April 2009 - Boost - lists.preview.boost.org

Re: [boost] [multi-index] Changing hash_index_node.hpp to double linked list
by JOAQUIN M. LOPEZ MUÑOZ 28 Apr '09

28 Apr '09

________________________________________ De: boost-bounces(a)lists.boost.org [boost-bounces(a)lists.boost.org] En nombre de brad higgins [bhiggins(a)arbor.net] Enviado el: martes, 28 de abril de 2009 21:56 Para: boost(a)lists.boost.org Asunto: Re: [boost] [multi-index] Changing hash_index_node.hpp to double linked list > Hi Joaquín, > Thanks for the quick response. I have attached the files I edited. > > Thank you very much for the help, Please allow a day or two till I find time to delve into this. I'll get back to you. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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[interprocess] patch for AIX
by Etienne PIERRE 28 Apr '09

28 Apr '09

Hello, Currently interprocess doesn't work on AIX for two reasons : - detail/os_thread_functions.hpp uses ::pthread_equal but this fails because pthread_equal is a macro under AIX and it fails because of the :: prefix - in detail/atomic.hpp there is no implementation of PowerPC under AIX so I added one that uses the combination of lwarx and stwcx for each function to implement. I saw that under AIX, the detail/atomic_count.hpp and detail/sp_counted_base.hpp falls back to a pthread implementation, I could submit a patch for a real atomic implementation under AIX but I wonder if there are other places in boost where this should be done ? Thanks, Etienne PIERRE

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[Boost.any] Nightly trunk testing failures
by K. Noel Belcourt 28 Apr '09

28 Apr '09

Hi, Most nightly trunk testing results are failing with this error message. Have their been recent changes to Boost.any that could have caused this? # Making "/var/scratch/boost/results" directory... # Starting tests ("/var/scratch/boost/tools_bjam/bin.linuxx86/bjam" "- sBOOST_BUILD_PATH=/var/scratch/boost:/var/scratch/boost/tools_bb" "- sBOOST_ROOT=/var/scratch/boost/boost" "--boost=/var/scratch/boost/ boost" "--boost-build=/var/scratch/boost/tools_bb" "--debug- configuration" -l300 intel-10.0 -d2 preserve-test-targets=off --dump- tests -j8 link=static "--build-dir=/var/scratch/boost/results" >>"/ var/scratch/boost/results/bjam.log" 2>&1)... # Running Boost.Build tests Traceback (most recent call last): File "run.py", line 60, in <module> runner(root) File "/var/scratch/boost/tools_regression_src/regression.py", line 193, in __init__ self.main() File "/var/scratch/boost/tools_regression_src/regression.py", line 551, in main getattr(self,action_m)() File "/var/scratch/boost/tools_regression_src/regression.py", line 516, in command_regression self.command_test() File "/var/scratch/boost/tools_regression_src/regression.py", line 317, in command_test self.command_test_boost_build() File "/var/scratch/boost/tools_regression_src/regression.py", line 354, in command_test_boost_build "boost/bin.v2/libs/any/test/any_test.test")); OSError: [Errno 2] No such file or directory: '/var/scratch/boost/ results/boost/bin.v2/libs/any/test/any_test.test' We get the exact same error message on all Sandia testers, and from the looks of it, most other testers are having the same problem. Any help in getting testing going again would be appreciated. Thanks. -- Noel

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mpl::print and the sun compiler
by Dmitry Goncharov 28 Apr '09

28 Apr '09

The sun c++ compiler doesn't issue a warning about comparison between signed and unsigned integer expressions. The attached patch makes mpl::print produce "implicit int is not supported" warning. With the patch applied the compiler output looks like this: $ CC +w -c print.cpp "/home/dgoncharov/boost/trunk/boost/mpl/print.hpp", line 55: Warning: Implicit int is not supported in C++. "print.cpp", line 3: Where: While specializing "boost::mpl::print<int>". "print.cpp", line 3: Where: Specialized in non-template code. 1 Warning(s) detected. Br, Dmitry

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Re: [boost] [encrypted strings]
by Kasra 28 Apr '09

28 Apr '09

Sid Sacek Wrote: >This sounds very cool. Let me know when you're done. I would definitely >use it. For your needs the library is fully implemented, you don't need to look into RC4 implementation since the library already has many algorithms. On your encrypted string problem, it is best to user during installation techniques. Create an encrypted archive where the user has to provide a product key for the installation to commence. Read decrypted contents from the archive, encrypt it using any encryption algorithm you like however, use a PRNG to generate the key. Seed the PRNG from the available hardware and host OS and etc. Then each time you want the plaintext you regenerate your PRNG then decrypt your ciphertext. -- Kasra

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Re: [boost] [asio] send blocks with MSG_DONTWAIT (linux)
by Stefan Pledl 28 Apr '09

28 Apr '09

> You can switch your socket in the non-blocking mode with > basic_stream_socket::non_blocking_io(). > Though asio should handle MSG_DONTWAIT as well. > > BR, Dmitry Hi Dimitry, that's right, but i need a blocking read and a non-blocking wirte. With basic_stream_socket::non_blocking_io() both, read and write are non-blocking. When i use C-functions read is blocking and write is non-blocking (when passing MSG_DONTWAIT). Best regards Stefan

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Help with VMS port of CMake
by Bill Hoffman 27 Apr '09

27 Apr '09

Hi, I am trying to port CMake to VMS. For the first pass I am going to use the GNV tools and gmake. I am very close, but I am having trouble with files that have more than one "." in the name. CMake uses files like that in several places, as do many CMake based projects. Assuming I use POSIX paths on VMS, does anyone on this list know what magic the GNV cat program uses to handle the following: This works: cat /idisk1/devel/Windows-cl.cmake.in I wrote a simple C++ program that uses fstream to open argv[1], and get the following results: These work: ./test. Windows-cl.cmake.in ./test. Windows-cl^.cmake.in ./test. idisk1:[devel]Windows-cl^.cmake.in This does not: ./test. /idisk1/devel/Windows-cl.cmake.in Any help would be appreciated. Sorry if this is not very boost related, but in previous CMake discussions on the list the topic of VMS came up, so I thought there might be someone that could help me out. Thanks. -Bill

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[reference_wrapper] feature request
by Thorsten Ottosen 27 Apr '09

27 Apr '09

Hi, It came up again in the RangeEx review that we really need reference_wrapper<T> to implement a forwarding operator(). Personally I don't care much for more than one or two arguments, but I guess others will. Thanks -Thorsten

