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[switch] Is there any interest in library switch extention?
by Kasra (Math & ComSci) 14 Sep '08

14 Sep '08

Hello to all; I came up with an idea of extending the current switch functionality using library extensions. The problem is mostly when we have char[] (or any other object) in the switch statement: void do_switch(const char *cstr) { switch( cstr ) { case "Sunday": case "Saturday": ... break; case "Monday": ... }; } Obviously we can't do this using C++ alone, so if we have something like BOOST_SWITCH() which would accomplish this would be great. I have a runtime solution (with need of some attention) for this, however, a compile time solution is desirable. The library should do something like: BOOST_SWITCH( "hello world" ) { BOOST_CASE( "hello" ): BOOST_CASE( "world" ): ... break; BOOST_DEFAULT: ... }; (Please don't suggest 'enum' solutions since they are not as dynamic and are confined to very small domain) Any suggestions, ideas & etc? With best regards Kasra

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[RangeEx] Range & RangeEx
by Robert Jones 14 Sep '08

14 Sep '08

RangeEx appears to have the functionality I'm seeking, which is the std algorithms overloaded for ranges, but there's few things I'm not clear about. I've downloaded the range_ex.zip archive from the vault, but I'm not clear if it replaces or extends Boost.Range. Am I now able to write things like #include <vector> #include <iostream> #include <iterator> #include <boost/range.hpp> void f( vector<int> const & v ) { using namespace std; using namespace boost; copy( v, ostream_iterator<int>( cout, " " ); }

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[Xpressive] vs libpcre performance
by Sebastian Redl 14 Sep '08

14 Sep '08

Hi, A German journal recently published a small programming contest with a very simple text processing problem. The program needs to renumber and sort footnotes in a long text. I wrote a solution in C++ using a number of Boost libraries, among them Xpressive, but also Interprocess for memory-mapping the input file. Then I looked at the submissions page and found one C++ solution already there, an admirably short (but rather inflexible) program using libpcre. http://www.linux-magazin.de/static/listings/magazin/2008/10/leser/cpp/footn… Comparing the performance, my program was sightly but consistently slower than this small program, even when I felt that my usage of memory-mapping and then scanning the whole file instead of going line by line ought to give me a speed advantage. So to test the performance I took the existing submission and replaced libpcre with Xpressive (see attached file). I believe the solutions to be functionally equivalent. However, the original takes 6 seconds to process a 55MB file, whereas my variation takes ~15 seconds. That's on the second run of each program, meaning that the entire file is in the OS cache. This seems awfully slow. Has anyone done a proper performance comparison between Xpressive and libpcre? Boost.Regex's performance pages lists PCRE, but in version 4.1, where 7.8 is the most recent release. My system: Athlon 64 2000MHz (64-bit mode) 1GB RAM Linux 2.6.23, GCC 4.1.2 Boost trunk as of 2008-09-11 libpcre 7.7 Sebastian Redl

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warnings in tests
by Emil Dotchevski 13 Sep '08

13 Sep '08

In Boost testing, wouldn't it be a good idea to have a script that scans the output generated from each successful test for the word "warning" and indicate its presence in the test matrix? Perhaps leave the box green but instead of "pass" have it say "pass/w" or something. Without this, platform-specific warnings can only be addressed after they're reported by the end users. Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode

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[Dataflow] [Review] Dataflow review has ended
by jarvi＠cs.tamu.edu 13 Sep '08

13 Sep '08

The number of reviews for the dataflow library was very low (one, positive). Rather than extending the review period in hopes for more reviews, the review period of the data-flow library is now over, and at this time the library is not accepted as a Boost library. The discussions indicated that there's some confusion regarding the library's role; this concern needs to be addressed prior to moving forward with the library. Stjepan is content of the feedback received during the review, and will use it to clarify the library's documentation and further develop the library. He intends to bring the library for review again when the concerns raised have been addressed. Even though the review period is over, I encourage everyone to submit their comments, half-written reviews, reviews that you were planning to write, etc. as those will help Stjepan in his efforts in improving the library. Thank you for everyone for participating in the review, and thank you Stjepan for your work for Boost! Jaakko Järvi Review Manager

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[thread_pool]: formal review request
by Oliver Kowalke 12 Sep '08

12 Sep '08

Hello, I'd like to request a review of my thread_pool library - it is available at the boost vault/Concurrent Programming. The library provides: - thread creation policies: determines the managemnt of worker threads - fixed set of threads in pool - create workerthreads on demand (depending on context) - let worker threads ime out after certain idle time - channel policies: manages access to queued tasks - bounded channel with high and low watermark for queuing tasks - unbounded channel with unlimited numer of queued tasks - rendezvous syncron hand-over between producer and consumer threads - queueing policy: determines how tasks will be removed from channel - FIFO - LIFO - priority queue (attribute assigned to task) - smart insertions and extractions (for instance remove oldest task with certain attribute by newst one) - tasks can be chained and lazy submit of taks is also supported (thanks to Braddocks future library). - returns a task object from the submit function. The task it self can be interrupted if its is cooperative (means it has some interruption points in its code -> this_thread::interruption_point() ). Oliver -- GMX Kostenlose Spiele: Einfach online spielen und Spaß haben mit Pastry Passion! http://games.entertainment.gmx.net/de/entertainment/games/free/puzzle/61691…

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[Iterator] Zip iterator for back_insert_iterators?
by Kris Rousey 12 Sep '08

