April 2010 - Boost - lists.boost.org

[Bind] Function arithmetic (sample impl inside)
by ivan.lelann＠free.fr 12 Apr '10

12 Apr '10

Hi, It's my first message here, so please excuse possible mistakes. I found that Boost.Bind offers logical operators but no arithmetical operators. Looking into boost/bind/bind.hpp, and using "logical_not" impl, I wrote the following naive patch against version 1.40. It is certainly not as robust as Boost exspects, it is quickly tested, but it seems to do the job, as you can see in the test. Please use attached documents as you see fit. Regards, Ivan. PS: attached main.cpp is compiled with g++ 4.4.1, -std=c++0x, "my" bind.hpp in same directory, and boost 1.40 in include path.

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Re: [boost] Crypto Proposal
by Chad Seibert 12 Apr '10

12 Apr '10

> Hi, > > Perhaps this link will work: > > http://socghop.appspot.com/gsoc/student_proposal/show/google/gsoc2010/chads… > Yep, it worked, thanks. > Thanks to all who gave advice, please ask if you have any questions! > It all sounds very good. Can you give an example of what porting some > Botan functionality would look like? Would it be as simple as replacing > the namespace Botan with boost::crypto/whatever in the source code? > An example of what one of the Botan tutorial examples would look like in > the new world would be nice. > Honestly, I think there is no point if you can't commit to part 2. > However, splitting it up into GSoC/non-GSoC is smart on your part. How > do you plan to commit to part 2? > Thanks and good luck :) Here's an example of boostified code, from one of the examples on the site. It's not too different from the original code (it's just commented out); this is because I don't want it to be a chore to port from Botan to Boost.Botan. Also, it is intuitively designed and I see no reason to change it. Of course, if it needs redesigning, we can discuss that afterwards. Also, there are at least 600 files to move that total 2 mb's of source, so it'll take a while, even if it is just changing namespaces and the like. But I'll get started on part 2 if part 1 finishes early. As for committing to part 2, I have some (rough) guidelines for the work to be done afterwards. I'm also taking a lighter courseload so I can spend more time working. I don't know how else to convince you. Anyways, thank you for considering my proposal! Chad Seibert #include <boost/botan.h> #include <iostream> #include <memory> int main(int argc, char* argv[]) { if(argc != 5) { std::cout << "Usage: " << argv[0] << " <passphrase> " << "<ca cert> <ca key> <pkcs10>" << std::endl; return 1; } try { const std::string arg_passphrase = argv[1]; const std::string arg_ca_cert = argv[2]; const std::string arg_ca_key = argv[3]; const std::string arg_req_file = argv[4]; //AutoSeeded_RNG rng; boost::botan::rng::auto_seeded rng; //X509_Certificate ca_cert(arg_ca_cert); boost::botan::x509::certificate ca_cert(arg_ca_cert); //std::auto_ptr<PKCS8_PrivateKey> privkey(PKCS8::load_key(arg_ca_key, rng, arg_passphrase)); std::auto_ptr<boost::botan::pkcs8::private_key> privkey(pkcs8::load_key(arg_ca_key, rng, arg_passphrase)); //X509_CA ca(ca_cert, *privkey); boost::botan::x509::ca ca(ca_cert, *privkey); // got a request //PKCS10_Request req(arg_req_file); boost::botan::pkcs10::request req(arg_req_file); // you would insert checks here, and perhaps modify the request // (this example should be extended to show how) // now sign the request //X509_Time start_time(system_time()); //X509_Time end_time(system_time() + 365 * 60 * 60 * 24); //X509_Certificate new_cert = ca.sign_request(req, rng,start_time, end_time); boost::botan::x509::time start_time(system_time()); boost::botan::x509::time end_time(system_time() + 365*60*60*24); boost::botan::x509::certificate new_cert = ca.sign_request(req, rng, start_time, end_time); // send the new cert back to the requestor //std::cout << new_cert.PEM_encode(); std::cout << new_cert.pem_encode(); } catch(std::exception& e) { std::cout << e.what() << std::endl; return 1; } return 0; } _________________________________________________________________ The New Busy is not the too busy. Combine all your e-mail accounts with Hotmail. http://www.windowslive.com/campaign/thenewbusy?tile=multiaccount&ocid=PID28…

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[preprocessor] BOOST_PP_IS_UNARY()
by Lorenzo Caminiti 12 Apr '10

