- Boost - lists.preview.boost.org

[thread] Questions about broken_promise
by Klaim - Joël Lamotte 29 Jul '13

29 Jul '13

I have a few questions concerning broken promises (exception): 1. is the broken_promise exception a standard, or future standard behaviour? So far I assumed it wasn't because http://en.cppreference.com/w/cpp/thread/promise/~promise don't say anything about this and I only read about broken_promise exceptions on Boost.Thread documentation. I would like to know if I should expect the future standard library to have the same concept. I see no configuration macro to deactivate these exceptions. I don't want to actually, but if I'm correct that it's not standard or future standard, then it's surprising that I can't setup a standard-like setup. 2. I have a case that could be summarized like this: ///////////////////////////////////////////// Updated by thread A: struct X { /*... */ }; struct K { future<shared_ptr<X,U>> m_ft_x; shared_ptr<X,U> m_x; K( Foo& foo ) : m_ft_x( foo.create<X>() ) {} void update() // this is always called by a loop in the thread A { if( !m_x ) { if( m_ft_x.has_value() ) m_x = m_ft_x.get(); } else work(); } void work(); // uses m_x }; Updated by thread B: // special deleter which will just push a task in Foo work queue for deleting the object // in sync with thread B struct U { /* ... */ }; struct Foo { template< class T > future<shared_ptr<T,U>> create() // will push a creation task in a work queue updated in update() void update(); // called by a loop in the thread B, will execute all the work pushed in the work queue. }; ///////////////////////////////////////////// (this is an exageratedly simplified version of what I'm doing) It works nicely (even if I think it could be improved with future.then and other tools) but there is a minor problem appearing when an instance of K is constructed then almost immediately destructed, before the instance of Foo executed the creation of the X instance. In this case, visual studio (which is configured to detect all throw calls) detect a broken_promise exception thrown from the destructor of the promise which was in the code generated by Foo::create() and pushed in a work queue. I look at the destructor and I see: if(!future_->done && !future_->is_constructed) { future_->mark_exceptional_finish_internal(boost::copy_exception(broken_promise()), lock); } Here is the full copy_exception code: template <class T> inline exception_ptr copy_exception( T const & e ) { try { throw enable_current_exception(e); } catch( ... ) { return current_exception(); } } This code triggers actually two "first-chance" exceptions this is the first one) which are catch immediately intentionally. My question is: why is copy_exception necessary and why does it have to do it this way? It's a very minor problem as just re-setting my visual studio debugging settings to default makes the exception transparent -only visible in the console log. However each time I activate debug breaking on all c++ exception so that I can debug some potential issues, I can have a breakpoint which is actually "noise" as it is only used to implement a copy of exception. Is it possible to eliminate this noise? Or, as I'm guessing, is there a language or compiler limitation which forces this code to be written this way? Thanks for your time. Joel Lamotte

2 2

safe bool not safe enough ?
by John Maddock 28 Jul '13

28 Jul '13

Just discovered (oops!) that the so called safe bool ideom is not as safe as it appears, for example: class Testable { bool ok_; typedef void (Testable::*bool_type)() const; void this_type_does_not_support_comparisons() const {} public: explicit Testable(bool b=true):ok_(b) {} operator bool_type() const { return ok_==true ? &Testable::this_type_does_not_support_comparisons : 0; } }; Testable t(true); bool b = t; // Compiles OK - Ooops! Which is causing multiprecision to misbehave when used in conjunction with uBlas: https://svn.boost.org/trac/boost/ticket/8292#comment:2 I guess making the conversion explicit in C++11 mode would help (I still need to test that), but is there a C++03 solution? Thanks, John.

4 9

radix sort
by Sourav 28 Jul '13

28 Jul '13

Hi All, I wanted to know if someone is/was working on Radix Sort or not. I did check the SoC listings and did not see radix sort in the list. If no one is working, may someone help me provide some pointers/details as to what the expectation is with regards to Radix sort for boost ? Regards, -Sourav

7 27

boost::python help?
by David M. Cotter 26 Jul '13

26 Jul '13

i'd like my app to be "available" to python while it's running. for example, say my app is "FooBar.app". when my FooBar.app is running, now there is a python interface available to python, and the user can write python scripts to make use of it with their scripts, they can control my running application when FooBar.app is NOT running, perhaps making use of any of the python functions of "FooBar.app" would either return an error, or possibly launch "FooBar.app". can boost::python help with this? i've never worked with extending or embedding python, so any help would be super great