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Re: [boost] [encrypted strings]
by Kasra 27 Apr '09

27 Apr '09

Hi, I am working on a Crypto library for that could do compile time encryption/decryption, however, requires 'constexpr' support from the compiler: template<class T> constexpr void encrypt(T& cipher_text, const T& plain_text) const throw(bad_state); template<class T> constexpr void decrypt(T& cipher_text, const T& plain_text) const throw(bad_state); -- Kasra

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Re: [boost] [encrypted strings]
by raindog＠macrohmasheen.com 27 Apr '09

27 Apr '09

Boost does not have one. If I were you however I would look into a commercial protector such as themida (www.oreans.com) or armadillo or asprotect. ------Original Message------ From: Sid Sacek Sender: boost-bounces(a)lists.boost.org To: boost(a)lists.boost.org ReplyTo: boost(a)lists.boost.org Sent: Apr 27, 2009 8:21 AM Subject: [boost] [encrypted strings] Does boost have any compile-time classes for string encryption? Is it even possible? When a hacker dumps an executable, they can see all of the strings the program might use, and some of those strings may contain sensitive information. Does boost have any classes that can encode the strings at compile-time? Ideally, the third string in the code below would never compile the "secret" string into the final binary. Regards, -Sid void foo( void ) { char const * s1 = "abc"; string s2 = "xyz"; encrypted_string s3( "secret" ); } _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost Sent from my Verizon Wireless BlackBerry

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[tokenizer] Deprecated class used by default
by Boris Schaeling 27 Apr '09

27 Apr '09

I just noticed that although the class char_delimiters_separator is deprecated it is used by default by Boost.Tokenizer. I don't know when char_delimiters_separator was deprecated in favor of char_separator but it goes back to 1.33.1 (see http://www.boost.org/doc/libs/1_33_1/libs/tokenizer/index.html) Any plan to change the default class soon (doesn't need to be in 1.39.0 of course as it's pretty late for such a change)? Boris

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beta docs on the website
by Michael Marcin 27 Apr '09

27 Apr '09

Shouldn't http://beta.boost.org/doc/ have 1.39 docs at this point? -- Michael Marcin

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[asio] send blocks with MSG_DONTWAIT (linux)
by Stefan Pledl 27 Apr '09

27 Apr '09

If i pass the flag MSG_DONTWAIT to basic_stream_socket::send(buffers, flags) the call blocks in the following situation. -> Connection is established (boost::asio::socket_base::send_buffer_size option(2048) is set) -> sending data form local endpoint to remote endpoint -> remote endpoint does not read the data due to software bug/crash etc. -> sendqueue (see netstat) on local endpoint runs full -> send on local endpoint blocks at this point I think the flag MSG_DONTWAIT should avoid this blocking call. If i do the same using C-function send(fd, buf*, len, flag) the call does not block. I have analyzed the code and i think the problem is in send function in asio/detail/reactive_socket_service.hpp socket_ops::send returns but socket_ops::poll_write blocks. I have added the following changes (see comments __SP__) and all works ok for me. Is the blocking desired or where is my mistake? modified code form asio/detail/reactive_socket_service.hpp ---------------------------------------------------------- // Send the given data to the peer. template <typename ConstBufferSequence> size_t send(implementation_type& impl, const ConstBufferSequence& buffers, socket_base::message_flags flags, boost::system::error_code& ec) { if (!is_open(impl)) { ec = boost::asio::error::bad_descriptor; return 0; } // Copy buffers into array. socket_ops::buf bufs[max_buffers]; typename ConstBufferSequence::const_iterator iter = buffers.begin(); typename ConstBufferSequence::const_iterator end = buffers.end(); size_t i = 0; size_t total_buffer_size = 0; for (; iter != end && i < max_buffers; ++iter, ++i) { boost::asio::const_buffer buffer(*iter); socket_ops::init_buf(bufs[i], boost::asio::buffer_cast<const void*>(buffer), boost::asio::buffer_size(buffer)); total_buffer_size += boost::asio::buffer_size(buffer); } // A request to receive 0 bytes on a stream socket is a no-op. if (impl.protocol_.type() == SOCK_STREAM && total_buffer_size == 0) { ec = boost::system::error_code(); return 0; } // Send the data. for (;;) { // Try to complete the operation without blocking. int bytes_sent = socket_ops::send(impl.socket_, bufs, i, flags, ec); // Check if operation succeeded. if (bytes_sent >= 0) return bytes_sent; // Operation failed. if ((impl.flags_ & implementation_type::user_set_non_blocking) || (ec != boost::asio::error::would_block && ec != boost::asio::error::try_again)) return 0; // __SP__ // do not poll if flag MSG_DONTWAIT is set if (flags & MSG_DONTWAIT) return 0; // __SP__ // Wait for socket to become ready. if (socket_ops::poll_write(impl.socket_, ec) < 0) return 0; } }

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Re: [boost] discussion of garbage collection in C++
by Kasra 27 Apr '09

27 Apr '09

Edward Diener wrote: >Also, for people looking for a runtime envrironment for C++, they can look >at Ch. Or CERN.ROOT.CINT project. Either way we are looking at GC in C++ from the wrong direction. I like to know and be able to determine where the memory allocation deallocation occurs. When the constructor and destructor is called using RAII, however, this doesn't mean I shouldn't use GC. GC is supposed to release unused memory, not to call the destructors of objects; although it does on most implementations. [example bool g(int); for(int i=0; i<10000; i++) { // allocate a memory of size = sizeof(Foo) // then construct an instance of Foo on that memory gc_ptr<Foo> f(new (gc) Foo()); // if g(i) == true, delete the memory if( g(i) ) operator delete(f, gc); } // delete all of the objects. GC::collect(); example] The distinction is between construction/destruction of objects and allocation/deallocation of memory. We let GC to perform allocation/deallocation of memory, while we allow ourselves optionaly to take control of construction/destruction of the objects allocated on that memory. This distinction is so important while everyone ignores :D -- Kasra

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[ASIO] Host not found (authoritative)
by Alexander Dong Back Kim 27 Apr '09

27 Apr '09

Dear members, This is a very beginner's question on ASIO. I followed the tutorial example "daytime" in the ASIO document. Server one seems running well because nestat shows the port has been opened and listening. However, when I run the client one, the application prints out "Host not found (authoritative)" message only. I'm using port 21165. $ ./client localhost:21165 Is my command wrong? cheers, Alex Kim

