December 2011 - Boost - lists.preview.boost.org

[graph] running test leda_graph_cc.cpp fails - header not found
by Jens Müller 15 Dec '11

15 Dec '11

Hi all, I tried to run the tests for the LEDA adapter in the Boost Graph library. I checked out the latest trunk from SVN. I made the Boost.Build v2, works fine. When running ./../../tools/build/v2/bjam in libs/graph/test, all tests run fine. I installed LEDA (free version) in /home/jens/devel/leda-free/LEDA-6.3-free-fedora-core-8-64-g++-4.1.2-mt After successfully running all other tests, the one for LEDA fails: $ ../../../tools/build/v2/bjam -s LEDA=/home/jens/devel/leda-free/LEDA-6.3-free-fedora-core-8-64-g++-4.1.2-mt/ Performing configuration checks - has_icu builds : yes ...patience... ...patience... ...patience... ...found 6503 targets... ...updating 2 targets... gcc.compile.c++ ../../../bin.v2/libs/graph/test/leda_graph_cc.test/gcc-4.6.1/debug/leda_graph_cc.o In file included from leda_graph_cc.cpp:10:0: ../../../boost/graph/leda_graph.hpp:20:30: fatal error: LEDA/graph/graph.h: No such file or directory compilation terminated. "g++" -ftemplate-depth-128 -O0 -fno-inline -Wall -g -fPIC -DBOOST_ALL_NO_LIB=1 -I"../../.." -c -o "../../../bin.v2/libs/graph/test/leda_graph_cc.test/gcc-4.6.1/debug/leda_graph_cc.o" "leda_graph_cc.cpp" ...failed gcc.compile.c++ ../../../bin.v2/libs/graph/test/leda_graph_cc.test/gcc-4.6.1/debug/leda_graph_cc.o... ...failed updating 1 target... ...skipped 1 target... Note that I edited boost/graph/leda_graph.hpp, fixing a syntax error and making it point to the now location of the LEDA header files (which contains an additional "graph" sub-directory). But the problem seems to be that the include directory is not at all passed to the compiler. What is going wrong here? Best, Jens

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[graph] LEDA adapter
by Jens Müller 15 Dec '11

15 Dec '11

Hi all, are there still people who want to use the LEDA adapter in the Graph library? Back in 2007, I contributed adapters for some property maps. The checkin unfortunately introduced a typo (let's call it a transmission error ...) which is still there. So apparently no-one used it since then?! There also have been some discussions on removing the support, and patch requests were denied due to a lack of maintainer ... If there is _any_ interest in still maintaining leda_graph.hpp, I'd do it, as Douglas had already offered to me in 2007. I have more time and a better understanding now, and I'd really like to dive a bit more into Boost development. Besides, there apparently now is a free (as in beer) version of LEDA available, which should facilitate more widespread testing. Regards, Jens

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Request: sanity check for a jamfile
by Daryle Walker 15 Dec '11

15 Dec '11

I just added a new test file for Boost.CRC on the SVN trunk. I also tried to adapt the test jamfile to accommodate two test programs. I'm not sure that I did it right, so can anyone check that it works. (I use XCode to build and test my programs.) The new file, "crc_test2.cpp", uses the unit-testing apparatus. The old file, "crc_test.cpp", uses the header-only minimal Testing facility. (I'm not sure that its link to the Test Execution monitor, in the jamfile, is needed.) I added a new testing file because I want to add a test case for a bug and Boost.Test has advanced so much that the first file is way too obsolete to be safely extended. It's change #75959 on the trunk, a.k.a. [https://svn.boost.org/trac/boost/changeset/75959]

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[python] [concept] CallPolicies implementation
by Lorenzo Caminiti 15 Dec '11

15 Dec '11

Hello all, Does Boost.Python implement the CallPolicies concept? I couldn't find it... http://www.boost.org/doc/libs/1_48_0/libs/python/doc/v2/CallPolicies.html If not, would something like this be OK?? template<class P> struct CallPolicies { BOOST_CONCEPT_ASSERT((ResultConverterGenerator<P::result_converter>)); BOOST_CONCEPT_ASSERT((Metafunction<P::extract_return_type>)) BOOST_CONCEPT_USAGE(CallPolicies) { bool b = x.precall(a); // convertible to bool PyObject* o = x.postcall(a, r); // convertible to PyObject* } private: P x; PyObject* a; PyObject* r; }; I'd have to implement ResultConverterGenerator and Metafunction as well. Thanks. --Lorenzo

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[parameter] compiler errors with operators
by Lorenzo Caminiti 15 Dec '11

15 Dec '11

Hello all, Does Boost.Parameter support operators? The following example is from the docs but it doesn't compile. Looking at the preprocessed code /EP, the errors seem to be because the macro defines a struct template postfixing it with the operator name and symbol "template <class Args> struct boost_param_result_11operator() { ... };". Maybe this worked once before and it's now broken? #include <boost/parameter.hpp> #include <iostream> BOOST_PARAMETER_NAME(arg1) BOOST_PARAMETER_NAME(arg2) struct callable2 { BOOST_PARAMETER_CONST_MEMBER_FUNCTION( (void), operator(), tag, (required (arg1,(int))(arg2,(int)))) { std::cout << arg1 << ", " << arg2 << std::endl; } }; int main ( void ) { callable2 c; c(1, 2); return 0; } On MSVC 8 with latest Boost trunk: c02.cpp c02.cpp(11) : error C2988: unrecognizable template declaration/definition c02.cpp(11) : error C2059: syntax error : 'type' c02.cpp(11) : error C2334: unexpected token(s) preceding '{'; skipping apparent function body c02.cpp(11) : error C2988: unrecognizable template declaration/definition c02.cpp(11) : error C2059: syntax error : 'type' c02.cpp(11) : error C2334: unexpected token(s) preceding ':'; skipping apparent function body c02.cpp(11) : error C2143: syntax error : missing ';' before '<' c02.cpp(11) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c02.cpp(11) : error C2238: unexpected token(s) preceding ';' c02.cpp(11) : error C2143: syntax error : missing ';' before '<' c02.cpp(11) : error C4430: missing type specifier - int assumed. Note: C++ does not support default-int c02.cpp(11) : error C2238: unexpected token(s) preceding ';' c02.cpp(11) : error C2988: unrecognizable template declaration/definition c02.cpp(11) : error C2059: syntax error : '<' c02.cpp(11) : error C3861: 'boost_param_parameters_11operator': identifier not found c02.cpp(11) : error C2039: 'type' : is not a member of '`global namespace'' c02.cpp(11) : error C3861: 'boost_param_parameters_11operator': identifier not found c02.cpp(11) : error C2039: 'type' : is not a member of 'boost::parameter::aux::match' ..\..\..\..\..\boost\trunk.windows\boost/parameter/preprocessor.hpp(99) : see declaration of 'boost::parameter::aux::match' c02.cpp(11) : error C2039: 'type' : is not a member of '`global namespace'' c02.cpp(11) : error C2334: unexpected token(s) preceding '{'; skipping apparent function body c02.cpp(14) : error C2270: 'boost_param_default_11operator' : modifiers not allowed on nonmember functions c02.cpp(14) : error C2091: function returns function c02.cpp(20) : error C2064: term does not evaluate to a function taking 2 arguments Thanks. --Lorenzo

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[multiprecision] Docs missing the basics
by Beman Dawes 15 Dec '11

15 Dec '11

Looking at http://boost-sandbox.sourceforge.net/libs/multiprecision/doc/html/multiprec… http://boost-sandbox.sourceforge.net/libs/multiprecision/doc/html/multiprec… I see a lot of details and commentary, but nothing about the big picture. * Needs an explanation of what "multiple precision" means. I would expect the first sentence to be something like "The multiprecision library, like other multiple precision libraries, provides arithmetic types that are not limited to the precision of the built-in C++ arithmetic types." * Needs an early explanation of what kinds of arithmetic types are supported. I would expect the second sentence to be something like "Integer, floating, and user defined types are supported." (I can't even tell from the current intro whether integers and UDTs are supported!) * Needs an early "Hello World" level example. The third sentence might begin a new paragraph, something like "Here is a simple example of muliprecision use: ..." Please remember that the point of a "Hello World" example is to introduce the simplest possible use of the library, not to demonstrate its power! * Although, not as critical as the previous issues, a bullet list of key features would be easier to read than plowing through a bunch of dense text. Once you've done that, the reader can make a quick blink decision as to whether to read on. A reader who isn't interested with thank you for not wasting their time plowing through a lot of text only to discover the library isn't of interest to them. Once docs provided the above view from 30,000 feet, then the remaining introductory details you've provided become interesting and the reader has enough orientation to absorb them. Good luck with this library! --Beman

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Andriod development using boost
by Jan Stetka 14 Dec '11

14 Dec '11

Anyone done any andriod development. I'm interested on how much you can use boost for andriod development. Also JNI looks like the way of using C++ code, does anyone have experience of using JNI?

