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[review][assign] Assign v2 review result
by John Bytheway 04 Jul '11

04 Jul '11

There was only one explicit review of the Assign v2 library, from Lars Viklund, which voted against inclusion. Other discussion about the library did not have an overwhelmingly positive tone. Therefore, the library is NOT accepted for Boost at this time. Some of the issues raised in discussion were: - The tutorial examples are terse, and move too quickly into the more advanced features of the library. - Code written with the library is too obtuse to those not familiar with it. - The naming conventions are unintuitive, in particular several people did not understand 'csv' without consulting the docs. - Does the impending arrival of initializer lists in C++0x render some or all of the functionality obsolete? - The documentation's performance metrics do not cover compile time. - There are portability issues to some less mainstream compilers. In conclusion, I think the review highlighted a few serious and interrelated issues with the library as it stands: 1. The scope of the library is not clear. If it is simply intended to save typing, and act as a filler for such things as initializer lists, then why does it need such complexity? On the other hand, if it is intended for more than this, then what is the motivation? The docs do not make this clear. 2. The tutorial moves too quickly, is unclear to newcomers, and lacks clear motivation for its examples. It would be better to spend more time explaining each example, perhaps with English or with equivalent code not using Assign v2. The existing Boost.Assign docs were compared favourably with the Assign v2 docs by more than one reviewer, and might serve as a model for improvement. 3. Code written with the library is obtuse and a developer unfamiliar with its ideas would be unable to decipher it without documentation. Furthermore, in some cases even with the existing documentation the intent of the code was unclear. For a task as conceptually simple as the library attempts to tackle it should be possible to make the code using it much more clear. There may be more problems with the library, but the presence of these issues prevented most reviewers investigating any more deeply. If Erwann wishes to continue his development of the library, and perhaps have it, or some subset of it, included in Boost in the future, then I recommend that he first establish a clearly motivated scope, and then strive for a syntax clear even to the uninitiated. I would like to thank Erwann again for all his hard work, and everyone who participated in the discussion during the review. John Bytheway Review Manager

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Re: [boost] [math] Empirical distribution function
by Denis Arnaud 04 Jul '11

04 Jul '11

2011/6/15 <boost-request(a)lists.boost.org> > Date: Wed, 15 Jun 2011 09:35:49 -0400 > From: er <er.ci.2020(a)gmail.com> > > > distributions< > http://www.boost.org/doc/libs/1_46_1/libs/math/doc/sf_and_dist/html/math_to… > >. > > But an accumulator is just fine for now. By the way, does it mean that if > we > > have a set of 1 million of distinct real numbers, the corresponding > > accumulator will store a pretty big number of counters? > > > > Only if the million are distinct values. Otherwise it keeps each > distinct value + a count. > Ok, that's how I understood it, then (even though I'm not sure that that's the way accumulators are supposed to be used). > I'm glad you like the idea of a wrapper on top of an accu, but I only > plan to do the accu. Please give me a bit of time to do a bit of > maintenance work, though. I'll keep you updated. > It sounds perfect: thanks! D

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[log] init_from_settings - problem with applying format and filter
by Petrovskiy Yuriy 04 Jul '11