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[1.39] Merge to release
by Daniel James 27 Apr '09

27 Apr '09

Is it okay to merge this? https://svn.boost.org/trac/boost/changeset/52598 It's just a trivial CSS bug fix. thanks, Daniel

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[gc] new implementation in boost vault that solves the issue of finalization order
by Achilleas Margaritis 26 Apr '09

26 Apr '09

Hi. I have posted a new gc implementation in the boost vault here: http://www.boostpro.com/vault/index.php?action=downloadfile&filename=gc1.zi… The code included in the file is a garbage collector with the following differences from the previous one: 1) finalization order that respects destructor semantics, except when there are cycles. In the previous collector, the order of finalization was random. In the new collector, an unreachable object A that is pointed to by another unreachable object B will be finalized after B is finalized. This allows the use of gc ptrs within destructors. 2) O(1) detection of member ptrs: pointers registers themselves to the appropriate ptr list as they are created. In the previous collector, pointers where discovered in the collection phase by look-up on the sorted blocks. The code is not completed or polished, but it is published for discussing possible implementation ideas. The main bottleneck right now is how to locate blocks from pointers. The current solution is to sort the blocks by address at collection time, then use std::upper_bound to locate the blocks. This has O(log2(N)) complexity, where N is the number of blocks.

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[ANN] Spirit V2.1 (beta) committed to the Boost SVN
by Hartmut Kaiser 26 Apr '09

26 Apr '09

Hi all, The Spirit team proudly announces that we committed Spirit V2.1 (beta) to the Boost SVN (trunk). We will continue the development there, so please don't use the Spirit SVN anymore as it will quickly go out of sync. Spirit V2.1 is a complete rewrite of V2.0, while maintaining most of the V2 interface. We will add a comprehensive document explaining what's changed soon. Here are some of the highlights: - More homogeneous interface (multi-attribute API similar to printf/scanf, but using Qi/Karma format descriptions) - More balanced set of primitives and directives (Qi and Karma now better complement each other) - Reduced compile times! Compilation is up to 50% faster if compared to equivalent code from V2. - Optimized execution times. Spirit is now faster than ever before. - Simplified usage of grammars and token definitions - Fixed a whole bunch of bugs and inconsistencies - etc. Please report any experience you might gain (good and bad)! As a side note: Joel and I will give a talk about Spirit V2.1 at BoostCon in Aspen slightly more than a week from now. You still can register (www.boostcon.com) if you haven't done yet. On behalf of the Spirit team Regards Hartmut PS: We would like to thank all who participated and contributed to this. It really was a major team work!

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Boost 1.39.0 beta 1 is available for download
by Beman Dawes 26 Apr '09

26 Apr '09

Boost 1.39.0 beta 1 is available for download from SourceForge. See http://sourceforge.net/project/showfiles.php?group_id=7586&package_id=8041&… New Libraries: Signals2. Updated Libraries: Asio, Flyweight, Foreach, Hash, Interprocess, Intrusive, Program.Options, Proto, PtrContainer, Range, Unordered, Xpressive. Updated Tools: Boostbook, Quickbook. Plus the usual bug fixes to numerous libraries. Please report any problems to the Boost users or developers mailing list. Thanks, --Beman Dawes, Daniel James, and all the other Boosters who help get releases out

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[quick-book] suggestion about library compatibility
by Thorsten Ottosen 26 Apr '09

26 Apr '09

Hi, quickbook already has Admonitions like [note a note] which generates a nice box with an icon. I think it would be useful to have addition admonitions to indicate the following - the library can be serialized with Boost.Serialization - the library can be compiled without exceptions (BOOST_NO_EXCEPTION) - the library can be used with Boost.Interprocess so these can be stated in a consistent manner up front in the documentation. Perhaps it is better that these are written up front like [library Boost.AutoBuffer [quickbook 1.4] [copyright 2009 Thorsten Ottosen] [compatibility noexceptions serialization interprocess] ] ? Any comments? -Thorsten

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[mpl] mpl::string, help needed (vacpp, sun, borland)
by Eric Niebler 25 Apr '09

25 Apr '09

A few days ago, I added mpl::string (a compile-time string class template) to trunk. I expected horrific portability problems with my use of multi-character literals, but it's not as bad as all that judging from the test results. There are only a few failures on compilers I don't have access to: vacpp, sun and borland. I invite anybody with access to these compilers to "bjam string" in the libs/mpl/test directory, try their hand at fixing the problems and submitting a patch. Thanks! -- Eric Niebler BoostPro Computing http://www.boostpro.com

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Proposed templated integer_sort
by Steven Ross 25 Apr '09

25 Apr '09

Would there be interest in an integer_sort call that is faster than std::sort? Spreadsort is an in-place hybrid radix-based and comparison-based algorithm with better worst-case and average-case (roughly 20-50%) performance than introsort on random integer data. The worst-case advantage is algorithmic, with Spreadsort taking the better of O(n(square_root(bit_sizeof(data) - log(n)))) and O(nlog(n)) time. For 32-bit integers, that's O(n(square_root(32 - log(n)))), so for a log(n) of 16 (65536 items), it's 4n (plus a small constant times n), vs 16n for introsort. For larger n, the advantage vs. pure comparison-based algorithms increases. In effect, Spreadsort smoothly transitions from pure MSB Radix sort to std::sort with its data cut up by a couple iterations of MSB Radix sort (reducing the size of the log(n) factor), depending upon the distribution and size of the data. I could write a templated version of Spreadsort for the Boost library if there is interest. It would work for anything that supports the << and - operators. It could also handle standard floats sorted as integers. Functors supporting << and - could make it more general. Multi-dimensional sorting is also sped up by Spreadsort. I could also write a similar string_sort, that should also be significantly faster than std::sort. This would look much like postal sort, just using introsort after a certain number of iterations. Is this of interest? http://sourceforge.net/projects/spreadsort

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BoostCon 2009 Registrar's Report
by Kim Scheibel 24 Apr '09

24 Apr '09

I'm very happy to report that, despite the current economic climate, we currently have a very solid number of confirmed registrations for BoostCon 2009. 84 registrations to be precise, of which 6 were registered in the last two days alone. You still have time to register at the discounted price of USD599 at http://www.boostcon.com/registration, on or before Apr. 26th. After that, the fee is USD699. Best regards, Kim Scheibel BoostCon 2009 Registrar

