- Boost - lists.boost.org

[filesystem] to support Windows NTFS symlinks
by David Sirovsky 14 Mar '08

14 Mar '08

Hello All, As far as I understand Boost.Filesystem assumes that there is no symbolic link support in Windows (is_symlink() always returns false, it is impossible to create, etc.), but only hardlinks (using the CreateHardLink API call). As you probably know, symlinks have been introduced in Vista (NTFS only): the API now includes CreateSymbolicLink and a user is able to create symlinks using mklink and see them using dir. [ http://en.wikipedia.org/wiki/NTFS_symbolic_link]<http://en.wikipedia.org/wiki/NTFS_symbolic_link> However, creating fully functional symbolic links was quite possible already in Windows 2000 on NTFS drives - using junction reparse points. [ http://en.wikipedia.org/wiki/NTFS_junction_point]<http://en.wikipedia.org/wiki/NTFS_junction_point> A junction is created with 2 main API calls: hFile = CreateFile( LinkDirectory, GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_FLAG_OPEN_REPARSE_POINT|FILE_FLAG_BACKUP_SEMANTICS, NULL ); . . . DeviceIoControl( hFile, FSCTL_SET_REPARSE_POINT, reparseInfo, reparseInfo->ReparseDataLength + REPARSE_MOUNTPOINT_HEADER_SIZE, NULL, 0, &returnedLength, NULL ) . . . A popular free SysInternals' http://www.microsoft.com/technet/sysinternals/FileAndDisk/Junction.mspx tool is usually used to create/list junctions in Win2000, XP, Vista. Its source-code can be found here: http://web.archive.org/web/20060106050745/www.sysinternals.com/Utilities/Ju… [At the Web-Archive, as the source-code has not yet been officially re-released by Microsoft since SysInternals migration to Technet] (There is also another pre-Vista tool - the Microsoft's fsutil)<http://technet2.microsoft.com/windowsserver/en/library/14cb706b-2a38-48e0-a…> As far as I understand, junctions behave similar to symbolic links - they point to specific "real" locations not only on the same drive, they can be deleted without deleting the target, they still point to already deleted file/directory, etc. They are even in formal use in Windows Vista: for example, "Documents and Settings" is no longer a directory but a junction pointing to some newly introduced user folder; junctions are supported in the mklink tool and are shown using dir. Maybe it is worth considering to introduce Windows NTFS symlinks support in Boost.FileSystem - a straightforward approach would be to use new symbolic link API for Vista target build and junctions for 2000 and XP. [I am sorry if this subject has already been discussed - I have not found any posts on it] Best Regards, David Sirovsky.

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GCC 4.3.0 is available (with some C++0x support)
by Doug Gregor 14 Mar '08

14 Mar '08

GCC 4.3.0 has been released. It contains support for some new C++0x features in its experimental C++0x mode, including rvalue references, variadic templates, and decltype. Please see http://gcc.gnu.org/gcc-4.3/cxx0x_status.html for more information about the C++0x features available in this GCC release. Now would be a great time to start experimenting with C++0x features, to improve Boost libraries or just for fun. Or, come to BoostCon this year for some hands-on experience with the experts. - Doug

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[bind] private member functions
by Robert Dailey 14 Mar '08

14 Mar '08

Hi, Currently I have a class named Foo. Foo is using Boost.Bind to bind one of its own private methods to *this. However, since the method I'm binding is private, boost.bind cannot call it. Is there a way to make Boost.Bind a friend of my class? What is the recommended solution to such a problem? I did some quick searching on google about this issue but I came up with no results. Thanks.

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[thread] [trunk] mutex: Invalid argument
by Dean Michael C. Berris 14 Mar '08

14 Mar '08

Hi Everyone, This has been bothering me a while -- as I'm working on the Memcache++ Client that I'm maintaining and continuing to develop, when I try running the unit test(s) I've written in a specific platform I get 'mutex: Invalid argument' errors being thrown with regards to either locking, unlocking, or destroying mutexes. The platform I'm working on is: Intel Core 2 Quad CPU @ 2.40 Ghz Ubuntu Gutsy Gibbon 7.10 Linux Kernel 2.6.22-14-server (x86_64) gcc (GCC) 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2) I'm working off of Boost's SVN trunk revision 43586. The system is running in 64-bit mode (which may or may not say what the problem can be, because I don't see this problem in 32-bit systems as well as other 64-bit systems). Pointers would be greatly appreciated. -- Dean Michael Berris Software Engineer, Friendster, Inc. <dmberris(a)friendster.com> +639287291459

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Boost asio documentation
by Heckl, Jochen (ext) 14 Mar '08

14 Mar '08

Hi all, I would like to do some experiments with asio, but unfortunately i can't get the documentatino compiled to html. Is there a step by step howto available on how to genreate the asio documentation? Best Jochen

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Boost 1.36 planning
by James Sharpe 14 Mar '08