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Boost.Algorithms organization question
by Marshall Clow 14 Dec '11

14 Dec '11

So, while I'm waiting for my review result, I've been implementing the new algorithms that were to the standard library for C++11 (at least the ones that don't require the new language features) They are: all_of any_of none_of find_if_not copy_if copy_n is_partitioned partition_point is_sorted is_sorted_until minmax -- this one is already in boost minmax_element -- this one is already in boost, but doesn't satisfy the C++11 performance gaurantees iota (and, of course, Boost.Range versions wherever appropriate) I have not done: shuffle -- requires rvalue references random_shuffle -- requires rvalue references move -- already in Boost.Move; maybe just a forwarding header file? move_backward -- already in Boost.Move; maybe just a forwarding header file? Anyway - my question is: Should these all go into a "c++11" subdirectory? If so, should I create a "c++11.hpp" header file that includes all of them, so that users can just #include <boost/algorithm/C++11.hpp> and get all the C++11 algorithms? Alternately, should they just live in boost/algorithm ? -- Marshall

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[review] [Local] Review Result - ACCEPTED
by Lorenzo Caminiti 14 Dec '11

14 Dec '11

On Mon, Dec 12, 2011 at 3:15 AM, Jeffrey Lee Hellrung, Jr. <jeffrey.hellrung(a)gmail.com> wrote: > Local is ACCEPTED into Boost. :) > After following the lively Local review discussion several weeks ago, and > reviewing the discussion a second (and sometimes third) time, I have come to > the above conclusion. There was quite a bit of passion on both the sides of > "aisle", and thus, obviously, no decision I make would be well-received by > all. > > Let me start by summarizing the main arguments against including Local in > Boost: > > (a) Local functions are not very useful, at least in the presence of > existing alternatives (e.g., namespace functions and Boost.Phoenix). > (b) Local is really a portability library for C++03 presenting an imperfect > emulation of features readily available in C++11. > (c) Local's interface is primarily macro-based, making code ugly and > difficult to read. > > In my opinion as the review manager, a sufficient number of individuals in > the discussion found the library "useful" to address (a) (sometimes with > additional positive adverbs); indeed, at least a couple individuals have > shared positive experiences with real-world use. Namespace functions require > one to move code to somewhere other than where one may prefer to have it, > and often requires a significant amount of boilerplate when binding local > variables. Aside from any perceived issues with Boost.Phoenix's syntax and > compiler error messages, it has been noted that binding member functions > within Boost.Phoenix can get ugly. As far as (b) is concerned, the community > seems pretty far from reaching a consensus on whether a library described by > (b) belongs in Boost. There are certainly libraries currently in Boost that > could be pegged to satisfy (b) as well, though they all have other > mitigating features they make their situation different from Local in some > way. As far as (c) is concerned, several have acknowledged that a > macro-based interface is necessary to implement local functions in C++03, > and it seems to have been generally agreed that, given this limitation, > Lorenzo has done an admireable job making the interface as easy-to-use as > possible. Some find it ugly, others find it reasonable. > > In addition to the counterarguments of (a-c) above, the following facts > weighed into my final decision: > * Lorenzo has been engaging and in constant communication with the > developer's list during the development of Local. This gives me confidence > that he will continue to actively maintain (and improve?) Local. > * The documentation is unanimously agreed to be of Boost quality. > * The transition of some organizations from C++03 to C++11 may take several > more years, and Boost has a history of supporting "ancient" compilers (for > better or worse). The point being, a library that eases the transition from > C++03 to C++11 has some merit based on current precedent. > * There had been previous work on local functions by Alexander Nasanov and > Steven Watanabe shared on the developer's list, suggesting a desire for this > functionality for some time. > * Local is approximately an extension of Boost.ScopeExit; indeed, it > basically fulfills the request to Alexander Nasanov from the review result > [2] of Boost.ScopeExit to create such an extension. > > Lastly, my own opinion of "what Boost is" factored in here. I view Boost as > *partly* a collection of general purpose libraries that can be used in wide > variety of applications (and thus Boost frequently acts as a staging ground > for standard adoption). Based on review feedback, I believe Local satisfies > this criterion; and based on the mailing list discussion, I believe this > view of Boost is not entirely inconsistent with others on the mailing list. Thank you for the detailed explanation of the rationale of the decision. > Ultimately, it wasn't so much a # of "yes" votes versus # of "no" votes as > it was the above general considerations. Regardless, I think independent of > how the votes were counted, the "yes" votes outnumbered the "no" votes. This > required some discretion on my part as not everyone who expressed an opinion > submitted a formal review, and some participants were only arguing in favor > of some specific point supporting either acceptance or rejection of Local. My thanks to you and to the Boost community for clarifying two process questions I had during the review: 1) How to count votes-- not just yes vs. no but it's up to the review manager how to count and weight votes. 2) Should active authors' opinion count more-- yes if the review manager decides so. These points make sense to me. > "Yes" reviews (7) > -------- > Krzysztof Czainski > Andrzej Krzemienski > Pierre Morcello > Nat Lindon > John Bytheway > Edward Diener > Gregory Crosswhite > > "No" reviews (3) > -------- > Vicente J. Botet > Thomas Heller > Hartmut Kaiser > > Paul A. Bristow and Alexander Nasanov (the author of Boost.ScopeExit) both > submitted reviews but did not express an opinion (as far as I could tell) on > whether Local should be included in Boost, though if I had to peg Paul's, it > would be to reject Local. From what I gathered, Joel de Guzman, Joel Falcou, > Dean Michael Berris, and Lucanus J. Simonson were opposed to including Local > in Boost (the aforementioned did not submit a formal review, though a formal > review might be unnecessary if your vote is "no"). On the other hand, Brian > Wood, Philippe Vaucher, Mathias Gaunard, Robert Ramey, Nathan Ridge, Brent > Spillner, Thomas Klimpel, Christopher Jefferson, Daniel James, Rafael > Fourquet, Matthias Schabel, and Robert Stewart participated in the > discussion and argued in favor of some point that supported accepting Local > in Boost. I want to be clear here that certainly not everyone in the > aforementioned list even implied that they supported acceptance of Local (I > would guess that only roughly half implied as much), but they indirectly > helped its case by addressing arguments against inclusion. Overall, that > indicates to me that more individuals support acceptance of Local into Boost > than rejection. > > [Apologies for any name misspellings and absent accents.] My personal thanks to /everyone/ that participated to the discussions. > Regarding Boost.ScopeExit: 4 reviews were in favor of deprecating > Boost.ScopeExit; 3 reviews felt there was nothing wrong with both > Boost.ScopeExit and Local coexisting; and 3 reviews mentioned the > possibility of improving Boost.ScopeExit with the features provided by > Local's exits. As such I'm inclined to let Alexander (who opposed any kind > of merging of Local and Boost.ScopeExit) work with Lorenzo on improving > Boost.ScopeExit as he sees fit, and hopefully both libraries can address > this apparent duplication of functionality within their respective > documentation to avoid user confusion. I will add void and this_ to ScopeExit (keeping it's compatibility with C++11 lambda style binding) and remove local exits from my library. (I will add a note to my library docs on how to use local function to easily implement scope exits with constant binding-- rarely needed.) > Regarding local::function::overload: Based on the review comments, it makes > the most sense to add this to Boost.Functional. I will move overload to Functional. > Regarding BOOST_IDENTITY_TYPE: This should be added to Boost.Utility. On the > other hand, there doesn't appear to be a compelling use case for > BOOST_IDENTITY_VALUE. I will add IDENTITY_TYPE to utility while IDENTITY_VALUE will not be included in Boost. > The following are some suggested *possible* improvements that reviewers > brought up. This list is by no means exhaustive. Further, I personally don't > think all of these suggestions are necessarily "good", but I think it's fair > for Lorenzo (and the community) to consider them nonetheless. Parenthetic > comments are my own opinions. > > * Some aren't convinced of the utility of LOCAL_BLOCK. (It's use cases > appear fairly narrow so it might be best to simplify the library and remove > this capability.) I will remove local blocks (I will document how to trivially implement them with a void local function with no parameters invoked right after it is defined). > * Use "this_" (as opposed to "_this") as an alias for "this" within function > bodies, and possibly also within bind declarations. > * Present Boost.PP sequence interface as a workaround for the variadic > interface? (I don't have a problem with supporting both interfaces at the > top level.) > * "Local" and "Locale" look too much alike, suggesting a name change to > "Scope", "Scoped", "LocalFunction", "Closure" may be a good idea? Given that local exits and blocks will be removed, I will rename Boost.Local to Boost.LocalFunction. > * Allow use without dependence on Boost.TypeOf. > * Rename prefix and postfix macros from XXX_PARAMS/XXX_NAME to XXX/XXX_END? > (I don't mind the current macros.) > * Explicitly separate bound variables from function parameters. (I think > this suggestion has merit but I don't know what the interface could look > like.) > * Remove support for default parameters to simplify interface and > documentation? (It doesn't seem like default function parameters would be > very useful.) > * Use "capture" instead of "bind" for the bind/capture keyword? (I like and > prefer "bind".) I will keep bind and add a note to the docs. > Finally, here the links to the submitted formal reviews, for reference. Of > particular note are Krzysztof's and John's reviews for their comments on the > documentation. Some "yes" votes were conditional, but AFAIK Lorenzo has > already agreed to address the relevant conditions. > > Krzysztof Czainski > http://permalink.gmane.org/gmane.comp.lib.boost.devel/225543 > > Vicente J. Botet > http://permalink.gmane.org/gmane.comp.lib.boost.devel/225604 > > Andrzej Krzemienski > http://permalink.gmane.org/gmane.comp.lib.boost.devel/225656 > > Paul A. Bristow > [...cannot find link to review...] > > Pierre Morcello > http://permalink.gmane.org/gmane.comp.lib.boost.devel/225694 > > Nat Lindon > http://permalink.gmane.org/gmane.comp.lib.boost.user/71508 > > Thomas Heller > http://permalink.gmane.org/gmane.comp.lib.boost.devel/225736 > > Hartmut Kaiser > http://permalink.gmane.org/gmane.comp.lib.boost.devel/225745 > > John Bytheway > http://permalink.gmane.org/gmane.comp.lib.boost.devel/225746 > > Alexander Nasanov > http://permalink.gmane.org/gmane.comp.lib.boost.devel/225783 > > Edward Diener > http://permalink.gmane.org/gmane.comp.lib.boost.devel/225795 > > Gregory Crosswhite > http://permalink.gmane.org/gmane.comp.lib.boost.devel/225807 Here's a list of all the changes I will make as they were identified during the review: http://sourceforge.net/apps/trac/contractpp/report/1 #2 Remove local blocks #3 Remove local exits #5 Rename the library Boost Local Function #4 Rename FUNCTION_PARAMS/_NAME to FUNCTION/_END #21 Use this_ also in local function declaration #7 Leave BOOST_IDENITY_TYPE but not _VALUE #8 Move PP_KEYWORD macros to implementation details #10 Move local::function::overload to Boost Functional #16 Make sure that the local function closures work like C++11 lambda closures #6 Expose result_type, argN_type, and arity #9 Use Boost Preprocessor built-in variadic support #12 Present the sequencing syntax as a work-around #14 Allow to specify result type within the LOCAL_FUNCTION macro #15 Try to reduce dependency on Boost Typeof #17 Improve motivation section #24 Document that local function can access protected/private members #11 Create regression tests #20 Fix documentation typos #22 Investigate MSVC errors with /ZI #26 Consider using assert instead of example writing to cout #28 Improve docs on need for Typeof registration #29 Document that a local function cannot be named recursive #1 Change the order of the Tutorial subsections #13 Add example for the GCC_LAMBDA macros #19 Document that bind cannot be use as a parameter type #23 Add the C++11 lambda const-binding workaround to the Alternatives #25 Indicate Phoenix and Lambda version numbers in Alternatives #27 Free arrays in examples without checking !=0 Please let me know if I missed anything. Two personal reflections from this experience: 1) I should have studied Phoenix more before the review started. I would have been better prepared for some of the discussions. 2) A while back, someone on this ML suggested that an library author should participate to 3 reviews before being able to have his/her library reviewed. This comment was in the context of getting more participation to the reviews. I thought the comment made sense (it was "fair") so I participated to 3 reviews before my library was reviewed. I have to say that such experience really helped me during the review of my library. I don't know if it'd make sense to make "participating to 3 reviews" a requirement for a library submission... maybe a requirement that can be waived only by the review wizards. > Finally, really big thanks to everyone for participating in the review and > ancillary discussions. I attempted to be as transparent as possible in > outlining the rationale for my decision above, but if you have any further > questions, do not hesitate to ask. > > - Jeff, Review Manager for Local Thank you very much Jeff for managing the review! --Lorenzo > [1] http://thread.gmane.org/gmane.comp.lib.boost.devel/168612 > [2] http://lists.boost.org/boost-announce/2008/05/0190.php

