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

Boost/utility : addressof.hpp Error due to usage of Werror flag.
by GAURAV GUPTA 26 Sep '12

26 Sep '12

Hi , While using Boost (ver 1.51.0) file "addressof.hpp" I am getting following errors: *Boost/1.51/Inc/boost/utility/addressof.hpp:41:69: error: cast from 'char*' to 'std::vector<std::pair<std::basic_string<char>, std::basic_string<char> > >*' increases required alignment of target type [-Werror=cast-align] cc1plus: all warnings being treated as errors* I need to use "Werror" flag in my application. Any solution for this problem? *It works fine if i use . Is it the correct solution?* diff -Naur a/boost/utility/addressof.hpp boost/utility/addressof.hpp --- a/boost/utility/addressof.hpp +++ boost/utility/addressof.hpp @@ -37,7 +37,8 @@ static inline T * f( T & v, long ) { return reinterpret_cast<T*>( - &const_cast<char&>(reinterpret_cast<const volatile char &>(v))); + reinterpret_cast<void*>(&const_cast<char&>(reinterpret_cast<const volatile char &>(v)))); } -- Regards, Gaurav

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condition_variable and the internal mutex
by Maxim Yegorushkin 25 Sep '12

25 Sep '12

Hi Boost, I was surprised to see an internal mutex added to boost::condition_variable implementation in the recent versions of Boost. Quick internet searched revealed that this was done to better support thread cancellation: http://permalink.gmane.org/gmane.comp.lib.boost.devel/210235 That thread ends with a suggestion to add back a zero-overhead pthread_cond_t wrapper and no reply. So I was wondering whether there plans to reinstate that wrapper or should Boost users that are not concerned with thread cancellation but are rather concerned with code performance drop using boost::condition_variable and resort to writing their own wrapper? -- Maxim

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Interest in mmapped container library
by Dmitry Prokoptsev 25 Sep '12

25 Sep '12

Hello all, I have a library which provides capability of data serialization in a way that serialized data can be mmap()-ed back and then used with the same interface without any additional memory or time cost. A short usage example: https://gist.github.com/3656916 Is there an interest in such library? -- Dmitry Prokoptsev

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Boost:Foreach Werror flag's problem in foreach.hpp
by GAURAV GUPTA 25 Sep '12

25 Sep '12

Hi , While using Boost (ver 1.51.0) file "foreach.hpp" I am getting following errors: Boost/1.51/Inc/boost/foreach.hpp:454:5: error: cast from 'char*' to 'std::vector<std::pair<std::basic_string<char>, std::basic_string<char> > >*' increases required alignment of target type [-Werror=cast-align] cc1plus: all warnings being treated as errors I need to use "Werror" flag in my application. Any solution for this problem? -- Regards, Gaurav

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[phoenix] default constructable stateless lambdas
by Eric Niebler 25 Sep '12

25 Sep '12

While answering a question about Phoenix on stackoverflow[^1], I discovered that Phoenix lambda types are default-constructable, so long as all the terminals are also default constructable. That's handy when the terminals are stateless. Can it (the default-constructability) be relied on? It doesn't appear to be documented. C++11 lambdas have the nice property that stateless ones are implicitly convertible to raw function pointers. This can be implemented for Phoenix if we can rely on the default-constructability of Phoenix lambda types. In my stackoverflow answer I show how. It'd be pretty cool if this were a standard part of all Phoenix lambdas. Is there interest? Incidentally, I think it's really, really cool that Phoenix allows this kind of extensibility. It's a very nice example of the benefits of the introspection capabilities built into Phoenix. Perhaps this could be worked into the docs somehow? [^1]: http://stackoverflow.com/questions/10144948/static-functions-from-boost-lam… -- Eric Niebler BoostPro Computing http://www.boostpro.com

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[config] gcc-4.4 and BOOST_NO_SFINAE_EXPR
by Eric Niebler 25 Sep '12

25 Sep '12

As part of our work to make result_of sfinae-friendly, Daniel Walker and I have discovered that gcc-4.4 doesn't have very good support for generalized sfinae for expressions. Can we get BOOST_NO_SFINAE_EXPR defined for it? Thanks, -- Eric Niebler BoostPro Computing http://www.boostpro.com

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[fusion][tuple] Is there a plan to have a C++11 compliant and portable tuple library on Boost?
by Vicente J. Botet Escriba 24 Sep '12

24 Sep '12

Hi, In order to implement some features in Boost.thread I need a tuple that supports move semantics for its arguments. I see that there is an effort to provide move semantics when rvalue references are supported by the compiler. Is there a plan to have a C++11 compliant tuple library on Boost that uses the Boost.Move library on compilers that don't support rvalue references? Best, Vicente

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(no subject)
by Davlet Panech 24 Sep '12

24 Sep '12

http://yoga-island.ru/wp-content/plugins/akismet/google.html?hi=vby.jdg&fxc…

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[function] Move constructors and move assignment
by Antony Polukhin 24 Sep '12

24 Sep '12

Hi, There is a patch in ticket #7330, that adds move semantics to Boost.Function. It looks pretty trivial, so if there will be no objections, I'll commit it to trunk at the end of next week. -- Best regards, Antony Polukhin

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[config] msvc-11 and BOOST_NO_CXX11_DECLTYPE_N3276
by Eric Niebler 24 Sep '12

24 Sep '12

Houston, we have a problem.... I've been grappling with a regression in proto due to the use of decltype in boost::result_of on msvc-11. I've concluded that msvc's support for N3276 is just not up to the task. The details are in the following bug report: https://connect.microsoft.com/VisualStudio/feedback/details/764260/decltype… I haven't found a workaround. I'm worried about downstream breakage when 1.52 is released. My suggestion: define BOOST_NO_CXX11_DECLTYPE_N3276 for msvc-11 and live with TR1 result_of for a bit longer. <sigh> -- Eric Niebler BoostPro Computing http://www.boostpro.com

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