July 2008 - Boost - lists.preview.boost.org

[release] merging doc changes?
by joaquin＠tid.es 08 Jul '08

08 Jul '08

Is it OK to merge documentation changes to the release branch? Thank you, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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[fusion] fusion sequence of non-copy-constructible types
by Oliver Mueller 08 Jul '08

08 Jul '08

hello, at the last boostcon i had the chance to be introduced to fusion by dan and joel. i appreciate the idea of fusion a lot and the library amazingly detailed. since we have already had great exposure to the mpl the fusion concepts present ample opportunity for new ideas. still, some little things sometimes make it hard for me to keep rolling with fusion: i need to have a vector/list of non-copy-constructible types. using e.g. a standard fusion::vector that does not seem to be possible since objects are constructed first, then copied. of course, i could provide a public copy-constructor but that would in other places remove the compiler enforced contract that those objects are not copied under any circumstances. i also cannot think of a good reason why it is nesseccary to copy in that case. so is there a way of having a fusion sequence that does work on non-copy-constructible types? thanks for any suggestions, oliver

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Re: [boost] [1.36.0] Libraries with unmerged changes?
by Jan Gaspar 08 Jul '08

08 Jul '08

Hi Thorsten, I've just found your emails in the spam folder. ?? Will merge the changes into the release branch. Jan ----- Original Message ---- From: Thorsten Ottosen <thorsten.ottosen(a)dezide.com> To: boost(a)lists.boost.org; Jan Gaspar <jano_gaspar(a)yahoo.com> Sent: Tuesday, 8 July, 2008 10:45:01 AM Subject: Re: [1.36.0] Libraries with unmerged changes? Beman Dawes skrev: > Below is a list of libraries whose header files appear to differ between > the trunk and branches/release. > circular_buffer I have had diffuculties reaching Jan regarding this library. There are some quite imortant changes here, especially for the default constructor. If we can't reach Jan soon, I wonder if I could just patch the constructor in the release branch for him? -Thorsten __________________________________________________________ Not happy with your email address?. Get the one you really want - millions of new email addresses available now at Yahoo! http://uk.docs.yahoo.com/ymail/new.html

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Fusion Question
by Tom Brinkman 08 Jul '08

08 Jul '08

Joel de Guzman, I'd like to enhance my future boost::layout library proposal to use your boost::fusion. Here is a simple example of the boost::layout framework, that uses boost::gill as the view parameter. A boost::layout functor takes the following form: struct layer { template <typename view_t> void operator()(view_t& view) {} }; Examples of layers could be: fill_layer<> fill; border_layer<> border; text_layer<> text; Lets say I want to combine three layers into a single drawing operation. Currently, I do it like this: typedef boost::function<void (view_t&) > layer_t; layer_t layers[] = { fill_layer<>, border_layer<>, text_layer<> } draw_layers draw(layers,sizeof(layers)/sizeof(layer_t)); boost::gil::rgb8view_t view; draw(view); This works fine, but I would like to improve it by using boost fusion. Any suggestions or hints to get me started?

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patch for NetBSD support
by brook＠biology.nmsu.edu 07 Jul '08

07 Jul '08

I tried to build boost-trunk on a NetBSD system. The following patch is required to get most of the way through (the math lib has additional errors). Because these changes are completely dependent on identifiers of NetBSD, I cannot see how they might negatively affect anything else. What is the procedure for getting this patch applied? Thanks for your help. Cheers, Brook =========================================================================== --- ./boost/config/platform/bsd.hpp.orig 2008-07-05 12:13:48.000000000 -0600 +++ ./boost/config/platform/bsd.hpp 2008-07-05 15:58:45.000000000 -0600 @@ -43,7 +43,7 @@ // // No wide character support in the BSD header files: // -#if !(defined(__FreeBSD__) && (__FreeBSD__ >= 5)) +#if !(defined(__FreeBSD__) && (__FreeBSD__ >= 5) || defined(__NetBSD__)) # define BOOST_NO_CWCHAR #endif // --- ./tools/build/v2/tools/python.jam.orig 2008-07-05 12:37:43.000000000 -0600 +++ ./tools/build/v2/tools/python.jam 2008-07-05 16:03:18.000000000 -0600 @@ -647,6 +647,8 @@ case darwin : return ; case windows : return ; + case netbsd : return <library>pthread <toolset>gcc:<library>util ; + case hpux : return <library>rt ; case aix : return <library>pthread <library>dl ;