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[Serialization] (Commented) assertion when using types in multiple DLLs on Windows (Ticket #3934 and #4394)
by Martin B. 14 Dec '11

14 Dec '11

[Serialization] (Commented) assertion when using types in multiple DLLs on Windows (Ticket #3934 and #4394) ----------------------------------- ## Problem: We were using boost serialization in a DLL that is "statically" loaded into our main application. We are using Boost 1.44 and the serialization library as a DLL. (boost_serialization-vc80-mt-gd-1_44.dll) Now, the serialized types that we are using in this DLL have also been pulled into the main application -- that is, the .h+.cpp files of these types are included and linked in the exe as well as in the DLL project. (But the types are used independently in the exe and the dll module.) In Boost 1.44 this leads to a runtime assertion in void_cast.cpp[1_44_0, line 230]. ## Investigation: Since this code is in the function called void_caster::recursive_register I *assume* that this is the point where the types registered for serialization are registered with the library. I have found that this runtime assert was commented out in release 1.45 and all subsequent versions: std::pair<void_cast_detail::set_type::const_iterator, bool> result; // comment this out for now. result = s.insert(this); //assert(result.second); *Apparently* this was done in response to trac ticket #4394[1], at least judging from the comment Robert Ramey added to the ticket: > For now I'm going to comment out the assert. > When I have time, I'll likely re-enable it with a way to override it. I can only assume that ticket #3934[2] refers to the same or a similar problem. ## Issue with the conclusion in #4394 Robert writes in his comment: > The problem is that the way the code is structured, > you'll have multiple instances of some functions. > The best way would be eliminate the source of the > problem by structuring code like this: > ... > and he proposes to move the `template<class Archive> void serialize` function of the classes from the header file into the cpp file. However, *our* code already does this, and we get this assertion regardless. The reason I suspect is that both the main module code as well as the DLL module code are calling into the recursive_register function to register the type, and since the code for the class is (identically) duplicated in the DLL as well as in the executable, obviously it is registered twice. ## Question: Am I correct? So, the first question obviously is whether I'm correct in my analysis. I.e., the `assert(result.second);`that is currently commented out can *never* work properly for types that live in two modules (DLLs) in the same process and Boost:serialization is used as DLL. ## Question: Any harm done? Secondly, is there any adverse effect of a type being registered twice with the serialization DLL? What will happen on unload? Is it possible the type is unloaded too early because of this setup? Note: What about accidentally identical type keys for actually different types in different DLLs? ## Question: Solutions? What is a proper solution? Should we use dllexport types, so that the type is only registered once per process? What else? Robert, I hope you can chime in on this. I'll try to add a link to this mail to the trac issue #4394. cheers, Martin [1] : https://svn.boost.org/trac/boost/ticket/4394 [2] : https://svn.boost.org/trac/boost/ticket/3934

