March 2005 - Boost - lists.boost.org

[boost] [Assign] list_inserter.hpp missing include for boost::begin, boost::end
by Douglas Gregor 30 Mar '05

30 Mar '05

The BGL GraphViz test is failing on GCC 3.4.3 with this error message: In file included from /boost/head-regression/boost/boost/assign/std/map.hpp:19, from ../libs/graph/test/graphviz_test.cpp:17: /boost/head-regression/boost/boost/assign/list_inserter.hpp: In member function `boost::assign::list_inserter<Function, Argument>& boost::assign::list_inserter<Function, Argument>::range(const SinglePassRange&)': /boost/head-regression/boost/boost/assign/list_inserter.hpp:260: error: `begin' is not a member of `boost' /boost/head-regression/boost/boost/assign/list_inserter.hpp:260: error: `end' is not a member of `boost' Date: 2005-03-29 12:25 It looks like we need to include something from the range library to get these functions. Thorsten? Doug

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set_property on reverse_graph fails
by Manish Mangal 30 Mar '05

30 Mar '05

Hi I am not able to use set_property function for reverse Graphs. I am using C++7.0 on .Net2003 compiler. I read an earlier question posted at http://lists.boost.org/MailArchives/boost-users/msg06970.php This sounded similar to my problem. The solution posted by Jeremy http://lists.boost.org/MailArchives/boost/msg66361.php runs fine on my machine . So I decided to use get_property instead of set_property as suggested in the solution. This did not solve my problem So I took Jeremy's solution and replaced subgraph by reverse_graph. Even that code generated: error C2784 could not deduce template argument list.. The code is: #include <string> #include <iostream> #include <boost/cstdlib.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/reverse_graph.hpp> int main() { using namespace boost; using std::string; typedef adjacency_list<vecS, vecS, directedS,no_property, property<edge_index_t, int>, property<graph_name_t, string> > graph_t; graph_t g; get_property(g, graph_name) = "graph"; std::cout << "name: " << get_property(g, graph_name) << std::endl; typedef reverse_graph<graph_t> reverse_graph_t; reverse_graph_t sg = reverse_graph_t(g); get_property(sg, graph_name) = "Reverse graph"; std::cout << "name: " << get_property(sg, graph_name) << std::endl; return exit_success; } Can anyone suggest how to make this work? Much appreciated Manish Mangal Stratagen Systems 1-425.821.8454 ext. 136

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Re: Asynchronous I/O
by Don G 29 Mar '05

29 Mar '05

Of the mechanisms discussed, I am not sure I understand what you mean by async I/O with only one thread. I can imagine a nonblocking/select style approach that has no extra threads, but as soon as the main thread is not waiting on I/O itself (my interpretation of "async"), there needs to be threads to do the waiting. Unless I am missing something (which happens often<g>) or we are having terminology problems (also a frustratingly frequent occurrence). Best, Don --- Caleb Epstein <caleb.epstein(a)gmail.com> wrote: > I'd say coupling asynchronous I/O to multi-threading would be a > mistake. It is at its most useful IMHO in single-threaded cases. > > -- > Caleb Epstein > caleb dot epstein at gmail dot com __________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/

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Warnings in Boost.Thread
by Janusz Piwowarski 29 Mar '05

29 Mar '05

Hi all, When Boost.Thread is compiled in release mode, there are a lot of warnings about unused variable 'int loop_count' in read_write_mutex.cpp. They comes from code like: int loop_count = 0; while (m_state == -1) { BOOST_ASSERT(++loop_count == 1); ++m_num_waiting_readers; m_waiting_readers.wait(l); --m_num_waiting_readers; } If loop is for second evaluation of condition only, i think it would be better to write: if (m_state == -1) { ++m_num_waiting_readers; m_waiting_readers.wait(l); --m_num_waiting_readers; BOOST_ASSERT(m_state != -1); } Regards, Janusz

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Re: [boost] Re: Classpath to C++ conversion
by Iain Hanson 29 Mar '05

29 Mar '05

> Do I understand this to mean that "ClassPath" is the entire Java > API? If not, you've failed to answer Dave's query on what > "Classpath" actually is. I have no idea what it is, so I > cannot discuss the merits of the idea for Boost. > Classpath is the GNU project for the full Java API. > > You didn't explain what GCJ is, and given that you used the term "GCJ > > classes" I'm beginning to think I don't really know what you mean by > > GCJ. > > I also don't know what "GCJ" is. IOW, I have no idea what this > proposal is for and can't comment on whether it is useful. > GCJ is the Java part of gcc. /ikh

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repost: [Post review] Pointer Container
by Thorsten Ottosen 29 Mar '05

29 Mar '05

Dear all, I really need some feedback. Please comment! Thanks ------------------- The Pointer Container library is very almost finished. Since the review, the following major changes has been made - improved docs with new tutorial and improved browsing - new indirect functions - new Cloneable and Clone Allocator concepts - support for null values - refactored template interface off all classes - implementation guarantees to only instantiate std::container<void*> - rewritten iterators - improved tests The new docs, and code can be downloaded from the files section: http://groups.yahoo.com/group/boost/files/pointer%20container/ptr_container… The test runs with vc7.1 and gcc.3.3.3. Comments, suggestions and portability fixes are welcome. There are one major issue and one minor I need to have resolved during the post-review. Minor issue: allocation in map:operator[] ---------------------------------------- should a default allocated object use operator new or heap_clone_allocator::allocate_default(); ? This happens in ptr_map<string,int> m; m["foo"] = 5; // will allocate an int with new Normally the use can control all allocations because he always add objects manually or via cloninin (which he also controls). But the default object is just allocated with operator new inside ptr_map::operator[]. Should some hook be provided in a new allocator concept, map_heap_allocator? Major issue: ptr_iterator implementation. ----------------------------------------- So what is the problem? Well, since void* is used internally, the iterators must cast to the proper type in operator*; that is no problem for the default indireted iterators; the problem is with the iterators from ptr_iterator ptr_begin(); ptr_iterator ptr_end(); One way to define would be to say typedef internal_container::iterator ptr_iterator; Then the reference type would be void*& and not T*& as we would like. So if the user wanted to sort the container, he would do std::sort( cont.begin(), cont.end(), void_ptr_indirect_fun< std::less<T>, T>() ); This give us a rather insecure interface where you have to cast manually to T* inside the functor. So I wish we could get a T*& reference type. I think, from discussion with David Abrahams, that the current implementation is non-portable even though my test works: typedef T*& reference; reference dereference() const { // void_type is void* or const void* // I'm not sure why this is needed, but it seems to be return reinterpret_cast<reference>( const_cast<void_type&>( *iter_ ) ); } Does anybody knows how to rewrite this crappy code propoerly? I think we're faced with three options 1. keep the current behavior and describe in the docs that it is non-portable 2. go back to making ptr_iterator the default iterator with void*& reference type; 3. add a small subset of algorithms to the classes themselves; I'm thinking that the subset from std::list is appropriate: - sort - remove_if - remove - unique - reverse - merge Let me hear what you think best regards Thorsten -- Thorsten Ottosen ---------------------------- www.dezide.com http://www.cs.aau.dk/index2.php?content=Research/mi www.boost.org www.open-std.org/JTC1/SC22/WG21/

