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Boost.units autoscaling doesn't seem to work with the measurement type.
by Paul A. Bristow 27 Apr '12

27 Apr '12

I have previously used Boost.Units and autoscaled using << engineering_prefix nicely, and this works as expected for quantity of type double. but it seems that code that I believe worked previously does not autoscale when using a *user-defined type*, like the measurement example in kitchen_sink.cpp. To confirm this, I have added after //[kitchen_sink_snippet_8 in kitchen_sink.cpp at line 445 a measurement quantity where the length is long enough to trigger conversion to km, thus quantity<length,measurement<double> > biglen(measurement<double>(12345.0,123.0)*meters); std::cout << "Biglen autoscaled "<< engineering_prefix << biglen << std::endl; but I get a *unscaled* value :-( Biglen autoscaled 12345(+/-123) m rather than the expected conversion to kilometers 12.345(+/- 0.123) km Am I doing something wrong, or has something changed? Thanks Paul PS Using Microsoft Visual Studio 2010 Version 10.0.40219.1 SP1Rel Microsoft .NET Framework Version 4.0.30319 SP1Rel Boost-trunk (Boost.1.49) --- Paul A. Bristow, Prizet Farmhouse, Kendal LA8 8AB UK +44 1539 561830 07714330204 pbristow(a)hetp.u-net.com

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Re: [boost] [decimal] Proposed portable implementation of std::decimal
by Josh Quigley 27 Apr '12

27 Apr '12

As previously mentioned, the plan is to wire up existing (C interface) packages to a C++ std::decimal, raising licensing issues around the 3rd party code. I don't believe there is an issue, the licences are very short and read like plain English to me. Also, gcc includes both of these in it's implementation, and distributes under an open licence. I've copy-pasted below the relevant bits out of the EULAs. If anyone thinks there might be an issue, please let me know. INTEL EULA Copyright (c) 2011, Intel Corp. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. * Redistributions in binary form must reproduce the above copyright notice, his list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. * Neither the name of Intel Corporation nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. IBM Licence Copyright (c) 1995-2012 International Business Machines Corporation and others All rights reserved. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, provided that the above copyright notice(s) and this permission notice appear in all copies of the Software and that both the above copyright notice(s) and this permission notice appear in supporting documentation.

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Variadic to Head/Tail TMP List
by Fernando Pelliccioni 27 Apr '12

27 Apr '12

Hi, Is this piece of code useful ? http://pastebin.com/tRrqVHTw The purpose is to tranform code like the following: typedef cons<int, cons<float, cons<char, cons<string>>>> t0; // fusion::cons or similar data structures in typedef chain_generator<cons, nil> cons_gen; typedef cons_gen::gen<int, float, char, std::string>::type t1; I don't know if there is something similar in a library. I think it could be useful. Compiler tests: GCC 4.7 -> Compiler Error GCC 4.7.1 & Trunk -> OK http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53108 Clang Trunk -> OK MSVC 11 beta -> has no Variadic Templates Regards, FP.

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Boost.ntree_container (bi_tree, quad_tree, oct_tree, etc ptr containers) Is there any interest in this?
by Dan Walters 27 Apr '12

27 Apr '12

Hi all, I am proposing adding spacial containers for efficiently storing and accessing data of a spacial nature in fixed size trees. n-tree data structures would be useful where data relates to a 1D, 2D or 3D location, providing n-array searching of an n-array volume. N-tree data structures are commonly used in 3d applications, and are rarely particularly specialized. Their use is fundamental however they are frequently written by application programmers, due to a lack of free open source implementations (to the limit of my research). Their sophistication, like any container, is slim but easy to get wrong and beyond the ability and time contraints that should be assumed of the application programmer. It is a flexible and standard enough concept that a single implementation can be expected to meet a majority of requirements. I think there is the opportunity to create a solid implementation of templated n-tree pointer containers. The ntree container would be a tree representing an narray of elements with all dimensions being the same and being a power of two. The tree is memory efficient where areas within the volume are not occupied, and so "branches" and "leaves" are not created. The tree is well suited to geometrical operations such as ray picking or plane culling of the volume. An n-tree structure could be used in the place of any sparely populated n dimensional array where memory saving is the objective. The existing libraries I have found are licensed under GNU licenses. A ntree container should implement: get reset overloaded (array style) operators Optional implementations: views - a subset object representing an area or volume within the tree for accelerated access to a group of leaves that are positioned near to each other raycasting plane culling (getting leaves within a set of planes) etc. Is there interest in such a library? Many thanks, Dan