14 Mar '08

Since the release candidate for 1.35 is now iminent might I suggest that its time to start thinking about appointing a release manager for 1.36 so that the next release management process can begin? There are a number of tasks that I'd argue can be done now - especially as subversion makes this process relatively easy to be managing multiple branches at once. I'm thinking tasks such as establishing supported platforms, integrating newly accepted libraries into the source tree could all begin to happen whilst the final touches are done to 1.35. Then as soon as 1.35 is released, regression testing can begin on 1.36 (as I know that testing resources are limited). This will also help gain some momentum in the release process as library developers can start targeting features towards the 1.36 release as opposed to just general library development with no foreseeable target. I believe that a stronger concept of a code freeze for new features should be employed to try and encourage a quicker release cycle, which should hopefully mean that there are less regressions to deal with as new features will be tested more thoroughly and not left as test failures for so long as they might otherwise be. As a result this suggestion would mean that a release manager should never manage two releases in a row, as it would require some overlap at a particularly crucial stage in the release process, which I think will work well and it also means that should bug fix releases e.g. 1.35.1 be required then the manager for 1.35 would be able to coordinate that without adding any delay to the 1.36 (which will be tracking any bug fixes from 1.35 via the trunk). Note that the other advantage is that release tool development can occur in parallel as problems are found - there was a discussion some time earlier about a suggested tool update(I don't recall what it was now - may have been docs related) which was dismissed as 'lets fix it when 1.35 is done' whereas I think that the correct response should have been 'that can be developed on trunk(or release branch 1.36)' Thoughts? James

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[bind] Automatic argument counting
by Robert Dailey 14 Mar '08

14 Mar '08

Hi, I wish to use boost::bind to simply wrap a member function pointer. I'm passing a member function into a slot in the Boost.Signals library, and I would like the convenience of not having to specify the number of arguments each member function has in boost.bind. For example, assume I have the following class: class Foo { public: void Function1( int ) {} void Function2( int, int, bool ) {} }; I would like to be able to do the following: Foo myFoo; boost::bind( &Foo::Function1, myFoo ); In the case above, I now have an object bound to my function pointer, however I am required to explicitly place a _1, _2, _3 (etc) depending on how many parameters the member function takes. Is there a way that this can be automated? Thanks.

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[Review] Proto review starts today, March 1st
by Hartmut Kaiser 13 Mar '08

13 Mar '08

Hi all, The review of Eric Nieblers Proto library starts today, March 1st 2008, and will end on March 14th. I really hope to see your vote and your participation in the discussions on the Boost mailing lists! --------------------------------------------------- About the library: Proto is a framework for building Domain Specific Embedded Languages in C++. It provides tools for constructing, type-checking, transforming and executing expression templates. More specifically, Proto provides: * An expression tree data structure. * Operator overloads for building the tree from an expression. * Utilities for defining the grammar to which an expression must conform. * An extensible mechanism for immediately executing an expression template. * An extensible set of tree transformations to apply to expression trees. * A mechanism for giving expressions additional behaviors and members. Documentation is here: http://boost-sandbox.sourceforge.net/libs/proto Download proto.zip from here: http://www.boost-consulting.com/vault/index.php?directory=Template%20Metapro gramming Proto is a very important infrastructure library, IHMO. It has been used as the backbone for several other library writing efforts already, such as Xpressive and the rewrite of Spirit (there it has been used for all three parts: the parser, the lexer and the generator modules), and it is a key enabling technology in the long-planned unification of Phoenix and the Lambda Library. --------------------------------------------------- Please always state in your review, whether you think the library should be accepted as a Boost library! Additionally please consider giving feedback on the following general topics: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? - Are you knowledgeable about the problem domain? Regards Hartmut Review Manager

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Trac open bugs - by assignee
by Marshall Clow 13 Mar '08