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[Boost-bugs] [ boost-Bugs-1164057 ] boost::filesystem::exists has bugs with UNC paths
by SourceForge.net 29 Mar '05

29 Mar '05

Bugs item #1164057, was opened at 2005-03-15 14:02 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1164057&group_… Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Nobody/Anonymous (nobody) Assigned to: Nobody/Anonymous (nobody) Summary: boost::filesystem::exists has bugs with UNC paths Initial Comment: boost::filesystem::exists(path("//computer")) always fails, even if the computer exists. boost::filesystem::exists(path("//computer/share")) always succeeds, even if the share doesn't exist. The attached patch fixes this by: - always succeeding for //computer (this is better than always failing) - correctly detecting the existance or not of a share. (The problem here was that the code was missing an error code check) ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1164057&group_… ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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Re: [boost] type_traits: recent changes break EDG compilations
by Ralf W. Grosse-Kunstleve 29 Mar '05

29 Mar '05

--- John Maddock <john(a)johnmaddock.co.uk> wrote: > I was able to track this down to some preprocessor logic - a particular > compiler workaround was being applied when it should not have been, so > cv-qualified member functions were not being detected as such - should now > be fixed in cvs. Yes, wonderful! With the latest CVS I am back in business. Thanks!!! Ralf __________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/

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Re: Boost.Threads bug?
by Michael Glassford 29 Mar '05

29 Mar '05

Alexander Nasonov wrote: > There is a less comparison in several places of time-related stuff. I > believe that less-or-equal is better. Take a look for example at if > statement here: [snipped example] This is now fixed. Mike

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Singleton Documentation Complete
by Jason Hise 29 Mar '05

29 Mar '05

The documentation for the singleton is finished. I didn't end up writing a tutorial for extending the library after all, because it turned out that I already described the policy interfaces clearly in my reference section and didn't have much to add to them. Instead, I made sure that the tutorial had lots of links to the most important reference pages. New in this release is the addition of the cleanup class and the zombie singleton walk through. In addition, I did a bunch of minor bug fixing, most of which I don't remember, and most of which wouldn't affect most client code. I think one of the things I fixed was making sure that the malloc_creator frees the memory if construction throws. Anyhow, the new package is in the sandbox, enjoy! -Jason

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Re: Asynchronous I/O
by Don G 29 Mar '05

29 Mar '05

Hi Jon, Thanks for the reply! Please see below for my responses. --- Jonathan Wakely <cow(a)compsoc.man.ac.uk> wrote: > How the kernel chooses to implement the aio system calls is an > implementation detail - it certainly doesn't require use of > Boost.Thread types! I think what Robert was saying is that an > application can use POSIX aio without ever having to use or > know about POSIX threads. But if it calls your callback on a thread other than main, you do care and need to know that detail. If the callback is called on the main thread, that thread either has to cooperate or for signals (again) be prepared to handle the special execution state inside the callback. > You and Don seem to be requiring that the application > explicitly create and manage threads. Several people have > suggested they'd like to use some form of AIO without having > to use threads. In the "Asynchronisity" thread, I suggest a mechanism that has certain thread-safe properties, but the user need never create a thread. That being said, I am proposing the the network layer (not the application) create and manage I/O threads. The callbacks it makes to the application would occur in those threads, but by using a technique like bind_async_call (see the "Asynchronicity" thread for details), the callback to user code can be delivered on the one and only thread that the user knows about. In pseudo code: char buf[256]; channel ch; stream::ptr st; int main () { nexus nx; ch.open(&nx); network::ptr net = ?; // create the network object st = net->new_address("foo:1234")->new_stream(); st->async_connect(ch.bind_async_call(&on_connect)); nx.pump(); // callbacks go until nx.close() is called } void on_connect () { st->async_read(buf, sizeof buf, ch.bind_async_call(&on_read_done)); } void on_read_done () { ... } Notice that all this is done inside main(). The user, however, must cooperate to deliver the async messages (the nx.pump() call). But this level of cooperation is required for most async mechanisms on most systems. I hope this clarifies what I am proposing. Best, Don __________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/

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Asynchronous I/O
by Boris 29 Mar '05

29 Mar '05

While trying to find a reasonable interface for a socket class to support asynchronous I/O I was examining various implementations. Scott Woods had thought loudly about an asynchronous library which could be the platform for a network library and maybe others. I like this idea but look at this mess: 1) Signal-Driven I/O SIGIO is sent to a process whenever something happens with the socket. As there are too many things happening with a TCP socket the signal is generated too often and "signal-driven I/O is next to useless with a TCP socket" (W. Richard Stevens in his network bible). As there is just one signal handler per signal it shouldn't be used in a library anyway. 2) Threads There are different solutions possible eg. every thread calling a blocking function or one thread blocking while the other threads handle requests. However these are just variations of the blocking I/O model and multiplexing with the disadvantage of increased complexity because of threads. 3) AIO AIO is part of the Single UNIX Specification and an official standard for asynchronous input and output. The AIO API is based on file descriptors and defines a few functions inluding aio_read() and aio_write(). I/O is asynchronous because the process is notified when an input or output operation is completed - there is either a signal sent to the process or a callback function is executed (as a thread). Further more it is possible to poll a file descriptor if the process doesn't want to wait for the signal or the callback function. Now to the disadvantages: Linux 2.6 doesn't support AIO with sockets (see http://lse.sourceforge.net/io/aio.html) There are some AIO patches for Linux 2.4 but nothing official. Even if AIO support was complete there are no aio_connect() and aio_accept() functions. I wonder if connections have to be built up synchronously (I guess so as AIO wasn't designed only for sockets anyway). 4) I/O completion ports This I/O model is based on a concept called port. A port is similar to a multiplexor and waits for several input or output operations to complete. There can be several ports each multiplexing on several file descriptors. Windows XP, Windows 2000 Pro and Windows NT 3.5 support I/O completion ports. However the application has to call a blocking function for a port to be notified when an I/O operation is complete. 4) Event completion framework The event completion framework behaves like I/O completion ports. However the process can be notified of different types of events not only of the completion of I/O operations. Solaris 10 supports these events: AIO, timer, file descriptor, user-defined and waking up threads (see http://developers.sun.com/solaris/articles/event_completion.html) FreeBSD, OpenBSD and NetBSD support: read, write, AIO, file descriptor, process IDs (exit, fork etc. of other processes), signal, timer and network (see http://www.freebsd.org/cgi/man.cgi?query=kqueue&apropos=0&sektion=0…) The framework of *BSD is called kqueue and not compatible to Solaris. I don't know what other operating systems like Mac OS X support. There is kqueue() is their man pages (see http://developer.apple.com/documentation/Darwin/Reference/ManPages/index.ht…) but I don't know if it is supported. AIO doesn't seem to be supported. Microsoft operating systems provide WaitForMultipleObjects() since Windows 95 which supports these objects: change notification, console input, event, job, memory resource notification, mutex, process, semaphore, thread and waitable timer (see http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/ba…) Then I had a look at ACE as I wondered how they support asynchronous I/O with their Proactor class on different operating systems: They don't. They use this preprocessor directive in the beginning of Proactor.h: #if ((defined (ACE_WIN32) && !defined (ACE_HAS_WINCE)) || (defined (ACE_HAS_AIO_CALLS))) // This only works on Win32 platforms and on Unix platforms supporting POSIX aio calls. Someone wanted to port a Windows applications to Linux which was using the Proactor class. The ACE people told him he should say good-bye to Proactor (see http://groups.yahoo.com/group/ace-users/message/38548) Last but not least Linux 2.5 introduced a new API called epoll (see http://www.linuxmanpages.com/man4/epoll.4.php) It doesn't support asynchronous I/O but tries to get rid of all the disadvantages select() and poll() have. The Linux world seems to pursue the traditional multiplexing approach trying to improve it. Now who has an idea how the asynchronous C++ library should look like? ;) Boris

