June 2014 - Boost - lists.preview.boost.org

Re: [boost] Interest in bit-wise flags?
by Jeffrey Bush 28 Jun '14

28 Jun '14

> > > > > Hi Boost! > > > > I have developed a type-safe bit-wise flags class for my own personal use > > and > > am wondering if it would be of interest for me to submit it as a Boost > > library. > > At the moment it is not ready for submission (code is messy) but I am > > testing > > the waters so I present an overview below. > > * Fully ISO standard C++11 (except for an MSVC version which is > > API-compatible > > except it doesn't support as many an infinite number of flag names) > > * They are type-safe, requiring explicit casts to and from > integers/booleans > > * Supports standard bit-wise operations, and always keep values within > the > > possible set of flags > > * Supports getting the name of a flag and looking up flags by name at > > run-time > > (when a flag is actually multiple-flags it gives something like "A|B") > > * Supports getting an array of all flags at run-time > > > > Now the bad things, which may be a deal-breaker: > > * Because of limitations in C++ the syntax can feel a bit awkward. You > have > > to > > use a macro to define flag-names (which actually creates a class) then > you > > can pass those flag-names as template arguments to the flags. An > example: > > FLAG_NAME(A); > > FLAG_NAME(B); > > FLAG_NAME(C); > > typedef Flags<std::uint8_t, Flag_A, Flag_B, Flag_C>::WithValues<0x01, > > 0x02, 0x04> MyFlags; > > * I also couldn't get around using the ::WithValues nested class > > * I use a set of macros to make this cleaner (e.g. the above could be > > FLAGS(A, B, C)) and once defined there is no more ugliness > > > > Thanks for consideration! > > Jeff > > > > _______________________________________________ > > Unsubscribe & other changes: > http://lists.boost.org/mailman/listinfo.cgi/boost > > > > > > Jeffrey Bush <jeff <at> coderforlife.com> writes: > > I have posted the current (ugly) code online: > https://gist.github.com/coderforlife/6d8bac451d49dd1a0c81#file-flags-hpp > > Above that is the even uglier MSCV-specific implementation. > > I focused on function not readability when making it, I understand that it > would take significant work to make it Boost ready. > > Differences from BOOST_BITMASK or lordodinscpplib are that it supports ~ > that is value-constrained (only flips bits that are covered by flags, it > supports names at run-time (converting to and from strings), and it can > default-value then flags with powers of two. > > If those features are undesired, then this class is unnecessary seeing that > those other solutions are significantly simpler or more portable. > > However, looking at those has given me some ideas on how to simplify my > code > and make it possibly work in Clang. > > Jeff > I have updated it, simplifying the design while keeping the same API and provided a simple test program, both available at https://gist.github.com/coderforlife/6d8bac451d49dd1a0c81. It now works fine in all compilers I have tested (MSVC 2010, MSVC 2013, mingw-w64 4.8.2, gcc 4.8.2, clang 3.4). This simplification greatly reduced the amount of code and allowed me to combine the fallback version that doesn't need variadic templates into the main version. I have also made it so the declaration can be inside a class or shared header and the definition elsewhere. This separation was necessary because const non-integral values cannot be defined in classes. Additionally, I have cleaned up the code quite a bit to fit better with Boost standards, although not complete yet (still uses tabs and some lines are longer than 80 characters although most are not). The only difference in API is that you can no longer pre-declare flag name objects or do `typedef Flags<uint8_t, Name1, Name2, Name3>::WithValues<1,2,4> MyFlags` or similar like before, you must use the macro FLAGS()/FLAGS_WITH_VALUES() [which was available before]. I have compiled a very detailed list of differences between BOOST_BITMASK and (BOOST_)FLAGS. The first is an advantage of BITMASK, the second is a draw, and the remainder are advantages of FLAGS. - BITMASK requires an enum or scoped enum to be declared and then the macro to be used, but can entirely within a shared header. FLAGS would be a single-line, or if in a shared header have separate declarations and definitions. Both support being inside classes by having some macro outside the class. - BITMASK supports unlimited flags with less than 2^32 while FLAGS supports at most 32 flags but any underlying integral type. Both could have their limits increased. - BITMASK when used with scoped enums requires full bool casting and does not support the ! operator for checking if any/no flag is set and when used with original enums has some type safety issues (can compare values from different enums directly). FLAGS has the best of both, have strong type safety while also supporting the ! operator and an explicit bool cast (safe-bool). - BITMASK allows (and actually the ~ operator causes) bits that aren't associated with flags to be set while FLAGS prevents these bits from ever being set. This is a numerical safety (I have examples when this would be important). - FLAGS will automatically set the flag-values to powers of two if you want it to, reducing possibility of typos for simple flags while still allowing you to have explicit flag values when necessary (for example, when having pre-defined names for combinations of flags or retaining number-compatibility after dropping a particular flag name). BITMASK always requires you to set the values explicitly. - FLAGS support runtime value-name conversion, allowing something like XML reading/writing using the flag names instead of the numbers, debugging output, user-input parsing, etc. Additionally, BOOST_BITMASK is in boost/detail, does this mean it shouldn't be used outside of Boost? (I have a method of making it so there is no need for a separate declaration vs definition, however it is "ugly" but does work [and the end-user wouldn't have to really know] - it makes each flag-name a static function instead of static-const variable and adds an implicit constructor that takes such a static function and calls it to get the real value which is a static-const local variable). Jeff

