February 2012 - Boost - lists.preview.boost.org

[intrusive] advanced lookup/insertion suggestion
by Rei Thiessen 16 Feb '12

16 Feb '12

Something that has bothered me with the advanced lookup and insertion functions is that I have to specify the hash/equality functors at every invocation site: c.find(key,key_hash(),key_equality()); c.insert_check(key,key_hash(),key_equality(),cd); If we don't consistently use the same (key_hash,key_equality) pair for a given (element_type,key_type) pair, the container invariant will likely be broken. Thus, I think it's very un-"C++ like" to have to specify these two types at every invocation site. Assuming that we don't want to embed (key_type,key_hash,key_equality) directly into the type of a container, the library could use a type operator to automatically deduce the appropriate hash/equality functions given an element/key type pair at the find/insert member function instantiation point: // library template<typename ElementType, typename KeyType> struct element_key_info {}; // different name to avoid overload confusion. // instantiation succeeds only when // element_key_info is properly specialized template<typename KeyType> iterator unordered_set::find_key( KeyType const& k ) {...} ... // user namespace intrusive{ template<> struct element_key_info<element_type,key_type> { typedef key_hash hash_type; typedef key_equality equality_type; }; } element_type e(...); c.insert( e ); key_type k(...); ... = c.find_key( k ); These new signatures do not allow non-default-constructible hash/equality functors, but the original signatures that do are still available. I think this makes the code simpler and safer in exchange for some additional type declarations. Would this be a worthwhile addition to the intrusive associative containers?

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Offering sorted_vector for Boost, any interest?
by Frank Birbacher 15 Feb '12

15 Feb '12

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi! I've come across lots of code that uses std::set where I think a sorted vector would perform better. Those places a characterized by: 1. fills the set only once, 2. just wants to drop duplicates or 3. calls set::find very often. Facing such code I often wished there was a ready to use sorted_vector implementation. I think a new container that stores elements in a vector instead of a tree offers strong advantages: a. one call to std::sort instead of managing a red-black-tree b. less memory overhead c. better data locality for lookup Possible things that I currently consider: - - offer one-time initialization read-only sorted container? - - offer mutable container with std::set-like interface (complexity changes)? - - offer taking contents from std::vector for init without copying - - offer equivalent to std::map also? - - provide a pointer container, too? Is there general interest in such a container? I'd like to develop an implementation and offer it to Boost. Frank -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.17 (Darwin) Comment: GPGTools - http://gpgtools.org Comment: keyserver x-hkp://pool.sks-keyservers.net iEYEARECAAYFAk87/wQACgkQhAOUmAZhnmqVdQCggs40nPsT7wXvoEuO3TsSWlqS Wt4An06uRHECRercybiKC0Jq/ZKobEsu =zAK6 -----END PGP SIGNATURE-----

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Adding support for auto in Boost.Foreach
by paul Fultz 15 Feb '12

15 Feb '12

I have a macro that I use on older compiers that let's me use auto inside of a foreach loop using the typeof operator. My original implementation relies on variadiac macros, but it can be rewritten without requiring variadiac support(possibly using the new keyword facility from Lorenzo Caminiti). Here is examples of some foreach loops it would support: BOOST_FOREACH(auto x, range) {} BOOST_FOREACH(auto& x, range) {} BOOST_FOREACH(const auto& x, range) {} BOOST_FOREACH(volatile auto x, range) {} Also, on compilers that support variadiac macros, it would be nice to add support for commas in the type, such as: BOOST_FOREACH(pair<string, string> p, range) {} This would work by poping off the back of the sequence in order to get the container. Now, you could only have commas in the type and not the container, so this wouldn't work: //Won't work BOOST_FOREACH(auto x, get_some_range<A, B>()) {} However, 1) We can place parenthesis around the container, like this: BOOST_FOREACH(auto x, (get_some_range<A, B>())) {} 2) Almost 95% of the gotchas with the foreach seemed to be with using commas in the type. So ultimately, I think it would reduce the number of gotchas drastically. Is there interest in adding something like this? Or maybe just part of it? Also if there interest, what kind of process would I go through to get them submitted and reviewed? -paul

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[trunk] test compilation fails on Cygwin
by Bernd Prager 15 Feb '12

15 Feb '12

I am getting following error with g++ (GCC) 4.5.3 on Cygwin 1.7.20: In file included from libs\test\src\debug.cpp:16:0: ./boost/test/impl/debug.ipp: In function ‘bool boost::debug::attach_debugger(bool)’: ./boost/test/impl/debug.ipp:899:9: error: ‘::select’ has not been declared

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[Format] Making a change
by John M. Dlugosz 15 Feb '12

15 Feb '12

I'd like to make a change to the Boost Format library, to add a conversion operator to the matching string class. It appears to have not been worked on in a number of years. Reading through the web site, I find details on how to submit new libraries, and how to edit the web page, but nothing on submitting updates to existing libraries. How would I go about doing that, for this library in particular? —John

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Vector quantity?
by sultana rashid 15 Feb '12

15 Feb '12

Hello all, I was finding something on Vector quantity in Boost library, as: Vector decomposition ,cross product,absolute value of a vector quantity ,projection of a vector etc. I am afraid whether I could not find or Boost missing it. Thanking you, Sultana rashid.

