (0) 50 8648-4111 E-Mail: peter.klotz(a)ith-icoserve.com ---------------------------------------------------------------- ITH icoserve technology for healthcare GmbH A-6020 Innsbruck, Innrain 98 www.ith-icoserve.com Rechtsform: Gesellschaft mit beschränkter Haftung Firmensitz: 6020 Innsbruck, Innrain 98 Firmenbuchnummer: FN 174117f Firmenbuchgericht: Innsbruck DVR: 0983039

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compatibility between g++ and msvc8
by Guo Xu 19 Aug '08

19 Aug '08

#include <iostream> #include <vector> #include <boost/functional.hpp> #include <boost/algorithm/string.hpp> using namespace std; using namespace boost; int main() { vector<string> strs; strs.push_back( "Beijing" ); strs.push_back( "Olympic" ); strs.push_back( "Game" ); vector<string>::iterator it = std::find_if( strs.begin(), strs.end(), boost::bind2nd( boost::contains<string, string> , "mp" ) ); return 0; } why this part of programe can be compiled on the mscv8, but can not be compled on the g++? the error prompt is: stringalgo.cpp: In function 'int main()': stringalgo.cpp:29: error: no matching function for call to 'bind2nd(<unresolved overloaded function type>, std::string&)'

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Extended Subgraph
by Alexander Löhr 19 Aug '08

19 Aug '08

Hi! Is there an extended version of subgraph.hpp available somewhere, which is able to remove subgraphs. I need something like: subgraph p(5) subgraph c = p.create_subgraph(); v1 = add_vertex(c); v2 = add_vertex(p); add_edge(v1, v2); p.remove_subgraph(c); In this case c should be removed from p and edge (v1,v2) and v1 should be destroyed. Thanks, Alex

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Programming practices for asynchronous operations (asio, etc)
by dizzy 19 Aug '08

19 Aug '08

Hello I have recently started to rework a network server project that uses a thread per connection (with blocking/synchronous network I/O) handling model to using asio and an asynchronous operation model (where the number of threads should depend on hardware resources and be decoupled of software design constraints). The problem I have with this is that it makes one write too much boiler plate code for all those "completion handlers". Take very this simple example of code that is using the one thread per connection synchronous I/O model: // synchronously resolves, connects, throws on error connection con("1.2.3.4"); { // application "packet", usually known as "record" // uses "con" and starts an application packet with a given type packet pack(con, PacketTypeRequest); // serializes portably given data and synchronously sends the data // throws on error pack << uint32(10) << std::string("/home/user") << uint8(3); } // calls packet::~packet() which signals in the "con" stream end of packet Now to transform this very simple (I repeat, this is a very simple example, a lot more complex examples write "packets" of dozens of fields of which the last one may have "infinte" length meaning you cannot know the size of it to put it in the stream and you just have to send it as much as you can and then signal the end of the "packet") into an asynchronous version one would need: connection con; // breaks invariants of "con" being always connected // should asynchronously resolve and connect con.async_connect("1.2.3.4", handle_connect); // break code flow here // handle_connect() // breaks invariant of allowing "serialization" only after packet type // has been sent over the network packet pack(con); pack.async_serialize(uint32(10), handle_serialize1); // return to caller // handle_serialize1 pack.async_serialize(std::string("/home/user"), handle_serialize2); // return to caller // handle_serialize2 pack.async_serialize(uint8(3)), handle_serialize3); // return to caller // handle_serialize3 // breaks RAIIness of original packet which automatically signaled // "end" from the dtor of it pack.async_end, handle_endpacket); // return to caller And imagine that the original code was just a small function a big class, so now each such small function transforms into dozens of smaller functions, the code explosion is huge. I am curious to the code practices that some of you employ to solve these issues (to still have compile time checked code as much as possible by strong invariants and RAII idioms and not have to write millions of small functions). Some of the things I have thought of that seem to solve these issues: - instead of packets being adhoc serialized have structures encapsulating the network packets and have serialization code moved into them and let them deal with all the small functions (they could use some buffer to cache serialization of the fixed fields and async_write that buffer contents in a single operation); this however means an additional copy of the data vs how the code was before and it just moves the problem, instead of having many small functions in the high level code you have them in the lower level packet structures serialiation code (thu the output buffer being can reduce some of them) - using template expressions or whatever do some kind of "lazy evaluation"; basically still use syntax similar to the synchronous solution like: pack << uint32(10) << std::string("/home/user") << uint8(3); but this code instead of doing network I/O would enqueue the serialization actions needed have all those completion handlers internally and completely abstract to the user all those details; the user just does a pack.async_write(user_handler) and "user_handler" will be called after all the serializations have been asynchronously written - if this weren't C++ but C then we could use setjmp/longjmp to transparently (to the user) simulate synchronous operation while asynchronous operation is done behind the scenes; the user writes code such as: pack << uint32(10) << std::string("/home/user") << uint8(3); but what it does is on each op<< (each asynchronous serialization) the code does an async_write() with an internal handler, saves the context (setjmp) then longjmp()s to the previously saved context in the main event loop; when the async_write completes the handler does setjmp to restore the original user context and continue with the next op<< and so on; this however does not work in C++ because the jumped code path with longjmp may have exceptions being thrown/catched and as the standard says that's UB not to mention form what I could gather on the Internet some C++ compilers call dtors of auto objects when you longjmp "back" thus not leaving the original context untouched (which is what I need) -- Mihai RUSU "Linux is obsolete" -- AST