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[interprocess] ppc compile error
by Tim Blechmann 27 Apr '12

27 Apr '12

hi all, one of my users reported the following compile error when building my application for ppc/osx(10.5): /var/folders/+D/+DUo7PxAEgCfHTatXKIeMU+++TI/-Tmp-//ccPubDFs.s:5566:Unknown pseudo-op: .subsection /var/folders/+D/+DUo7PxAEgCfHTatXKIeMU+++TI/-Tmp-//ccPubDFs.s:5566:Rest of line ignored. 1st junk character valued 50 (2). /var/folders/+D/+DUo7PxAEgCfHTatXKIeMU+++TI/-Tmp-//ccPubDFs.s:5569:Unknown pseudo-op: .previous the specific part of the assembly is: -- 4010 L686: 4011 sync 4012 lwarx r8,0,r11 4013 cmpw r8, r3 4014 bne- 2f 4015 stwcx. r9,0,r11 4016 bne- 2f 4017 addi r2,0,1 4018 1:.subsection 2 4019 2: addi r2,0,0 4020 b 1b 4021 .previous 4022 4023 cmpwi cr7,r2,0 4024 mr r3,r8 4025 beq cr7,L686 4026 stw r8,20(r10) 4027 mulli r3,r8,12 4028 add r3,r3,r10 4029 addi r3,r3,28 4030 bl L__ZNK5boost12interprocess10offset_ptrIfimLm0EE14to_raw_pointerEv$stub 4031 addi r1,r1,96 4032 stw r3,4(r30) 4033 lwz r0,8(r1) 4034 nop 4035 lmw r30,-8(r1) 4036 mtlr r0 4037 blr -- this error occurs with boost-1.49.0 ... is this a known issue or some workaround? thanks, tim

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[OT][RFC] standardized compile-time reflection
by Matus Chochlik 27 Apr '12

27 Apr '12

Dear members of the Boost community, (Sorry for being slightly off-topic here) In the last couple or years I've been working on the design and implementation of portable reflection in C++. I've written several reflection libraries (that are hopefuly gradually improving). For the latest incarnation see the Mirror reflection utilities written in C++11: http://kifri.fri.uniza.sk/~chochlik/mirror-lib/html/ Recently I've learned that the Standardization Committee has issued a call for proposals for additions to the standard to the wider community, so I've decided to write down my own ideas on how compile-time reflection should look like in C++. Afterwards I discussed it with several people including Dean Michael Berris, who is the co-author of n3340 "Rich pointers" and is also interested in adding run-time (and static) reflection to C++. We've decided that we merge the ideas from my paper into his proposal (which has not happened yet and will probably take a while). However, n3340 deals with more than just static reflection, so I would like to start a discussion and ask the members of the Boost community for their opinions about the compile-time-specific parts that are described in the following paper, before writing the final proposal: http://kifri.fri.uniza.sk/~chochlik/jtc1_sc22_wg21/std_cpp_refl.pdf It is a bit lengthy so you can skip sections 1., 2. and probably also section 3., if you are knowledgeable about the domain. The most important parts are: the whole section 4. "Technical specification" and also 5., 6. and 7. Section 7. "Unresolved issues" lists several important things that need to be worked out and 3. has some rationale for the design decisions. Note that the paper has the basic structure of a standard proposal, but is not written in standardese nor is it "polished" (since it will be merged into another paper and probably re-worded). It is my first attempt at a standard proposal and I'm not a member of the Committee so please bear with me :-). Dean and I have also independently decided to write proof-of-concept implementations - compiler extensions for clang and gcc respectivelly. The sources for the gcc plugin are hosted here: https://github.com/matus-chochlik/std_cpp_refl It's in a very early stage, but if someone has some tips or hints they'll be welcome. Thanks in advance for any (negative or positive) feedback. Best regards, Matus Chochlik

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[assign] How to create a container wrapper for tuple_list_of
by Robert Dailey 26 Apr '12

