June 2008 - Boost - lists.boost.org

[thread] proposal to manage portable and non portable thread attributes
by vicente.botet 22 Jan '09

22 Jan '09

Hello, Boost.thread has already a non portable interface to get the thread handle class thread { public: ... typedef np_native_handle_type native_handle_type; native_handle_type native_handle(); ... }; Boost.Thread do not allow to pass thread attributes on the thread constructor. I supose that this is due to portable issues. Could we identifiy which attributes are portable and which one not? The portable attributes (as stack size, ...) can be grouped on a thread_attributes class. In order to be able to pass whatever attribute to the thread constructor we can add the setting of non portable attributes to this thread_attributes class, and making the thread constructor take a thread_attributes in addition to the existing parameters. class thread { public: class thread_attributes { // portable attributes public: // set/get of attributes // .. #if defined(BOOST_THREAD_PLATFORM_WIN32) // ... window version #elif defined(BOOST_THREAD_PLATFORM_PTHREAD) private: pthread_attr_t native_attributes; public: set_np_attributes(const pthread_attr_t* h); // ... other #else #error "Boost threads unavailable on this platform" #endif }; thread(const thread_attributes*p, F f,A1 a1); ... }; The portable application needing some specific configuration can construct portable threads using the following schema thread::thread_attributes attr; // set portable attributes // ... #if defined(BOOST_THREAD_PLATFORM_WIN32) // ... window version #elif defined(BOOST_THREAD_PLATFORM_PTHREAD) // ... pthread version pthread_attr_t native_attributes; pthread_attr_init(&native_attributes); pthread_attr_setstacksize(&native_attributes, 1000000); attr.set_np_attributes(&native_attributes); #else #error "Boost threads unavailable on this platform" #endif thread th(attr, f,ctx); What do you think? Vicente

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[proto][design]why unary_expr,binary_expr; but no nullary_expr?
by Larry Evans 14 Dec '08

14 Dec '08

Although there's unary_expr<Tag,*>, binary_expr<tag.*,*> in traits.hpp there's no nullary_expr<Tag>. I realize this would be a replacement to the current terminal template but with a user specified tag. After all, if a user specified tag for n-ary (where n>0) expressions *is* desirable, why is a user specified tag for 0-ary expressions *not* desirable? On case where this would be useful is for algebraic morphisms where n-ary ops in a source algebra are mapped to n-ary ops in a target algebra. This *includes* 0-ary ops. An op would be the equivalent to proto tags. I think this could be done by another transform similar to the pass_through transform but allowing transformation of the tag. Currently pass_through just uses the source tag in the target expression. It seems like it should be pretty easy to allow transformation on the tag also.

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[integer] Promotion of endian library code from vault
by Neil Mayhew 01 Oct '08

01 Oct '08

On 2006-07-22 12:21:01, Beman Dawes wrote: > [boost] [integer] endian-0.6 posted w/ names changed > endian-0.6.zip has been posted in the integer directory of the file > vault at http://boost-consulting.com/vault/ This code is still in the vault, but I'd like to see it in the main part of boost. What needs to be done to make this happen? The endian library is exactly what I've been looking for, and I would really like to use it in my work, but I can't justify that to my colleagues if it's not an official part of boost. I would hate to become yet another person that reinvents this particular wheel. However, I notice there was a lot of discussion <http://lists.boost.org/Archives/boost/2006/07/108125.php> about PODs vs constructors, because of unions, so maybe not enough consensus was reached? There were some interesting proposals but no agreed-upon solution. In which case, I suspect that people will need to copy the code and each hack it to suit their own purposes, which is not what boost is all about. I have two use cases from my own work: TrueType fonts, and Mac HFS+ file systems. Both of these are big-endian file formats that need to be read into memory and processed, so (FWIW) I would support the POD approach. Currently, I can't use the code as-is because of the need to use the types in unions. References: http://lists.boost.org/Archives/boost/2000/03/2495.php http://lists.boost.org/Archives/boost/2006/05/105621.php http://lists.boost.org/Archives/boost/2006/06/105695.php http://lists.boost.org/Archives/boost/2006/06/105779.php http://lists.boost.org/Archives/boost/2006/06/105968.php http://lists.boost.org/Archives/boost/2006/06/106655.php http://lists.boost.org/Archives/boost/2006/07/108125.php http://lists.boost.org/Archives/boost/2006/07/108202.php --Neil