12 Apr '10

Hello all, Do you know what are the drawbacks of using BOOST_PP_IS_UNARY()? If you have used it, what is your experience with its portability? BOOST_PP_IS_UNARY() is *not* part of the Boost.Preprocessor public API as it is #defined in boost/preprocessor/detail/is_unary.hpp. However, Boost.Preprocessor, Boost.Typeof, and Boost.Spirit seem to use BOOST_PP_IS_UNARY() at least internally: $ find /usr/include/boost/ -name "*.[hc]pp" -exec grep -Hn "BOOST_PP_IS_UNARY" {} \; /usr/include/boost/preprocessor/facilities/apply.hpp:24:# define BOOST_PP_APPLY_I(x) BOOST_PP_EXPR_IIF(BOOST_PP_IS_UNARY(x), BOOST_PP_TUPLE_REM_1 x) /usr/include/boost/typeof/template_encoding.hpp:61: BOOST_PP_IS_UNARY(x),\ /usr/include/boost/spirit/utility/rule_parser.hpp:826: BOOST_PP_EXPR_IIF(BOOST_PP_COMPL(BOOST_PP_IS_UNARY(elem)),elem) In addition, Paul Mensonides mentioned the following in http://lists.boost.org/Archives/boost/2004/08/70238.php > Paul Mensonides wrote: > I know. They (and other types of detection macros) are very useful. Right now, > the Borland configuration is used by the IBM preprocessor and the Sun > preprocessor also. I'd like to know whether or not those macro definitions work > correctly on those preprocessors before I add it. Though those macros aren't > part of the public interface, they are part of the internal interface. I.e. > they are used internally as if they were a public interface (though they are > used carefully on some preprocessors). They are stable, and the worst thing > that might happen in the future is that they will be moved to a different > directory. Thus, you can use them, but beware of VC and versions of MWCW prior > to v9. They in particular have severe problems with expansion order. E.g. VC > will even fail this test: My Boost.Contract code internally uses BOOST_PP_IS_UNARY() and it works fine on GCC 4.2.4 (Ubuntu Linux), MSVC 8.0 (Windows XP), and GCC 3.4.4 (Cygwin) but I have not tried other compilers (including Borland's). Thank you. Lorenzo

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[Locale] Static locale initialisation
by Alexander Lamaison 11 Apr '10

11 Apr '10

I'm encountering a crash with Boost.Locale as the process terminates I initialise the global Boost.Locale in the contructor of a class with a single static instance (the ATL module to be exact) as I don't have access to the code of my main method (it comes from the Boost.Test runner). A static object seems to be the only logical place to put this code: #include <boost/locale.hpp> // boost::locale::generator class CModule : public ATL::CAtlModule { public : CModule() : ATL::CAtlModule() { try { // Initialise Boost.Locale translation mechanism generator gen; gen.add_messages_path("C:/My/Path"); gen.add_messages_domain("swish"); std::locale::global(gen("")); // default locale } catch (std::exception) {} } HRESULT AddCommonRGSReplacements(IRegistrarBase*) { return S_OK; } }; CModule _AtlModule; // Global module instance However, when I run my EXE, it crashes as it terminates with: Unhandled exception at 0x5ba43d93 (msvcp80d.dll) in test-shell_folder.exe: 0xC0000005: Access violation reading location 0x0321f4e4. and the following stack trace: msvcp80d.dll!std::_DebugHeapDelete<std::locale::facet>(std::locale::facet * _Ptr=0x023af590) msvcp80d.dll!_Deletegloballocale(void * ptr=0x5bb25258) msvcp80d.dll!tidy_global() msvcp80d.dll!_Init_atexit::~_Init_atexit() msvcp80d.dll!`dynamic atexit destructor for 'init_atexit''() msvcp80d.dll!_CRT_INIT(void * hDllHandle=0x5ba30000, unsigned long dwReason=0x00000000, void * lpreserved=0x00000001) msvcp80d.dll!__DllMainCRTStartup(void * hDllHandle=0x5ba30000, unsigned long dwReason=0x00000000, void * lpreserved=0x00000001) msvcp80d.dll!_DllMainCRTStartup(void * hDllHandle=0x5ba30000, unsigned long dwReason=0x00000000, void * lpreserved=0x00000001) ntdll.dll!_LdrpCallInitRoutine@16() ntdll.dll!_LdrShutdownProcess@0() ntdll.dll!_RtlExitUserProcess@4() kernel32.dll!76843b69() msvcr80d.dll!__crtExitProcess(int status=0x00000000) msvcr80d.dll!doexit(int code=0x00000000, int quick=0x00000000, int retcaller=0x00000000) msvcr80d.dll!exit(int code=0x00000000) test-shell_folder.exe!__tmainCRTStartup() test-shell_folder.exe!mainCRTStartup() If I move the initialisation code to run just before each point I need to use translate() then it works fine. So maybe this has something to do with the way static data is destroyed. This is on Windows - not sure about other platforms. Any ideas? Many thanks. Alex Lamaison P.S. I realise Boost.Locale isn't in Boost yet but previous discussions have been here so it seems a reasonable place to ask.