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[Boost] Is there any interest in min-max heap and bounded priority queue implementations?
by Andrea Sansottera 14 Dec '11

14 Dec '11

Dear Boost developers and users, I have implemented the min-max heap<http://www.akira.ruc.dk/~keld/teaching/algoritmedesign_f03/Artikler/02/Atki…> algorithms and a bounded priority queue container adapter. I was wondering if anyone is interested in including this code in Boost. I have made the code <https://www.assembla.com/code/sway-1/subversion/nodes/trunk>available here, under the BSD license (I might switch to the Boost license if needed). For those not familiar with min-max heaps, a min-max heap is an implicit data structure that can be build in linear time and provides constant time access to both the minimum and maximum elements. Other operations require logarithmic time. Hence, they allow the efficient implementation of double ended priority queues. My min-max heap implementation is designed similarly to the STL heap algorithms and consists of the following template functions: make_minmaxheap, push_minmaxheap, popmin_minmaxheap, popmax_minmaxheap. The bounded priority queue container adapter is built on top of the min-max heap algorithms and its interface is similar to the STL priority_queue. The methods of the bounded_priority_queue template class are: push, top, bottom, pop_top, pop_bottom, size, max_size, empty. The template arguments are the item type, the container type and the compare functor. The code compiles and works correctly with the GNU, Intel, Clang and Microsoft compilers. I have unit tests based on Boost.Test. Any feedback would be appreciated. Regards, Andrea Sansottera

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Proposal for a Differential Evolution C++ library
by Adrian Michel 14 Dec '11

14 Dec '11

Hello everybody, Would there be interest in a C++ Differential Evolution optimization (DE) library as part of boost? The library is functional but hasn't been made public yet. The full documentation is at http://www.amichel.com/de/doc/html but I'd suggest these pages for a first read http://www.amichel.com/de/doc/html/dd/d53/overview.html and http://www.amichel.com/de/doc/html/db/d4e/tutorial.html . The zip containing the DE C++ library and helper files is at http://www.amichel.com/de/de.zip. The DE main page is at http://www.icsi.berkeley.edu/~storn/code.html . Thanks, Adrian Michel

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Error in docs or code when trying zero unit tests
by Daryle Walker 14 Dec '11

14 Dec '11

[Woah, Hotmail's Web interface doesn't do unformatted mail; it implements it as formatted mail surrounded by <pre> tags and hex-conversion to almost all the punctuation!] When I tried the example on <http://www.boost.org/doc/libs/1_48_0/libs/test/doc/html/tutorials/new-year-…>: //===#define BOOST_TEST_MODULE const_string test#include <boost/test/unit_test.hpp>//=== Instead of getting: //===*** No errors detected//=== I got: //===[Session started at 2011-12-11 18:18:15 -0500.]Test setup error: test tree is empty CRC Unit Test has exited with status 200.//=== (The first and last lines are from my compiler's IDE.) Either the docs are wrong claiming that an empty test program is OK, or the code is wrong for choking when running with zero unit tests. It's probably the former but I personally prefer the latter to be fixed instead.

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Boost Interchange / Carbon
by Tom Sanham 13 Dec '11

13 Dec '11

Hello I am new to this list. I wonder if someone can help me: Is it possible to use XCode on OS X 10.7 to build a .dylib which depends on Boost Interchange library (which we need to be statically linked), for Carbon? The reason I ask is that: when XCode version >=4.2, Carbon is (apparently) no longer supported, but Boost Interchange Library compiles successfully. when XCode version <4.2, Carbon is supported, but Boost Interchange library cannot compile (due to an compiler error involving the handling of Templates, where it appears the library employs a mechanism supported only in the later XCode versions). Is it possible to achieve this? Could somebody offer some pointers? Thank you in advance Tom

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Interested in bounded buffer class for threaded producer/consumer communication?
by André Offringa 13 Dec '11

13 Dec '11

Hi all, I seem to have come across a producer/consumer situation a few times now, and everytime I do, I seem to want a slightly different functionality for a bounded buffer-kind of class that is not generally provided. I am looking for such a class that is also efficient for large amounts of data, and so I wonder if there does already exists a class in boost to efficiently push work between producers and consumers when they are running in different threads, i.e., that is thread safe. Asio seems to have a lot of communicating mechanisms, but I did not yet come across such a mechanism (pipe/channel/lane/unidirectional stream/bounded buffer... I'll call it a 'lane' for now) between two threads. If it does not exist yet in boost, I wonder if there is a general interest for such a class. The situation, is that - one or more threads produce data 'packages' of some type T, until the buffer is full. - one or more other threads have to wait for the availability of these packages, and once available, get one and process them. Googling around there are numerous suggestions (e.g. blog entries) for an implementation of thread safe queues that synchronize writing/reading and wake readers when data is available. However, I think there are fewer implementations that both use a circular buffer and will also block the producer when the buffer is 'full', and even less that are efficient for large amounts of data. Typical examples for this situation occur in signal processing. For example, it could be that one thread reads packets of work from the hard disk or some other device, write it to the lane-object, while one or a few different other threads try to read packets from the lane-object for processing. In a particular case, I had a consumer which needed a certain amount of packets at a time. The lane holds a (circular) buffer of a given size, and if it is full, producing threads will be blocked. Consuming threads will be blocked if the buffer is empty. There is a bounded_buffer example given to implement such a thing with the circular buffer. It does exactly what I suggest, but I assume it is not so efficient for pushing large amounts of data over, as each individual object requires a push, thus a lock if implemented as in bounded_buffer, and involves unnecessary updates of the counters (involving a decrement() each time) on each push, which is not necessary if you know you are pushing a number of elements at once. I assume this could be fixed by wrapping the insert(range) method instead of the individual push functions. What I found most useful however, is when the 'main' interface of such a class consists of these methods: template<typename T> class lane { public: lane(size_t capacity); void write(const T& element); // (or push if you wish) void write(const T* elements, size_t n); // or as a data range void write_end(); bool read(const T& element); // false if write_end() has been called and empty() size_t read(const T* elements, size_t n); // returns n, unless write_end() has been called and is empty() size(), empty(), etc. } ..and that's basically how I implemented it right now. The lane is just like the circular buffer in boost, and owns the elements, and thus copies the data once on write to its own buffer and once on read. The write_end() method will change the state of the lane, such that blocked reading threads will no longer be blocked, i.e., it assumes the producer(s) is finished and the consumer should finish as well after the last data has been read. No element ever gets overwritten before being read. In my case I never needed it to be an actually "real" container, thus valid iterators and begin() and end()'s are not necessary. With such a class, setting up an efficient multi-threaded consumer/producer scenario, that can be easily end by either the producer or yet another separate (e.g., user interface) thread, is really easy. As said, especially in signal processing application (why it is somewhat low-leveler), this kind of class is very nice to have. I guess there are many flavours of such a 'lane', e.g. with deque's or circular_buffers, with or without owning data, with or without bounding the producer and with or without providing efficient large data pushers. In my case, the above interface seemed to have been the solution a few times, but I don't know how common it really is. So, I'm curious if this problem frequently arises, if it's solved already and/or if there would be interest in such a class. Regards, André Offringa

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[review] [Local] Review Result - ACCEPTED
by Jeffrey Lee Hellrung, Jr. 13 Dec '11