04 Jul '11

I am trying to use boost::log for tracking application activity. I need message with severity level output to console and more detailed output to file. I have the following code (most of it is copied from boost::log documentation): /* boostLogTest.cpp */ #include <boost/log/sources/severity_logger.hpp> #include <boost/log/sources/record_ostream.hpp> #include <boost/log/utility/init/from_settings.hpp> using namespace boost::log; enum logMessageSeverityLevels { trace = 0 , debug = 1, info = 2, warning = 3, error = 4, fatal = 5 }; #define LOG(x) BOOST_LOG_SEV(logger, x ) typedef boost::log::sources::severity_logger< logMessageSeverityLevels > loggerType; loggerType logger(keywords::severity = error); int main() { boost::log::settings setts; //setts["Core"]["Filter"] = "%Severity% >= 0"; //if set - no output anywhere setts["Core"]["DisableLogging"] = false; setts["Sink:Console"]["Destination"] = "Console"; setts["Sink:Console"]["Filter"] = "%Severity% >= 3"; // no output to console in result setts["Sink:Console"]["Format"] = "[%Severity%] %_%"; setts["Sink:Console"]["AutoFlush"] = true; setts["Sink:File"]["Destination"] = "TextFile"; setts["Sink:File"]["FileName"] = "test_%3N.log"; setts["Sink:File"]["Format"] = "[%TimeStamp%] <%Severity%> %_%"; setts["Sink:File"]["AutoFlush"] = true; boost::log::init_from_settings(setts); LOG(info) << "!!!Hello World!!!"; LOG(warning) << "NO TimeStamp and Severity"; LOG(error) << "NO output if Filter is set "; return 0; } result: no output to console file (test_000.log) is being rewritten on each run: [] ** !!!Hello World!!! [] ** NO date [] ** NO severity [] ** NO output if Filter is set if I add #include <boost/log/trivial.hpp> and replace LOG definition with #define LOG(x) BOOST_LOG_TRIVIAL( x ) I get also no console output but TWO! logs: (boostLogTest.log) 1 [2011-Jul-04 12:14:06.331749] [0x73d190] [info] !!!Hello World!!! 2 [2011-Jul-04 12:14:06.338750] [0x73d190] [warning] NO TimeStamp and Severity 3 [2011-Jul-04 12:14:06.339750] [0x73d190] [error] NO output if Filter is set .... ( test_000.log ) [2011-Jul-04 12:14:06.331749] ** !!!Hello World!!! [2011-Jul-04 12:14:06.338750] ** NO TimeStamp and Severity [2011-Jul-04 12:14:06.339750] ** NO output if Filter is set Built with: g++ -Ipath\to\boost -O0 -g3 -Wall -c -fmessage-length=0 -osrc\boostLogTest.o ..\src\boostLogTest.cpp g++ -Lpath\to\boost\libs -oboostLogTest.exe src\boostLogTest.o -lboost_log-mgw45-mt-d-1_46_1 -lboost_log_setup-mgw45-mt-d-1_46_1 Environment: Windows 7 x64 / MinGW (gcc 4.5) / Eclipse Boost version 1.46.1 Boost log from https://boost-log.svn.sourceforge.net/svnroot/boost-log/trunk/boost-logRevi… 603 Boost built with the same toolset. The questions are: - How to configure severity_logger using init_from_settings() to get the custom severity levels in the log? - Why "Format" variables do not work? (and why %TimeStamp% starts to work if using BOOST_LOG_TRIVIAL for output)? - What should be done to make logger append to log (not overwrite)? - Is it possible to log file and line using format variables (only to file)? I had explored boost::log documentation but had not found answers for these questions. Thank you in advance. Yuriy Petrovskiy

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Is boost log dead?
by Espen Harlinn 04 Jul '11

04 Jul '11

Has the boost log library died? Regards Espen Harlinn <mailto:espen@harlinn.no> mailto:espen@harlinn.no

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[1.47] Merge request for Boost.Build testsuite
by Vladimir Prus 03 Jul '11

03 Jul '11

May I please merge this change: https://svn.boost.org/trac/boost/changeset/72883 which unbreaks Boost.Build regression tests. Since Boost.Build tests are not run unless they are explicitly run, this change has no potential to break the release. However, it certainly will make Boost.Build tests look much better than they are now. OK? -- Vladimir Prus CodeSourcery / Mentor Graphics +7 (812) 677-68-40

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[1.47.0] Merge request for quickbook+random
by Daniel James 03 Jul '11

03 Jul '11

Hello, Please can I merge this change: https://svn.boost.org/trac/boost/changeset/72799/ There's a constexpr method in that file which isn't just a return statement, which was causing random (and libraries which depend on it) to fail on gcc 4.6.0 in C++0x mode. So the change just disables use of constexpr. A proper fix is pretty simple so I'll do that for the next release if necessary. Also this small documentation fix: https://svn.boost.org/trac/boost/changeset/72823/ thanks, Daniel

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[filesystem] Partial fix for POSIX locale("") problems; tickets 4688, 5100, 5289
by Beman Dawes 02 Jul '11

02 Jul '11

AFAIK, the problems discussed here are non-issues for Windows and Mac OS X, so you can ignore this post if you only care about those two operating systems. http://svn.boost.org/trac/boost/changeset/72855 fixes the problem of misconfigured POSIX system throwing an exception before main() has started. See: http://svn.boost.org/trac/boost/ticket/4688 http://svn.boost.org/trac/boost/ticket/5100 http://svn.boost.org/trac/boost/ticket/5289 There are at least two remaining problems: * There may be other BSD based operating systems that like Mac OS X should not even try to use std::locale("") to get the codecvt facet for conversion between wide and narrow strings. If you know of such a system (FreeBSD? Solaris? Others?), please let me know (1) the system, (2) the predefined macro to use to identify the system, and (3) what codecvt facet should be used instead. * For systems such as Linux, the code is currently still assuming that if std::locale("") throws, the best action is to let that exception propagate up the call stack. One of the tickets [5289] supplies a patch that tries various alternatives, and eventually falls back on the Boost UTF-8 codecvt. See below. It strikes me that such fallbacks are better left to user code. User code can always try {path(L"foo");} and then imbue their preferred fallback facet. What do others think? --Beman + // Get default OS encoding + char const *plang = getenv("LC_CTYPE"); + if(!plang) + plang = getenv("LC_ALL"); + if(!plang) + plang = getenv("LANG"); + if(!plang) + return global_loc; + + std::string lang = plang; + size_t charset_start = lang.find('.'); + if(charset_start == std::string::npos) + return global_loc; + charset_start ++; + size_t end_of_charset = lang.find(charset_start,'@'); + std::string encoding = lang.substr(charset_start,end_of_charset - charset_start); + for(size_t i=0;i<encoding.size();i++) { + if('a' <= encoding[i] && encoding[i]<='z') { + encoding[i]=encoding[i]-'a' + 'A'; + } + } + // + // Support at least the most popular and widely used encoding + // + if(encoding!="UTF-8" && encoding!="UTF8") + return global_loc; + std::locale loc(global_loc, new boost::filesystem::detail::utf8_codecvt_facet); + return loc;