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Adding helpful requires macros to the enable_if utility
by paul Fultz 28 Jun '14

28 Jun '14

These following set of macros, I have found very useful in C++: #define BOOST_ERROR_PARENTHESIS_MUST_BE_PLACED_AROUND_THE_RETURN_TYPE(...) __VA_ARGS__>::type #define BOOST_FUNCTION_REQUIRES(...) typename boost::enable_if_c<(__VA_ARGS__), BOOST_ERROR_PARENTHESIS_MUST_BE_PLACED_AROUND_THE_RETURN_TYPE #define BOOST_CLASS_REQUIRES(...) typename boost::enable_if_c<(__VA_ARGS__)>::type #define BOOST_REQUIRES(...) typename boost::enable_if_c<(__VA_ARGS__), int>::type = 0 Which I use like the following For functions: template <class T> BOOST_FUNCTION_REQUIRES(boost::is_arithmetic<T>::value) (T) foo(T t) { return t; } And C++11 functions: template <class T, BOOST_REQUIRES(boost::is_arithmetic<T>())> T foo(T t) { return t; } Class specializations: template <class T, class Enable = void> class A { ... }; template <class T> class A<T, BOOST_CLASS_REQUIRES(is_integral<T>())> { ... }; template <class T> class A<T, BOOST_CLASS_REQUIRES(is_float<T>())> { ... }; It would be nice if these were the added with the enable_if utility with boost. Thanks, Paul

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[quickbook] controlling headers in tables
by Andrzej Krzemienski 27 Jun '14

27 Jun '14

Hi Everyone, Does anyone know if in QuickBook it is possible to create a table without the header row, or to create a table with both header row and a header first column? Regards, &rzej

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[regression][build] Missing tests after the addition of sublibs file
by Adam Wulkiewicz 27 Jun '14

27 Jun '14

Hi, In order to display separated tests for the main and 'spatial index' parts of the Geometry we added a sublibs file to the master branch. The result is that new tests for the main part of the library are missing. I remember the same issue with the develop branch but don't remember how it was fixed. There is probably some collision of names/paths of the old and new tests. Could we do something about it? Could it be fixed by some manual cleanup? Or must the old tests dissapear naturally? Could this be considered as a bug in Build? For convenience: http://www.boost.org/development/tests/master/developer/geometry.html http://www.boost.org/development/tests/master/developer/geometry-index.html Regards, Adam

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dynamically coupling documentation to unit testing
by Roger Martin 27 Jun '14

27 Jun '14

Hi, Been thinking. What I've come to like in documentation is a section at the top of a class or functor that includes some real examples code in the 'doxygen' section that shows how to use. My question is how difficult would it be to make unit testing pick these up and actually run them? If written with unit equalities this would gain by making me and developers write good header examples at the same time as making unit tests and continuously validate documentation isn't getting out-of-date as well. And have the output from the tests be compatible with jenkins or other build system's reporting? How feasible to do this? Is this a possibility to add to boost? Or should it be an llvm based project?