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Re: [boost] [GSoC]Bits and Ints
by shiyang yang 10 Apr '10

10 Apr '10

Hi Thanks for the help. But I am still not very sure about the meaning of dynamic_bitfields. Does it mean the size of the bitfield is dynamic? Shiyang

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[GSoC]Bits and Ints
by shiyang yang 10 Apr '10

10 Apr '10

Hi I have been working on the proposal of this project, but still have some questions, could anyone please give me some help? For the bits part, what does the 'compressed' mean, what is the main difference between the array, vector and the normal ones? Is there any other existing integral special functions that mentioned in the second part? Where can I find them? Thanks a lot Shiyang Yang

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Re: [boost] Boost.Botan final proposal
by Chad Seibert 10 Apr '10

10 Apr '10

Hi, Perhaps this link will work: http://socghop.appspot.com/gsoc/student_proposal/show/google/gsoc2010/chads… Thanks to all who gave advice, please ask if you have any questions! Chad Seibert _________________________________________________________________ The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with Hotmail. http://www.windowslive.com/campaign/thenewbusy?tile=multicalendar&ocid=PID2…

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Message Hashing Interface (SHA-1/256/384/512, MD4/5)
by Scott McMurray 10 Apr '10

10 Apr '10

I wrote up some SHA message hashers recently, which came out rather nicely using templates to handle the commonalities between SHA-1/256/384/512. The one issue that came up is how to handle retrieving the hash from the accumulator. When working with just the raw SHA compressor it's not a problem, but when hashing messages, getting the hash of the message requires appending padding and a length. That means that SHA and MD[45] hashing cannot use the same simple interface of Boost.CRC that, in essence, consists of calling process_byte() and inspecting the cheap, const member function hash() as needed. Here are a couple of options: 1) The hash() function is non-const, and it appends the passing and length, calculates the hash, and resets the accumulator to be ready for the next message. This is perhaps the most efficient interface. 2) The hash() function is const, and copies the accumulator, then pads and length-appends the copied version, getting the hash from there instead. That gives perhaps the nicest interface, but the extra copying would be somewhat expensive. That said, it's overhead per message, not dependant on the length of the message, so it may be acceptable. Also, the hash function would still be quite expensive, contrary to usual expectations for const member functions. 3) The hash() function is just a cheap const that returns the current state of the compressor. This would require an additional end_of_message() function that would apply the padding and probably things up such that the next process_byte function would start a new message by resetting the compressor. That would allow the hash() function to be cheaply called as many times as desired between calling end_of_message() and providing the data for the next message. One big problem with this one is that hash() can be called after providing data but before calling end_of_message(), at which point is return value is essentially useless. I think I like (1) best, because it allows the user to copy it and get (2) if they'd rather, and doesn't have the potential call sequencing problem of (3). Any opinions, suggestions, alternatives, or comments? ~ Scott McMurray P.S. Yes, the point here is to create Boost.MD and Boost.SHA libraries. The first client would be Boost.UUID to allow it to offer the MD5 name-based UUIDs it currently cannot. It needs a hashing concept so that it can parametrise name_generator similarly to how it currently parametrises basic_random_generator [1]. [1] http://www.boost.org/doc/libs/1_42_0/libs/uuid/uuid.html#Random%20Generator

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Log/tropical semiring for boost math
by Alex Graves 10 Apr '10

10 Apr '10

Hi, I work in machine learning, and often need to do probability computations in the log scale to avoid underflows. A nice way to do this is to use a class where the add, divide etc. operators are overloaded by their log scale equivalents (e.g. log(a*b) = log(a) + log(b)). In other words a class implementing the log semiring <http://en.wikipedia.org/wiki/Semiring>. Also useful in this context is the tropical semiring, where adding is replaced by taking the maximum (or minimum) of the arguments. I looked for these in the boost math library, but couldn't find anything. So I wrote my own. Did I miss something? And if not, is anyone interested in adding my implementation to boost math? Alex

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Phoenix.bind VS Lambda.bind
by Alexey Tkachenko 10 Apr '10

10 Apr '10

Hi, Now I'm looking at Phoenix and Lambda libraries. Could somebody explain why Lambda allows to use the following expression: void foo(int) { ... } ... bind(foo, _1)(10); yet Phoenix does not. Phoenix requires to use helper variable: void foo(int) { ... } ... int i = 0; bind(foo, _1)(i); I've read document about "Forwarding Function Problem" (http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2002/n1385.htm) I understand the core issue, but how does Lambda.bind solve it? Thank you, Alexey.

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