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Re: [boost] request for interest in a garbage collection library
by Kasra 24 Apr '09

24 Apr '09

>One of the advertised advantages was that is was written purely in >standard C++, which isn't the case of Boehm which isn't portable. I am sure Boehm supports so many platforms and many compilers. Even so, an interpretation from C to ISO C++ is enough for that problem. >> auto_ptr<char*> traced_buffer(new (gc_traced) char[1024]); > This raises undefined behaviour, I believe. gc allocated memory slab is always zero, so there would be no live pointers on the traced_buffer memory slab. I think we the concept of the GC should encapsulate two things separately. memory allocation/deallocation object construction/destruction [example class foo; { auto_ptr< foo > foo_bar(new (gc) foo()); } // call foo_bar->~foo(); example] the RAII call the destructor but the memory that was occupied is not necessarily free. the gc::collect(), collects the memory as well as calling the destructor for non-destructed objects. -- Kasra

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Re: [boost] [soc2009] Proposal for serialization library
by uwe.arzt 24 Apr '09

24 Apr '09

Hartmut Kaiser wrote: > > >> implementation has not responded to my email. You can check out the >> code >> here: >> http://code.google.com/p/google-summer-of-code-2008- >> boost/downloads/list > > In this case you might want to contact the mentor of last year's YAML > project: Joel de Guzman (joel at boostpro dot com). > > Do you know if the merge to boost is planned in the (near) future? Who should be contacted about that? Is help needed? Thanks :q! Uwe -- View this message in context: http://www.nabble.com/-soc2009--Proposal-for-serialization-library-tp226009… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Re: [boost] Boost.Process article: Tutorial and request for comments
by Boris Schaeling 24 Apr '09

24 Apr '09

On Tue, 21 Apr 2009 16:05:04 +0200, Mathias Gaunard <mathias.gaunard(a)ens-lyon.org> wrote: > [...]I assume the name of the executable should be in the locale > character set. > So std::string, or even const char*, appear suitable. > > Now, if you want to perform automatic translation from unicode to locale > character set, why not, but that's another layer on top of that. An > unicode string type should be convertible to the locale character set > easily enough so that you don't need to that in your library, however. > > You could eventually add support for wide characters, though. While wide > characters are Unicode on Windows, they are as far as C++ is concerned > just another locale character set, and I think considering them as > nothing more than that is best. > > As far as I know, POSIX systems simply don't have APIs for wide > characters, however. Another problem on Windows might be that new projects in VC++ 2008 automatically assume Unicode is used. Thus all Windows API functions expect wide character strings which again means for executable names std::wstring would need to be used. And I don't know if developers really think about it and not simply assume that they can use std::string in all cases. I think Ion faced a similar problem when he developed Boost.Interprocess which only accepts const char* strings (and according to http://www.boost.org/doc/libs/1_38_0/doc/html/interprocess/acknowledgements… waits for string conversion utilities which would be the additional layer you mentioned). >> * 'handle' is the underlying native file handle of a stream (file >> descriptor on POSIX systems, handle on Windows). The concept is based >> on a >> class in the detail namespace of Boost.Process. There is just one class >> and it's not meant to be used by users of the library either. Thus I'm >> not >> sure what's the benefit of having an explicit 'handle' concept at all. > > Isn't it in case Boost.Process doesn't implement the features I need, so > that I may use them directly with the native functions? Before I had added a handle() function to the stream classes there was no way to access a handle. Indeed I had added handle() because I wanted to use the file descriptor/Windows HANDLE for asynchronous I/O. I think I agree with you that it should be possible to access native handles. However I'm not sure if a concept has to be defined. Maybe I understand concept wrong but if I hear concept I think about extensibility and different types. In that sense a concept for an executable name makes sense to me (if it wasn't so difficult to support it). But I'm not sure how it fits to a handle? Boris > [...]

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Boost Serialization problem
by Suhail 24 Apr '09

24 Apr '09

Hallo I have currently installl the Boost boost_1.38 . Start new program in VC2003 add following lib in my project boost_serialization-vc71-mt-1_38.lib boost_serialization-vc71-mt-gd-1_38.dll example code: #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <iostream> #include <fstream> #include <stdio.h> using namespace std; void save() { std::ofstream file("archiv.txt"); boost::archive::text_oarchive oa(file); int i = 7; oa << i; } void load() { std::ifstream file("archiv.txt"); boost::archive::text_iarchive ia(file); int i = 0; ia >> i; std::cout << i << std::endl; } //========================================================== /// Main function //========================================================== void main(int argc, char* argv[]) { save(); load(); } After executing this example "archiv.txt" only stores 22 serialization::archive 5 instead of 22 serialization::archive 5 1 Could someone help me where i am making mistake??

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Interest in atomic library?
by Seth LaForge 23 Apr '09

23 Apr '09

In this day and age, running our C++ programs off fossil fuels makes a dangerous contribution to global warming and requires purchase of carbon offsets for ethical programming. Thus I think it's time for a Boost atomic power library. Oops, sorrry, wrong meaning of atomic. What would people think of an atomic integer library, along the lines of Linux's asm/atomic.h? I'd propose a class atomic<T> implementing operations like atomic read (implicit conversion to T), atomic set (assignment from T), and compare-and-exchange. For integral types it would support atomic add and return result (operator+=), atomic subtract and return result (operator-=), atomic increment and return result (prefix operator++), and atomic decrement and return result (prefix operator--). For arbitrary architectures or unhandled types of T, there would be a naive implementation using a mutex. On supported architectures there would be specializations for integral T types, using assembly to implement more efficient atomic operations. This assembly could pretty much just be borrowed from the Linux asm/atomic.h headers. What do people think? I see pros: + Cross-platform efficient atomic operations for efficient threaded apps. I see cons: - Hard to predict whether your atomic ops will be efficient (no specialization for your architecture/T). - Some architectures may implement different atomic ops, making the above ops not the most efficient. I think the pros outweight the cons. I'd personally much rather use a Boost.atomic library than asm/atomic.h. Seth

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Re: [boost] request for interest in a garbage collection library
by Kasra 23 Apr '09

23 Apr '09

>This library is not better than Boehm's gc (certainly slower than Boehm's), >but it is portable C++. I have looked at the library more thoroughly now. If you are interested in improving performance I have a method that could improve the performance big time. Just drop me a personal email. -- Kasra