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[Boost.Interprocess] int key and flat_multimap_index
by Robert Kubrick 19 Aug '08

19 Aug '08

A couple of beginner questions on basic_managed_heap_memory: 1) I want to access elements in the contiguous memory segment by using an int key, rather than a char string. Can I declare something like this: typedef basic_managed_heap_memory < int, /* my key is an integer */ rbtree_best_fit<null_mutex_family>, flat_map_index > managed_heap_memory; I need to lookup objects using an external integer ID but the ID can have any value (ie, does not match the 0-N array element order of my memory segment). 2) If I want to insert multiple objects with the same char* name (ala multimap) can I create a flat_multimap_index?

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[[Boost]][[Interprocess]] Defining a common wrapper for all IPC-Types
by Daniel Clemens 19 Aug '08

19 Aug '08

Hi erveryone, The goal: I am currently on a coding project, that offers a common interface for all IPC-Types: - shared memory - message-queues - ... by meaning interface, I don't want the user to be bothered with the details of Inter process communication. I just want him to say what type he wants to use and then just use an instance of my class IPC and the read() or write() method, to simply use the according interprocess type provided by boost. this should be programmed for SLES 10 (=Suse Linux). I would like to have something like: class IPC{ //Attributes + string sName + int iStatus + iMaxMsgSize + iMaxMessages + enum ipcType //Methods + IPC();//constructor + string read(); + void write(string); }//end class The explanation of the code: Depending on the type I suggest on creation of an IPC-Instance the rest should be handled by the class - e.g. instanciating a boost::interprocess::message_queue mq( foo ); Now the question I have is, if the containers offer some sort of way of providing this functionality. Maybe I am currently just too blind to find the answer to the problem. Approaches so far (and failures): My current approach is, that depending on the type-setting, the read() and write() methods use the boost.Interprocess libraries to ither build a message_queue or a shared memory. The example provided for message_queues works fine. I then tried to assign an instance of boost::interprocess:message_queue to an attribute of an instance of IPC. But it says I am assigning a temporary to a pointer. I then tried assigning not an address, but to return a boost::interprocess:message_queue instance from the read()-method and assign it to an attribute. It seems it called the copy-constructor and didn't like that approach ither. Aproach suggestion and questions: Now I thought that the solution to getting a re-usable message_queue working is to use the pointers provided with the boost::interprocess to assign an instance of the established message-queue to the IPC-instance-Attribute. Is this the right way of doing this? And if so, could you give me an example? Thank you! -- GMX startet ShortView.de. Hier findest Du Leute mit Deinen Interessen! Jetzt dabei sein: http://www.shortview.de/wasistshortview.php?mc=sv_ext_mf@gmx