13 Dec '11

Local is ACCEPTED into Boost. After following the lively Local review discussion several weeks ago, and reviewing the discussion a second (and sometimes third) time, I have come to the above conclusion. There was quite a bit of passion on both the sides of "aisle", and thus, obviously, no decision I make would be well-received by all. Let me start by summarizing the main arguments against including Local in Boost: (a) Local functions are not very useful, at least in the presence of existing alternatives (e.g., namespace functions and Boost.Phoenix). (b) Local is really a portability library for C++03 presenting an imperfect emulation of features readily available in C++11. (c) Local's interface is primarily macro-based, making code ugly and difficult to read. In my opinion as the review manager, a sufficient number of individuals in the discussion found the library "useful" to address (a) (sometimes with additional positive adverbs); indeed, at least a couple individuals have shared positive experiences with real-world use. Namespace functions require one to move code to somewhere other than where one may prefer to have it, and often requires a significant amount of boilerplate when binding local variables. Aside from any perceived issues with Boost.Phoenix's syntax and compiler error messages, it has been noted that binding member functions within Boost.Phoenix can get ugly. As far as (b) is concerned, the community seems pretty far from reaching a consensus on whether a library described by (b) belongs in Boost. There are certainly libraries currently in Boost that could be pegged to satisfy (b) as well, though they all have other mitigating features they make their situation different from Local in some way. As far as (c) is concerned, several have acknowledged that a macro-based interface is necessary to implement local functions in C++03, and it seems to have been generally agreed that, given this limitation, Lorenzo has done an admireable job making the interface as easy-to-use as possible. Some find it ugly, others find it reasonable. In addition to the counterarguments of (a-c) above, the following facts weighed into my final decision: * Lorenzo has been engaging and in constant communication with the developer's list during the development of Local. This gives me confidence that he will continue to actively maintain (and improve?) Local. * The documentation is unanimously agreed to be of Boost quality. * The transition of some organizations from C++03 to C++11 may take several more years, and Boost has a history of supporting "ancient" compilers (for better or worse). The point being, a library that eases the transition from C++03 to C++11 has some merit based on current precedent. * There had been previous work on local functions by Alexander Nasanov and Steven Watanabe shared on the developer's list, suggesting a desire for this functionality for some time. * Local is approximately an extension of Boost.ScopeExit; indeed, it basically fulfills the request to Alexander Nasanov from the review result [2] of Boost.ScopeExit to create such an extension. Lastly, my own opinion of "what Boost is" factored in here. I view Boost as *partly* a collection of general purpose libraries that can be used in wide variety of applications (and thus Boost frequently acts as a staging ground for standard adoption). Based on review feedback, I believe Local satisfies this criterion; and based on the mailing list discussion, I believe this view of Boost is not entirely inconsistent with others on the mailing list. Ultimately, it wasn't so much a # of "yes" votes versus # of "no" votes as it was the above general considerations. Regardless, I think independent of how the votes were counted, the "yes" votes outnumbered the "no" votes. This required some discretion on my part as not everyone who expressed an opinion submitted a formal review, and some participants were only arguing in favor of some specific point supporting either acceptance or rejection of Local. "Yes" reviews (7) -------- Krzysztof Czainski Andrzej Krzemienski Pierre Morcello Nat Lindon John Bytheway Edward Diener Gregory Crosswhite "No" reviews (3) -------- Vicente J. Botet Thomas Heller Hartmut Kaiser Paul A. Bristow and Alexander Nasanov (the author of Boost.ScopeExit) both submitted reviews but did not express an opinion (as far as I could tell) on whether Local should be included in Boost, though if I had to peg Paul's, it would be to reject Local. From what I gathered, Joel de Guzman, Joel Falcou, Dean Michael Berris, and Lucanus J. Simonson were opposed to including Local in Boost (the aforementioned did not submit a formal review, though a formal review might be unnecessary if your vote is "no"). On the other hand, Brian Wood, Philippe Vaucher, Mathias Gaunard, Robert Ramey, Nathan Ridge, Brent Spillner, Thomas Klimpel, Christopher Jefferson, Daniel James, Rafael Fourquet, Matthias Schabel, and Robert Stewart participated in the discussion and argued in favor of some point that supported accepting Local in Boost. I want to be clear here that certainly not everyone in the aforementioned list even implied that they supported acceptance of Local (I would guess that only roughly half implied as much), but they indirectly helped its case by addressing arguments against inclusion. Overall, that indicates to me that more individuals support acceptance of Local into Boost than rejection. [Apologies for any name misspellings and absent accents.] Regarding Boost.ScopeExit: 4 reviews were in favor of deprecating Boost.ScopeExit; 3 reviews felt there was nothing wrong with both Boost.ScopeExit and Local coexisting; and 3 reviews mentioned the possibility of improving Boost.ScopeExit with the features provided by Local's exits. As such I'm inclined to let Alexander (who opposed any kind of merging of Local and Boost.ScopeExit) work with Lorenzo on improving Boost.ScopeExit as he sees fit, and hopefully both libraries can address this apparent duplication of functionality within their respective documentation to avoid user confusion. Regarding local::function::overload: Based on the review comments, it makes the most sense to add this to Boost.Functional. Regarding BOOST_IDENTITY_TYPE: This should be added to Boost.Utility. On the other hand, there doesn't appear to be a compelling use case for BOOST_IDENTITY_VALUE. The following are some suggested *possible* improvements that reviewers brought up. This list is by no means exhaustive. Further, I personally don't think all of these suggestions are necessarily "good", but I think it's fair for Lorenzo (and the community) to consider them nonetheless. Parenthetic comments are my own opinions. * Some aren't convinced of the utility of LOCAL_BLOCK. (It's use cases appear fairly narrow so it might be best to simplify the library and remove this capability.) * Use "this_" (as opposed to "_this") as an alias for "this" within function bodies, and possibly also within bind declarations. * Present Boost.PP sequence interface as a workaround for the variadic interface? (I don't have a problem with supporting both interfaces at the top level.) * "Local" and "Locale" look too much alike, suggesting a name change to "Scope", "Scoped", "LocalFunction", "Closure" may be a good idea? * Allow use without dependence on Boost.TypeOf. * Rename prefix and postfix macros from XXX_PARAMS/XXX_NAME to XXX/XXX_END? (I don't mind the current macros.) * Explicitly separate bound variables from function parameters. (I think this suggestion has merit but I don't know what the interface could look like.) * Remove support for default parameters to simplify interface and documentation? (It doesn't seem like default function parameters would be very useful.) * Use "capture" instead of "bind" for the bind/capture keyword? (I like and prefer "bind".) Finally, here the links to the submitted formal reviews, for reference. Of particular note are Krzysztof's and John's reviews for their comments on the documentation. Some "yes" votes were conditional, but AFAIK Lorenzo has already agreed to address the relevant conditions. Krzysztof Czainski http://permalink.gmane.org/gmane.comp.lib.boost.devel/225543 Vicente J. Botet http://permalink.gmane.org/gmane.comp.lib.boost.devel/225604 Andrzej Krzemienski http://permalink.gmane.org/gmane.comp.lib.boost.devel/225656 Paul A. Bristow [...cannot find link to review...] Pierre Morcello http://permalink.gmane.org/gmane.comp.lib.boost.devel/225694 Nat Lindon http://permalink.gmane.org/gmane.comp.lib.boost.user/71508 Thomas Heller http://permalink.gmane.org/gmane.comp.lib.boost.devel/225736 Hartmut Kaiser http://permalink.gmane.org/gmane.comp.lib.boost.devel/225745 John Bytheway http://permalink.gmane.org/gmane.comp.lib.boost.devel/225746 Alexander Nasanov http://permalink.gmane.org/gmane.comp.lib.boost.devel/225783 Edward Diener http://permalink.gmane.org/gmane.comp.lib.boost.devel/225795 Gregory Crosswhite http://permalink.gmane.org/gmane.comp.lib.boost.devel/225807 Finally, really big thanks to everyone for participating in the review and ancillary discussions. I attempted to be as transparent as possible in outlining the rationale for my decision above, but if you have any further questions, do not hesitate to ask. - Jeff, Review Manager for Local [1] http://thread.gmane.org/gmane.comp.lib.boost.devel/168612 [2] http://lists.boost.org/boost-announce/2008/05/0190.php

7 6

[test, parameter, fusion] en/disable_if name clash in trunk
by Tim Blechmann 13 Dec '11

13 Dec '11

it seems that the new boost::unit_test::decorator::enable_if, introduced in [1] clashes with boost::enable_if under certain circumstances. this currently breaks the boost.heap testsuite (see [2]). maybe the test/parameter/fusion maintainers could discuss, how that can be resolved? thanks, tim [1] https://svn.boost.org/trac/boost/changeset/74663 [2] http://www.boost.org/development/tests/trunk/developer/heap.html

4 14

Question regarding parallel boost graph library status
by Delalondre Fabien Jonathan 13 Dec '11

13 Dec '11

Hi, I would like to use the parallel boost graph library for projects I am working on and was wondering whether I could get an update on its development. I am for example wondering: 1) Whether this is still an projet under active development and how many people are working on it. 2) What the status of the mpi/threading implementation is. 3) What are the machines on which the implementation has been tested (and on how many processors). I am interested in using it on HPC machines such as Cray and IBM which includes more than 100k processors. Thank you, Fabien Delalondre

2 1

Use constexpr with BOOST_STATIC_CONSTANT?
by Daryle Walker 12 Dec '11

12 Dec '11

Should BOOST_STATIC_CONSTANT be changed to add the C++11 "constexpr" attribute, if it's defined? I guess we would need a preprocessor flag to check if constexpr is available.

