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Re: [boost] Reminder: review will end March 28th
by Cédric Venet 27 Mar '08

27 Mar '08

Hi, I am not sure to be qualified to make a review but I will give it a try. First, I think the library should be accepted. > - What is your evaluation of the design? Seems good. I must say I didnt read or try the transform part of proto. > - What is your evaluation of the implementation? Didnt read the code > - What is your evaluation of the documentation? I think there is some (more) work to do on it. I had some probleme with users_guide\expression_construction\construction_utils.html Because it was not clear to me how to put it in pratice. In fact after a fast read of the doc, I mostly used the exemple as reference of how to do something. So, I don't know exactly what can be done but some ideas may be: *Provide more basic exemple *Refer to the exemple in the documentation to show the practical use of what is described. *make a FAQ One difficulty I didn't had time to study is how to do polymorphic grammar or semantic checking. (perhaps I should not put this in the review). Mor clearly, I add two example: First I would like to have a grammar which can work on any terminal but can only have compatible terminal in a one expression (for example, you can't have vector and list in one expression but you can have one expression with lists and one with vector and they would follow the same grammar). My idea was to do a basic proto grammar which just check operator use and then to use a transform to fold the type of the terminals, checking they are all compatible. Second, I have a grammar where I can add terminals 'a+b' and index terminal 'a[b]'. you can have '(a+b)[c]'. some terminals may be indexable but other not. I could make a grammar for indexable terminal and another for not indexable but it would be duplicated. And if I add more properties to my terminals (for example Boolean, integer or float), the number of grammar explode. I was thinking to again use a transform to check the 'semantic' of the expression. Is it the way to go? I didn't see any reference to this in the documentation, but this seems a common pattern to me? The proto grammar would only check the 'parsing' and one transform would check the semantic. A yes, I would add two note which seem relevant for VS user: * the compiler flag -Zm (for example -Zm150) to change the maximum size of the precompiled header * the pragma inline_recursion and inline_depth (default off and 8) > - What is your evaluation of the potential usefulness of the library? Extremely useful. > - Did you try to use the library? With what compiler? Did you have any > problems? I used it with VS2005. I didnt had any problem (at least not one which wasnt my fault) > - How much effort did you put into your evaluation? A glance? A quick > reading? In-depth study? I read the doc and started writing a small test. Didnt had the time to try transform. Regards, -- Cédric

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[proto] I'm trying to write a vector class
by Noah Stein 27 Mar '08

27 Mar '08

Eric, I spent a few hours the other week trying to convert my last matrix-vector class library over to proto. It implemented expression trees, but I’d never gotten around to adding some features that proto should make much, much easier to implement such as expression optimization. I figured it would be a good way to experiment with the library to review. I eventually gave up on refactoring my class towards proto and instead tried refactoring your lazy_vector example towards my class. It's raised some questions/points. I'll illustrate with questions that are based on your lazy_vector example. 1) lazy_vector seemed like it could derive from lazy_vector_expr in CRTP fashion. I figured your use of std::vector<T> as the terminal type was just to make initialization easier; however, using CRTP fails to compile. Did I miss this in the documentation or is it not explicitly mentioned? 2) How can I handle scalar values transparently? My attempts to accept "v1=v2*5" have failed. I can't get the 5 to implicitly construct into a scalar_vector type I have defined. I had that working in my old one, but I can't seem to figure out the correct way of setting that up in proto. 3) My vector class' signature is very simple: template<typename T> class Vector : VectorExpr<terminal<T> > . The type T contains a number of traits defining the vector: the type of the elements, the dimension, how the data is stored. I can't figure out how to specify the terminals in my grammar. In your example, you use terminal<std::vector<_> > as your terminal. The std::vector part is unknown to me. That's my point of variation in my vector concept thus I can't know all the different types that could be used in the terminal. I tried deriving my storage classes from a common base class; however, that failed. Is there any way to encode some sort of restriction in the grammar for this situation? Right now, I'm using _, but that's clearly not a great solution. Proto looks very interesting. I was quite excited the first I saw it mentioned. There seems to be a lot of power there. I just need to figure out how to use it. You have a lot of documentation, but it seems to be attacking the problem from the opposite direction I'm approaching from, so it's been a little slow going. I hate asking questions about something I can investigate on my own, but I'd like to get far enough along that I can properly review it. Thanks, Noah No virus found in this outgoing message. Checked by AVG. Version: 7.5.519 / Virus Database: 269.22.0/1342 - Release Date: 3/25/2008 10:26 AM