4 5

Patch bonanza for VS2013 Preview support
by Lars Viklund 25 Jul '13

25 Jul '13

Hi list. What's the best way to spend your vacation if not trying to get Boost to build on bleeding-edge compilers. I set out to see how well Boost 1.54.0 behaved on the newly released go-live-ready Visual Studio 2013 Preview. Below is the list of bugs filed against Boost and Microsoft. Enjoy. With these patches in place, I can get a complete build working with all libraries normally available on a fresh machine (means that I didn't test Python, MPI, ICU, compressed streams). I haven't been able to find out how to run the tests in any human-readable form, but this should not cause any regressions as it's either increasing workaround bounds or adding headers that the standard mandates already. Boost.Config VS2013 Preview version bump https://svn.boost.org/trac/boost/ticket/8753 The Visual Studio 2013 Preview toolchain has _MSC_VER 1800 and _MSC_FULL_VER 180020617. See the attached patch for the minimum changes that are needed to get anywhere at all. Boost.Build needs support for the VS2013 Preview toolset (18.00.20617.1) https://svn.boost.org/trac/boost/ticket/8754 Visual Studio 2013 Preview is out and claims to be 12.0. I copy-pasted everything related to 11.0 to refer to 12.0 and it Works On My Machine, see attached patch. Boost.Signals VS2013 Preview version bump https://svn.boost.org/trac/boost/ticket/8755 The BOOST_WORKAROUND macros at boost/signals/detail/named_slot_map.hpp:130 and libs/signals/src/named_slot_map.cpp:27 needs to be increased to <= 1800 in order to encompass the Visual Studio 2013 Preview compiler. Boost.MPL VS2013 Preview version bump https://svn.boost.org/trac/boost/ticket/8756 The BOOST_WORKAROUND macros at boost/mpl/assert.hpp lines 37 and 247 need to be changed to also consider BOOST_MSVC, == 1800, patch attached. Boost.Serialization lacks algorithm header include for std::min https://svn.boost.org/trac/boost/ticket/8757 The <algorithm> header providing std::min is not included in boost/archive/iterators/transform_width.hpp, this breaks on Visual Studio 2013 Preview due to library changes. Boost.Asio lacks algorithm header include for std::min https://svn.boost.org/trac/boost/ticket/8758 The <algorithm> header providing std::min is not included in boost/asio/detail/impl/win_iocp_io_service.hpp, this breaks on Visual Studio 2013 Preview due to library changes. std::bind broken with boost/tuple/tuple.hpp or anything else providing a ADL tie https://connect.microsoft.com/VisualStudio/feedback/details/792163/std-bind… Not our fault, I filed a bug on Connect and am hoping that they'll notice it before RTM. 'std::bind' finds our 'tie' if a type from a boost namespace is used in the 'std::function' argument type list. -- Lars Viklund | zao(a)acc.umu.se

13 35

[preprocessor] ARRAY_REPLACE bug?
by Mostafa 25 Jul '13

25 Jul '13

On Windows 7/Cygwin, using boost 1.53, preprocessing the following snippet: pp_array.cc ----------- #include <boost/preprocessor.hpp> //#define BOOST_PP_TUPLE_REM_0() // nothing #define ARRAY (3, (a, x, c)) BOOST_PP_ARRAY_REPLACE(ARRAY, 1, b) via: g++ -E -P -I /... pp_array.cc gives the following incorrect result: (3, (BOOST_PP_TUPLE_REM_0 () a, b , c)) Uncommenting the pound define in the snippet gives the correct result for the preprocessor. Is this a bug?

1 0

[dynamic_bitset] Compiler intrinsics to accelerate. whos agree?
by Jairo Andres Velasco Romero 25 Jul '13

25 Jul '13

I noted detail for dynamic_bitset<> is not using the far old ASM instruction BSF which could accelerate find_first() and find_next() methodsI checked asm generated with current table based implementation.On x64 and x86 BSF and BSR are available long time ago.Population count can be implemented with LZCNT for performance oriented ways to build.Core i7 with AVX2 enable new wide block bit manipulation but it needs to code with specific GNU g++ intrinsics and MSVC intrinsics. Someone agree? Jairo.