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Asynchronicity (long)
by Don G 29 Mar '05

29 Mar '05

Hi All, I've renamed the subject from "Asynchronous I/O" because I wanted to float the notion that async behavior not be viewed as an aspect of I/O, though it is highly desired in that space. Below is a sketch and some pseudo-code of how I've done this over the past few years, in a portable manner. The trick to portability for me was integrating into various kinds of threads or main loops. For example: the main GUI thread of a Windows application, or a Motif (Xt) based application, or a Mac application's main event loop. These are the hard ones. Once they are possible, most (more likely "all") others are possible as well. Unfortunately, the needs of these integrators is not portable, but can be hidden behind simple wrapper classes for anticipated cases. To handle other cases, the integration mechanism needs to be visible. In the case of the GUI thread integrations, I have a single class to instantiate, though its details were wildly different for each platform. Depending on how this discussion goes, I plan to convert these ideas into a proposed library. Best, Don ------ Sketch -------- 1. The user creates one or more "nexus" objects. These objects store the queue of events, typically one-per-thread. Since some action is typically required as messages are enqueued, a callback is supplied to open() which gets called as each message is added. 2. The owner of the nexus is responsible for calling the pump() method to drain the messages. This method is intended for only one thread and hence is not internally thread-safe (i.e., BYOM ... Bring Your Own Mutex). 3. To queue calls, client code needs to create a "channel" object and connect it with a nexus. The reason for this object is that it is a proxy for the "ability to still dispatch a message". In other words, if a receiver object finds itself in its destructor, it will want to cancel any queued calls to it. Of course, this can be applied externally to objects, which is why channel is not a base class. 4. Once a channel is open, the async_call() method is used to put a message in flight. This is thread-safe. 5. Where other code needs a function<>, the channel can be used to create a shim function<> that accepts N arguments, and binds them into a queued call. ------ Pseudo-code -------- class nexus { friend class channel; public: typedef function<void (void)> message; // Return true if there is an object associated with // the current thread. static bool available (); // Return the object associated with the current // thread. Throw if there is none. static nexus & get_current (); // Connect this object with the current thread. The // ntfy callback is made whenever a message is added // to this queue. void open (const message & ntfy); void close (); // Remove a message from the queue. Don't wait any // longer than "t". If t == 0 and there is a message // in the queue, dispatch it now. void pump (const timeout & t = timeout::infinite); private: struct entry { channel * ch; message msg; }; typedef std::list<entry> messages; messages msgs_; message ntfy_; void enqueue (channel * ch, const message & msg) { msgs_.push_back(entry(ch, msg)); ntfy_(); } // Remove all entry's in msgs_ with == channel*. void purge (channel * ch); }; class channel { typedef nexus::message message; public: void open (nexus * nx = 0) { if (!nx) nx = &nexus::get_current(); close(); target_ = nx; } void close () { target_->purge(this); } void async_call (const message & msg) { target_->enqueue(this, msg); } // Create a callback that calls "this->async_call(msg)". message bind_async_call (const message & msg); // Create a callback that accepts T and calls // "this->async_call(bind(msg, t))". template <typename T1> function<void (T)> bind_async_call (const function<void (T)> & msg); // More flavors of bind_async_call() private: nexus * target_; }; __________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/

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ublas test4+5 failures
by Stefan Slapeta 29 Mar '05

29 Mar '05

Please could somebody look into these: http://tinyurl.com/49lg5 http://tinyurl.com/4lvn8 These failures have occured for a long time now. The failing assertions produce popups that are very annoying for tests without the build monitor! Thanks, Stefan

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type_traits: recent changes break EDG compilations
by Ralf W. Grosse-Kunstleve 29 Mar '05

29 Mar '05

The current Boost CVS does not work for compiling Boost.Python with the EDG front-end versions 238, 245, and 303 (and possibly any other EDG). E.g. using icc 8.1: icc -fPIC -DBOOST_DISABLE_THREADS -DNDEBUG -O2 -DBOOST_PYTHON_MAX_BASES=2 -I/net/legless/scratch1/rwgk/hot/boost -I/usr/local_cci/Python-2.4_ticker/include/python2.4 -c -o boost/libs/python/test/args.os /net/legless/scratch1/rwgk/hot/boost/libs/python/test/args.cpp /net/legless/scratch1/rwgk/hot/boost/boost/python/detail/invoke.hpp(75): error: expression must have (pointer-to-) function type return rc(f( BOOST_PP_ENUM_BINARY_PARAMS_Z(1, N, ac, () BOOST_PP_INTERCEPT) )); ^ detected during: The full error messages are here: http://cci.lbl.gov/~rwgk/tmp/edg238_problem_2005_03_27_1250 http://cci.lbl.gov/~rwgk/tmp/edg245_problem_2005_03_27_1250 http://cci.lbl.gov/~rwgk/tmp/edg303_problem_2005_03_27_1250 I've tracked down the failures to this CVS commit: date: 2005/03/23 11:22:25; author: johnmaddock; Modified function testing to make it configuration-friendly, future changes should require no more than a config macro change. If I check out the CVS HEAD, but run this command % cvs -q update -P -D'2005/03/23 11:00 UTC' U config.hpp U is_convertible.hpp U is_function.hpp U is_member_function_pointer.hpp U type_traits_test.hpp U detail/is_function_ptr_helper.hpp U detail/is_function_ptr_tester.hpp U detail/is_mem_fun_pointer_impl.hpp U detail/is_mem_fun_pointer_tester.hpp in boost/boost/type_traits, compilation succeeds again. The full diffs are here: http://cci.lbl.gov/~rwgk/tmp/edg_problem_2005_03_27_1250_type_traits_diffs I noticed that is_convertible.hpp was modified at a later time (2005/03/24 18:18:36), but this change does not make a difference for the EDG failures. Thanks in advance for any help! Cheers, Ralf __________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/

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Threading and Visual C++
by Rasmus Christian Kaae 29 Mar '05

29 Mar '05

Hello, I am currently starting a project using the boost libraries and Visual C++. In this project we wish to minimize the number of DLL's shipped with our final product. However, we have discovered that the boost thread library is fixed to be dynamically loadable, is there any way to get around this? Short: How do i statically link the boost thread library in Visual C++ projects? -- Best regards / Med venlig hilsen Rasmus Christian Kaae - kaae(a)cs.auc.dk or kaae(a)daimi.au.dk Office: E4-119, Aalborg University. Phone: +45 75 88 04 13 Mobile: +45 28 72 04 13