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Status of thread safe signals?
by James Talbut 27 Mar '08

27 Mar '08

What is the status of the thread safe signals library in sandbox/thread_safe_signals? Will it go in the main boost library at some point? Thanks Jim P Consider the environment. Please don't print this email. ________________________________________________________________________ This e-mail, and any attachment, is confidential. If you have received it in error, do not use or disclose the information in any way, notify me immediately, and please delete it from your system. ________________________________________________________________________

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[pending/relaxed_heap.hpp] assert problem
by Dawson, Paul (UK Filton) 27 Mar '08

27 Mar '08

Using relaxed_heap I'm getting a problem with the asserts in the top() and pop() functions: assert(smallest_value->value != 0); Where value is a ::boost::optional<T>, and T is the indexed type of the heap. The problem that I'm having is that when my T is an int, and the int in question is perfectly valid and has an initialised value of zero, it fails the assert test. Based on my limited understanding, we would actually want to be asserting either (smallest_value != 0) since smallest_value is a pointer, or (smallest_value->value.is_initialised()) since this is an optional. Apologies if I have misunderstood something, as I am a newcomer to boost. Many thanks, Paul. --------------------------- Paul Dawson BAE Systems (Operations) Limited Registered Office: Warwick House, PO Box 87, Farnborough Aerospace Centre, Farnborough, Hants, GU14 6YU, UK Registered in England & Wales No: 1996687 ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ********************************************************************

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[gsoc2008] contacting the mentors
by Gautam Sewani 27 Mar '08

27 Mar '08

Hi, I am working on my proposal for GSOC 08 under Boost and I'd like to talk to the mentors.I was unable to find their contact details, can anyone help me in this regard? Yours Sincerely, Gautam Sewani

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[interprocess] [shared_ptr] Failure to type convert offset_ptr<T> to T *
by Aleksey Midenkov 27 Mar '08

27 Mar '08

The failure is in sp_counted_impl.hpp:66: 64 template<class Ptr> 65 sp_counted_impl_pd(const Ptr & p, const A &a, const D &d ) 66 : this_allocator(a), D(d), m_ptr(p.get()) 67 {} p is of type offset_ptr<T> and m_ptr is of type T * Test case source, compiler output and quick fix patch (which is not fully correct, I suspect) are attached. $ g++ --version g++ (GCC) 4.2.3 (Debian 4.2.3-2) Copyright (C) 2007 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

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Trac open bugs - by assignee
by Marshall Clow 27 Mar '08

