October 2008 - Boost - lists.boost.org

Tests are a mess
by Gennaro Prota 23 Dec '08

23 Dec '08

Few questions: * BGD-Ubuntu is among tested platforms for release, but not for trunk. How is a poor fellow supposed to test on trunk first? * Same as above for BGD-Windows, with the fellow getting poorer and poorer * Are RW_WinXP_VC and RW_WinXP_VCrtl the same? * Can anyone please have a look at the trunk failures for HP-UX_ia64_aCC? For a bunch of libraries I've looked at it gives an Unsatisfied symbol "boost::exception_detail::refcount_ptr<..." What's that? Compiler bug, misconfiguration, phase of the moon? Sorry, but if this is the status quo I'm just going to merge to branches/release and be done with it. -- Genny

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[swap] How to fix ADL barrier for XL, Intel, GCC, Sun and Como?
by Niels Dekker - mail address until 2008-12-31 19 Dec '08

19 Dec '08

The boost::swap utility from Joseph Gauterin has an ADL barrier against infinite recursion or ambiguity, as recommended by Steven Watanabe and David Abrahams, last year at the mailing list: "Re: [boost] Koenig lookup swap." http://lists.boost.org/Archives/boost/2007/08/125938.php Last Friday I added "test_adl_barrier" to test this ADL barrier. Unfortunately it fails on many compilers, including XL (AIX), Intel (version 9 and 10), GCC, Sun and Como: http://www.boost.org/development/tests/trunk/developer/utility-swap_.html While I usually use MSVC, and for that specific compiler, the ADL barrier appears successful! Do you know how to fix the ADL barrier for the other compilers? I'm afraid we'll need to have #if BOOST_WORKAROUND statements in there... FYI, the boost::swap utility is at: http://svn.boost.org/svn/boost/trunk/boost/utility/swap.hpp The ADL barrier test is at: http://svn.boost.org/svn/boost/trunk/libs/utility/swap/test/test_adl_barrie… Kind regards, -- Niels Dekker http://www.xs4all.nl/~nd/dekkerware Scientific programmer at LKEB, Leiden University Medical Center

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Measuring compile time performance
by dan marsden 15 Dec '08

15 Dec '08

Hi We're looking at optimizing some of the compile time performance in Boost.Fusion. I'm looking for any experience in Boost of measuring build times / compile time cost, how to structure tests that cover it etc. Does Boost.Build provide any support for measuring compile time for example? I'm aware there's a Perl script by Steven Watanabe that measures template instantiations if I understand correctly. Are there any other techniques that are being used that I should be aware of? Cheers Dan Send instant messages to your online friends http://uk.messenger.yahoo.com

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[proto][design]why unary_expr,binary_expr; but no nullary_expr?
by Larry Evans 14 Dec '08

14 Dec '08

Although there's unary_expr<Tag,*>, binary_expr<tag.*,*> in traits.hpp there's no nullary_expr<Tag>. I realize this would be a replacement to the current terminal template but with a user specified tag. After all, if a user specified tag for n-ary (where n>0) expressions *is* desirable, why is a user specified tag for 0-ary expressions *not* desirable? On case where this would be useful is for algebraic morphisms where n-ary ops in a source algebra are mapped to n-ary ops in a target algebra. This *includes* 0-ary ops. An op would be the equivalent to proto tags. I think this could be done by another transform similar to the pass_through transform but allowing transformation of the tag. Currently pass_through just uses the source tag in the target expression. It seems like it should be pretty easy to allow transformation on the tag also.

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[MultiIndex] Random Access mental model?
by David Abrahams 29 Nov '08

29 Nov '08

Hi, I'm trying to get a grip on what it means when I have a random access index in a multi_index_container. I have no mental model for what data structure you're actually creating, which makes it difficult to evaluate multi-index vs. hand-rolling my own container. If I was doing this myself, I'd use a combination of these two: hash_map<key, value> deque<hash_map<key, value>::pointer> because I need to maintain an LRU cache of what has been put in the map (i.e. I need O(1) push_back and pop_front). MultiIndex only lets me use sequenced<> which it implies essentially has the properties of list<hash_map<key, value>::iterator>... although I can imagine you could save a lot by using the same nodes for the hash_map and the list. Do you do that? Regardless, I could still save roughly one pointer per node with my deque. I'd think about trying to modify MultiIndex to let it do random access with deques, but I can't make head or tail of the implementation code used for random access. Could someone clarify what's going on in there? -- Dave Abrahams BoostPro Computing http://www.boostpro.com

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[lambda][test] _set_se_translator() requires /EHa
by David Walthall 22 Nov '08

22 Nov '08

I was looking at one of the failures on vc 7.1 and noticed that there was the following warning: ..\boost\test\impl\execution_monitor.ipp(825) : warning C4535: calling _set_se_translator() requires /EHa the command line options /EHc and /GX are insufficient See: http://beta.boost.org/development/tests/release/developer/output/daw-msvc71… or: http://tinyurl.com/5osfqr Is this a spurious warning, or is really an issue? Thanks, David