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Merge Boost.Build branding changes to release
by Vladimir Prus 02 Jul '11

02 Jul '11

I would like to ask for permission to merge a couple of Boost.Build "branding" changes to the release branch: https://svn.boost.org/trac/boost/changeset/72773 https://svn.boost.org/trac/boost/changeset/72793 They are mostly changes in messages, except for a bit in bootstrap.{sh,bat} that installs a differently named binary. Obvious, it would be better to merge that later, and I apologise for doing this at this time, but then: - The change is easy - I've tested it on Windows and Linux, and it does not depend on anything much - Most of associated code changes are already merged to release branch in due time, and leaving this change outside would just make things more confusing. Comments? Thanks, -- Vladimir Prus CodeSourcery / Mentor Graphics +7 (812) 677-68-40

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returning floating point values from a metafunction
by Kenny Riddile 01 Jul '11

01 Jul '11

This isn't directly Boost-related, but this is still probably the best place to ask this question. Just for fun, I was trying to write a compile-time approximation of cosine using the following Maclaurin series: cos( x ) ~= 1 - ( x^2 / 2! ) + ( x^4 / 4! ) - ( x^6 / 6! ) + ... I ended up at a point where I needed to assign a const floating point value to the result of an integer division, kind of like this: static const float value = integerA / integerB; My problem is of course that you can't cast to non integral/enum types in a constant expression, which means that I end up with the truncated result of integer division. Suggestions?

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[gui] Help with a little experiment.
by Germán Diago 01 Jul '11

01 Jul '11

Hello. I'm trying to implement a little experiment of what I see should be the future of c++ guis. For that I'm going to need a handful of proto and fusion, and I have some questions. Besides that, there have been many times that a GUI for boost has been discussed. As I have some questions and something to expose, I thought it would be a good idea to post this message in both boost users and boost developers. I don't have an entire proposal for this, but for now I'm experimenting how a GUI framework should look like in my opinion. My opinion is that it should be AS declarative as possible, so, taking as a backend the gtk framework, I came with a syntax like the following one: #define CONTROLLER_CLASS GuiController #include <Gui/Layout.h> #include <iostream> class GuiController { void onEntryChanged(Entry & entry) { auto text = entry.getText(); std::cout << text << std::endl; } void onButtonClick(Button & button) { std::cout << "Button was clicked" << std::endl; } }; auto gui_definition = Window(title="Hello, world!") << VBox(expand=true) << HBox(expand=true) << Label(text="Name:") && Entry[SLOT(onEntryChanged)]) << End(HBox); << Button(text="hello")[SLOT(onButtonClick)]; << End(VBox) << End(Window); The properties are mapped to objects like title corresponding to the gtk properties. The << operator means insert into and the << End(WidgetName) means that no more widgets should be inserted inside that closed widget. The && operator means put widgets at the same level. Regarding signals, they're put inside operator[]. That gui definition would be used like this template <class UI, class Controller> ?? createGUI(UIDefinition & ui_def, Controller & controller); int main(int argc, char * argv[]) { GuiController controller; auto window = createGUI(gui_definition, controller); window.show_all(); window.run(); } The function createGUI would generate a GUI from the definition and it would bind SLOTS automagically. It's very little code making use of a DSEL. The problem is that I must learn a lot of proto to code this, but if it works, do you think it would be an improvement? It's all compiler-checkable and the code is very short. After this first step I could start thinking beyond gtk and separate the library in backend and frotend so that not just gtk+ is used. My question is: Can I make something like End(VBox) work with boost.proto? I mean if it's possible to close the expression for a VBox with end and insert the next widget to the same level that the HBox. Thanks for your time and feedback is welcome.

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