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preprocessor puzzle
by Edward Bishop 29 Mar '05

29 Mar '05

I came up with this great macro called IS_UNSIGNED_CHAR() such that IS_UNSIGNED_CHAR(unsigned char) expands to 1 and IS_UNSIGNED_CHAR(hello world) or any other input, expands to 0. It almost works, but it gets confused by IS_UNSIGNED_CHAR(unsigned world) which expands to garbage: BOOST_PP_IIF_I, EQUALS_42_57, RETURN_0)((42) world_U_I_O_P)); Any suggestions? Here is the code: #include <boost/preprocessor.hpp> #define Q_W_E_R_T_Y_unsigned 42) #define char_U_I_O_P (57 // Transmogrify t #define MOG(t) Q_W_E_R_T_Y_ ## t ## _U_I_O_P // Check if t is (42)(57) #define EQUALS_42_57(t) BOOST_PP_AND(BOOST_PP_EQUAL(42,BOOST_PP_SEQ_ELEM(0, t)), \ BOOST_PP_EQUAL(57,BOOST_PP_SEQ_ELEM(1, t)) ) // return 0 #define RETURN_0(t) 0 #define IS_UNSIGNED_CHAR(t) BOOST_PP_IIF(BOOST_PP_EQUAL(2,BOOST_PP_SEQ_SIZE((MOG(t)))), \ EQUALS_42_57, RETURN_0)((MOG(t))) // Here is some test data: IS_UNSIGNED_CHAR(unsigned char); // should expand to 1 IS_UNSIGNED_CHAR(hello world); // should expand to 0 IS_UNSIGNED_CHAR(unsigned world); // should expand to 0

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[patch] lambda bug with GCC debug mode
by Jonathan Wakely 29 Mar '05

29 Mar '05

The libstdc++ debug mode doesn't work with forward declarations of std templates (since when using the debug mode std::vector is really __gnu_debug_def::vector, visible in std due to GCC's "strong using" extension) Lambda's boost/lambda/detail/operator_return_type_traits.hpp seems to account for this, but only checks for GCC 3.4 not 4.0, causing the error shown here for GCC 4.x in debug mode (*): http://www.redi.uklinux.net/src/boost/status/cs-Linux-links.html#lambda-con… The workaround on line 876 should be changed to account for GCC 4.x or alternatively, test for the debug mode explicitly. The attached patch does the test explicitly and disables all forward decls of std templates when _GLIBCXX_DEBUG is defined. I don't know whether it's preferred to simply disable the forward decls for non-debug mode as well. jon (*) regression test results for GCC 4.0 & 4.1 on x86_64 GNU/Linux here: http://www.redi.uklinux.net/src/boost/status/cs-Linux.html All toolsets use GCC's concept-checks, the gcc-debug-mode toolset also uses the libstdc++ debug mode. -- "Always Read the Label" - anon.

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[mpl] eval_if has default parameters?
by Andy Little 29 Mar '05

29 Mar '05

The following compiles (VC7.1, gcc3.2), and I am wondering if this is the intended behaviour(boost 1.32) Note the two default parameters to eval_if. here #include <iostream> #include <boost/mpl/eval_if.hpp> int main() { typedef boost::mpl::eval_if< boost::mpl::true_ // whatever nullary metafunction >::type type; std::cout << type::value <<'\n'; // outputs 0 } regards Andy Little

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Re: Serialization issuses under MS VC++ 7.1 ....
by Jason Earl 29 Mar '05

29 Mar '05

If you have look at my original code, it does use BOOST_SERIALIZATION_SPLIT_MEMBER() inside the class (sorry the code doesn't intend with tabs nicely). I also have tried including both... #include <boost/serialization/split_member.hpp> #include <boost/serialization/split_free.hpp> but neither work. I assume that the split free is obviously used by the list data type as it's not intrusive, and the member one is what I should include and have been including. I'll look running the tests later when I get round to figuring out how to run them etc. I'll need to RTFM first though. From the regression thingy, it said MSVC++7.1 worked OK though. I think this could be a little bug in the library (I won't speak too loudly here as I'm still a C++ beginner, and therefore there's a good chance I'm still doing something very dumb), maybe someone else could confirm they get the same problem as me when trying to serialize an class member varaible that is a list of objects using load / save methods that are class members under VS.NET 2003, like in my example.... anotherwords I have class A with separate load/save members, and then I have class B which has a member inside it that is of type std::list<A*>. Sorry in advance if I break the threaded reply structure on this list. I didn't have the list mail me replies. I'm new to all this mailing list stuff. Jason

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Re: [boost] [mpl] float representation
by Cromwell Enage 29 Mar '05

29 Mar '05

--- Andy Little wrote: --- > Why not call this one mixed_number? >> > IMO your fraction \ fraction_c functionality should > be called rational \ rational_c for compatibility > with the runtime boost::rational. Okay. I suppose my choice of names was somewhat pedantic, more appropriate in elementary school than in here. > FWIW IMO with your current 'rational, the extra > parameters extend the range but not indefinitely and > the extra number and especially sign parameters are > cumbersome. You prefer something like the following? rational_c<int,-11,16> mixed_number_c<int,-4,5,8> mixed_number_c<long,0,-6,7> I guess the added readability would be worth the extra logic required to calculate the sign. > Surely better functionality and less namespace > pollution could be had with a big_int parameter to > the two param type. You mean allowing Big Integral Constants as template arguments? This would eliminate the need for big_fraction/big_rational and big_mixed_number, but not the concepts they were meant to model. Shouldn't be too difficult to implement, but I need to cut down the compile times of the other big_integral test programs before testing rationals with such arguments becomes feasible. > However currently the docs state the integral > constant requirement on parameters which IMO is an > unnecessary restriction. Once I attempt to allow template arguments beyond Integral Constants and Big Integral Constants, I risk duplicating the functionality already provided by mpl::divides<>. Any good reason you'd want me to do this? For example, what would a recursive rational provide that dividing the fraction numerator by the fraction denominator would not? > For example a more generic alternative to > abs_integral could be implemented as follows, > which might be a useful mpl function anyway. Come to think of it, mpl::abs<> would be a useful metafunction indeed. I'll work through all of this when I get the chance. I have lots of personal matters to attend to before then. Cromwell D. Enage __________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/

2 1

Brainbench.com testing is free until 4th of April. Let's get the top
by Pavel Chikulaev 29 Mar '05

29 Mar '05

Hi all, This is not an ad. Test your C++ skills! There is no-one booster in the top 25. Let's do that. P.S. Sorry for off-topic. I just wanted to let you know.