27 Mar '08

[ 237 open bugs today, 235 yesterday ] If you are maintaining a library, and have not logged into the trac system at <http://svn.boost.org/trac/boost/>, please do so ASAP. Until you do that, no tickets can be assigned to you, and will remain under "None". Instructions on working with tickets can be found at: <http://svn.boost.org/trac/boost/wiki/TicketWorkflow> and a mapping of user names to "real names" can be found at: <http://svn.boost.org/trac/boost/report/16> Bug summary 24 djowel 21 az_sw_dude 15 vladimir_prus 14 grafik 13 dgregor 13 dave 12 doug_gregor 11 no-maintainer 11 bemandawes 11 agurtovoy 8 anthonyw 7 turkanis 7 jsiek 6 johnmaddock 5 witt 5 ramey 5 igaztanaga 4 matias 4 ebf 3 nesotto 3 nasonov 3 kaalus 3 danielw 3 danieljames 2 shammah 2 samuel_krempp 2 rogeeff 2 pavol_droba 2 marshall 2 jmaurer 2 hkaiser 2 aaron_windsor 2 None 1 urzuga 1 t_schwinger 1 speedsnail 1 pdimov 1 garcia 1 fcacciola 1 dlwalker 1 chris_kohlhoff None 1644 Boost.Test missing documentation file BOOST_CHECK_CLOSE_FRACTION.html None 1719 [addressof] Can't obtain the address of an instance of an anonymous struct aaron_windsor 1622 Adjacency list needs to handle self-edges correctly aaron_windsor 778 top-level configure is broken agurtovoy 1001 gcc 4.1.2 segfaults on mpl/test/apply.cpp agurtovoy 1051 MPL header ordering triggers bug agurtovoy 1099 unable to iterate through a "non-explicitly-declared" mpl::set agurtovoy 1215 Boost 1.34.1_ mpl: Wrong workaround detection using MinGW32 (or.hpp_ line #33) agurtovoy 1317 has_xxx randomly broken in msvc agurtovoy 1469 [mpl] nested typedef of set has two different meanings agurtovoy 1476 always<> is not nullary. agurtovoy 1528 g++ 4.3.0 reports error because of redeclaration of next agurtovoy 1549 Boost.MPL: 'index_of' algorithm is not documented agurtovoy 1568 duplicate include guards agurtovoy 588 mpl::remove compile error with gcc 4.1.0 anthonyw 1154 tss destruction segfaults in conjunction with dlopen/dlclose anthonyw 1168 [thread] tss crashes randomly anthonyw 1268 xtime_cmp changes to deal with overflow were reverted anthonyw 1470 Boost.Thread: Compilation errors with non-__cdecl calling convention anthonyw 1657 Bug in boost::threads sample anthonyw 1713 no definitions for copy ctor and assignment operator for basic_condition_variable anthonyw 876 xtime documentation incomplete anthonyw 881 errors when build with Apache stdcxx az_sw_dude 1028 typo in boost header: date_time/time_defs.hpp az_sw_dude 1078 from_iso_string cannot read the output from to_iso_string az_sw_dude 1098 Urgent libboost-date-time1.33.1 : bugs on ia64 ? az_sw_dude 1147 date_time library contains global #define ERROR az_sw_dude 1160 warning: month_format shadows a member of this az_sw_dude 1162 warning: ticks shadows a member of this az_sw_dude 1289 posix_time::time_facet forgets to pass a_ref argument to base class az_sw_dude 1299 change in typedef stringstream_type in format_date_parser.hpp causing compilation error az_sw_dude 1306 invalid docbook in date_period.xml az_sw_dude 1384 Linking problem with date_time library on Visual C++ 2008 Express az_sw_dude 1386 date_time documentation Jamfile breaks building of boost docs az_sw_dude 1524 format_date_parser.hpp(221) : cannot convert parameter 1 az_sw_dude 1574 operator<< for boost::posix_time::ptime ignores ostream flags az_sw_dude 1674 date_time::date_formatting.hpp: incorrectly formats year using global locale az_sw_dude 1695 add correct namespace to class to fix compilation bug az_sw_dude 287 wrong usage of ios_base::narrow az_sw_dude 316 date_time type conversion warning az_sw_dude 604 from_ftime incorrectly processes FILETIME filled with zeros az_sw_dude 642 operator<< for gregorian::date_duration not found az_sw_dude 889 Insane Dependencies az_sw_dude 890 date_time library supports only the current dst rule bemandawes 1378 filesystem path invalid name for hidden files (LINUX) bemandawes 1389 filesystem::ostream << boost::format generates operator ambigious error (in MSVC++) bemandawes 1458 Darwin Tiger throws std::runtime_error: locale::facet::_S_create_c_locale name not valid bemandawes 1578 bug in readdir_r_simulator() in a multi-threaded