12 Sep '08

I just tried to make a zip iterator out of two vector back_insert_iterators and got a very curious compile failure: /usr/include/boost/iterator/iterator_facade.hpp:653: error: invalid parameter type 'void' /usr/include/boost/iterator/iterator_facade.hpp:653: error: in declaration 'typename boost::detail::operator_brackets_result<Derived, Value, Reference>::type boost::iterator_facade<I, V, TC, R, D>::operator[](Difference) const' /usr/include/boost/iterator/iterator_facade.hpp:693: error: invalid parameter type 'void' /usr/include/boost/iterator/iterator_facade.hpp:693: error: in declaration 'Derived& boost::iterator_facade<I, V, TC, R, D>::operator+=(Difference)' /usr/include/boost/iterator/iterator_facade.hpp:699: error: invalid parameter type 'void' /usr/include/boost/iterator/iterator_facade.hpp:699: error: in declaration 'Derived& boost::iterator_facade<I, V, TC, R, D>::operator-=(Difference)' /usr/include/boost/iterator/iterator_facade.hpp:705: error: invalid parameter type 'void' /usr/include/boost/iterator/iterator_facade.hpp:705: error: in declaration 'Derived boost::iterator_facade<I, V, TC, R, D>::operator-(Difference) const' It seems that even though back_insert_iterator has an output_iterator tag, iterator_facade still trying to define random access operators. If assignment and incrementing are the only valid operations on an iterator (as is the case with output iterators), then doesn't it make sense to support a difference_type of void? Is this a curiosity of my stdlib implementation? A Boost.Iterator library oversight? A Boost.Iterator conscious design decision? Or a loose nut behind the keyboard trying something he shouldn't? I'm using version 1.35.0 on Ubuntu 8.04 x86_64 with g++ version 4.2.3. Here's the code I used to get this error: #include <iterator> #include <iostream> #include <boost/iterator/zip_iterator.hpp> #include <vector> #include <algorithm> using namespace std; using namespace boost; int main() { vector<int> ha1; vector<double> ha2; make_zip_iterator( make_tuple( back_inserter(ha1), back_inserter(ha2) ) ); return 0; } Thanks, Kris

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[In_Place_Factory] Typo
by Manuel Jung 12 Sep '08

12 Sep '08

Hi, I found a typo: Here: http://www.boost.org/doc/libs/1_36_0/libs/utility/in_place_factories.html Chapter: Framework In the First example: struct C { template<class InPlaceFactory> C ( InPlaceFactory const& aFactoty ) //<----------Here! should be "aFactory" : contained_ ( uninitialized_storage() ) { aFactory.template apply<X>(contained_); } ~C() { contained_ -> X::~X(); delete[] contained_ ; } char* uninitialized_storage() { return new char[sizeof(X)] ; } char* contained_ ; } ; void foo() { C c( in_place(123,"hello") ) ; } Greetings Manuel

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Re: [boost] HP-UX_pa_risc_aCC test failure
by Kotari, Preethi (STSD) 12 Sep '08

12 Sep '08

Hi, We are investigating this issue and will keep you updated with the progress. Thanks, Preethi > -----Original Message----- > From: boost-bounces_at_[hidden] > [mailto:boost-bounces_at_[hidden]] On Behalf Of Emil Dotchevski > Sent: Tuesday, September 09, 2008 3:29 PM > To: boost_at_[hidden] > Subject: [boost] HP-UX_pa_risc_aCC test failure > > I'm looking at this failure: > > http://www.boost.org/development/tests/trunk/developer/output/ > HP-UX_pa_risc_aCC-boost-bin-v2-libs-exception-test-throw_excep > tion_test-test-acc-pa_risc-debug.html > > The assertion is an indication that a particular function that throws > an exception returned without throwing an exception. Does this > platform support exception handling? If not, shouldn't > BOOST_NO_EXCEPTIONS be #defined? > > Emil Dotchevski > Reverge Studios, Inc.

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Re: [boost] [hash] Is there any interest in cryptographic hash functions?
by Kasra (Math & ComSci) 12 Sep '08

12 Sep '08

I am back from being busy => I am free. I have thought about the design decisions: "It doesn't really make sense to hook this up to an fstream. Such a remove_file_securely() functionality should be implemented as free function." I disagree, say you have a file 'x' which you don't want the local police to be able to recover, and you have a 'xx' file which you don't want the FBI to be able to recover (a little too hard to achieve). Here the security differs, and thus the wipe method ought to be different. secure_wipe< aStream, onePassAlgorithm > x; // single overwrite secure_wipe< aStream, gutmannAlgorithm > xx; // 35 x overwrite "Well there are two classes of ciphers, block ciphers and stream ciphers. Block ciphers encrypt data by working on x bytes at a time. Stream ciphers on the other hand (like RC4) encrypt data continuously and don't need a padding parameter because they don't need to pad data to a multiple of some block size. So what you call a cipher is a stream cipher. I see now where you're going with this and I will think about it. " In general blocks cipher is an element of stream cipher which in turn is an element of cipher set. So I guess the terminology doesn't bother me much. But I think you know where I am coming from now. "I remember that table lookups generally are susceptible to cache timing attacks. That does not mean we shouldn't use the optimized rijndael version though." I totally agree with you, the cache-timing attack is believed to be impossible on more than 1 network loop. I have written the wrapper class for the optimised implementation. Conclusion: All of us like: * basic_crypto_stream. * optimised implementations Haven't agreed on yet but are thinking in the same lines: * block_cipher, stream_cipher, cipher thing Disagree on: * secure_wipe I agree 'secure_wipe' is not very useful for a memory buffer. A secure allocator works fine (i.e. memset() ). But on the other hand when it comes to files 'secure_wipe' is very useful. So we need to agree on the interface which the 'secure_wipe' task is achieved. With best regards, kasra

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