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Re: [boost] request for interest in a garbage collection library
by Kasra 23 Apr '09

23 Apr '09

I have interest in garbage collection. However, I have few questions about this library. * How is it going to be better than The Boehm GC? * Why isn't it a wrapper for Bohem? This header is what is used within our organisation for GC memory management. [C++ =============================================== C++] #ifndef __GC__ #define __GC__ #define GC_NOT_DLL #include <bohem/gc.h> #include <bohem/gc_allocator.h> #undef GC_NOT_DLL #ifdef BOOST_MSVC # pragma comment(lib, "gc.lib") #endif namespace { using gc_allocator; using gc_traceable; extern const struct gc_memory_t { } gc; extern const struct gc_traceable_t { } gc_traced; inline void* operator new(size_t size, const gc_memory_t&) throw(bad_alloc); inline void* operator new[](size_t size, const gc_memory_t&) throw(bad_alloc); inline void operator delete(void* memory, const gc_memory_t&) throw(bad_alloc); inline void operator delete[](void* memory, const gc_memory_t&) throw(bad_alloc); inline void* operator new(size_t size, const nothrow_t&, const gc_memory_t&) throw(); inline void* operator new[](size_t size, const nothrow_t&, const gc_memory_t&) throw(); inline void operator delete(void* memory, const nothrow_t&, const gc_memory_t&) throw(); inline void operator delete[](void* memory, const nothrow_t&, const gc_memory_t&) throw(); inline void* operator new(size_t size, const gc_traceable_t&) throw(bad_alloc); inline void* operator new[](size_t size, const gc_traceable_t&) throw(bad_alloc); inline void operator delete(void* memory, const gc_traceable_t&) throw(bad_alloc); inline void operator delete[](void* memory, const gc_traceable_t&) throw(bad_alloc); inline void* operator new(size_t size, const nothrow_t&, const gc_traceable_t&) throw(); inline void* operator new[](size_t size, const nothrow_t&, const gc_traceable_t&) throw(); inline void operator delete(void* memory, const nothrow_t&, const gc_traceable_t&) throw(); inline void operator delete[](void* memory, const nothrow_t&, const gc_traceable_t&) throw(); } #endif /* __GC__ */ [C++ =============================================== C++] [example auto_ptr<char*> gc_buffer(new (gc) char[1024]); auto_ptr<char*> traced_buffer(new (gc_traced) char[1024]); example] -- Kasra

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[1.39.0] [Lambda] [Iterator] Warnings with gcc 4.3?
by Beman Dawes 22 Apr '09

22 Apr '09

In an email about something else, someone asked: ... we will be eager to use your upcoming version 1.39. One point we would be interested is to remove the following warnings on gcc 4.3. Would you know if those were fixed? <warning value="boost-1_38/boost/lambda/detail/lambda_functors.hpp:137: warning: type qualifiers ignored on function return type" /> <warning value="boost-1_38/boost/lambda/detail/select_functions.hpp:55: warning: type qualifiers ignored on function return type" /> <warning value="boost-1_38/boost/lambda/detail/select_functions.hpp:60: warning: type qualifiers ignored on function return type" /> <warning value="boost-1_38/boost/lambda/detail/select_functions.hpp:65: warning: type qualifiers ignored on function return type" /> <warning value="boost-1_38/boost/iterator/iterator_facade.hpp:652: warning: type qualifiers ignored on function return type" /> Does anyone know the status of these? --Beman

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[Boost-announce] Review Conclusion - Futures Library
by Tom Brinkman 21 Apr '09

21 Apr '09

Review Conclusion - Futures Library Braddock Gaskill http://braddock.com/~braddock/future Anthony Williams http://www.justsoftwaresolutions.co.uk/files/n2561_future.hpp The lack of examples and documentation made them difficult to review. Nevertheless, Anthony Williams futures library did receive almost unanimous and enthusiastic support. Unfortunately, the depth of the support was very shallow. I just finished my first read of Anthony's book "C++ Concurrency in Action and acknowledge his expertise in the areas of multi threaded and parallel programming. (http://www.manning.com/williams/) Anthony is the maintainer of boost::threads. Anthony's Future library has been approved for the next major release of c++ standard. Conclusion Braddock Gaskill - Rejected Anthony Williams - Approved Anthony's Futures library is approved for inclusion into boost::threads. As he is the maintainer of that library, he should be given maximum latitude about how that is to be done. In the future, if Anthony wants to re-publish the library as a top-level boost library, then he needs to resubmit it again with samples and test cases, which are lacking. Requirements As per the usual boost library requirements, examples and test cases are needed. Anthony should also improve the documentation, which should not be a problem as he is a prolific author in the area of multi threaded programming. Review Manager Tom Brinkman _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost-announce

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[mpi] Automatically Cascading/Nested Reduce?
by Dean Michael Berris 21 Apr '09

21 Apr '09

Hi Guys, I'm writing quite a number of parallel-distributed applications in the day job, and I'm missing a facility which allows for "automagically" nesting my reductions. The reduction strategy I'm looking for is one of a networked approach where (if you can imagine a tree): 0 |-1 | |-2 | |-3 | |-4 |-5 |-6 Nodes 2 and 3 send their data to node 1, node 5 and 6 send their data to node 4, and eventually node 1 and 4 send their (reduced) data to node 0. My idea is that it should be simple to implement this without having to go through too much trouble with communicators -- or that it could be automagically done by hiding the communicator splits in the special reduce implementation. Would something like this be best implemented within Boost.MPI? Or is there a way of implementing this by composing the functionality already available in Boost.MPI? The reason I ask is that sometimes the reduction step dominates the amount of time the application spends especially when you have quite a number of nodes (around 90ish). Being able to parallelize (or nest) the reduction would definitely help, but the cost of supporting that routine over a number of applications seems to warrant a special implementation of the Boost.MPI reduce. TIA -- Dean Michael Berris | Software Engineer, Friendster, Inc. blog.cplusplus-soup.com | twitter.com/mikhailberis | linkedin.com/in/mikhailberis | profiles.friendster.com/mikhailberis | deanberris.com