3 2

[Boost-bugs] [ boost-Bugs-1169920 ] Generate patches for Graph bugs in 1.32.0
by SourceForge.net 28 Mar '05

28 Mar '05

Bugs item #1169920, was opened at 2005-03-24 09:49 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1169920&group_… Category: graph Group: None Status: Open Resolution: None Priority: 5 Submitted By: Douglas Gregor (dgregor) Assigned to: Douglas Gregor (dgregor) Summary: Generate patches for Graph bugs in 1.32.0 Initial Comment: There are several critical bugs in the BGL in Boost 1.32.0 that have been fixed since the release, but 1.33.0 is too far off for users to wait. We should create a patch of some sort that allows users to get at these bug fixes, without introducing any big changes into the library. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1169920&group_… ------------------------------------------------------- This SF.net email is sponsored by Microsoft Mobile & Embedded DevCon 2005 Attend MEDC 2005 May 9-12 in Vegas. Learn more about the latest Windows Embedded(r) & Windows Mobile(tm) platforms, applications & content. Register by 3/29 & save $300 http://ads.osdn.com/?ad_id=6883&alloc_id=15149&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[Boost-bugs] [ boost-Bugs-1172109 ] Support for bundled properties in graph adaptors
by SourceForge.net 28 Mar '05

28 Mar '05

Bugs item #1172109, was opened at 2005-03-28 16:21 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1172109&group_… Category: graph Group: None Status: Open Resolution: None Priority: 5 Submitted By: Douglas Gregor (dgregor) Assigned to: Douglas Gregor (dgregor) Summary: Support for bundled properties in graph adaptors Initial Comment: The graph adaptors (such as subgraph) do not support bundled properties, but they should. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1172109&group_… ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

1 0

Re: [C++ Template Metaprogramming] Selected Answers Posted
by Ariel Badichi 28 Mar '05

28 Mar '05

Edward Diener wrote: > David Abrahams wrote: > >>Ariel Badichi has generously established a wiki page containing his >>answers to many of the exercises in the book "C++ Template >>Metaprogramming: Concepts, Tools, and Techniques from Boost and >>Beyond" by me and Aleksey Gurtovoy. Please see the book's home page >>at >> >> http://www.boost-consulting.com/metaprogramming-book.html >> >>for details. > > >>From someone struggling <g> to learn MPL, thank you very much ! No problem. I think that's the little I could do to show my appreciation to the authors of the book. One thing to mention: Don't hesitate to contribute your own solutions, 'improve' on mine, or post comments or question. I have noticed that some of my solutions are not ideal, but I have left them as I wrote them. I also experimented a bit with the formatting of the code so some inconsistencies show up.

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[C++ Template Metaprogramming] Selected Answers Posted
by David Abrahams 28 Mar '05

28 Mar '05

Ariel Badichi has generously established a wiki page containing his answers to many of the exercises in the book "C++ Template Metaprogramming: Concepts, Tools, and Techniques from Boost and Beyond" by me and Aleksey Gurtovoy. Please see the book's home page at http://www.boost-consulting.com/metaprogramming-book.html for details. -- Dave Abrahams Boost Consulting www.boost-consulting.com

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[comp.lang.c++.moderated] question about dynamic_any
by David Abrahams 28 Mar '05

28 Mar '05

FYI. -- Dave Abrahams Boost Consulting www.boost-consulting.com

2 1

Cleaning delete
by Igor Smirnov 28 Mar '05

28 Mar '05

Hi All, What do you think about optional set of new/delete operators which clean memory in delete() by filling it with zeros. I mean an implementation with the standard syntax, so that any old program using the standard new/delete can be linked with the modified version of new/delete without any change in the program text and even without its recompilation. I have never heard whether this simple idea was implemented anywhere. In fact, these operators are useful for sequre aplications, which are not expected to leave significant information in the dynamic memory. This is also useful for debug of any program that uses direct allocations with raw pointers, the style which it known to be prone to errors. The use of already deleted information is more likely to be detected, if this information is physically deleted. The cleaning new/delete operators might be made very simple (almost trivial, except exception safety) and perhaps completely portable. Does this idea look useful? Regards Igor Smirnov

2 2

size limit on files in Sandbox File Vault
by Eric Niebler 28 Mar '05

28 Mar '05

I just tried to upload a new version of xpressive to the Boost Sandbox File Vault, and I received this error: "A file with the name xpressive.zip exceeds maximum allowed size (256 Kb)!" This seems pretty restrictive. The PDF version of xpressive's docs by itself exceeds this limit! I want to include the source code, the regression and perf tests, PDF and HTML documentation, and samples in a single download, but my .zip weighs in at 444 Kb. Can the limit be increased? -- Eric Niebler Boost Consulting www.boost-consulting.com

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Re: [boost] [mpl] float representation
by Cromwell Enage 28 Mar '05

28 Mar '05

--- Andy Little wrote: --- > What is the rationale for the 4 different types > representing rational fractions? Presumably you mean fraction, fraction_c, rational, and rational_c? The fraction_c struct template is simply a metafunction that returns a fraction type, and the rational_c struct template returns a rational type. (Or was it the other way around?) The fraction struct template covers a smaller range of numbers than the rational struct template, but the rational struct template models the concept of a mixed number, which consists of a whole number part and a fraction part, so I figured both the fraction and rational representations were essential. It certainly made implementation simpler. > What is the rationale for making the numerator and > denominator types in fraction_c? In an earlier version, the numerator and denominator were defined by BOOST_STATIC_CONSTANT. Looking through the Integral Constant Guidelines and the MPL source code, I read that certain compilers were likely to complain about the very code I used to have: BOOST_STATIC_CONSTANT before typedef statements, fraction_c<long,7,8>::value inside macros, etc. Not that I have these compilers on hand, but I figured I wasn't making this sub-library just for myself, either, so I searched for a better representation. Lo and behold, Aleksey Gurtovoy created a set of arithmetic metafunction classes that do the dirty work for me. I simply built on top of his work. Thanks for your interest! Cromwell D. Enage __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

2 2

Binary files in CVS
by Peter Dimov 27 Mar '05

27 Mar '05

The following files in the main CVS are binary but do not appear to be marked as such: M libs/program_options/test/ucs2.txt M libs/program_options/test/utf8.txt M libs/ptr_container/doc/cboost.gif The sandbox CVS also contains such files: M boost/ptr_container/ptr_container.tgz M libs/numeric/bindings/doc/c++boost.gif M libs/ptr_container/doc/cboost.gif M libs/sequence_algo/doc/cboost.gif These are corrupted by the Windows CVS clients on every checkout via CR insertion. The easiest way to avoid this is to just not check in binary files in the CVS. -- Peter Dimov http://www.pdimov.com

2 1

Serialization issuses under MS VC++ 7.1 ....
by jason 27 Mar '05

27 Mar '05

I'm all new to C++, let alone Boost, so do excuse me if this is a dumb post, I've only been using C++ for a few weeks now, and come froma web design background. Anyway, I am getting a Error C2780 .\boost_1_32_0\boost\serialization\split_free.hpp(45): error C2780: 'void boost::archive::save(Archive &,const T &)' : expects 2 arguments - 3 provided message when I use STL containers in Boost and the BOOST_SERIALIZATION_SPLIT_MEMBER() macro in my class. I have found when I don't split the serialize method into load / save methods it works fine. However, I need separate load / save methods as some of the members in my class are not serializable (they are SDL resources, and therefore uploading I need to do some other work to restore these members). Here is a chunk of example code that fails... class P { private: int qw; friend class boost::serialization::access; template<class Archive> void serialize(Archive& ar, const unsigned int version) { ar & qw; } public: P() : qw(0) {} P(int Qw) : qw(Qw) {} }; typedef std::list<P*> pList; class Test { pList p; friend class boost::serialization::access; BOOST_SERIALIZATION_SPLIT_MEMBER() template<class Archive> void load(Archive& ar, const unsigned int version) { ar & p; } template<class Archive> void save(Archive& ar, const unsigned int version) const { ar & p; } public: Test() {} }; Using Test t; std::ofstream ofs("frameTest"); boost::archive::text_oarchive oa(ofs); oa << t; ofs.close(); creates this error. To me it seems like this might be a library issue. However could someone point out what I am doing wrong if it is me, and if it is a lib issue, could they hint /suggest some sort of cleanish workaround. I am going to mess about and hack together a workaround by not splitting the serialize method into load/save methods in the class affected for now, however I'm sure other people on this list will be able to suggest better solutions than mine. And yes, I am including the list.hpp file incase anyone thinks I'm not including it. Jason.