3 2

[regex] compilation warnings questions by a newbee
by Rai, Neeraj 12 Dec '11

12 Dec '11

Hi All, Reposting this based on feedback from Beman. I get the same error with latest boost. I earlier posted this to user group and atleast one user confirmed (s)he was getting the same error with newer version and not getting any error with older one. It is a simple program (just declares regex). Pls advise. Thx Neeraj _____________________________________________ From: Rai, Neeraj [ICG-MKTS] Sent: Friday, December 09, 2011 1:29 PM To: 'boost(a)lists.boost.org' Subject: [boost-dev] compilation warnings questions by a newbee Hi, I am writing my first boost program and having trouble with the compiler warning against boost 1.44.0. Is there any way to get rid of those warnings so I can focus on real warnings in my code ? This seems to happen with newer version of g++ : tried 4.4.5 and 4.6 The gist of warning is : boost_1_44_0/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: warning: the result of the conversion is unspecified because '-0x00000000000000001' is outside the range of type 'boost::numeric::udt_builtin_mixture_enum' [-Wconversion] Any help or pointers are appreciated. Neeraj ====== The following program is a cut down version of my code, just declares sregex #include <iostream> #include <boost/xpressive/xpressive.hpp> int main (int _argc, const char** _argv) { std::cout << "argc=" << _argc << " argv=" << _argv << std::endl; using namespace boost::xpressive; std::string keyword(""); sregex const re(sregex::compile(keyword, sregex::icase)); } ====== The following cmd is used to build it (tried g++ v 4.4.5 and 4.6 with same results) g++ -ftemplate-depth-128 -O0 -fno-inline -Wall -g -Wconversion -Wno-strict-aliasing -Wextra -Wnon-virtual-dtor -Wno-missing-field-initializers -Wno-array-bounds -Wno-ignored-qualifiers -Wno-parentheses -Wno-strict-aliasing -fPIC -DBOOST_ALL_NO_LIB -I/work/loc1/atddds -I/work/loc1/boost_1_44_0/include -Iinclude -c -o boost_regex_test.o boost_regex_test.cpp ====== The following cmd is used to build it (tried g++ v 4.4.5 and 4.6) g++ -ftemplate-depth-128 -O0 -fno-inline -Wall -g -Wconversion -Wno-strict-aliasing -Wextra -Wnon-virtual-dtor -Wno-missing-field-initializers -Wno-array-bounds -Wno-ignored-qualifiers -Wno-parentheses -Wno-strict-aliasing -fPIC -DBOOST_ALL_NO_LIB -I/work/loc1/atddds -I/work/loc1/boost_1_44_0/include -Iinclude -c -o boost_regex_test.o boost_regex_test.cpp In file included from /work/loc1/boost_1_44_0/include/boost/mpl/integral_c.hpp:32:0, from /work/loc1/boost_1_44_0/include/boost/type_traits/integral_constant.hpp:11, from /work/loc1/boost_1_44_0/include/boost/type_traits/detail/bool_trait_def.hpp:15, from /work/loc1/boost_1_44_0/include/boost/type_traits/is_volatile.hpp:40, from /work/loc1/boost_1_44_0/include/boost/type_traits/remove_const.hpp:14, from /work/loc1/boost_1_44_0/include/boost/proto/proto_fwd.hpp:25, from /work/loc1/boost_1_44_0/include/boost/xpressive/xpressive_fwd.hpp:53, from /work/loc1/boost_1_44_0/include/boost/xpressive/detail/detail_fwd.hpp:24, from /work/loc1/boost_1_44_0/include/boost/xpressive/regex_primitives.hpp:21, from /work/loc1/boost_1_44_0/include/boost/xpressive/xpressive_static.hpp:24, from /work/loc1/boost_1_44_0/include/boost/xpressive/xpressive.hpp:18, from boost_regex_test.cpp:2: /work/loc1/boost_1_44_0/include/boost/mpl/aux_/integral_wrapper.hpp: In instantiation of 'mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u>': /work/loc1/boost_1_44_0/include/boost/numeric/conversion/detail/meta.hpp:30:13: instantiated from 'boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u> >' /work/loc1/boost_1_44_0/include/boost/mpl/if.hpp:67:11: instantiated from 'boost::mpl::if_<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u> >, boost::mpl::identity<boost::numeric::convdetail::get_subranged_BuiltIn2BuiltIn<unsigned char, int> >, boost::mpl::eval_if<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)1u> >, boost::mpl::identity<boost::mpl::identity<boost::numeric::convdetail::subranged_BuiltIn2Udt<unsigned char, int> > >, boost::mpl::if_<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)2u> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2BuiltIn<unsigned char, int> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2Udt<unsigned char, int> > > > >' /work/loc1/boost_1_44_0/include/boost/mpl/eval_if.hpp:37:41: instantiated from 'boost::mpl::eval_if<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u> >, boost::mpl::identity<boost::numeric::convdetail::get_subranged_BuiltIn2BuiltIn<unsigned char, int> >, boost::mpl::eval_if<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)1u> >, boost::mpl::identity<boost::mpl::identity<boost::numeric::convdetail::subranged_BuiltIn2Udt<unsigned char, int> > >, boost::mpl::if_<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)2u> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2BuiltIn<unsigned char, int> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2Udt<unsigned char, int> > > > >' /work/loc1/boost_1_44_0/include/boost/numeric/conversion/detail/meta.hpp:82:9: instantiated from 'boost::numeric::convdetail::ct_switch4<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)1u>, mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)2u>, boost::numeric::convdetail::get_subranged_BuiltIn2BuiltIn<unsigned char, int>, boost::mpl::identity<boost::numeric::convdetail::subranged_BuiltIn2Udt<unsigned char, int> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2BuiltIn<unsigned char, int> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2Udt<unsigned char, int> > >' /work/loc1/boost_1_44_0/include/boost/numeric/conversion/detail/udt_builtin_mixture.hpp:45:9: instantiated from 'boost::numeric::convdetail::for_udt_builtin_mixture<mpl_::integral_c<boost::numeric::udt_builtin_mixture_enum, (boost::numeric::udt_builtin_mixture_enum)0u>, boost::numeric::convdetail::get_subranged_BuiltIn2BuiltIn<unsigned char, int>, boost::mpl::identity<boost::numeric::convdetail::subranged_BuiltIn2Udt<unsigned char, int> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2BuiltIn<unsigned char, int> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Udt2Udt<unsigned char, int> > >' /work/loc1/boost_1_44_0/include/boost/numeric/conversion/detail/is_subranged.hpp:206:11: [ skipping 9 instantiation contexts ] /work/loc1/boost_1_44_0/include/boost/xpressive/regex_compiler.hpp:281:13: instantiated from 'boost::xpressive::detail::sequence<BidiIter> boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::parse_alternates(FwdIter&, FwdIter) [with FwdIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, BidiIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, RegexTraits = boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> >, CompilerTraits = boost::xpressive::compiler_traits<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> > >]' /work/loc1/boost_1_44_0/include/boost/xpressive/regex_compiler.hpp:212:75: instantiated from 'boost::xpressive::basic_regex<BidiIter> boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::compile_(FwdIter, FwdIter, boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::flag_type, std::forward_iterator_tag) [with FwdIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, BidiIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, RegexTraits = boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> >, CompilerTraits = boost::xpressive::compiler_traits<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> > >, boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::flag_type = boost::xpressive::regex_constants::syntax_option_type]' /work/loc1/boost_1_44_0/include/boost/xpressive/regex_compiler.hpp:120:60: instantiated from 'boost::xpressive::basic_regex<BidiIter> boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::compile(InputIter, InputIter, boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::flag_type) [with InputIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, BidiIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, RegexTraits = boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> >, CompilerTraits = boost::xpressive::compiler_traits<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> > >, boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::flag_type = boost::xpressive::regex_constants::syntax_option_type]' /work/loc1/boost_1_44_0/include/boost/xpressive/regex_compiler.hpp:129:71: instantiated from 'typename boost::disable_if<boost::is_pointer<InputRange>, boost::xpressive::basic_regex<BidiIter> >::type boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::compile(const InputRange&, boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::flag_type) [with InputRange = std::basic_string<char>, BidiIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, RegexTraits = boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> >, CompilerTraits = boost::xpressive::compiler_traits<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> > >, typename boost::disable_if<boost::is_pointer<InputRange>, boost::xpressive::basic_regex<BidiIter> >::type = boost::xpressive::basic_regex<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> > >, boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::flag_type = boost::xpressive::regex_constants::syntax_option_type]' /work/loc1/boost_1_44_0/include/boost/xpressive/basic_regex.hpp:193:61: instantiated from 'static boost::xpressive::basic_regex<BidiIter> boost::xpressive::basic_regex<BidiIter>::compile(const InputRange&, boost::xpressive::basic_regex<BidiIter>::flag_type) [with InputRange = std::basic_string<char>, BidiIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, boost::xpressive::basic_regex<BidiIter>::flag_type = boost::xpressive::regex_constants::syntax_option_type]' boost_regex_test.cpp:9:57: instantiated from here /work/loc1/boost_1_44_0/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: warning: the result of the conversion is unspecified because '-0x00000000000000001' is outside the range of type 'boost::numeric::udt_builtin_mixture_enum' [-Wconversion] /work/loc1/boost_1_44_0/include/boost/mpl/aux_/integral_wrapper.hpp: In instantiation of 'mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u>': /work/loc1/boost_1_44_0/include/boost/numeric/conversion/detail/meta.hpp:30:13: instantiated from 'boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u>, mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u> >' /work/loc1/boost_1_44_0/include/boost/mpl/if.hpp:67:11: instantiated from 'boost::mpl::if_<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u>, mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u> >, boost::mpl::identity<boost::numeric::convdetail::get_subranged_Int2Int<unsigned char, int> >, boost::mpl::eval_if<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u>, mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)1u> >, boost::mpl::identity<boost::mpl::identity<boost::numeric::convdetail::subranged_Int2Float<unsigned char, int> > >, boost::mpl::if_<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u>, mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)2u> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Float2Int<unsigned char, int> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Float2Float<unsigned char, int> > > > >' /work/loc1/boost_1_44_0/include/boost/mpl/eval_if.hpp:37:41: instantiated from 'boost::mpl::eval_if<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u>, mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u> >, boost::mpl::identity<boost::numeric::convdetail::get_subranged_Int2Int<unsigned char, int> >, boost::mpl::eval_if<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u>, mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)1u> >, boost::mpl::identity<boost::mpl::identity<boost::numeric::convdetail::subranged_Int2Float<unsigned char, int> > >, boost::mpl::if_<boost::numeric::convdetail::equal_to<mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u>, mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)2u> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Float2Int<unsigned char, int> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Float2Float<unsigned char, int> > > > >' /work/loc1/boost_1_44_0/include/boost/numeric/conversion/detail/meta.hpp:82:9: instantiated from 'boost::numeric::convdetail::ct_switch4<mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u>, mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u>, mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)1u>, mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)2u>, boost::numeric::convdetail::get_subranged_Int2Int<unsigned char, int>, boost::mpl::identity<boost::numeric::convdetail::subranged_Int2Float<unsigned char, int> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Float2Int<unsigned char, int> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Float2Float<unsigned char, int> > >' /work/loc1/boost_1_44_0/include/boost/numeric/conversion/detail/int_float_mixture.hpp:63:9: instantiated from 'boost::numeric::convdetail::for_int_float_mixture<mpl_::integral_c<boost::numeric::int_float_mixture_enum, (boost::numeric::int_float_mixture_enum)0u>, boost::numeric::convdetail::get_subranged_Int2Int<unsigned char, int>, boost::mpl::identity<boost::numeric::convdetail::subranged_Int2Float<unsigned char, int> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Float2Int<unsigned char, int> >, boost::mpl::identity<boost::numeric::convdetail::subranged_Float2Float<unsigned char, int> > >' /work/loc1/boost_1_44_0/include/boost/numeric/conversion/detail/is_subranged.hpp:184:35: [ skipping 10 instantiation contexts ] /work/loc1/boost_1_44_0/include/boost/xpressive/regex_compiler.hpp:281:13: instantiated from 'boost::xpressive::detail::sequence<BidiIter> boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::parse_alternates(FwdIter&, FwdIter) [with FwdIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, BidiIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, RegexTraits = boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> >, CompilerTraits = boost::xpressive::compiler_traits<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> > >]' /work/loc1/boost_1_44_0/include/boost/xpressive/regex_compiler.hpp:212:75: instantiated from 'boost::xpressive::basic_regex<BidiIter> boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::compile_(FwdIter, FwdIter, boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::flag_type, std::forward_iterator_tag) [with FwdIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, BidiIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, RegexTraits = boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> >, CompilerTraits = boost::xpressive::compiler_traits<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> > >, boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::flag_type = boost::xpressive::regex_constants::syntax_option_type]' /work/loc1/boost_1_44_0/include/boost/xpressive/regex_compiler.hpp:120:60: instantiated from 'boost::xpressive::basic_regex<BidiIter> boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::compile(InputIter, InputIter, boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::flag_type) [with InputIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, BidiIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, RegexTraits = boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> >, CompilerTraits = boost::xpressive::compiler_traits<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> > >, boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::flag_type = boost::xpressive::regex_constants::syntax_option_type]' /work/loc1/boost_1_44_0/include/boost/xpressive/regex_compiler.hpp:129:71: instantiated from 'typename boost::disable_if<boost::is_pointer<InputRange>, boost::xpressive::basic_regex<BidiIter> >::type boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::compile(const InputRange&, boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::flag_type) [with InputRange = std::basic_string<char>, BidiIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, RegexTraits = boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> >, CompilerTraits = boost::xpressive::compiler_traits<boost::xpressive::regex_traits<char, boost::xpressive::cpp_regex_traits<char> > >, typename boost::disable_if<boost::is_pointer<InputRange>, boost::xpressive::basic_regex<BidiIter> >::type = boost::xpressive::basic_regex<__gnu_cxx::__normal_iterator<const char*, std::basic_string<char> > >, boost::xpressive::regex_compiler<BidiIter, RegexTraits, CompilerTraits>::flag_type = boost::xpressive::regex_constants::syntax_option_type]' /work/loc1/boost_1_44_0/include/boost/xpressive/basic_regex.hpp:193:61: instantiated from 'static boost::xpressive::basic_regex<BidiIter> boost::xpressive::basic_regex<BidiIter>::compile(const InputRange&, boost::xpressive::basic_regex<BidiIter>::flag_type) [with InputRange = std::basic_string<char>, BidiIter = __gnu_cxx::__normal_iterator<const char*, std::basic_string<char> >, boost::xpressive::basic_regex<BidiIter>::flag_type = boost::xpressive::regex_constants::syntax_option_type]' boost_regex_test.cpp:9:57: instantiated from here /work/loc1/boost_1_44_0/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: warning: the result of the conversion is unspecified because '-0x00000000000000001' is outside the range of type 'boost::numeric::int_float_mixture_enum' [-Wconversion]