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[align] git update problem
by Fletcher, John P 27 Jun '14

27 Jun '14

I am attempting to update my local copy of boost develop, which I can usually do with the commands: git checkout develop git pull --recurse-submodules git submodule update --init and then git submodule foreach git checkout develop git submodule foreach git pull I have not done this for some time. When I did it today I get a lot of messages from boost align with unmerged files and it will not update. I have not worked on these files myself. What do I need to do to get boost align restored to a good state? Thanks John

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Issue Running Regression Tests on msvc-12.0
by Matthew Musto 27 Jun '14

27 Jun '14

I have been trying to run a regression test against msvc-12 on Windows 8.1 and I am getting the following errors. In the past, this has run fine. I run this command from my cmd prompt: python run.py --runner=Matusi143 --toolsets=msvc-12.0 -tag=master Everything appears to go fine until... Fetching submodule tools/build Fetching submodule tools/inspect Fetching submodule tools/litre Fetching submodule tools/quickbook Already up-to-date. # Executing GIT command: c:\boost_dev\boost_root> git submodule "update" "--init" # Executing GIT command: c:\boost_dev\boost_root> git checkout "master" Already on 'master' Your branch is up-to-date with 'origin/master'. # Executing GIT command: c:\boost_dev\boost_root> git submodule foreach ""git reset --quiet --hard; git clean -fxd"" Entering 'libs/accumulators' error: unknown option `hard;' usage: git reset [--mixed | --soft | --hard | --merge | --keep] [-q] [<commit>] or: git reset [-q] <tree-ish> [--] <paths>... or: git reset --patch [<tree-ish>] [--] [<paths>...] -q, --quiet be quiet, only report errors --mixed reset HEAD and index --soft reset only HEAD --hard reset HEAD, index and working tree --merge reset HEAD, index and working tree --keep reset HEAD but keep local changes -p, --patch select hunks interactively Stopping at 'libs/accumulators'; script returned non-zero status. Traceback (most recent call last): File "run.py", line 83, in <module> runner(root) File "c:\boost_dev\tools_regression_src\regression.py", line 264, in __init__ self.main() File "c:\boost_dev\tools_regression_src\regression.py", line 650, in main getattr(self,action_m)() File "c:\boost_dev\tools_regression_src\regression.py", line 604, in command_regression self.command_cleanup() File "c:\boost_dev\tools_regression_src\regression.py", line 274, in command_cleanup self.git_source_checkout(True) File "c:\boost_dev\tools_regression_src\regression.py", line 939, in git_source_checkout self.git_checkout(git_info['boost'], self.git_branch(), clean) File "c:\boost_dev\tools_regression_src\regression.py", line 917, in git_checkout self.git_command( 'submodule foreach', '"git reset --quiet --hard; git clean -fxd"') File "c:\boost_dev\tools_regression_src\regression.py", line 899, in git_command raise Exception( 'GIT command "%s" failed with code %d' % (git_cli, rc) ) Exception: GIT command "git submodule foreach ""git reset --quiet --hard; git clean -fxd""" failed with code 1 c:\boost_dev> Any help is greatly appreciated. -- -------------------- Matthew Musto

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[parameter] #line markers in literate tests
by Edward Diener 27 Jun '14

27 Jun '14

Is there any logical reason for the #line markers in the source files for the 'literal' tests in Boost parameter ? VC++ will not compile these tests with them and although they appear to me as completely valid C++ I would like to create a pull request to fix the VC++ problem. If there is no reason for the #line markers I can remove them, else I can wrap in "#if !defined(BOOST_MSVC)/#endif" pairs after including boost/config.h.

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Boost Build question
by Emil Dotchevski 27 Jun '14

27 Jun '14

Hello, I'm trying to instruct bjam to attempt to output an iphone executable (btw I'm not trying to build Boost itself.) What's the correct way to do this? I apologize if this is explained somewhere, but searching online mostly finds xcode-related information, and the suggestions in the few pages that looked relevant didn't work for me. -- Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode

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[utility]Re-assigned tickets
by Niklas Angare 26 Jun '14

26 Jun '14

I just re-assigned these tickets that were incorrectly filed against the regression testing component to the utility library: https://svn.boost.org/trac/boost/ticket/9945 https://svn.boost.org/trac/boost/ticket/9944 https://svn.boost.org/trac/boost/ticket/9925 They are now owned by "no-maintainer". Regards Niklas Angare

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