environment bemandawes 1583 Serious flaw in boost::filesystem filename handling (opensuse) bemandawes 1589 [filesystem] 'mbstate_t' : is not a member of 'std' bemandawes 1606 filesystem/src/exception.cpp doesn't build with gcc bemandawes 1613 Link Errors against file_system on OS X with Intel Version 10.1 C++ compilers bemandawes 1682 path_traits needs imbue() bemandawes 1701 boost::filesystem::remove_all - segmentation fault with wpath on Linux bemandawes 752 directory_iterator doesn't work with catch chris_kohlhoff 1703 [asio] Compiler warnings on VC8/9 + warning level 4 danieljames 1554 When BOOST_HASH_NO_EXTENSIONS is defined hash doesn't support new string types. danieljames 1555 When BOOST_HASH_NO_EXTENSIONS is defined hash doesn't support boost::system::error_code danieljames 1705 [boostbook] Spaces in reference file names for types like 'long long' danielw 1044 Argument pack inaccessable in a functions return type danielw 1054 Parameter takes an "infinite" amount of time to compile with the Intel compiler. danielw 1097 keyword.hpp generates many warnings C4180: qualifier applied to function type has no meaning; ignored dave 1010 linking boost.python on freebsd dave 1019 iterator_facade::pointer should be the return type of operator-> (DR 445) dave 1085 Python rules for compiling in Mac OS X dave 1179 [boost.python] can not export a union in VC2005sp1 dave 1181 [boost.python] can modify enum value dave 1387 Review / update docs to reflect changes dave 1460 Python classes with multiple bases are convertible only to the first class in the lists dave 1482 boost::python::throw_error_already_set should be marked noreturn dave 1516 [python] Failing VC9 regression tests dave 1599 [python] '_set_se_translator': identifier not found dave 1697 [utility][noncopyable] ADL barrier broken by msvc-9.0 dave 865 Use of C++0x keyword as identifier dave 910 gcc strict-aliasing problems with python dgregor 1009 Improper overflow handling in shortest paths algorithms dgregor 1164 Floyd Warshall broken with unsigned edge weights dgregor 1192 [boostbook] problem when two files have the same name dgregor 1199 configure doesn't work with path containing whitespaces (MacOS X) dgregor 1310 [result_of] const-qualified function pointer doesn't work dgregor 1326 Unable to check graph isomorphism using LEDA adapter dgregor 1391 dominator_tree_test on Borland/CodeGear outputs overly long line dgregor 1395 Write Tests for Python Bindings dgregor 1630 gcc-4.3: adjacency_list.hpp includes deprecated header dgregor 1680 long long and wchar_t support in MPI dgregor 556 Bundled graph properties dgregor 732 Johnson All-Pairs needs better "no path" information dgregor 736 Const correctness violation djowel 1170 Emit Warnings instead of # symbols in the syntax highlighter djowel 1171 Quickbook title output djowel 1172 non-utf djowel 1176 Space after inline code djowel 1206 Escaping from within code? djowel 1273 CR+LF newlines in position_iterator djowel 1276 spirit problem with _GLIBCXX_DEBUG djowel 1277 Closing section like [pre with } causes Quickbok to crash djowel 1280 sections in imported source files get put inside <para> elements in docbook output djowel 1281 Quickbook produces invalid BoostBook/DocBook XML djowel 1324 tuple should have a swap() that operates element-by-element djowel 1396 wrong result_of invocation around transform_view djowel 1436 [quickbook] inline code inside headings djowel 1484 Quickbook produces illegal docbook for some docinfo fields. djowel 1500 [Spirit/Phoenix] C4512 Compiler warnings from VC8 djowel 1570 Some boost headers aren't ready for gcc 4.3 djowel 1600 duplicate include guard djowel 1601 distane of boost::tuple djowel 1607 Tuple Library Documentation Changes djowel 1610 [MSVC/STLport] [tree/common.hpp] Standard library requirements violation(incomplete type as vector parameter) djowel 1614 vector workaround needed for MSVC9 djowel 1617 spirit gcc-4.3 fix djowel 1619 [Fusion] C4512 warnings from VC9 (Visual Studio 2008) djowel 1722 [TR1/Fusion] Conflict between TR1 and Fusion headers dlwalker 613 boost/crc.hpp uses non-standard conforming syntax doug_gregor 1021 [Graph][reverse_graph] Problem using