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[cryptography] concept
by Kasra Nassiri(Math & ComSci) 10 Nov '08

10 Nov '08

Hi all, I mentioned not a while ago that I am planning to write a boost cryptographic library. I am getting there. We have template classes that implement a certain interface (not virtual functions). These classes are: secure_allocator: An allocator which removes the buffers allocated when they are destructed by overwriting them. block_cipher: Any class that could set a key and encrypt/decrypt a constant size of message. (I have included AES, Serpent, Twofish and MARS, however, we could always add more algorithms) stream_cipher: By definition stream_cipher is a cipher that could process messages of any length. hash_function: Is a class that could compute a cryptographically secure hash signature for an arbitrarily long messages. (I have added whirlpool and will be adding more). wipe_algorithm: An algorithm that provides the patterns of wipe for a given pass and fills a given buffer with patterns (It needs to have a prng template to be used on random patterns). By using a mode of operation we could turn the concept of block_cipher into a stream_cipher. For example cryptolib::ctr<cryptolib::aes> is a stream_cipher concept. I have implemented ictr, ctr and will be implementing XTS, LRW soon. classes: cryptolib::entropy_poll<cryptolib::hash_function>: A class that polls random data and mixes the data using a hash function. cryptolib::entropy_thread<cryptolib::entropy_poll>: Calling the polling function of the entropy_poll at "random" but regulated intervals using boost::thread library. cryptolib::crypto_istream<cryptolib::stream_cipher>: cryptolib::crypto_ostream<cryptolib::stream_cipher>: cryptolib::crypto_oistream<cryptolib::stream_cipher>: classes that behave similar to 'std' iostream ,however, they seamlessly encrypt/decrypt the data as they operate. cryptolib::wipe_fstream<cryptolib::wipe_algorithm>: Wipes the file using the patterns by the template wipe algorithm. This class would determine the cluster size and wipe the entire cluster occupied by the file (this is platform specific, so we need to implement the algorithm for different platforms). finally we have the cryptolib::crypto_fstream that could be given a direction (i.e. encryption or decryption) and will operate seamlessly on the data. What do you think? Anything that I am missing on? Best regards Kasra __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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[flyweight] post-review version available
by JOAQUIN M. LOPEZ MUÑOZ 08 Nov '08

08 Nov '08

Hello, I'm happy to announce the availability of the post-review version of Boost.Flyweight: *Online docs:* http://tinyurl.com/2sstyr http://svn.boost.org/svn/boost/sandbox/flyweight/libs/flyweight/index.html *Download as .zip:* http://tinyurl.com/hrdm6 http://www.boost-consulting.com/vault/index.php?&direction=0&order=&directo… *Check out from SVN:* https://svn.boost.org/svn/boost/sandbox/flyweight *Tested with:* MSVC++ 8.0 and GCC 3.4.4. Compilation reports most welcome. Older compilers like MSVC++ 6.5 are no longer supported. *What's new:* I've tried to address most of the suggestions and comments raised during the review. The two most important changes are: 1. Alberto Barbati's insightful review has led to the introduction of so-called key-value flyweights (http://tinyurl.com/5mnwjp ). This type of flyweights is meant for the situations where constructing the underlying type is expensive and must be avoided except if absolutely necessary. I think the design is robust enough and covers the variants (inner/outer key) that arose during the discussion with Alberto. 2. A comprehensive performance section is provided (http://tinyurl.com/5ap5kt ). *What's pending* 1. Some of the suggestions given at the review, like reducing intermodule_holder to static_holder when permissible (Vicente Botet) or studying read/write locking policies are still pending or have been postponed to later releases of the library. I felt the current state is sufficiently robust for publication. 2. Serialization support is currently broken, pending the resolution of a proposed feature to add to Boost.Serialization (run-time archive helpers). I'd be very grateful if you can take a look at the post- review version of Boost.Flyweight (specially if you were a reviewer), test it and comment on it, with emphasis on the new features like key-value flyweights. If people are happy with this revision my target release for inclusion will be Boost 1.38. Thank you, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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make_shared and allocate_shared for classes with private constructors
by Michael Marcin 06 Nov '08

06 Nov '08

I have some classes that derive from enable_shared_from_this which I've given private constructors and static creation methods which return a shared_ptr. This prevents someone from using the class inappropriately. It seems obvious that at a minimum using make_shared internally here would be an improvement. Unfortunately this requires that make_shared be made a friend for every arity and probably won't work with the variadic template implementation of make_shared. Is it possible to make declaring friendship for make_shared and allocate_shared simpler? I thinking something like serialization does with friend class boost::serialization::access. Thanks, -- Michael Marcin

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[FileSystem] portable Temp, Desktop & Applications directories?
by Jeff Flinn 06 Nov '08

06 Nov '08

Is there any existing facility to get in particular the path to the user's temp directory in FileSystem? I couldn't find one in boost_1_35_0, but I've might have missed it. Any plans for this functionality? On Win and Mac there's getenv TEMP/TmpDir, or is there a better way. Thanks, Jeff

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