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size_type doubts / integer library..
by Zeljko Vrba 19 Aug '08

19 Aug '08

Integer types in C and C++ are a mess. For example, I have made a library where a task is identified by a unique unsigned integer. The extra information about the tasks is stored in a std::vector. When a new task is created, I use the size() method to get the next id, I assign it to the task and then push_back the (pointer to) task structure into the vector. Now, the task structure has also an "unsigned int id" field. In 64-bit mode, sizeof(unsigned) == 4, sizeof(std::vector::size_type) == 8 I get a warnings about type truncation, and obviously, I don't like them. But I like explicit casts and turning off warnings even less. No, I don't want to tie together size_type and task id type (unsigned int). One reason is "aesthetic", another reason is that I don't want the task id type to be larger than necessary (heck, even a 16-bit type would have been enough), because the task IDs will be copied verbatim into another std::vector<unsigned> for further processing (edge lists of a graph). Doubling the size of an integer type shall have bad effects on CPU caches, and I don't want to do it. What to do? Encapsulate into "get_next_id()" function? Have a custom size() function/macro that just casts the result of vector::size and returns it? == Another example: an external library defines its interfaces with signed integer types, I work with unsigned types (why? to avoid even more warnings when comparing task IDs with vector::size() result, as in assert(task->id < tasks.size()), which are abundant in my code). Again, some warnings are unavoidable. What to do to have "clean" code? == Does anyone know about an integer class that lets the user define the number of bits used for storage, lower allowed bound and upper allowed bound for the range? Like: template<int BITS, long low, long high> class Integer; BITS would be allowed to assume a value only equal to the one of the existing integer types (e.g. 8 for char, 16 for short, etc.), and the class would be constrained to hold values in range [low, high] (inclusive). All operations (+-*/<<>><>) would be compile-time checked to make sense. For example, it would be valid to add Integer<32, 0, 8> with Integer<8, 0, 8> and store into Integer<8, 0, 16> (or Integer<8, 0, 17>) result, but NOT into Integer<8, 0, 8> result. The operations would also be checked at run-time to not overflow. Address-of operator would convert to signed or unsigned underlying integer type, depending on the lower bound. Mixing operations with native integer types would be allowed, provided ranges are respected[*]. And, of course, the library should have a "production mode" where the class would turn off all checks. Does anybody know about such a library? Is a unified numeric tower too much to ask for, at least in the form of a library? How do you deal with these issues? [*] If there's no such library in existence, I might be willing to think about a set of "sane" axioms and checks for automatic conversions. And I have "Hacker's Delight" at home, so I can peek into it and get formulas for deriving bounds of arithmetic operations. And yes, is this even easily implementable within C++ template framework; one has to deal with integer overflow.. What happens in template<long A, long B> class blah { const long T = A+B; }; when A+B overflows? Compiler error? Undefined result? Did C++0x do anything to clean up the integer types mess? This is a proposal for extension to the C language: http://www.cert.org/archive/pdf/07tn027.pdf Anything similar available for C++? </rant> Or should I just listen to the devil on my shoulder and turn off the appropriate warnings?