reverse_graph adapter with an adapted user defined graph doug_gregor 1076 compile error: disconnecting struct with operator()() doesn't work in VS2005 SP1 doug_gregor 375 LEDA graph adaptors do not handle hidden nodes properly doug_gregor 402 random_vertex/random_edge are unnecessarily inefficient doug_gregor 403 Document copy_component doug_gregor 447 reverse_graph and constness of property maps doug_gregor 708 Dijkstra no_init version should not require VertexListGraph doug_gregor 733 Numbered headers don't work with "preferred" syntax doug_gregor 735 Fruchterman-Reingold grid performance can be improved doug_gregor 738 Memory leaks with signal::connect? doug_gregor 829 Implicit graph not implement doug_gregor 852 Problem with Boost and GCC 4.1 ebf 1507 [variant] C4512 warnings from VC8.0 ebf 1548 [variant][docs]typo: formal arg_ operand_ should be v in times_two arglist ebf 1654 recursive variants do not handle nested variants correctly. ebf 993 Variant should use least common multiple of alignments_ rather than maximum fcacciola 1666 Visualizer for boost::optional garcia 1581 Boost.MultiArray: Resizing bug if the index is not 0-based grafik 1041 Cygwin requires PATH setting. grafik 1322 trac rejects patch attachment as spam grafik 1417 Regresson tests hang in Darwin (Tiger) grafik 1430 Regression fails under Cygwin grafik 1433 Trac's spam detection rejects too many valid messages grafik 1512 Broken link to vacpp in bjam docs. grafik 1513 Broken link to bcpp in bjam docs. grafik 1571 boost bugtracker displays a patch incorrectly grafik 1576 cannot read non-ASCII output messages grafik 1577 Some commands don't work because hStdInput == 0 grafik 1663 build.bat cannot set/reset ERRORLEVEL grafik 616 Boost Jam_ and non english directorys grafik 959 linking fails when Boost is compiled with STLport 5.1.* on Linux (names mismatch) grafik 986 Problem building Python modules on boost 1.34.0 hkaiser 1079 boost-1.34.0 fails to compile. concept checks not satisfied. hkaiser 1670 wave almost unusably slow on real-world input igaztanaga 1080 boost::interprocess win32 global file mapping issue igaztanaga 1210 interprocess::barrier hangs during second use under linux (boost 1.33.1) igaztanaga 1390 Interpocess: managed shared memory failing completely under OS X igaztanaga 1634 boost::interprocess::vector cannot contain volatile int igaztanaga 1635 Incomplete include guard in boost/intrusive jmaurer 351 Diff in state of mersenne_twister gen between GCC3.41 & CW9 jmaurer 599 uniform_01 copies engine instead of using a reference johnmaddock 1081 Empty string rejected as perl-style regex johnmaddock 1314 Using SSE-intrinsics in VC8 causes static assert in type_with_alignment.hpp johnmaddock 1411 Fix BOOST_PARTIAL_SPECIALIZATION_EXPLICT_ARGS johnmaddock 1446 POSIX API doesn't use C locale johnmaddock 1451 error: use of C99 long long integer constant johnmaddock 1626 [type_traits] "bad_alloc is not a member of std" in has_virtual_destructor_test.cpp jsiek 1531 segfault in dynamic_bitset::reference assign operator jsiek 1540 Poisson distribution very slow for large mean (and may also overflow). jsiek 575 Calling subgraph::global_to_local on a root graph jsiek 636 strange compiling problem for transitive_closure jsiek 815 remove_edge core dumps on self-circle jsiek 875 No iterator based constructor for adjacency_matrix jsiek 900 graphml reader namespace handling is broken kaalus 1184 property_tree assignment (operator) bug kaalus 1604 property_tree xml parser doesn't compile with gcc kaalus 1678 Boost.property_tree::read_xml does not parse UNICODE file with BOMs marshall 1252 [pool] severe overhead with unaligned sizes. marshall 1493 SVN files making it through to install matias 1406 Understanding the Tables outdated matias 1651 incorrect typedefs in examples matias 1676 Dead links on Boost.Test example documentation. matias 1707 small typos in Boost.serialization documentation nasonov 1220 lexical_cast requires RTTI nasonov 1704 [any] 4512 warning from VC8/9 on warning level 4 nasonov 754 boost::any - typeid comparison across shared boundaries nesotto 1629 range/iterator_range.hpp bug nesotto 1675 [range] VC8 - compiler warnings