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Re: [boost] FW: FW: Proposal for a Differential Evolution C++ library
by Adrian Michel 12 Dec '11

12 Dec '11

On 12/12/2011 7:19 AM, Sebastian Redl wrote: > Your website went down, it redirects the webhost's site. My apologies - I ftp-ed an updated version of the documentation with the wrong structure - instead of it being located at .../de/doc/html/... it was at .../de/html, as Thomas Kimpel noted in his reply. It should work again shortly. Also, I realized posting urls for individual documentation pages was a mistake, as I don't believe doxygen guarantees they will stay the same as the documentation evolves, so if you notice any errors when accessing the Overview or Tutorial urls, try the documentation home page http://www.amichel.com/de/doc/html/. Thanks both. Adrian

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A demonstration of why horrendous error messages can destroy usability
by Gregory Crosswhite 12 Dec '11

12 Dec '11

At the unfortunate risk of reopening a poisonous argument, I just wanted to relate an experience I had just earlier today to emphasize a point that I and others tried to make a couple of weeks ago. For the last couple of days I have been trying to get Digikam to compile on my machine using MacPorts. Getting software written for Linux to compile on OSX is always a bit of a black art, so I wasn't surprised when I started running into hurdles. The first problem that I ran into was that I had set Python 3.1 to be my default rather than Python 2.7, which screwed up the libplist CMake configuration script; fortunately, although I had to scratch my head for a few minutes, it was clear roughly where the error was taking place and that gave me enough information to eventually figure out where the problem was. I also went ahead and filed a bug report to MacPorts to let them know about this problem. After that it was smooth sailing until I got to the final package, Digikam itself. Unfortunately, it refuses to build. Why is that? For reasons that apparently took an overwhelming *56 kilobytes of error message* to explain. (See attached, if you dare. ) Now, you could argue that this is the fault of the compiler for not being more helpful, the fault of Digikam for using deprecated methods, the fault of MacPorts for creating a bad environment for configuration, or whatever else you want. You could also argue that were I familiar with Boost and/or the Digikam codebase then the implication of this message would be obvious --- heck, maybe it even *is* obvious to many of the people here. All of this is beside the point, though. I am not an expert in any of these codebases and I really don't care whether it is ultimately the fault of Boost, Digikam, Qt, MacPorts, or the compiler for producing such horrendous error messages. All that matters to me is that these pages of error messages are so overwhelming that they make it very difficult for me to get any sense at all of what kind of thing is going wrong so that I can track down what needs to be done to fix it. Furthermore, the error message is such a mess that it is hard for me to even *motivate* myself to *want* to go through it to figure out where is going on, and seeing the impact that this kind of thing can have on end users really turns me off a bit from the idea of continuing to use Boost libraries in my projects in the future. That is to say, I had heard people in the past say that they actively avoid Boost (and sometimes even C++) because of the way they introduced nasty complexities (like horrible error messages), and I used to (politely :-) ) scoff at them because I figured that they were overstating the problems in practice. Now however, having experienced these problems from the viewpoint of a casual user who just wants to get some darn code to compile so that I can run a program I wanted to try out, I can really appreciate their point. To be perfectly clear, I am not saying that this has made me never want to use Boost again, for I really hate rolling out my own code to solve a problem when somebody else has already developed and tested a solution for me. :-) My point is exactly and *only* the following: horrendous error messages are a *big deal* with a *serious impact* on usability not only for the developers using a library, but for end-users who want to compiler and use the software being developed. Most people here fortunately already seem to recognize this, but I have been truly shocked to hear so many arguments that horrendous error messages are *not* a serious problem, either because they are someone else's fault, because they only occur when the code is wrong, or --- worst of all --- because it is ultimately the fault of the user for being ignorant or lazy when he or she cannot quickly figure out what the problem causing the message was. So I just wanted to share this anecdote to provide a real-world example where horrendous error messages have added an incredible cost for a relatively technically experienced end-user to actually use a particular piece of software. And once more, I am sorry to bring this tired point up again, it's just that the experience I had today really reminded me just how frustrating these kinds of error messages can be, and the absurdity of denying that this is in any way a problem. I feel very strongly that the ultimate goal of writing software is not merely to push the boundaries of what we can do but to provide people with tools that make their lives easier. Horrendous error messages, even when there is no better design to accomplish a particular task (in C++, at least), are *really bad things* and should *not* be dismissed as something not worth fussing about, *especially* when fault is then placed on the *user* (as in some cases it sadly seemed to be) for being too ignorant or lazy to be willing to go to the trouble to decipher them. I am not claiming to know what the solution is to these kinds of issues, and in many cases there might not even be better solutions given the current design of C++. I was just very concerned to see that in the eyes of many the presence of such error messages are not considered in any way to be a problem (*) with a library, and to hear it claims that if anything users turned off by horrendous messages are simply being lazy by not just sucking them up for the good of the cause. Cheers, Greg (*) And let me be clear that by "problem" here I really do mean "less than ideal circumstance" rather than "flaw", because in many cases these libraries are very elegantly designed codes which are probably close to the optimal solution given the limits imposed by the C++ language.

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[BGL] reverse_graph
by Fabien Castan 12 Dec '11

12 Dec '11

Hi, I have some troubles using boost::transpose_graph since boost 1.48. See the sample code. Fabien #include <boost/graph/graph_traits.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/copy.hpp> #include <boost/graph/transpose_graph.hpp> template<class GraphIn, class GraphOut> class Copier { public: Copier( const GraphIn& gIn, GraphOut& gOut ) : _gIn(gIn) , _gOut(gOut) {} template<class VIn, class VOut> void operator()(const VIn& vIn, VOut& vOut) { _gOut[vOut] = _gIn[vIn]; } private: const GraphIn& _gIn; GraphOut& _gOut; }; struct CustomVertex { }; struct CustomEdge { }; typedef boost::adjacency_list< boost::setS, // disallow parallel edges (OutEdgeList) boost::vecS, // vertex container (VertexList) boost::bidirectionalS, // directed graph CustomVertex, CustomEdge, boost::no_property, // no GraphProperty boost::listS // EdgeList > GraphContainer; int main( int argc, char** argv ) { const GraphContainer a; GraphContainer b; Copier< GraphContainer, GraphContainer > copier( a, b ); // still works as before boost::copy_graph( a, b, boost::vertex_copy(copier).edge_copy(copier) ); // works with boost 1.47, but doesn't compile with boost 1.48 boost::transpose_graph( a, b, boost::vertex_copy(copier).edge_copy(copier) ); //<<<<< }

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Re: [boost] Proposal for a Differential Evolution C++ library
by Adrian Michel 12 Dec '11

12 Dec '11

I was asked this question regarding DE: >... The Boost Graph Library (BGL) >is often used for graph optimization purposes, and the geometry stuff >is used to do things like lay out integrated circuits with lots of >costs and constraints. There are the math and statistical functions. >Are these and other Boost libraries complementary or orthogonal to >your library? > I'm not familiar with BGL, but from its documentation, DE and BGL seem to be rather orthogonal. As for the math and statistical functions, I believe DE could complement these as yet another mathematical tool. Adrian Michel

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Re: [boost] FW: Proposal for a Differential Evolution C++ library
by Adrian Michel 12 Dec '11

12 Dec '11

Hi Beman On 12/11/2011 6:31 PM, Beman Dawes wrote: > >> Would there be interest in a C++ Differential Evolution optimization (DE) >> library as part of boost? > > Seems interesting, and you've clearly put in a lot of work, and the > documentation makes a good initial impressions. But see below... > Thanks! >> The full documentation is at http://www.amichel.com/de/doc/html but I'd >> suggest these pages for a first read >> http://www.amichel.com/de/doc/html/dd/d53/overview.html and >> http://www.amichel.com/de/doc/html/db/d4e/tutorial.html . > > After skim reading the overview and the beginning of the tutorial, I > was left with several unanswered questions: > > * What are some practical scientific or engineering problems that DE > is good for? I personally got interested in DE while doing some research in the area of algorithmic trading system optimization. But DE is generic - it can be used to optimize any function that would otherwise be very hard or impossible to optimize using more traditional methods. DE is used in many areas, some of which are listed here: http://www.icsi.berkeley.edu/~storn/code.html#appl and here: http://www.icsi.berkeley.edu/~storn/code.html#comm or to summarize: chemistry, electronics, physics, agriculture, telecommunications etc. > I'm having trouble calibrating - is your library > primarily aimed at research and academic problems or is it an everyday > tool for use in a broad spectrum of organizations? > I believe the answer is "both". > * Who is the library aimed at? Is the library most likely to be used > by optimization specialists who already know about DE or is it > something that can be used by a wide range of programmers? > I tried to design the library so that it can be easily used "out of the box" by all programmers, who can choose any of the predefined policy classes for default behavior. The de_test application illustrates this usage mode: the user can implement a de::objective_function derived class with their own function to optimize, and then build and run the application to get the best output. However, those interested in tweaking its behavior, can create their own policy classes and override the defaults. One of the obvious advantage of a standardized DE library is that these customized components could then be shared with the community at large. BTW, DE has the added benefit of not having been patented by its authors, for the very purpose of making it widely available. Thanks, Adrian Michel

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