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[BENUM] Any interest in auto-generated enum-to/from-string functions, without longer/more-complex usage?
by Tony D 15 Sep '08

15 Sep '08

Anyone think this functionality belongs in boost? (I have working code) ENUM(X, B = N, C, D = B + C }; // or whatever X x1 = C; cout << x1 << '\n'; // outputs "C\n" X x2("D"); // construct from string... if (x2 == D) { will do } Tony __________________________________________________________ Sent from Yahoo! Mail. A Smarter Email http://uk.docs.yahoo.com/nowyoucan.html

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Proto<markus>::review()(proto::accept);
by Markus Werle 30 Aug '08

30 Aug '08

Hi! I think Proto should be accepted for inclusion into boost. A general purpose Expression Template library is hard to write. Proto is the most sophisticated and closest approach to perfection available today. - What is your evaluation of the design? Proto is well-designed in many aspects, though I got the impression that some beauty and purity was sacrificed on the altar of compile-time efficiency, but that's OK. (And yes, I hate BOOST_PP_MACROS!) Proto catches the most important issues of a general purpose expression template library, I especially like the way how expression storage and expression evaluation is strictly separated and the way I can add my own functionality. Proto covers the most important aspects of an ET library, sometimes in very elegant ways. Proto's design adressed compile time issues. That's a value in itself. OTOH: Transforms leave me with mixed feelings. I am not very good at catching ideas without good step-by-step documentation and I got messed up with grammars vs. transforms. This part of proto is new and it looks like a candidate for rework. I'd like to have an extra review in half a year only on the grammar and transform part of proto (*)[comment below]. That's a DSEL all by itself and I guess that interface may have some pitfalls. Larry Evans has worked that out in detail. There may be issues in the naming convention used there, e.g. I am unsure whether and_ is the appropriate name for what it does. - What is your evaluation of the implementation? None. Not enough time. Steven Watanabe did it for us all. Code looks clean. For my taste too many levels of nested namespaces, but that's the boost trend at the moment. I may appreciate this style later in my life, once I understand why you need it. - What is your evaluation of the documentation? The quality varies from excellent to hard to read. I agree with all what David writes about the docs. There is some potential for improvement, but that should not hinder the inclusion into boost: we need a community effort here since Eric's skill level probably is way too high in order to have some feeling for why the unaware might have problems with parts of the doc. The teacher should be one step ahead, not too far ahead. - What is your evaluation of the potential usefulness of the library? We really, really need this. Better today than tomorrow. The whole world is waiting for this to come. And C++ again rocks - Did you try to use the library? A couple of hours, but only for some of the examples. - With what compiler? VC8, Intel 10.1 - Did you have any problems? Nope. Eric-faster-than-lightning fixed those before I could run into them ... - How much effort did you put into your evaluation? I read the docs three times and worked through some details. I investigated the type representation of expressions by reading purposely generated compiler error messages and tried to figure out the design. - Are you knowledgeable about the problem domain? I had several attempts to write some kind of ET library on my own, some parts published at daixtrose.sourceforge.net. I also planned to write something like proto myself, but due to lack of time and programming skills I lost the race before it began. (rm -rf /work/markus/ideas/expresion_templates_revisited) Eric, thanks for the time saved by the publication of proto. Markus P.S. This review is short, sorry. I had some unexpected tasks to do the last week which hindered further investigation. I'll put some more effort into this in the future. (*) I'd like to have an extra review on _every_ boost library in a 2-year-cycle. By this boost::multi_array could probably be forced to model assignable like any other STL container and ::_1 from boost::bind will move into its own namespace - just to mention my two favourite change requests ...