2 3

Problem with write_graphviz
by Josep TORRAS FLAQUER 21 Apr '09

21 Apr '09

Hello, I'm working with boost graph library. I'm creating a graph and i'd like to write its description into a file or to display it on the screen. The properties of Edges and Vertex are bundled, and i'm not able to write them. I have read the doc once and again and i don't get to find a solution. I have looked for examples but i haven't found anything actually useful for me. Could anyone please help me or propose a possible solution? Here is my code: #include <boost/graph/iteration_macros.hpp> #include <string> #include <boost/tuple/tuple.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/visitors.hpp> #include <boost/graph/breadth_first_search.hpp> #include <map> #include <boost/graph/adj_list_serialize.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/multi_array.hpp> #include <cassert> #include <boost/graph/graphviz.hpp> //using namespace boost; struct VertexProperties{ std::string gate_type; int gate_level; int gate_index; int num_input; float prob_err; }; struct edge_properties { std::string name; }; typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, VertexProperties , edge_properties> Graph; typedef boost::graph_traits<Graph>::vertex_descriptor Vertex; typedef boost::graph_traits<Graph>::edge_descriptor Edge; int main() { int i=0; //const char* name = "123"; Graph g; Vertex u1; u1=add_vertex(g); g[u1].gate_type = "Input"; g[u1].gate_level=1; g[u1].gate_index=i; g[u1].num_input=0; g[u1].prob_err=0; i++; Vertex u2; u2=add_vertex(g); g[u2].gate_type = "Input"; g[u2].gate_level=1; g[u2].gate_index=i; g[u2].num_input=0; g[u2].prob_err=0; i++; Vertex u3; u3=add_vertex(g); g[u3].gate_type = "Input"; g[u3].gate_level=1; g[u3].gate_index=i; g[u3].num_input=0; g[u3].prob_err=0; i++; Vertex u4; u4=add_vertex(g); g[u4].gate_type = "XOR"; g[u4].gate_level=2; g[u4].gate_index=i; g[u4].num_input=0; g[u4].prob_err=0.001; i++; Vertex u5; u5=add_vertex(g); g[u5].gate_type = "AND"; g[u5].gate_level=1; g[u5].gate_index=i; g[u5].num_input=0; g[u5].prob_err=0.001; i++; Vertex u6; u6=add_vertex(g); g[u6].gate_type = "XOR"; g[u6].gate_level=1; g[u6].gate_index=i; g[u6].num_input=0; g[u6].prob_err=0.001; i++; Vertex u7; u7=add_vertex(g); g[u7].gate_type = "AND"; g[u7].gate_level=1; g[u7].gate_index=i; g[u7].num_input=0; g[u7].prob_err=0.001; i++; Vertex u8; u8=add_vertex(g); g[u8].gate_type = "OR"; g[u8].gate_level=1; g[u8].gate_index=i; g[u8].num_input=0; g[u8].prob_err=0.001; i++; Edge e1; e1=(add_edge(u1,u4,g)).first; Edge e2; e2=(add_edge(u1,u5,g)).first; Edge e3; e3=(add_edge(u2,u4,g)).first; Edge e4; e4=(add_edge(u2,u5,g)).first; Edge e5; e5=(add_edge(u3,u6,g)).first; Edge e6; e6=(add_edge(u3,u7,g)).first; Edge e7; e7=(add_edge(u4,u6,g)).first; Edge e8; e8=(add_edge(u4,u7,g)).first; Edge e9; e9=(add_edge(u5,u8,g)).first; Edge e10; e10=(add_edge(u7,u8,g)).first; const char* name[] = { "Input 1", "Input 2", "Input 3","XOR","AND","XOR","AND","OR"}; int index[] = {g[u1].gate_index,g[u2].gate_index,g[u3].gate_index,g[u4].gate_index,g[u5].gate_index,g[u6].gate_index,g[u7].gate_index,g[u8].gate_index}; write_graphviz(std::cout, g, boost::make_label_writer(name)); } I am able to write a label, but i can't write all the properties, and that's what i want. Thank you. Josep

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[Math] Making math compile on C99 archs with no long double
by Seth LaForge 21 Apr '09

21 Apr '09

In trying to compile Boost 1.38.0 for arm/gcc-4.1.2, which has no long double support, I ran into the following compile error: ./boost/math/special_functions/expm1.hpp: In function ‘long double boost::math::expm1(long double, const boost::math::policies::policy<boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy, boost::math::policies::default_policy>&)’: ./boost/math/special_functions/expm1.hpp:270: error: ‘::expm1l’ has not been declared The fix is simple - the expm1.hpp is trying to use a long double C99 function despite BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS being defined. The following patch (also attached in case gmail mangles it) fixes the problem: diff -r -u boost_1_38_0.orig/boost/math/special_functions/expm1.hpp boost_1_38_0/boost/math/special_functions/expm1.hpp --- boost_1_38_0.orig/boost/math/special_functions/expm1.hpp 2009-01-07 08:37:59.000000000 -0800 +++ boost_1_38_0/boost/math/special_functions/expm1.hpp 2009-04-20 18:24:33.312485307 -0700 @@ -267,10 +267,12 @@ #if defined(BOOST_HAS_EXPM1) && !(defined(__osf__) && defined(__DECCXX_VER)) # ifdef BOOST_MATH_USE_C99 inline float expm1(float x, const policies::policy<>&){ return ::expm1f(x); } +# ifndef BOOST_MATH_NO_LONG_DOUBLE_MATH_FUNCTIONS inline long double expm1(long double x, const policies::policy<>&){ return ::expm1l(x); } -#else +# endif +# else inline float expm1(float x, const policies::policy<>&){ return ::expm1(x); } -#endif +# endif inline double expm1(double x, const policies::policy<>&){ return ::expm1(x); } #endif

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BoostCon lodging
by Sebastian Redl 20 Apr '09

20 Apr '09

Hi list, Two things. First, a comment at the BoostCon lodging page[1] gave me the impression that lodging for two isn't actually cheaper than for one. Is this correct? Second, is anyone interested in sharing a room at a place where this actually is cheaper? (And do you have recommendations for such a place?) I have to pay for lodging myself and would like to reduce the costs. Regards, Sebastian [1] http://www.boostcon.com/location/lodging#reservations

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[smart_ptr] post 1.34 regression
by Gennadiy Rozental 20 Apr '09

20 Apr '09

Hi, Following snippet compiles fine with 1.34.1 -------------------------- #include "boost/shared_ptr.hpp" class Base { public: virtual ~Base() {} }; class Derived; boost::shared_ptr<Base> foo() { return boost::shared_ptr<Derived>(); } class Derived : public Base {}; -------------------------- It fails though with boost 1.36: a.cpp: In function `boost::shared_ptr<Base> foo()': a.cpp:13: error: conversion from `boost::shared_ptr<Derived>' to non-scalar type `boost::shared_ptr<Base>' requested Looks like it caused by additional argument in template constructor sp_enable_if_convertible. Is it intentional? Can we still support old use case? Gennadiy