2 1

semi lock-free Signals/Slots
by Andrew Ho 24 Jul '13

24 Jul '13

Hi, I've been doing some testing with implementing a semi lock-free Signals/Slots library. Basically: 1. emits are lock-free thanks to atomic shared_ptr's/other atomic operations. 2. Only a single writer is allowed at a time, uses a mutex for locking. The primary goal is to improve low and no slot-count signal emit performance. In tests, I have been able to get substantial performance boosts (~2 to 5 times) on low slot-count signals, approaching the same performance as signals2 in low-contention (basically, single thread testing). I haven't tested high emit contention performance, though I suspect this library will excel quite well here because there is no locking on emit. The test implementation is still incomplete, and notably uses many C++11 features, though I don't think any of features I'm using can't be ported one way or another for C++03 support. Even if the library isn't used in full, some of the ideas might be implemented into the existing Signals2 library. link: https://github.com/helloworld922/signals3

2 2

Announcing boost dependency analyzer
by Jens Weller 24 Jul '13

24 Jul '13

Hello to the boost community, I'd like to announce the release of a small tool, that allows you analyze the dependencies in boost. It is based on bcp, requirement is that you have bcp build and well a version of boost to analyze installed. Simply select the boost directory (the tool also might find BOOST_ROOT) and the location of bcp, and the tool will start. This will take a little time, depending on your machine, on my multicore intel ist 90 seconds - 2 minute. The tool will store this information into a database, so that with the next start, this will be a lot shorter. The tool allows to analyze the dependcies of a single boost library, but also of all of boost. Its build with Qt for the UI and processing part, and uses boost graph for the layout. Full information + download you'll find at my blogpost: http://www.meetingcpp.com/index.php/br/items/boost-dependency-analyzer.html Current Issues: What libraries might be missing? I'm reading the libs from maintainers.txt, which isn't all the boost libs. For example, lexical_cast is missing, and function_types is twice in there. (C&P error or missing library?) So far Windows is supported, linux support planned and improving, currently ownly the (beta) binaries for linux available. kind regards, Jens Weller

5 9

Re: [boost] [build][msvc] create PDBs
by Ahmed Charles 24 Jul '13

24 Jul '13

The size difference is LTCG, not debug info. ________________________________ From: Daniela Engert Sent: 7/23/2013 9:40 AM To: boost(a)lists.boost.org Subject: Re: [boost] [build][msvc] create PDBs Am 23.07.2013 17:47, schrieb Andrey Semashev: > On Tue, Jul 23, 2013 at 7:39 PM, Daniela Engert <dani(a)ngrt.de> wrote: >> >> libboost_log_setup-vc120-mt-1_54.lib 188.671.120 >> libboost_log_setup-vc120-mt-1_54.pdb 132.616.192 >> libboost_log_setup-vc120-mt-gd-1_54.lib 220.099.308 >> libboost_log_setup-vc120-mt-gd-1_54.pdb 132.837.376 >> libboost_log-vc120-mt-1_54.lib 53.565.446 >> libboost_log-vc120-mt-1_54.pdb 7.942.144 >> libboost_log-vc120-mt-gd-1_54.lib 32.516.250 >> libboost_log-vc120-mt-gd-1_54.pdb 8.114.176 >> > > It looks like static libs contain debug info anyway as they are always > larger than the generated pdb. In many cases, your observed size relationship is true, but not in all of them. E.g.: libboost_exception-vc120-mt-1_54.lib 53.642 libboost_exception-vc120-mt-1_54.pdb 102.400 libboost_exception-vc120-mt-gd-1_54.lib 11.440 libboost_exception-vc120-mt-gd-1_54.pdb 102.400 To exhibit the size advantage of PDBs over 'old-style' debug info embedded into static libs, I've rebuilt Boost.Log with link=static debug-store=object. This is the result: libboost_log_setup-vc120-mt-1_54.lib 343.234.460 libboost_log_setup-vc120-mt-gd-1_54.lib 374.488.888 libboost_log-vc120-mt-1_54.lib 79.564.296 libboost_log-vc120-mt-gd-1_54.lib 59.539.544 Ciao Dani _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

2 1

clang AST based static analysers - Booster's experience
by Niall Douglas 23 Jul '13