when including range/array headers nesotto 1694 NDEBUG vs. BOOST_ASSERT in iterator_range.hpp no-maintainer 1068 Mersenne twister disables streaming for Visual C++ no-maintainer 1222 lambda::ret<T> should declare result_type. no-maintainer 1270 uniform_smallint doesn't compile with lagged_fibonacci random number generators no-maintainer 1515 [lambda] C4512 warnings from VC8.0 no-maintainer 1544 uniform_01 w/ref template param causes ref to ref error no-maintainer 1546 Method boost::random::uniform_int::operator()(engine_ value) is missing no-maintainer 1572 [lambda] smart pointer const-ness affects its contents no-maintainer 1632 Default Interval rounding policies incomplete no-maintainer 1691 [Random] Brokem MSVC workaround no-maintainer 781 Lambda: (_1 + "y")(string("x")) Doesn't Compile no-maintainer 819 uniform_int<> with type's maximum availaible range error pavol_droba 1152 rle_example fails pavol_droba 1385 begin must be boost-qualified pdimov 1106 shared_ptr<T> should not convert to shared_ptr<U> when T* doesn't convert to U* ramey 1285 [serialization] problem when including shared_ptr_132.hpp ramey 1708 Can't serialize class with private destructor ramey 1711 Boost Serialization export facility broken on gcc 4.1_ 4.2 ramey 1715 gcc-4.3 doesn't compile polymorphic_(i)(o)archive.hpp ramey 1721 Serialization examples don't compile in trunk for G++ 4.1 rogeeff 1383 signal.h features not found on Mac OS rogeeff 1542 [test] compiler errors when building with stdcxx library samuel_krempp 1699 Compile warning about initialization order. samuel_krempp 859 boost::format ignores a user defined locale shammah 290 perfomance: memory cleanup for pool takes too long shammah 386 boost::pool_allocator breaks with vector of vectors speedsnail 1138 Problems with TSS and static thread library t_schwinger 1653 wave executable erroneously required for build of function_types lib turkanis 1523 [iostreams] VC8/VC9 compiler warnings turkanis 1545 [boost/rational.hpp] 'noskipws' is not a member of 'std' turkanis 1579 gzip compressor should model DualUseFilter turkanis 1580 Add static assert to prohibit instantiating a chain with mode dual_use turkanis 1649 Fix definition of JavaScript menu to avoid long chains of functions turkanis 1656 Consider implementing flush() for symmetric filters turkanis 1671 type mismatch of buffer size parameter causes overload resolution to fail urzuga 574 [boost::lambda] Compile error with libstdc++ debug mode vladimir_prus 1132 program_options documentation error. vladimir_prus 1165 more quoting problems vladimir_prus 1274 Useless error message vladimir_prus 1321 invalid docbook in tool documentation vladimir_prus 1527 [program_options] Second (and subsequent) lines in tabbed text not aligned correctly vladimir_prus 1530 Program options documentation - Overview - Syntactic Information example typo vladimir_prus 1537 no value given in 'mysql_password =' vladimir_prus 1584 cryptic bbv2 error building quickbook vladimir_prus 1587 [program_options] crashes if value part missing in external configuration file vladimir_prus 1588 [program_options] crashes if value part missing in external configuration file vladimir_prus 1645 Invalid unicode support for default_value vladimir_prus 1679 added 4-way universal binary support from mac osx (ppc_ ppc64_ i386_ x86_64) vladimir_prus 469 multitoken broken vladimir_prus 689 [program_options] Endless loop with long default arguments vladimir_prus 850 program_options strips off escaped quotes in some situations witt 1046 Boost.Python quickstart instructions mention nonexistent target witt 583 Fixes for build on IBM pSeries for AIX and Linux witt 834 Homepage regression links witt 957 The "Getting Started" page does not mention the stdlib option witt 973 zip_iterator has value_type == reference -- -- Marshall Marshall Clow Qualcomm, Inc. <mailto:mclow@qualcomm.com> The famous British scientist, Lord Kelvin, said: "When you measure what you are speaking about and express it in numbers, you know something about it, but when you cannot (or do not) measure it, when you cannot (or do not) express it in numbers, then your knowledge is of a meagre and unsatisfactory kind."