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[SCOPE_EXIT] compiler errors for structure members
by Sid Sacek 20 Apr '09

20 Apr '09

struct { int one; } test ; test.one = 55; BOOST_SCOPE_EXIT( ( test.one ) ) { } BOOST_SCOPE_EXIT_END The above code gives me lots of compiler errors. Is there a special syntax I have to provide to be able to use structure members? Thanks, -Sid Sacek The errors I get using MSVC 2008 are: error C2065: 'boost_se_tag_0_12' : undeclared identifier error C2144: syntax error : 'int' should be preceded by ')' error C2059: syntax error : ')' error C2065: 'boost_se_tag_0_12' : undeclared identifier error C2143: syntax error : missing ')' before 'constant' error C2039: 'type' : is not a member of '`global namespace'' error C2653: 'boost_se_wrapped_t_0_12' : is not a class or namespace name error C2143: syntax error : missing ';' before '{' error C2065: 'boost_se_param_t_0_12' : undeclared identifier error C2065: 'boost_se_tag_0_12' : undeclared identifier error C2065: 'boost_se_tag_0_12' : undeclared identifier error C2143: syntax error : missing ',' before 'constant' C2143: syntax error : missing ',' before ')' error C2653: 'boost_se_params_t_12' : is not a class or namespace name error C2143: syntax error : missing ';' before '{' error C2143: syntax error : missing ';' before '}' error C2143: syntax error : missing ';' before '}' error C2143: syntax error : missing ',' before ')'

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[graph] a patch for dominator_tree.hpp
by Jongsoo Park 20 Apr '09

20 Apr '09

Hi all, Recently, I've got few mails concerning about the performance of my dominator tree implementation in the boost graph library, which can be solved by a simple modification. The attached file is my patch on that problem which is based on the most recent version in the subversion repository. Could somebody who has a permission to modify the code apply this patch? The patch has only 5 lines difference and I've double checked it works correctly. Thanks, Jongsoo

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[math] merge of signbit(-NaN) fix?
by Francois Barel 20 Apr '09

20 Apr '09

Hi, Boost.Math had some changes on trunk a few months ago, on the implementation of signbit, to fix the invalid result of signbit(-NaN) (fixed by using Johan Rade's fp_traits library). Currently, in order to work with multiple Boost releases, Spirit2x uses: - a custom version of signbit when compiled against an older Boost release, - the Boost.Math implementation when compiled against Boost 1.39 or later (on the assumption that those changes will be in Boost 1.39). But looking at the schedule sent by Beman, we're nearing the 1.39 beta (some time this week), and those changes have not been merged to release branch. I was wondering, is it planned to merge them for 1.39, or will it only be done in a later release? Thanks, François

1 0

Building stage by default, pt. 2
by Vladimir Prus 19 Apr '09

19 Apr '09

Hi, previously, we discussed that building the 'stage' target by default would be a good idea -- since some users forget that and don't have an easy way to get at built libraries. See: http://thread.gmane.org/gmane.comp.lib.boost.devel/182787 I've now implemented the change, taking into account the comments in that thread. In particular: - the message now uses absolute paths - the location of headers is explicitly specified Here's an example of the message that is output if you do "./bjam" in Boost root: Building C++ Boost. After the build, the headers will be located at /home/ghost/Work/Boost/boost-svn The libraries will be located at /home/ghost/Work/Boost/boost-svn/stage/lib Use 'bjam install --prefix=<path>' if you wish to install headers and libraries to a different location and remove the source tree. I was considering outputting a 'summary' at the end of the build, as opposed at the beginning, but that would require some Boost.Jam changes and therefore cannot be accomplished at this point of release cycle. Anybody wishes to comment on the wording before this gets merged to release branch? - Volodya

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Re: [boost] [boost::exception] operator >>
by Gaydov Victor 19 Apr '09

19 Apr '09

> > Emil Dotchevski <emildotchevski(a)gmail.com> wrote: >> > hello! i'm using boost::exception in one project and did small modification >> > for myself, what do you think about it ? >> > >> > i don't want to create a lot of exception classes, because my 'catches' will >> > use only a few of them anyway. but while exception is throwing, some >> > functions add different information to it (with operator <<) that is useful >> > in diagnostic messages. >> > >> > so when we decide to extract that information from exception, we need to >> > study what useful information it has. instead of using if-else it'll be nice >> > to use inheritance of _errors_ (not exceptions), for example: >> > >> > throw our_exception () << error_1 (); >> > ... >> > catch (our_exception & e) >> > { >> > re-throw e << error_2 (); >> > } >> > ... >> > catch (our_exception & e) >> > { >> > shared_ptr <base_of_error_1_and_2> ptr; >> > while (e >> ptr) >> > cout << ptr->format_error_message(); >> > } >> > > I understand what you are doing but I don't understand why. Could you > provide a non-abstract example of a use case that benefits from this > addition? No problem. We have to basic exception classes: errors associated with external files or system calls and internal interpreter errors. To work properly, program don't need a lot of information about errors, but we need this information in error messages. boost::exception gives simple way to collect error context so each function does not need to worry about errors it catches, but should just add its context. In result, content of exception depends on it path throw function and modules. A few pieces of code (i omit boring parts): struct silent : virtual exception { inline silent (guid_t e) : exception (e) {} }; struct critical : virtual exception { inline critical (guid_t e) : exception (e) {} }; template <typename level> struct system_error : public level { inline system_error (guid_t e) : exception (e), level (e) {} }; struct info { virtual void printf (boost::format &) const = 0; virtual guid_t format (void) const = 0; virtual ~info () {} }; // in RL we generate them using boost macros :) struct module_info_e : public info { guid_t format (void) const { return 101; } void printf (boost::format & dest) const { const boost::tuple < string, string > & tuple = static_cast < const boost::error_info< module_info_e, boost::tuple <string, string> > *> (this) -> value(); dest % tuple.get<0>() % tuple.get<1>() ; } }; typedef boost::error_info < module_info_e, boost::tuple < string, string > > module_info ; enum { bad_module }; ....... // in Module::arch_dependent::load throw system_error <silent> (bad_module); ..... // in Module::load catch (silent & e) { throw e << module_info (make_tuple ("1.so", "error while loading")); } ..... // in Script::run that can run command that loads module (or not, we don't know) catch (silent & e) { throw e << context_info (make_tuple (current_line)); } ..... // some function that should be stable catch (exception & e) { print_error (e); } print_error() is a point where we should discover exception content. In above example it is like this: ostringstream message; for (boost::shared_ptr <info const> base ; e >> base ; ) { boost::format format (Sys::Instance().Reader <Resources> :: get <char_t*> (base->format ( ))); // get format string for error base->printf (format); // fill format string with error info content message << format << std::endl; } If we use exception hierarchy instead of error information hierarchy we don't have such freedom like this (using virtual functions) because we can't combine error information so random. So it is main purpose -- to avoid worrying about what errors we are catching). Also IMHO it is not too beautiful because a lot of functions shouldn't know anything about error information, only about exceptions, so they should be separated. I don't insist on this, just report changes that I need for myself. I'm sorry i'm too verbose (or sorry if i'm not verbose enough :)