23 Jul '13

Dear Boost Devs, I was wondering what the experience of the list is with clang AST based static analysers? They need not be clang AST based of course, so long as they are based on the frontend of a real compiler rather than trying their own implementation based on regex or something even worse. For this list's information, here are the three clang AST based static analysers I know of: 1. Clang's static analyser http://clang-analyzer.llvm.org/ 2. OCLint http://oclint.org/ 3. The commercial tool CppDepend can now use a clang AST (http://blog.llvm.org/2013/04/static-analysis-tools-using-clang-in.html) Some quick notes of mine which may be of dubious accuracy: Clang's static analyser is the more mature tool, but according to http://code.google.com/p/chromium/wiki/ClangStaticAnalyzer which was updated Mar 2013 it feels its default bundled C++ tests is lacking. The real strength in the clang static analyser is for writing your own tests (http://clang-analyzer.llvm.org/checker_dev_manual.html) which enforce specific coding patterns or constraints (usually on others, and usually pre-commit with commit rejection if fail). OCLint is a newer tool, but appears to have fuller support for C++ (http://docs.oclint.org/en/dev/rules/index.html) though many of those rules appear to check C syntax only (which also covers Objective C). Similar to clang's static analyser, new custom rules are easy to write (http://docs.oclint.org/en/dev/internals/rules.html) This project, at least from the outside, seems to have more legs than clang's static analyser. CppDepend I have no experience of, but there is a reasonably positive review at http://www.asawicki.info/news_1511_cppdepend.html. One of the CppDepend developers talks about how they added clang's AST at http://www.codeproject.com/Articles/475254/ClangplusRocks. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

1 0

[build][msvc] create PDBs
by Daniela Engert 23 Jul '13

23 Jul '13

Hi list! For various reasons I always preferred to have debug info separate from the binaries. Unfortunately, emitting debug info to PDBs doesn't work so well, in particular when it comes to static libs and precompiled headers. Because of that I tried to rectify this and created a patch against msvc.jam. (see ticket #8889 https://svn.boost.org/trac/boost/ticket/8889) This (and a tiny script to collect all generated PDBs into the library directory) got me there: boost_log_setup-vc120-mt-1_54.dll 1.158.656 boost_log_setup-vc120-mt-1_54.lib 24.244 boost_log_setup-vc120-mt-1_54.pdb 123.055.104 boost_log_setup-vc120-mt-gd-1_54.dll 3.206.144 boost_log_setup-vc120-mt-gd-1_54.lib 24.408 boost_log_setup-vc120-mt-gd-1_54.pdb 219.220.992 boost_log-vc120-mt-1_54.dll 486.400 boost_log-vc120-mt-1_54.lib 241.174 boost_log-vc120-mt-1_54.pdb 10.857.472 boost_log-vc120-mt-gd-1_54.dll 1.071.616 boost_log-vc120-mt-gd-1_54.lib 242.278 boost_log-vc120-mt-gd-1_54.pdb 18.918.400 libboost_log_setup-vc120-mt-1_54.lib 188.671.120 libboost_log_setup-vc120-mt-1_54.pdb 132.616.192 libboost_log_setup-vc120-mt-gd-1_54.lib 220.099.308 libboost_log_setup-vc120-mt-gd-1_54.pdb 132.837.376 libboost_log-vc120-mt-1_54.lib 53.565.446 libboost_log-vc120-mt-1_54.pdb 7.942.144 libboost_log-vc120-mt-gd-1_54.lib 32.516.250 libboost_log-vc120-mt-gd-1_54.pdb 8.114.176 Boost.Log was chosen for exhibition only. All files were built with debug-symbols=on debug-store=database. Link-time code generation was enabled for all release builds, too. May be, someone finds this helpful. Ciao Dani

2 2

[format] doc fix
by Tim Blechmann 23 Jul '13

23 Jul '13

not sure, how well-maintained boost.format is these days ... any objection if i commit this documentation fix? cheers, tim

1 0

Fwd: Re: Announcing boost dependency analyzer
by Stephen Kelly 23 Jul '13

23 Jul '13

Jens Weller wrote: >> Unfortunately the Boost dependency graph is as huge a hairball as I was >> afraid :-/ > > Hi, thanks for the feedback. Yes, dependency graph for boost is quite > large... I think with boost in git and modules available, this is going to > improve. That won't happen automatically. The git conversion is separate to reorganizing to resolve the solvable interdepency issues: http://thread.gmane.org/gmane.comp.programming.tools.ryppl.devel/201/focus=… The salient point is: > By modularizing and making the interdependencies explicit, we hope to > encourage developers to refactor. But we can only solve one problem at a > time. So, if you want to work on resolving interdependencies, don't wait for the git conversion to be done, because it won't help, and do pick up your editor and dig, because only that will help. Thanks, Steve.