3 2

[date_time] missing includes?
by Russell Hind 27 Mar '05

27 Mar '05

I'm just trying date_time on OS X. I've included #include <boost/date_time/posix_time/ptime.hpp> #include <boost/date_time/posix_time/conversion.hpp> This fails to compile with the following error. Including posix_time.hpp rather than ptime.hpp or a gregorian header solves the problem. posix_time/conversion.hpp:33: error: 'to_tm' undeclared in namespace 'boost::gergorian' posix_time/conversion.hpp:45: error: 'date_from_tm' undeclared in namespace 'boost::gregorian' Should the appropriate header be included by posix_time/conversion.hpp? Cheers Russell

2 1

rational variants/alternatives
by Andras Erdei 26 Mar '05

26 Mar '05

i've started to work on the variants that were brought up in a previous discussion about boost::rational<> the current code can be found at www.ccg.hu/pub/src/rat atm it is only for getting the calculations right, so no templates, optimizations, boostification, nice interface etc, and i only tested it with MSVC 7.1 there is also no implementation yet geared towards an unlimited precision representation the variants are: - legacy boost (no rounding, silently gives wrong results) - exceptions are thrown if the result overflows or cannot be represented - rounding - rounding & maintaining an exactness indicator is there anything missing from the list? there is also a simple test-bed, it runs the four basic operations 10000 times on random inputs, and collects some statistics: addition and substraction overflowed 0 times, and the result was exactly representable 44 times; the average error of the legacy code is 475%, and of the rounding code is 0.005% (the exception-throwing variant throws, so there is no error figure for that) multiplication and division overflowed once, and the result was exactly representable 79 times; the average error of the legacy code is 2025%, and of the rounding code is 0.01% it would be nice to get some advice on how the final interface should look like (and of course regarding everything else, including whether there is a point to continue the work): - any ideas for naming the variants? - how should the parameters of rational<> look like? my favourite would be rational<prec,method> where prec is the maximum absolute value allowed for numerators and denominators, and method is one of the variants from above, e.g. rational<10000,round> would be a rounding rational with four decimal digits for the numerator and denominator. of course this would cripple rational<> to be int-based, so maybe specifying the number of bits to be used instead of the maximum value is a sensible approach. (still don't know though how would user-defined types be selected based on this, so maybe the original boost approach is the only workable one.) br, andras ps: i have tried to search the archive for past discussions about rational<> to avoid repeating old stuff, but with very limited success (only the latest posts seem to be accessible) -- any hints?

3 11

boost::is_convertible failure on abstract classes
by Me here 26 Mar '05

26 Mar '05

Hello, The code below does not compile, when, I believe, it should. Compiler says that you can't instantiate abstact class. I'm really surprised - it is trivial use case, but I did not find a problem report. Do I miss something? Regards, Alexander --------------- sample code ------------ #include <boost/static_assert.hpp> #include <boost/utility/enable_if.hpp> #include <boost/type_traits.hpp> struct Data { virtual foo() =0; }; int main(int argc, char* argv[]) { BOOST_STATIC_ASSERT((boost::is_convertible<Data,Data>::value)); return 0; } --------------- sample code ------------ __________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/

