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

Use macro varargs within BOOST_NOEXCEPT_IF
by Daryle Walker 03 Feb '12

03 Feb '12

I was going to ask about adding a BOOST_NOEXCEPT, but I just checked that the trunk already has it: //---#ifdef BOOST_NO_NOEXCEPT# define BOOST_NOEXCEPT# define BOOST_NOEXCEPT_IF(Predicate)# define BOOST_NOEXCEPT_EXPR(Expression) false#else# define BOOST_NOEXCEPT noexcept# define BOOST_NOEXCEPT_IF(Predicate) noexcept((Predicate))# define BOOST_NOEXCEPT_EXPR(Expression) noexcept((Expression))#endif//--- If the compiler supports varargs in macros, should we have: //===# define BOOST_NOEXCEPT_IF(...) noexcept(__VA_ARGS__)# define BOOST_NOEXCEPT_EXPR(...) noexcept(__VA_ARGS__)//=== (I think that's the right syntax.) instead so comma expressions can be used within a noexcept without the extra parentheses? But I doubt that it makes a difference here, since anything within the noexcept must be interpretable as a single expression. (I think it does for decltype, though. Extra parentheses turn a value type into a reference type(?).) Daryle W.

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[metagraph]
by Kitten, Nicholas 03 Feb '12

03 Feb '12

Hi Gordon (and whoever else is involved), What's the current status of metagraph / mpl_graph? I've been using msm::mpl_graph for error-checking/scheduling in a compile-time filter graph framework (similar to state machines, but focus is on data flow), and I'd certainly like to see more. As is, I've already implemented a topological sort based on the BFS which doesn't yield errors on cyclic graphs (which I'd be happy to contribute if you don't already have one), and I have some thoughts on improvement. I saw the BoostCon slides and the current state of the sandbox, and I was wondering if there's more code lurking out there somewhere, unchecked-in. Anyway, the single biggest flaw I see with the current BFS and DFS (and the BGL models they're based on) is that there is no way for the user to specify a termination condition in the base algorithm. It seems silly that an algorithm called "Search" can't end without traversing the whole connected component! Indeed, if there were simply an optional predicate determining whether a candidate vertex should be added to the stack/queue, I wouldn't have needed to write a separate algorithm for topo sort. The other thing is that not all of the listed visitor operations are called in the current implementations. Adding things like "initialize_vertex" and "non_tree_edge" to BFS is an easy fix. Thanks, Nick Kitten Software Engineer Center for Video Understanding Excellence ObjectVideo, Inc. http://www.objectvideo.com

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[range] Performance benchmarks?
by Beman Dawes 02 Feb '12

02 Feb '12

A question came up in a long bikeshed discussion on a C++ committee mailing list as to the performance of range based interface versus a begin/end iterator interface (I.E. traditional STL interface) to the same algorithms. Out of curiosity, I checked the Boost.Range docs, but didn't see any performance measurements. It might encourage potential users to take the leap if the Boost.Range "Introduction" page made some mention of performance implications for use of the Boost library. The intro gives a "Push the even values from a map in reverse order into the container target" example: // Assume that is_even is a predicate that has been implemented elsewhere... push_back(target, my_map | map_values | filtered(is_even()) | reversed); Are there any benchmarks available for this? What does the straight STL version of the code look like? --Beman

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[1.49] No description about Boost.Heap in Library Documentation page
by Michel Morin 02 Feb '12

02 Feb '12

There is no description about Boost.Heap at http://www.boost.org/doc/libs/1_49_0_beta1/ Ditto for "trunk/boost/libs/libraries.htm" Regards, Michel

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[1.49.0] New libraries in 1.49.0?
by Beman Dawes 02 Feb '12

02 Feb '12

What are the new libraries in 1.49.0? --Thanks, --Beman

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[interprocess] utf8 file names in memory mapped files
by Thorsten Ottosen 01 Feb '12

01 Feb '12

Hi Ion, It would be great if we could support utf8 encoded file names on windows too. I guess all it requires is a utility function that converts from utf8 to utf16 on windows. Such a function is avaiable in the windows API, and I can supply it. kind regards Thorsten

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[1.49.0] Beta 1 release candidates available
by Beman Dawes 01 Feb '12

01 Feb '12

Release candidate files for 1.49.0 beta 1 are available at http://boost.cowic.de/rc/ As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. This helps ensure the candidates build OK before we push them out to SourceForge. Thanks, --The release managers --PS: I downloaded the 7z version, and it build without errors on Win7/VC++ Express 2010 sp1

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[1.49.0] Branches/release open for bug fixes and documentation updates
by Beman Dawes 01 Feb '12

01 Feb '12

branches/release is now open for bug fixes and doc updates, without need to ask for a release manager's permission. It will remain open until Monday, February 13th. The final release is scheduled for February 20th. The hope is that this somewhat longer beta period will allow time to fix more bugs that surface during the beta period. --Beman

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[local_function] ready
by Lorenzo Caminiti 01 Feb '12

01 Feb '12

Hello all, I have finished making the modifications requested by the Boost.Local(Function) review. The code is now in the sandbox ready to be moved into trunk. Can I get write access to the trunk? 1) Boost.LocalFunction New: This library allows to program functions locally, directly within the scope where they are needed. https://svn.boost.org/svn/boost/sandbox/local_function/libs/local_function/… 2) Boost.ScopeExit Improved APIs (variadic macros, this_, void, and C++11 closures) while keeping full backward compatibility. https://svn.boost.org/svn/boost/sandbox/local_function/libs/scope_exit/doc/… 3) Boost.Utility/IdentityType New: Macro to wrap type expressions within round parenthesis so they can be passed to macros even when they contain commas. https://svn.boost.org/svn/boost/sandbox/local_function/libs/utility/identit… 4) Boost.Functional/OverloadedFunction New: Overload different functions into a single function object. https://svn.boost.org/svn/boost/sandbox/local_function/libs/functional/over… All source files: https://svn.boost.org/svn/boost/sandbox/local_function/ Thanks. --Lorenzo

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