13 Mar '08

[ 221 open bugs today, 221 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 23 djowel 20 az_sw_dude 14 grafik 13 dgregor 12 vladimir_prus 12 doug_gregor 12 dave 11 agurtovoy 10 no-maintainer 9 bemandawes 8 anthonyw 7 turkanis 7 jsiek 6 johnmaddock 5 witt 5 igaztanaga 4 ebf 4 None 3 t_schwinger 3 ramey 3 matias 3 danielw 2 shammah 2 rogeeff 2 pavol_droba 2 nesotto 2 nasonov 2 kaalus 2 jmaurer 2 hkaiser 2 danieljames 2 aaron_windsor 1 urzuga 1 speedsnail 1 samuel_krempp 1 pdimov 1 marshall 1 garcia 1 dlwalker None 1493 SVN files making it through to install None 1644 Boost.Test missing documentation file BOOST_CHECK_CLOSE_FRACTION.html None 1666 Visualizer for boost::optional None 1678 Boost.property_tree::read_xml does not parse UNICODE file with BOMs 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 1640 [Thread] warnings from VC9 + warning level 4 anthonyw 1657 Bug in boost::threads sample 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 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 752 directory_iterator doesn't work with catch 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 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 865 Use of C++0x keyword as identifier dave 910 gcc strict-aliasing problems with python 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 1394 Translate libs/graph/build/python/Jamfile to BBv2 dgregor 1395 Write Tests for Python Bindings dgregor 1630 gcc-4.3: adjacency_list.hpp includes deprecated header dgregor 1655 Documentation of the depth_first_search() Function 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) 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 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 marshall 1252 [pool] severe overhead with unaligned sizes. matias 1406 Understanding the Tables outdated matias 1651 incorrect typedefs in examples matias 1676 Dead links on Boost.Test example documentation. nasonov 1220 lexical_cast requires RTTI 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 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 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 1628 Lack of wide character support prevents boost.serialization from linking ramey 1662 boost::serialization for boost::optional - missing include rogeeff 1383 signal.h features not found on Mac OS rogeeff 1542 [test] compiler errors when building with stdcxx library 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 1100 Building boost.function_types fails cvs rev-1.1_ no chdir command in bash t_schwinger 1602 function_types Jamfile depends on the source tree being in a specific place. 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 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 469 multitoken broken vladimir_prus 689 [program_options] Endless loop with long default arguments 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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[proto] construct_: typos in docs and not able to get this to work
by Markus Werle 13 Mar '08

13 Mar '08

> [calm down gmane erroneous top-post detector] Hi! Having hard times to catch the ideas of the construct_ example. First of all: There are 2 typos in the definition of construct: // Define the construct() function template that // constructs an object lazily. template<typename T, typename A0, typename A1> // That one led to a lot of confuion // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! // WRONG: typename proto::make_expr< typename proto::result_of::make_expr< proto::tag::function , construct_<T> const , A0 const & , A1 const & >::type const // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!VV!!!!!!!! // WRONG: construct(A0 const &a0, A0 const &a1) construct(A0 const &a0, A1 const &a1) { return proto::make_expr<proto::tag::function>( construct_<T>() , boost::ref(a0) , boost::ref(a1) ); } To keep it off the other thread that I will continue later this day: Could you please remark in the docs with big red letters that make_expr is a type in namespace proto::functional and a function in namespace proto and why name clashes won't appear? I do not like that naming convention, mainly because I cannot remember the rules for the compiler for cases where both are visible. And yes, if you remember, I like to learn them again - now. Also for beginners like me it would be nice to have struct construct_ be renamed to constructor. The '_' is easily overlooked at midnight when you print 2 pages on one as I did. And that text is not for the faint-hearted anyway. Note that I'd prefer code repetition in this example: please add definitions for _1 and _2, better: a complete, compilable example, see next section: Trouble -------- Below is code that does not compile. I get the impression that this led to the confusion in the other thread: I cannot see how proto::eval drops in in the std::transform call. Please correct the code in order to make it work. Markus VC8: 1>------ Build started: Project: Learn_Proto_1, Configuration: Debug Win32 ------ 1>Compiling... 1>test_make_expr_2.cpp 1>using typeof emulation 1>d:\programme\microsoft visual studio 8\vc\include\algorithm(739) : error C2679: binary '=' : no operator found which takes a right-hand operand of type 'const boost::proto::exprns_::expr<Tag,Args>' (or there is no acceptable conversion) ---snip--- #include <iostream> #include <boost/proto/proto.hpp> #include <boost/proto/context.hpp> #include <boost/typeof/std/ostream.hpp> #include <algorithm> #include <vector> #include <map> using namespace boost; typedef std::pair<double, double> S; template <typename T> struct construct_ { typedef T result_type; T operator()() const { return T(); } template<typename A0> T operator()(A0 const &a0) const { return T(a0); } template<typename A0, typename A1> T operator()(A0 const & a0, A1 const & a1) const { return T(a0, a1); } }; // Define the construct() function template that // constructs an object lazily. template<typename T, typename A0, typename A1> typename proto::result_of::make_expr< proto::tag::function , construct_<T> const , A0 const & , A1 const & >::type const construct(A0 const &a0, A1 const &a1) { return proto::make_expr<proto::tag::function>( construct_<T>() , boost::ref(a0) , boost::ref(a1) ); } // Define some placeholder types struct placeholder1 {}; struct placeholder2 {}; // Define the Proto-ified placeholder terminals proto::terminal< placeholder1 >::type const _1 = {{}}; proto::terminal< placeholder2 >::type const _2 = {{}}; int main() { // A lazy S constructor proto::terminal<construct_<S> >::type const construct_S = {{}}; // generate type information via compiler error // int i = construct_S; // Calls the lazy function and constructs an S proto::default_context ctx; S s = proto::eval( construct_S(1, 'a'), ctx ); //typedef proto::terminal<construct_<S> >::type c_t; // This does not work - WHY? // S s2 = construct<S>(_1, _2)(1, 'a'); std::vector<double> a, b; std::vector<S> buffer; std::transform(a.begin(), a.end(), b.begin(), std::back_inserter(buffer), construct<S>(_1, _2)); }

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