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[1.35.0] Last call for RC3 and final release
by Beman Dawes 27 Mar '08

27 Mar '08

As far as I know, all RC2 issues have been cleared. If there are any further changes to be made prior to generation of RC3 and the final release, please notify me immediately. A last run of the regression reports is being generated now. Unless that shows some unexpected regressions, RC3 will be generated immediately afterwards. The purpose of RC3 is to verify there were no packaging failures and no last minute breakages in the install scripts. Unless RC3 turns up showstoppers in those areas, it will then become the final release. --Beman

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Formal review request : Boost Logging Library, take 3
by John Torjo 27 Mar '08

27 Mar '08

Hi all, Just to make it formal, although I said this when v2 got rejected. I'd like another shot, mid July. So, looking for a review manager ;) Any volunteers? Best, John -- http://John.Torjo.com -- C++ expert http://blog.torjo.com ... call me only if you want things done right

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[pool] Tuning the growth characteristics of pool
by Chris Newbold 27 Mar '08

27 Mar '08

Greetings. We've started introducing boost::pool at various places in our software in order to manage allocation of small, short-lived objects. We have run into some difficulty, however, with the algorithm governing the growth of the blocks allocated internally. The currently implementation unconditionally doubles the number of chunks in each subsequent block. This works well for small to medium sized pools, but ends up becoming wasteful and, ultimately, scalability-limiting for pools holding several million objects. Right now we're using the get_next_size() and set_next_size() accessors to meddle with the growth curve and to enforce an absolute limit on next_size. This is somewhat clumsy, however, requiring us to wrap boost::pool with additional logic to inspect next_size and take evasive action when we don't like the new value. I think there might be value in formally parameterizing the algorithm used to expand the pool. My first thought on an interface for controlling the growth algorithm was to add it to the UserAllocator interface. Here's an example of how this might look with the default algorithm hoisted to default_user_allocator_new_delete: // Default UserAllocator implementation for boost::pool; // the block size is doubled on each allocation struct default_user_allocator_new_delete { typedef std::size_t size_type; typedef std::ptrdiff_t difference_type; static char* malloc(const size_type bytes) { ... } static void free(char* const block) { ... } static size_type next_size(size_type size) { return size << 1; } }; // An implementation of the UserAllocator interface for // use with boost::pool which allocates fixed-sized blocks // of 65536 chunks. struct fixed_block_size_allocator : public default_user_allocator_new_delete { static size_type next_size(size_type /* ignored */) { return 2 << 15; } }; One problem I can see with this approach is that "more clever" growth algorithms may want data assigned at runtime-- e.g. an absolute limit at which to stop doubling the block size. This need could be accommodated by making UserAllocators be copy-constructible and changing the boost::pool constructor to take an instance to UserAllocator to be copied and kept internally. Another alternative would be to keep the growth algorithm parameter separate from UserAllocator: // The default pool growth algorithm: it unconditionally doubles // the block size on each successive allocation struct default_growth_algorithm { static size_t operator()(size_t prev_size) { return prev_size << 1; } }; template <typename UserAllocator = default_user_allocator_new_delete typename GrowthAlgorithm = default_growth_algorithm> class pool; The same comments about the potential need to pass a copy-constructible instance of the algorithm to the boost::pool constructor apply to this solution too. I am more than willing to prototype some changes in the code if there is interest in extending boost::pool in this manner. -- Chris Newbold cnewbold(a)mathworks.com The MathWorks, Inc. +1.508.647.8077

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