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Request for comments on changes to the dynamic_bitset docs
by Gennaro Prota 07 Jul '08

07 Jul '08

Hi, I just fixed the dynamic_bitset docs for issue #1591; the problem is with a couple of duplication of sentences of this kind: Note that the expression b1 & b2 is equivalent to creating a temporary copy of b1, using operator&=, and returning the temporary copy. I think such sentences are almost without meaning and should simply be dropped. The only concern is for "breaking a contract" in this case, though frankly I don't see what the user could sensibly rely upon. And "equivalent" is so generic, anyway. In case you agree with removing the sentences, would you note that in the section "Changes from previous version(s)"? -- Genny

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[bimap] Excessive Compilation Memory Usage with VC8 - 1.35.0
by Bryan Petty 07 Jul '08

07 Jul '08

Hi, I've run into some serious problems getting my application to build after adding some usage of boost::bimap. In my application's case, a single bimap of any type causes the VC8 compiler to use more than 1GB of extra ram than it does normally (which is around 1GB). It compiles without errors, and runs flawlessly, but if I add a second bimap of any type elsewhere in my code, the additional ram usage becomes a problem and the build fails due to lack of sufficient memory to finish the compilation. These bimaps are declared and defined in a static library linked to my application which is setup with pre-compiled headers for that library. The compilation generally takes the most ram during compilation of the pre-compiled headers, and that's where this fails. This seems especially weird since from what I can tell, bimap is simply an implementation of boost::multi_index for a specific purpose, and we already make use of 4 different multi_index containers throughout our application without any memory consumption issues. I've taken the time to test this with a new skeleton Win32 project, and used the simple bimap example included with Boost. Without bimap, cl.exe only peaks at 3.25MB committed (measured with Process Monitor) in debug mode, but when I copy in the simple bimap example it peaks at 325MB committed in debug, and 148MB committed in release. I don't see anywhere near these kind of numbers with GCC on x86 linux, g++ stays around 3MB. System: Windows XP, VC8, 2GB RAM, Boost 1.35.0 One user on #boost experienced similar numbers when compiling with VC9 as well. When I add more bimaps in the simple example, it doesn't add as much of a jump as the first does, but it's still fairly significant (from 325MB to 360MB in debug with the second bimap). I have no idea how to go about debugging this. Regards, Bryan Petty

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Reassigning tickets #1531 and #1591 to me?
by Gennaro Prota 07 Jul '08

07 Jul '08

Hi guys, I sent the same request yesterday, to the Moderators address, but didn't get any reply (sorry if this duplication causes any inconvenience): could someone with sufficient privileges reassign tickets #1531 and #1591 to me, so that I can close them? Or should I ask Jeremy? Thanks, -- Genny

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How do I configure MPI?
by Daryle Walker 07 Jul '08

07 Jul '08

I'm trying out Boost.Build. I used to get warnings like: //=================================== warning: Graph library does not contain optional GraphML reader. note: to enable GraphML support, set EXPAT_INCLUDE and EXPAT_LIBPATH to the note: directories containing the Expat headers and libraries, respectively. warning: skipping optional Message Passing Interface (MPI) library. note: to enable MPI support, add "using mpi ;" to user-config.jam. note: to suppress this message, pass "--without-mpi" to bjam. note: otherwise, you can safely ignore this message. Building Boost.Regex with the optional Unicode/ICU support disabled. Please refer to the Boost.Regex documentation for more information (don't panic: this is a strictly optional feature). //=================================== I added a "using mpi ;" line, and now I'm getting errors like: //=================================== MPI auto-detection failed: unknown wrapper compiler mpic++ Please report this error to the Boost mailing list: http://www.boost.org You will need to manually configure MPI support. //=================================== So, how do I configure MPI support? Do I have to set up GraphML support first? -- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT hotmail DOT com

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determining if an object is faster to pass by value or const reference
by Michael Marcin 07 Jul '08

07 Jul '08

In general noone would write a function that took an int by const reference because doing so doesn't make sense from a performance standpoint. However often times we pass these trivial types to functions generically written to take const T&. It seems like type traits would make it simple to overload based on this convention. However I don't see a type trait that is fit for this use case. The has_trivial_copy trait would seem promising but it could return true for large pod objects that you wouldn't want to copy. The is_scalar trait seems promising but it will return false for lightweight user defined types and be suboptimal. Using has_trivial_copy together with some sizeof limit seems promising but a bit hand wavy. Is there a trait designed for this use case I'm overlooking? Thanks, Michael Marcin

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