1 0

C++ function bind
by claud.86＠email.it 19 Apr '09

19 Apr '09

Hi to all, i use libboost recently, it is the ideal solution for my software c++. Now I'm using asio and I need to invoke a function like this: fun(time_from_string("2010-01-30 5:03:02"),bind(&timer::run,this)); The body of fun will look like this: void fun(ptime t,void h) { ... timer.async_wait(h); ... } Obviously the return of the type of bind is not void and that is why there is an error. What kind should be the h parameter? Which is the prototype of fun? Thanks for your attention Claudio -- Caselle da 1GB, trasmetti allegati fino a 3GB e in piu' IMAP, POP3 e SMTP autenticato? GRATIS solo con Email.it: http://www.email.it/f Sponsor: Tutto in tempo reale sul tuo cellulare: news, messaggistica istantanea, email e molto altro ancora con m.email.Scopri di più Clicca qui: http://adv.email.it/cgi-bin/foclick.cgi?mid=8919&d=20090417

3 2

Extracting floating point constant exponent/mantissa at compile time
by Joel Falcou 19 Apr '09

19 Apr '09

I'm seeking a way to perform compile-time "bitwise" casting of floating value aka turning a float into an uint32_t value with the same bit pattern. Eg: -3.14f becoming 0xC048F5C3 I saw a mpl::double_ in the vault but I can't make tail nor head of the trick used in the large macros.hpp file. Considering I only need the capability of storing a flaot as a bit pattern and don't need the additional arithmetic, can someone enlighten me on the process used in mpl::double ?

2 5

[ptr_container] Documentation refers to a nonexistent member function
by Michael Marcin 19 Apr '09

19 Apr '09

The docs mention a release_back method which doesn't seem to exist. http://tinyurl.com/dyaumy -- Michael Marcin

2 1

[range] Extended... maybe?
by Vladimir.Batov＠wrsa.com.au 19 Apr '09

19 Apr '09

I am trying something looking fairly reasonable: string str1 = boost::replace_all_copy(str, 'x', '0'); It obviously fails to compile with: error: no matching function for call to 'begin(const char&)' error: no matching function for call to 'end(const char&)' as replace_all_copy() wants boost::ranges for the 2nd and 3rd parameters: replace_all_copy( const SequenceT &, const Range1T &, const Range2T &); and 'x' and '0' are not boost::ranges. Would that be sensible to extend boost::range along the following lines to allow string_algo to work with individual characters? namespace boost { template<> struct range_iterator<char> { typedef char* type; }; template<> struct range_const_iterator<char> { typedef char const* type; }; namespace range_detail { template<> inline char const* boost_range_begin(char const& c) { return &c; } template<> inline char const* boost_range_end(char const& c) { return &c + 1; } } } Thanks, Vladimir. P.S. I do understand that the following works string str1 = boost::replace_all_copy(str, "x", "0");

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[1.39] Release notes
by Daniel James 19 Apr '09

19 Apr '09

Hello all, If you haven't already, please can you add your release notes for 1.39. It's the same procedure as always, the notes are stored in 'boost_1_39_0.qbk' in the directory: https://svn.boost.org/svn/boost/website/public_html/beta/feed/history If you don't know quickbook please don't worry about the syntax, I'll clean up any problems and rebuild the page daily - all that matters is that your intent is clear. If for any reason you can't commit to the website then email your notes to the list and I'll add them. thanks, Daniel

1 0

[fusion] fix for Ticket #2761
by Stjepan Rajko 19 Apr '09

19 Apr '09

Hi, The attached (minimal) patch addresses ticket #2761: https://svn.boost.org/trac/boost/ticket/2761 I tested the fix on my platform (gcc 4.0.1/darwin) and it didn't break any tests. Could this be committed to trunk? (I *think* I might even be able to do the commit myself, if it is OK). Thanks, Stjepan

1 0

[smart_ptr] make_shared perfect forwarding bug
by Frank Mori Hess 18 Apr '09

18 Apr '09

Perfect forwarding doesn't seem to work quite correctly with boost::make_shared. The attached program, which tries to pass a move-only type through make_shared fails to compile with gcc in c++0x mode. To fix it, I had to change the definition of detail::forward in make_shared.hpp to use rvalue references: #if defined( BOOST_HAS_RVALUE_REFS ) template< class T > T&& forward( T &&t ) { return t; } #endif This is just based on looking at how gcc implements std::forward. Is this the right fix?

2 1

[boost::exception] operator >>
by Gaydov Victor 18 Apr '09

18 Apr '09

hello! i'm using boost::exception in one project and did small modification for myself, what do you think about it ? i don't want to create a lot of exception classes, because my 'catches' will use only a few of them anyway. but while exception is throwing, some functions add different information to it (with operator <<) that is useful in diagnostic messages. so when we decide to extract that information from exception, we need to study what useful information it has. instead of using if-else it'll be nice to use inheritance of _errors_ (not exceptions), for example: throw our_exception () << error_1 (); ... catch (our_exception & e) { re-throw e << error_2 (); } ... catch (our_exception & e) { shared_ptr <base_of_error_1_and_2> ptr; while (e >> ptr) cout << ptr->format_error_message(); } i attached 'test.cpp' and 'operator.cpp' with stupid realization and example. if somebody thinks it can be useful of cause i can rewrite it to make it more practical.

2 2