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FW: Snobol4 matching in C++
by Steven Kibler 15 Feb '12

15 Feb '12

I have an implementation of Snobol4 patterns and pattern matching that runs in C++. All of the Snobol4 patterns and replacements are implemented in addition to numerous extensions that have proven useful over the years. The patterns are built with overloaded operators and building patterns is simple, straight forward, easy to read and test. In many cases, I find that Snobol4 patterns and its matching algorithm is clearer, more intuitive, and more useful than regular expressions. I have been able to typically cut the required lines of code to accomplish pattern matching by half or a third over using regular expressions. The package is well integrated into C++ and its data types. For post circa 1980 'newbies' unaware of the power of Snobol4, a description of Snobol4 can be seen in a copy of several Snobol4 manuals at ftp://ftp.snobol4.com/spitman.pdf and ftp://ftp.cs.arizona.edu/snobol/gb.pdf. I would like the package to be published under the auspices of Boost. I would like to know if this package would be something that the users of the Boost community would be interested in. This package was originally written in Ada by Robert Dewar and AdaCore, translated to C/C++ by Philip Budne, and cleaned up and expanded by me. The Philip Budne version may be found at http://www.snobol4.org/ (Look for the SPIPAT link) along with many other references for SNOBOL and SPITBOL. Thanks Steven Kibler Facet Soft Tech, Inc.

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[local_function] trunk commit
by lcaminiti 15 Feb '12

15 Feb '12

Hello all, I have committed Boost.LocalFunction (and related libraries) to trunk. This is my first commit to Boost trunk :) . I will monitor this ML closely and I will be ready to make any fix in real-time in case I have broken something. However, I have ran all regressions tests of what I committed using MSVC 8.0 and GCC 4.5.3 (with and without C++0x features) and they all pass. I also have ran Boost's inspect on all files I committed. Boost.LocalFunction (new) boost/local_function[.hpp] libs/local_function Boost.ScopeExit (improved) boost/scope_exit.hpp libs/scope_exit Boost.Functional/OverloadedFunction (new) boost/functional/overloaded_function[.hpp] libs/functional/overloaded_function Boost.Utility/IdentityType (new) boost/utility/identity_type.hpp libs/utility/identity_type Thanks for your support and understanding. --Lorenzo -- View this message in context: http://boost.2283326.n4.nabble.com/boost-local-function-trunk-commit-tp4389… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Re: [boost] [filesystem] operations.hpp Won't Compile with VC10 using Boost 1.47
by Stewart, Robert 14 Feb '12

14 Feb '12

Stephan T. Lavavej wrote: > [Robert Stewart] > > When I try to include boost/filesystem/operations.hpp, my > > code won't compile on MSVC 10 (Visual Studio 2010). > > The error is from boost/filesystem/v3/config.hpp:49: > > # if defined( BOOST_NO_STD_WSTRING ) > > # error Configuration not supported: Boost.Filesystem V3 > and later requires std::wstring support > > # endif > > First, check your command line. If it isn't defining the > macro, preprocess with /P /d1PP . The second option is > undocumented and unsupported, but extremely useful - it > preserves #define directives, so you can see where macros are > coming from. I was looking for such an option! BOOST_NO_STD_WSTRING didn't appear in the output. This was a false alarm. Why does VC print #error messages that are conditionally compiled and don't apply! In this case, BOOST_NO_STD_WSTRING is *not* defined, yet the #error still appears in the output: In file included from D:/.../Boost/boost_1_47/include/boost-1_47/boost/filesystem/operations.hpp:31, from controller.cpp:22: D:/.../Boost/boost_1_47/include/boost-1_47/boost/filesystem/v3/operations.hpp:21:5: #error Configuration not supported: Boost.Filesystem V3 and later requires std::wstring support Emacs' compilation-mode dutifully marks that as an error and I didn't realize that the build progressed past that point. Arrrggghhh! Thanks for your help. _____ Rob Stewart robert.stewart(a)sig.com Software Engineer using std::disclaimer; Dev Tools & Components Susquehanna International Group, LLP http://www.sig.com ________________________________ IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses.

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[bjam] command for release/debug
by lcaminiti 14 Feb '12

14 Feb '12

Hello all, How can I program a Jamfile to execute the following on `bjam debug`: compile-fail const_block_err.cpp ; But the following on `bjam release`? run const_block_err.cpp ; Thanks. --Lorenzo -- View this message in context: http://boost.2283326.n4.nabble.com/boost-bjam-command-for-release-debug-tp4… Sent from the Boost - Dev mailing list archive at Nabble.com.

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