26 Apr '12

I have a vector of boost::tuple objects that is a member variable in a class of mine. I want to be able to create an instance of my wrapper class and construct it off of a tuple_list_of(), and essentially forward those values to the container itself. I haven't seen a way to do this yet. An example is below. Note that my constructor in the class was my attempt to get this working, but instead it will not compile. For some reason boost.assign thinks that the EnumErrorInfo class is the container. template<class T> class EnumErrorInfo { public: typedef boost::tuple<T, char const*, char const*> Tuple; typedef std::vector<Tuple> TupleVector; EnumErrorInfo( TupleVector const& assignment ) : m_errorInfo( assignment ) {} Tuple const& getErrorInfo( T error_code ) { TupleVector::const_iterator it = std::find_if( m_errorInfo.begin(), m_errorInfo.end(), MatchErrorCodePred( error_code ) ); if( it != m_errorInfo.end() ) { return *it; } static Tuple const unknown_info( error_code, "????", "No error info available for this code" ); return unknown_info; } private: class MatchErrorCodePred { public: MatchErrorCodePred( T error_code ) : m_errorCode( error_code ) {} bool operator() ( Tuple const& t ) { return t.get<0>() == m_errorCode; } private: DomInterfaceErrors m_errorCode; }; TupleVector m_errorInfo; }; And here is how I'd like to initialize the class: EnumErrorInfo<DomInterfaceErrors> g_errorInfo = tuple_list_of ( GDE_OK, "GDE_OK", "DBL: Opeartion successfully completed" ) ( GDE_GDD_DIRUSERS, "GDE_GDD_DIRUSERS", "AQX: Unable to get directory users." ) ;

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[interprocess] Sharing shared_memory_object across processes?
by Joseph Van Riper 26 Apr '12

26 Apr '12

I either do not understand what I am seeing, or I may have stumbled upon a bug, at least in a Windows environment. Or, of course, my expectations may be unrealistic. The short of this is that when I create a boost::interprocess::shared_memory_object that isn't removed for the duration of the program's run, the reading program's run can't seem to open the shared_memory_object, despite creating a boost::interprocess::permissions object and calling 'set_unrestricted()'. I get an exception indicating that access is denied. If nothing else, the code I've provided is an interprocess version of the classic read-writer's problem, second version (writers preferred). It may be of use to someone with a little cleaning. Environment: Compiler: MSVC++ 10 OS: Win 7 Pro, 64-bit. Steps to reproduce: 1. In VC++ 10, create an empty command-line project. 2. Replace contents of your .cpp with the code in this e-mail. 3. Compile. 4. Run the executable twice, first with an argument, next without. Expected results: The executable run without arguments indicates how much data was transferred on the same line. Actual results: The executable run without arguments complains that access is denied. NOTE: If you #define BOLD_NEW_TEST and recompile, this program runs according to expectations. This causes the objects to be compiled in a way where the shared_memory_objects only last for as long as it takes to write or read the data. I suspect this shouldn't be necessary, but perhaps I'm wrong. The error is especially peculiar to me, as I can open the file itself with a text editor. It doesn't seem like it should be denied. - Trey

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[result_of] Make `cpp0x_result_of_impl` public
by Michel Morin 26 Apr '12

26 Apr '12

There are two implementations of boost::result_of: a TR1-style implementation and a decltype-based implementation. While the TR1-style implementation has a public interface `boost::tr1_result_of`, decltype-based one doesn't have a public interface. By defining BOOST_RESULT_OF_USE_DECLTYPE, boost::result_of use decltype-based implementation. But this is not always a viable solution, since this breaks some Boost libraries. So how about adding `boost::cxx11_result_of` as public interface of the decltype-based implementation? Attached a patch to add `boost::cxx11_result_of`. (This patch also changes the name of `cpp0x_result_of_impl` to `cxx11_result_of_impl` to reflect the recent discussion on the cpp/cxx naming.) P.S. Is it worth trying to use this `boost::cxx11_result_of` in `boost::transform_iterator` code on trunk? Regards, Michel

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[result_of] Regression: compilation errors on C++03 compilers when defining BOOST_RESULT_OF_USE_DECLTYPE
by Michel Morin 25 Apr '12

25 Apr '12

If we define BOOST_RESULT_OF_USE_DECLTYPE, boost::result_of tries to use decltype-based implementation even on C++03 compilers. This causes compilation errors and it is a regression on C++03 compilers. Is it intentional change? Regards, Michel

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