1 0

Regression tests report page cycling slow
by Joaquin M Lopez Munoz 23 Jul '13

23 Jul '13

Hi, the page http://www.boost.org/development/tests/trunk/developer/summary.html seems to update very unfrequently, every two days or longer. Can something be done to speed this up? Thank you in advance, Joaquín M López Muñoz Telefónica Digital

2 1

Requesting number crunchers for trial complex classes
by Daryle Walker 22 Jul '13

22 Jul '13

I just pushed out commit "aaeabbd3fcc04956c4fd3d3825f6202355ab9297" of my trial hypercomplex number classes at https://github.com/CTMacUser/Complex. The classes now have all the arithmetic operators. They already have the condition functions (norm and conj), norm functions (taxi (ex L1), abs, sup, and sgn), and equality operators. There is an output operator, but not input. There are constructors for: default (both garbage bits and all zeros), copy and move (automatically defined), component (single or list), cross version, smaller hypercomplex (single and list), and (head of) larger hypercomplex. Look at the unit tests for usage examples. I haven't done any utility or transcendental functions yet, so let me know if you need them before proceeding. I just want people who do hard-core number crunching with complex, quaternion, and/or octonion numbers to see if my classes are worth it, performance-wise. You can also use the array-of-hypercomplex to array-of-many-reals reinterpret_cast trick. Everything should have Doxygen comments. I run this code on GCC 4.7.1 off MinGW for 32-bit Windows 8 Pro, so tests on other compilers will be appreciated. (It probably can't run on Visual C++, but GCC 4.8 and Clang 3.x will probably work.) Note on octonions: a month ago I found out, while looking for online octonion calculators, that octonion (and above) multiplication isn't standardized. I'm using the same philosophy from Wikipedia, which is also used by the existing Boost.Octonion. (Actually, I found a bug in B.O.'s octonion times quaternion code, since that author manually lists all the sub-terms, and my code is more automatic. I had to do the multiplication by hand to check who had it right.) So if your octonion products are different, it may not be a bug. I've tried to make as many constructors/operators/functions constexpr as possible. (That's why no std::initializer_list.) That may help move data into ROM, but you have to force non-inline-ness when you need to test runtime performance. Daryle W.

1 0

[Locale] does generator("") deliver the system's default locale?
by Michael Schinner 22 Jul '13

22 Jul '13

boost 1.54.0 When I use boost::locale::generator and generator("") I get different results for the decimal point than using std::locale(""). Boths methods are supposted to deliver the system's default locale. Example: // windows 7, de_AT std::use_facet<std::numpunct<char> >(std::locale("")).decimal_point(); // delivers a , boost::locale::generator generator; std::use_facet<std::numpunct<char> >(generator("")).decimal_point(); // delivers a . What does generator("")) deliver? Is it wanted that a '.' is deliverd as decimal point for a german locale? Best regards, Michael

2 1

[system] Do we need this library with latest (almost C++0x) compilers?
by Tonko Juricic 22 Jul '13

22 Jul '13

Can somebody please explain what is missing in current compiler implementations? What is preventing other libraries to have a macro like: #ifdef _CPP11_THREAD_ #include <thread> #include <mutex> #include <condition_variable> #else #include <boost/thread.hpp> #include <boost/thread/mutex.hpp> #include <boost/thread/condition_variable.hpp> #endif also when it comes to error codes and conditions? Thanks, Tony

3 2

windows_shared_memory - does memory block exists?
by piotr.ns 21 Jul '13

21 Jul '13

Hi, Why native windows shared memory does not include any means to check for existance of memory block without throwing exceptions? A small function would be enough: // boost::interprocess::windows_shared_memory static bool exists(const std::string &a_path) { using namespace boost::interprocess; try { unsigned long file_map_access = winapi::page_readonly; unsigned long map_access = winapi::file_map_read; void *test_handle = winapi::open_file_mapping(map_access, a_path.c_str()); bool res = (test_handle != NULL); if(res) winapi::close_handle(test_handle); return res; } catch(...) { return false; } } Without this I have to use Boost internals (winapi::*) in my application. Would somebody consider including this code or something similar? Regards, Piotr