3 3

test
by Igor Smirnov 25 Mar '05

25 Mar '05

Just a test

1 0

Boost Algorithms Library
by David Abrahams 25 Mar '05

25 Mar '05

As part of my work on the MTL rewrite (http://www.boost-consulting.com/projects/mtl) I have to re-implement the FAST library (http://www.osl.iu.edu/research/mtl/reference/html/#fast) I am re-imagining FAST to use "iterators" whose positions are represented in their types. This is a similar concept to that of a fusion iterator (http://www.boost.org/libs/spirit/fusion/readme.txt) That will allow full loop unrolling for fixed size arrays and their subranges -- the whole point of FAST -- without having to explicitly supply integral constants. Naturally such iterators can't be incremented in-place; traversal will be done with next(i). There will be a function to convert FAST iterators into regular std:: iterators. FAST iterators are different from Fusion iterators in that respect; fusion iterators are heterogeneous in general and so can't have a single value_type. It turns out that OSL (and probably Boost in general) are going to be writing several kinds of algorithm implementations for different kinds of iterators, including segmented algorithms (http://lafstern.org/matt/segmented.pdf) We also have the standard algorithms, Fusion algorithms, and who-knows-what-else so it makes sense to try to supply a common interface that can be used generically, without regard to the kinds of sequences are being operated on. It would also be nice to make the system extensible, so there's at least a chance of providing new algorithm implementations for new kinds of iterator and having things "mostly work." I am planning a sequence/range-based (as opposed to iterator-based) interface, to make sequence adaptation and chaining easier. In case you disagree, I consider that a comparatively uninteresting and orthogonal point, so I'd prefer to save any arguments on that for later. As far as I can tell, the only reasonable way to unify these libraries extensibly is to provide a central algorithm dispatcher that is called with qualification, e.g.: boost::algorithm::transform(input_sequence, op, output_sequence) The easiest way to do dispatching is to use ADL based on tags associated with the sequences or their iterators, something like: // algorithm.hpp namespace boost { namespace algorithm { template <class I, class Op, class O> something transform(I input_sequence, Op op, O output_sequence) { return transform_impl( input_sequence , algorithm::get_tag(input_sequence) , op , output_sequence , algorithm::get_tag(output_sequence)); } }} // fast.hpp namespace boost { namespace algorithm { namespace fast { struct fast_tag {}; template <class I, class Op, class O, class T> something transform_impl( I input_sequence, fast_tag, Op op, O output_sequence, T) { // ... whatever ... } }}} I believe ambiguities will be the greatest obstacle to extensibility, especially because many algorithms (e.g. the 2-sequence version of transform) can operate on utterly different sequences. It's possible to add another transform overload without the tag arguments in fast:: so that users can explicitly invoke fast::transform in case algorithm::transform is ambiguous, but that won't help when transform is being invoked from within some library whose code the user doesn't control. Another problem is that determining the type of "something" for the outer transform can be complicated. That's related to the use of ADL dispatching because we might have to determine how the ADL works out just to understand where to find the return type calculation. Yes, typeof would solve that problem. The ambiguity problem can be resolved by going to a specialization-based dispatch. It allows us to silently choose one of many equal implementations in case of ambiguity, which can be neccessary if you want to prevent ambiguities from arising in libraries over which the user has no control. The user can also add specializations to resolve the ambiguity, though that leads to the risk of clashing specializations. That approach adds a great deal of machinery for something we haven't even seen to be a problem in practice yet. For an example, see the end of the message. I am inclined to go with ADL-based dispatching, at least for now. Whether results should be lazy (as in Fusion) or greedy, as in standard algorithms, or whether both variants should be provided somehow, are interesting questions. The answers change the usage pattern, i.e.: copy(transform(s1,op), output) or output = transform(s1,op) // if output supports it vs. transform(s1,op,output) Your thoughts on these topics would be much appreciated. ---------- // Specialization-based dispatch example // algorithm.hpp namespace boost { namespace algorithm { // algorithm identifier struct transform_tag {}; // Map some implementation identifier into a transform implementation. template <class IO> struct transform_impl; // A metafunction to trace refinement relations among sequence // concept tags. E.G., // refines<random_access_sequence_tag>::type // yields bidirectional_sequence_tag. We can work out a protocol // for "multiple refinement," if neccessary. template <class Tag> struct refines; // implementation -- produce an implementation for an algorithm // and set of sequence types and category tags // // ID must be a function type of the form: // algorithm-identifier ( Seq1, tag1, ... SeqN, tagN ) // template <class ID> struct implementation { typedef mpl::false_ is_specialized; typedef mpl::int_<0> score; }; // If there's no closer specialization, then try again with the // "base" sequence category. template <class Algorithm, class S1,class Tag> struct implementation<Algorithm(S1,Tag)> : implementation<Algorithm(S1,typename refines<Tag>::type)> { typedef typename mpl::next< typename implementation< Algorithm(S1,typename refines<Tag>::type) >::score >::type score; }; // If there's no closer specialization, then try again with the // "base" sequence categories. template <class Algorithm, class S1, class Tag1, class S2, class Tag2> struct implementation<Algorithm(S1,Tag1,S2,Tag2)> : best_scoring< // definition left as exercise ;-) mpl::vector2< implementation< Algorithm(S1,typename refines<Tag1>::type,S2,Tag2) > , implementation< Algorithm(S1,Tag1,S2,typename refines<Tag2>::type) > > >::type {}; // ... // impl -- dispatch an algorithm and sequence types to a given // implementation // // ID must be a function type of the form: // algorithm-identifier ( Seq1, ... SeqN ) // template <class ID> struct impl; template <class Algorithm, class S1> struct impl<Algorithm(S1)> : implementation<Algorithm(S1, typename sequence_tag<S1>::type)> {}; template <class Algorithm, class S1, class S2> struct impl<Algorithm(S1)> : implementation< Algorithm( S1, typename sequence_tag<S1>::type , S2, typename sequence_tag<S2>::type )> {}; // ... // Dispatching wrapper for transform implementations template <class I, class Op, class O> impl<transform_tag(I,O)>::result_type transform(I input_sequence, Op op, O output_sequence) { impl<transform_tag(I,O)> ::execute(input_sequence, op, output_sequence); } }} // fast.hpp namespace boost { namespace algorithm { namespace fast { struct tag {}; // identify FAST sequences }}} namespace boost { namespace algorithm { // A transform algorithm implementation for FAST input sequences template <class I, class O, class OTag> struct implementation< transform_tag(I,fast::tag,O,OTag) > { // ... } }} -- Dave Abrahams Boost Consulting www.boost-consulting.com

2 4

[serialization] typo's in is_abstract.hpp
by Eelis van der Weegen 25 Mar '05

25 Mar '05

Line 25 in boost/serialization/is_abstract.hpp uses _GNUC__ and __GNU_MINOR. Both are incorrectly spelled; the correct names are __GNUC__ and __GNUC_MINOR__. Regards, Eelis

2 1

Weird "new vault" download behavior
by David Abrahams 25 Mar '05

25 Mar '05

If I click the leftmost link for Arkadiy's typeof() implementation, I get a window containing: File : typeof.zip Print Download Fatal error: session_start(): Failed to initialize storage module: user (path: /tmp) in /home/groups/b/bo/boost-sandbox/htdocs/vault/include/common.php on line 62 Something's not quite right here, I think. -- Dave Abrahams Boost Consulting www.boost-consulting.com

3 3

[test] Boost.Test broken on MSVC and CW 8.3?
by Jonathan Turkanis 25 Mar '05

25 Mar '05

Gennadiy, All the iostreams regression tests are failing on cw-8_3, msvc and msvc-stlport; the compiler output just links into the reports for Boost.Test. Looking at the regression reports for Boost.Test, it looks like just about everything is failing on these platforms. Just wanted to alert you if you don't already know. Jonathan

2 2

Interest poll: Define named char/wchar_t string constants in header files
by Alf P. Steinbach 25 Mar '05

25 Mar '05

Following the guidelines for Boost submission at <url: http://www.boost.org/more/submission_process.htm#interest> this is a request for interest. I've posted the file + one little file it depends on at <url: http://groups.yahoo.com/group/boost/files/named_strings/>. This utility lets you use literal strings in char/wchar_t-templated code (and even as template arguments): you can write things such as BOOST_DEF_NAMED_STRING( eq, "=" ) template< typename Char > bool is_assignment_op( std::basic_string<Char> const& s ) { return s == literal::eq::s<Char>(); }

1 0

re: How much should I care about allocators?
by Michael Stevens 24 Mar '05

24 Mar '05

Dan, I looked into allocators last year when implementing uBLAS's storage abstraction using allocators. You should definitely make use of the ISO standard text when working with allocators! On Monday 21 March 2005 04:19, Dan Rosen <dan.rosen(a)gmail.com> wrote: > In other words, to respect the allocator I've been given, I need to > make sure my internal node structure uses the rebound node allocator's > pointer and value types, and so forth. So my first question is, is > this assumption correct? This is correct but requires a lot of library programmer discipline! > The reason I ask is that looking over the > standard library implementation that comes with gcc 4.0, I noticed > that their implementation of std::list<> has nodes which contain > straight pointers, rather than the allocator typedef equivalents. To > me that seems to contradict my assumption, assuming the gcc > implementation is correct. GCC is correct. There is a get out clause in the library standard. Look at section 20.1.5 "Allocator requirements" paragraph 4: Implementations of containers described in this International Standard are permitted to assume that their Allocator template parameter meets the following two additional requirements beyond those in Table 32. All instances of a given allocator type are required to be interchangeable and always compare equal to each other. The typedef members pointer, const_pointer, size_type, and difference_type are required to be T*, T const*, size_t, and ptrdiff_t, respectively. I suspect many implementation (including those not in the standard) have this requirement! > My second question is about allocator's construct() method. The > implementation of std::allocator has construct() invoking the copy > ctor using placement new(). That much is self-explanatory. It also > seems reasonable to me that allocator does not have construct() > methods taking arbitrary parameters. But I'm not sure I understand the > reason why it does not have a construct() method to invoke an object's > default ctor.? In Table 32 "Allocator requirements" construct is specified as a.construct(p,t) Effect: new((void*)p) T(t) >From this I conclude the construct is semantically identical to calling placement new. In effect construct does nothing other then provide a nice bit of syntax. I could just as well use placement new syntax directly or indeed call placement new for any other constructor such as the default constructor. > What that implies to me, and seems to be supported by > gcc's list implementation, is that the nodes in my tree mustn't have a > default ctor that actually does anything, because the only way to > properly initialize objects using an allocator is through copying. Is > that correct I think not. My interpretation is that allocators require that their value_type is Copy Constructable but place no restriction on other ways they may be constructed. That said, STL containers have been carefully designed to avoid the need default construct an object which will be subsequently assigned to. They can keep memory in an uninitialised state until an element is needed and then use copy construction. All the standard containers require their value_type to be Assignable but not Default Constructable. Interestingly no mention is made of Copy Constructable in the value_type requirements. I assume this is inherited in the Allocator requirements. Hope this help, Michael -- ___________________________________ Michael Stevens Systems Engineering Navigation Systems, Estimation and Bayesian Filtering http://bayesclasses.sf.net ___________________________________