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[Intrusive] compile error with codewarrior
by David Klein 19 Aug '08

19 Aug '08

hi all, i'm trying to use the intrusive library but can't compile anything. i also tried member_hook's and the slist instead of list but it fails with the same error. any ideas on how to fix this? #include <boost/intrusive/list.hpp> struct foo : public list_base_hook<> { }; void dummy( void ) { list<foo> l; } 1>..\..\include\boost\intrusive\list.hpp(1435): illegal non-type template argument 1>..\..\include\boost\intrusive\list.hpp(1435): (point of instantiation: 'dummy()') 1>..\..\include\boost\intrusive\list.hpp(1435): (instantiating: 'boost::intrusive::list<foo, boost::intrusive::none, boost::intrusive::none, boost::intrusive::none>') 1>..\..\include\boost\intrusive\list.hpp(1435): (instantiating: 'boost::intrusive::list_impl<boost::intrusive::listopt<boost::intrusive::detail::base_hook_traits<foo, boost::intrusive::list_node_traits<void *>, 1, boost::intrusive::default_tag, 1>, unsigned long, true>>') 1>..\..\include\boost\intrusive\list.hpp(1435): note: (corresponding point of instantiation for 'boost::intrusive::list_impl<boost::intrusive::listopt<boost::intrusive::detail::base_hook_traits<foo, boost::intrusive::list_node_traits<void *>, 1, boost::intrusive::default_tag, 1>, unsigned long, true>>') 1>..\src\main.cpp(15): note: (corresponding point of instantiation for 'boost::intrusive::list<foo, boost::intrusive::none, boost::intrusive::none, boost::intrusive::none>') compiler: metrowerks c/c++ for embedded arm version 3.0 build 138 (it's the compiler for the nintendo ds platform) boost version: 1.35 + 1.36 -- regards, dave

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Boost.Filesystem 1.36.0: Define BOOST_FILESYSTEM_NO_DEPRECATED no longer works
by Peter Klotz 19 Aug '08

19 Aug '08

#include <boost/filesystem/convenience.hpp> int main(void) { return 0; } When compiling the above code with gcc 4.1 and define BOOST_FILESYSTEM_NO_DEPRECATED I obtain these error messages: boost/filesystem/convenience.hpp: In function 'std::string boost::filesystem::extension(const boost::filesystem::path&)': boost/filesystem/convenience.hpp:98: error: expected primary-expression before '>' token boost/filesystem/convenience.hpp: In function 'std::wstring boost::filesystem::extension(const boost::filesystem::wpath&)': boost/filesystem/convenience.hpp:100: error: expected primary-expression before '>' token boost/filesystem/convenience.hpp: In function 'std::string boost::filesystem::basename(const boost::filesystem::path&)': boost/filesystem/convenience.hpp:103: error: expected primary-expression before '>' token boost/filesystem/convenience.hpp: In function 'std::wstring boost::filesystem::basename(const boost::filesystem::wpath&)': boost/filesystem/convenience.hpp:105: error: expected primary-expression before '>' token boost/filesystem/convenience.hpp: In function 'boost::filesystem::path boost::filesystem::change_extension(const boost::filesystem::path&, const std::string&)': boost/filesystem/convenience.hpp:108: error: expected primary-expression before '>' token boost/filesystem/convenience.hpp:108: warning: left-hand operand of comma has no effect boost/filesystem/convenience.hpp: In function 'boost::filesystem::wpath boost::filesystem::change_extension(const boost::filesystem::wpath&, const std::wstring&)': boost/filesystem/convenience.hpp:110: error: expected primary-expression before '>' token boost/filesystem/convenience.hpp:110: warning: left-hand operand of comma has no effect boost/system/error_code.hpp: At global scope: It works, when compiled without BOOST_FILESYSTEM_NO_DEPRECATED. The problem seems to be a new #ifndef in convenience.hpp that did not exist in 1.35.0. Regards, Peter. Peter Klotz Software Engineer Phone: +43 (0) 50 8648-4100 Fax: +43 (0) 50 8648-4111 E-Mail: peter.klotz(a)ith-icoserve.com ---------------------------------------------------------------- ITH icoserve technology for healthcare GmbH A-6020 Innsbruck, Innrain 98 www.ith-icoserve.com Rechtsform: Gesellschaft mit beschränkter Haftung Firmensitz: 6020 Innsbruck, Innrain 98 Firmenbuchnummer: FN 174117f Firmenbuchgericht: Innsbruck DVR: 0983039

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