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Re: [boost] UTF-8 conversion etc. (Sebastian Redl) (Sebastian Redl)
by Graham 28 Aug '08

28 Aug '08

>> As I said to Phil, Rogier and I completed a Unicode character library >> for >> >> Release under boost, but never submitted it to Boost as we had intended >> to >> >> release it with a string library built on it, and never had time to do >> the >> >> second part of the work. >> >Post it, and we'll do the second part. It's open-source. > >Sebastian Sebasian, As requested, I have posted a Unicode character support library in the boost vault as Unicode_lib.zip. Please feel free to use this under the boost license. It would be great if somebody had the time to develop the existing character support to ad the string wrappers that we had intended to - but ran out of time doing. It should be well documented, but if you want any questions answered, please feel free to ask and I'll try and help! Thanks. Yours, Graham

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[asio]: extending asio
by Andreas Pokorny 18 Aug '08

18 Aug '08

Hello, I would like to add more asynchronous event sources to asio, like: - input events for mouse, keyboard and joystick .. - window exposure, move, resize events in some generic form, - generic "quit" events - file alteration With directFB/X11/Unix/Linux most of that can be done directly through select or epoll. But since reading the message and parsing events is mostly done by a third party library, I would only need the reactor part for these. Is this possible with asio? According to msdn it seems to be possible to create so called event objects for direct input devices. I am no win32 expert so I do not know if one can combine that with completion ports? Regards Andreas Pokorny

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Why I hate subversion
by Eric Niebler 02 Aug '08

02 Aug '08

U boost/indirect_reference.hpp U boost/parameter.hpp svn: In directory 'boost' svn: Can't move 'boost/.svn/tmp/foreach.hpp.2.tmp' to 'boost/foreach.hpp': Permission denied ericne@ericne-xps ~/boost/org/trunk $ svn up svn: Checksum mismatch for 'boost/.svn/text-base/enable_shared_from_this.hpp.svn-base'; recorded: '12d8c5183a709a7699c13b312073c36c', actual: 'c89a6b23045ff8c89d2de74213d1649a' Does this ever happen to anybody else? I get this random corruption of my local subversion repository about once a month. -- Eric Niebler Boost Consulting www.boost-consulting.com

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Possible library submissions: fuzzy logic library, new container
by Alex Shafir 01 Aug '08