6 7

boost::iostreams: only with std::cout?
by Dirk Griffioen 24 Mar '05

24 Mar '05

Hi, I would love to use the boost::iostreams lib, so I created a filter (which, in this case, does encryption) but instead of passing it std::cout I would like to pass it some other stream, a stringstream for instance (or any kind of ostream/istream, depending on the direction). However, I was very surprised to find the following code taking 100% cpu and not returning. It probably means I did something wrong, but I can't seem to find it. void test_encryption_filter() { const char* speech = "They sorely misunderestimate the American people if they " "think we will let them obtain nucular weapons. This " "malfeance will not stand."; // std::ostream which writes to standard output, filtered by a // encryption_output_filter. boost::io::filtering_ostream out; out.push(encryption::code_book::output_filter()); //out.push(std:cout); //this works std::ostringstream os; out.push(os); //this does not // Print unfiltered code. std::cout << "**** Speech unfiltered ****\n" << speech << "\n\n"; // Print filtered code: std::cout << "**** Speech with encryption filter ****\n"; out << speech << "\n\n"; } (testing puspose) filter looks like (namespace omitted): struct output_filter : public multichar_output_filter { template<typename Sink> void write(Sink& snk, const char* s, streamsize n) { while (n-- > 0) boost::io::put(snk, toupper(*s++)); } }; With std::cout this works fine, with std::ostringstream it does not. So could anyone please tell me what I am missing? Thanks in advance, Dirk ********************************************************************** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you are not the intended recipient, any disclosure, copying, use, or distribution of the information included in this message and any attachments is prohibited. If you have received this email in error please notify our system management at postmaster(a)optiver.com and immediately and permanently delete this message and any attachments. ********************************************

2 3

[build/regression testing] runtime failures
by Gennadiy Rozental 24 Mar '05

24 Mar '05

Is there any way to see a run command in case test fails at runtime? The same as we could see compiler command line if it fails at compile time Gennadiy

3 3

[Boost-bugs] [ boost-Bugs-1170106 ] Investigate other kinds of heaps for dijkstra_shortest_paths
by SourceForge.net 24 Mar '05

24 Mar '05

Bugs item #1170106, was opened at 2005-03-24 14:35 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1170106&group_… Category: graph Group: None Status: Open Resolution: None Priority: 5 Submitted By: Douglas Gregor (dgregor) Assigned to: Douglas Gregor (dgregor) Summary: Investigate other kinds of heaps for dijkstra_shortest_paths Initial Comment: There are many types of heaps that provide good theoretical performance when used as a priority queue, e.g., by Dijkstra's shortest paths algorithm. The BGL contains implementations of two such data structures: a binary heap and a relaxed heap. The latter is used because it has been shown to provide the best overall performance. However, we should investigate other kinds of heaps, e.g., Fibonacci heaps, relaxed Fibonacci heaps, and run-relaxed heaps, to determine which option is best for the BGL. Dietmar Kuhl implemented several kinds of heaps in his Heaps library, which could be found in earlier versions of Boost. It was removed from Boost in the 1.27.0 timeframe because it had never been reviewed and was not maintained, but may still prove valuable for experiments. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1170106&group_… ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[function] is function_equal used?
by Peter Dimov 24 Mar '05

24 Mar '05

The documentation says that comparisons require EqualityComparable, and contains_test never tests with objects that define function_equal instead of operator==. Also, there seems to be no test for boost::bind objects being put in a function<> (although there is one for lambda::bind). The reason I'm posting this is that I just switched boost::bind to implement function_equal instead of operator==, and this functionality isn't covered by our current tests. -- Peter Dimov http://www.pdimov.com

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[xpressive] doc bug?
by Thorsten Ottosen 24 Mar '05

24 Mar '05

The xpressive docs say sregex rex = sregex::compile( "(\\w+) (\\w+)!" ); can be expressed as sregex rex = (s1= +_w) >> ' ' >> (s2= +_w) >> '!'; . Shouldn't this be sregex rex = +_w >> ' ' >> +_w >> '!'; since you don't need to refer to previous matches? Thanks -Thorsten -- Thorsten Ottosen ---------------------------- www.dezide.com http://www.cs.aau.dk/index2.php?content=Research/mi www.boost.org www.open-std.org/JTC1/SC22/WG21/

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Naming Proposed Libraries
by David Abrahams 24 Mar '05

24 Mar '05

When discussing libraries in public that are under development but not yet accepted into Boost, I think it's problematic to refer to "The Boost <whatever> library" or "Boost.<whatever>" without qualification. Our peer-review process is respected, and these libraries are not yet officially blessed by Boost. I don't want to dilute the value of Boost acceptance. Can we please make a habit of prepending "The proposed" or something similar? For example, I suggest "The proposed Boost Interfaces library." Thanks! P.S. I hope it's obvious, but I don't think the documentation for the proposed library ought to resort to such contortions. -- Dave Abrahams Boost Consulting www.boost-consulting.com

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Does this algorithm exist?
by Michael Goldshteyn 24 Mar '05

24 Mar '05

Given: typedef std::deque<char> DequeString; std::string s("Hello sweet world!"); std::string word("sweet"); DequeString dequeString; // Copy "Hello sweet world!" into the deque string std::copy(s.begin(),s.end(),std::back_inserter(dequeString)); // Now, I want to find where "sweet" appears in the dequeString. An iterator to its location would be fine. // This doesn't quite do it, since it looks for _any_ occurrence of a character from word in dequeString std::find_first_of(dequeString.begin(),dequeString.end(),word.begin(),word.end()); // But, I want to find where _the whole_ word occurs in dequeString, similar to how std::string::find() does it: std::string::size_type wordPos=s.find(word); Is there something in boost or the standard C++ lib that can be used? Thanks, Michael Goldshteyn

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[type_traits] is_convertible regression on GCC 3.2 and 3.3
by Jonathan Turkanis 24 Mar '05

24 Mar '05

Hi, The following code causes a static assertion failure on GCC 3.2 (MinGW): #include <boost/static_assert.hpp> #include <boost/type_traits/is_convertible.hpp> struct base { }; struct middle : virtual base { }; struct derived : middle { }; BOOST_STATIC_ASSERT((boost::is_convertible<derived, middle>::value)); This problem is apparently responsible for the current failure of all the iostreams tests on the platforms gcc-3.2.3 and gcc-3.3.5. Jonathan

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