1 0

Status of various Boost initiatives?
by Robert Ramey 21 Jul '13

21 Jul '13

I'm trying to get a handle on the current state of the various boost migrations which have been underway. a) migration to GIT b) migration to CMake c) status of rypll when I try to track this down I find many dead links, repeated information. I also don't find some blogs I used to be able to find on these subjects. Anyone up to provide an current status snapshot? Robert Ramey

5 14

Mag Gam
by Mag Gam 21 Jul '13

21 Jul '13

http://yumaonline.it/bau/bcjk.xvdhjqpdiniqwmxf Mag Gam 7/21/2013 7:26:51 AM

1 0

Re: [boost] [regression] patch for running tests in parallel and out-of-sync files
by Robert Kawulak 20 Jul '13

20 Jul '13

> From: Robert Kawulak > When I was running tests in parallel (using b2 -j option) I was getting random > warnings in the results table because "msvc.manifest" lines were interleaved with > compile/link actions. I've fixed this with the attached patch - is it OK to apply > it to trunk/release? Due to the lack of feedback I've gone ahead and applied the fix in trunk for now. If nobody objects or reports issues, I'll merge it into release later. > BTW, I've noticed that the following files in tools/regression/src haven't been > updated in release branch even though they've been changed in trunk a long time > ago: > compiler_status.cpp (trunk date 2012-01-21, release date 2011-10-06) > library_status.cpp (trunk date 2013-03-25, release date 2013-03-09) > Is it OK to update these in release branch? Likewise, I've updated the two files in release. I've also added tools/regression/build/bin directory to ignore list (it's created when invoking b2 from tools). Best regards, Robert

1 0

[git conversion] type_traits problems; spurious headers
by Beman Dawes 20 Jul '13

20 Jul '13

libs/type_traits/include/boost has these files: aligned_storage.hpp call_traits.hpp config.hpp smart_ptr.hpp timer.hpp type_traits.hpp utility.hpp AFAIK, call_traits.hpp and type_traits.hpp are supposed to be there, but the rest are spurious, and are causing "b2 headers" to create some incorrect links that are preventing testing many libraries. --Beman

2 1

[git-help] Status?
by Rene Rivera 20 Jul '13

20 Jul '13

I started looking at making the final minor set of changes to the regression testing scripts to have the option of testing the modular git version of the boost super-project. Unfortunately it now seems that the super-project no longer has *any* of the references to the library sub-projects. Me not being able to get this work done now is rather annoying as it likely means that the testing will not be ready early in the 1.55 release cycle. Which is the release currently scheduled to switch to git. What is the status of the git transition? When will the Boost release team be able to start working on the switch? Rene. -- -- -- Grafik - Don't Assume Anything -- Redshift Software, Inc. - http://redshift-software.com -- rrivera/acm.org - grafik/redshift-software.com -- 102708583/icq - grafikrobot/aim - grafikrobot/yahoo

5 11

A more convenient Variant visitation syntax
by Kevin Wu Won 19 Jul '13

19 Jul '13

While Boost Variant is a wonderful library that fills a genuine hole in the C++ language, it is not as nice to use as it could be. The "correct" way to unwrap a variant is to apply a static visitor, but this method carries a high syntactic burden because it needs the user to define a class (probably somewhere far away) just so they can "switch" on the type of the object stored in the variant. I came up with a solution where the handler functions can be specified inline with C++11 lambdas. Here's an example: boost::variant< int, std::string > u("hello world"); int result = match(u, [](int i) -> int { return i; }, [](const std::string & str) -> int { return str.length(); }); The `match` function accepts the variant followed by the handler functions. The functions can be specified in any order. It will fail to compile if the functions do not match the types of the variant, if the return types are not all the same, or if a non-unary function is supplied. This is C++11 only because it's quite pointless without lambda functions. I've tested it with gcc 4.7. It doesn't work on gcc 4.6, which can't handle the variadic templates. Here's the code: https://github.com/exclipy/inline_variant_visitor What do you think? This started out for me as an exercise to learn template metaprogramming and C++11, but hopefully, it can actually evolve into something useful.

7 8