01 Aug '08

I am trying to determine if there might be any interest in a couple of possible library submissions. Both ideas were very useful and instrumental for many C++ development projects that I was doing for the last years. The fuzzy logic library is a simple, pure C++, optimized for speed, practical implementation of the fuzzy logic calculations that DOES NOT attempts to comply with the FCL(Fuzzy Control Language) standard (like IEC 1131). It CANNOT load FCL files. Instead similar to the Boost Spirit framework it provides a syntax that enables fuzzy logic rules to be written exclusively in C++. Compiled fuzzy model specifications are immediately executable. A snippet of what this syntax currently looks like is at the end of this message. The other idea is the “sparse array” container. Working for securities trading industry I used it innumerable number of times. It is useful in situations where there is a set of entities identified by integer(unsigned) numbers. Most often the numbers are identity keys in a database, a protocol field ids, etc. The potential range of the numbers makes it impractical to use a C++ array or the STL <vector>. On the other hand the average percentage of the keys that are really used in an application relative to the potential range is often less then 5% and there are huge holes of unused keys between zero and max(used key). The data elements or pointers to objects are kept in a structure similar to a balanced B-tree. Elements are directly accessed by an index operator. Access involves only a few arithmetic and redirection operations. When storing a new element that is outside of the range provided by exiting data structure the structure bilds itself up extending the indes range enough to accommodate a new index value. Existing data are never physically moved like in the STL vector. So, all references/pointers/iterators referencing existing elements are never invalidated. Feel free to comment. Fuzzy model syntax sample: ======================================== #include "TestModel.h" using namespace Fuzzy; // test model definition TestModel::TestModel(string file): Model(file), angle(-1), velocity(-1), speed(-1) { // fuzzy variables definitions created by the base class (Fuzzy::Model) // Input/Output methods; Input/Output arguments are refs // to double scalar variables Var& Angle = Input(angle); Var& Vlcty = Input(velocity); Var& Speed = Output(speed); // membership functions definitions created by fuzzy variables // Term method; Term method takes curve name as an argument; // cureve names are defined in the Fuzzy::Model curve definition // file MemFun& AngleNegHigh = Angle.Term("AngleNegHigh"); MemFun& AngleNegLow = Angle.Term("AngleNegLow"); MemFun& AngleZero = Angle.Term("AngleZero"); MemFun& AnglePosLow = Angle.Term("AnglePosLow"); MemFun& AnglePosHigh = Angle.Term("AnglePosHigh"); MemFun& VlctyNegHigh = Vlcty.Term("VelocityNegHigh"); MemFun& VlctyNegLow = Vlcty.Term("VelocityNegLow"); MemFun& VlctyZero = Vlcty.Term("VelocityZero"); MemFun& VlctyPosLow = Vlcty.Term("VelocityPosLow"); MemFun& VlctyPosHigh = Vlcty.Term("VelocityPosHigh"); MemFun& SpeedNegHigh = Speed.Term("AngleNegHigh"); MemFun& SpeedNegLow = Speed.Term("AngleNegLow"); MemFun& SpeedZero = Speed.Term("AngleZero"); MemFun& SpeedPosLow = Speed.Term("AnglePosLow"); MemFun& SpeedPosHigh = Speed.Term("AnglePosHigh"); // these are the model rules; syntax is pretty strightforward; // rules look like operator >> where lhs is the condition and // rhs is the conclusion; // lhs and rhs have to be in parens if they contain more then // one term because of the c++ operators precedence rules; // conclusion may be a comma separated list of output terms // in parens ((AngleZero and VlctyZero)or(AnglePosLow and VlctyNegLow)or(AngleNegLow and VlctyPosLow)) >> SpeedZero; ((AngleZero and VlctyNegLow)or(AngleNegLow and VlctyZero)) >> SpeedNegLow; ((AnglePosLow and VlctyZero)or(AngleZero and VlctyPosLow)) >> SpeedPosLow; ((AngleZero and VlctyNegHigh)or(AngleNegHigh and VlctyZero)) >> SpeedNegHigh; ((AnglePosHigh and VlctyZero)or(AngleZero and VlctyPosHigh)) >> SpeedPosHigh; } TestModel::~TestModel() { } void TestModel::run(double a, double v, double &s) { // we assign scalar variables to class members angle = a; velocity = v; speed = s; // then run the model // it should be pretty fast as it all designed to preallocate // all the needed large objects in the model constructor Model::run(); // and assign the values of output variables s = speed; }

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range_ex: status?
by Mathias Gaunard 31 Jul '08

31 Jul '08

I'm writing some piece of software working that does a lot of data structures traversal and that really needed filtering of traversal etc. I thought I'd get that from Boost.Range, but I was surprised to see Boost.Range provides very little: all the good stuff (the range-based algorithms and adaptors) are in another library, range_ex, which isn't in the main distribution yet. Will this library be included in Boost soon? It's really great. As for the open issues, here are my opinions: - Output ranges: don't adaptors already output ranges? - Two input ranges, or a range and an iterator?: two ranges can do more - For any algorithm foo(container, args...), if foo(args...) is valid then it should be called - Null-termination of C-style strings: Isn't that up to Boost.Range to decide whether it's a range or not?

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