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BOOST_FOREACH like macro for map
by mobi phil 21 Oct '09

21 Oct '09

Hello, new to this list... did not find anything similar on net. One of the annoyances with std::map is that if you work with const maps, then there is no "one line" code to get an element knowing the key. given the map const map<string, string> aStringMap; I cannot write const string &s = aStringMap["key"]; process(s); I should write: map<string, string>::const_iterator it=aStringMap.find("key") if( it != aStringMap.end() ) { process(it->second) } so would be nice to have a macro like BOOST_CONSTMAPFIND(aStringMap, "key", data) { processResult( data ); } the version if(BOOST_CONSTMAPFIND(l_map, l_key, l_data) ) { } Seems to be impossible to implement -- rgrds, mobi phil being mobile, but including technology http://mobiphil.com

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Re: [boost] linking on OSX
by David M. Cotter 21 Oct '09

21 Oct '09

okay we now know what the problem is, the question for the BOOST folk is: how do i do this with bjam? On Oct 20, 2009, at 7:23 PM, Chris Suter wrote: > Hi David, > > On Wed, Oct 21, 2009 at 1:03 PM, David M. Cotter <me(a)davecotter.com> > wrote: > okay. everything is working fantastically, however, it won't run on > G3 machine running 10.4.11 > it works perfectly on a G4 PPC machine also running 10.4.11 > > is there some way to "tune" bjam to emit G3-compatible code? > cuz i'm getting this: > > Host Name: TAZ-2 > Date/Time: 2009-10-20 05:56:18.099 -0700 > OS Version: 10.4.11 (Build 8S165) > Report Version: 4 > > Command: FooBar Pro > Path: /Applications/FooBar Pro.app/Contents/MacOS/FooBar Pro > Parent: WindowServer [310] > > Version: FooBar Pro 1.0d50r33 (1.0) > > PID: 445 > Thread: Unknown > > Link (dyld) error: > > Library not loaded: @loader_path/../SharedSupport/ > libboost_thread.dylib > Referenced from: /Applications/FooBar Pro.app/Contents/MacOS/ > FooBar Pro > Reason: no suitable image found. Did find: > /Applications/FooBar Pro.app/Contents/MacOS/../SharedSupport/ > libboost_thread.dylib: no matching architecture in universal wrapper > /Applications/FooBar Pro.app/Contents/MacOS/../SharedSupport/ > libboost_thread.dylib: no matching architecture in universal wrapper > > This is most likely because you're only building for G4 machines and > greater. If you run otool -f -v <binary>, you'll probably see > cpusubtype set to CPU_SUBTYPE_POWERPC_7400 (which basically means G4 > or greater). > > To fix, as a minimum, you need to make sure that your deployment > target is set to 10.4 or less and make sure your architecture > setting is ppc rather than ppc7400. > > Kind regards, > > Chris

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[interprocess] new problem with move-aware containers
by Thorsten Ottosen 20 Oct '09

20 Oct '09

Hi Ion, I'm using the boost::interprocess::multiset from trunk with vc9. After updating, some of my code stopped working. I use a set like multiset<const Node*,SomePredicate> and when calling set.insert( &obj ) I get compile errors. Specifically in interprocess\detail\move.hpp(79) I don't understand the details of these move-emulation tricks, but the compiler complains that T=U* for some U is not a legal base class. AFAICT, the compiler is right: template <class T> class rv : public T { rv(); ~rv(); rv(rv const&); void operator=(rv const&); }; -Thorsten

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bzip with spreadsort
by Steven Ross 20 Oct '09

20 Oct '09

I've added fasterbzip2-1.0.5.zip to the Boost Vault as an example application of the Spreadsort hybrid radix sorting algorithm. As bzip is written in C, I couldn't use the template library directly and had to modify the source. Using the Spreadsort algorithm causes a measurable speed improvement on Windows for the first 100MB of wikipedia from: http://cs.fit.edu/~mmahoney/compression/textdata.html<http://cs.fit.edu/%7Emmahoney/compression/textdata.html> along with other data I tested. Please note that bzip doesn't spend all its time compressing, already has two stages of radix sort, and has specialized and manually inlined comparison functions, so it's heavily optimized to begin with and improvements are minor.

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[mpl] Is there anyone working on mpl with variadic templates ?
by luozhiyuan 20 Oct '09

20 Oct '09

Is it possible that BOOST_MPL_LIMIT_/seq/_SIZE can be removed when we have variadic templates ?

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[bitfield] Pre-review request
by vicente.botet 19 Oct '09

19 Oct '09

Hi all, I have adapted the Boost.Bitfield library from Emile Cormier with its permision and I have requested the Review Wizards to include Boost.Bitfield on the review schedule. The library is now quite stable. Even if there were not too much interest in the Boost ML, only 140 dowloads from the Boost Vault, the version on which it is based had more that 1500 downloads, so I suppose that the subject interest a lot of people. I really think Boost.Bitfield is the complement the Boost.Endian library to manage with all the endian issue, allowing to mange not only endian interger issues, but also endian bitfield issues. I hope that including it on the review schedule will generate more interest and help me to improve the library. I would appreciate it if people could participate to this Pre-review, reading the documentation, testing on their compiler, .... Every comment is wellcome. BTW, I'm looking for a review manager. Thanks for all, Vicente Boost.Bitfield Author(s): Vicente J. Botet Escribá, Emile Cormier Download: `Boost Vault: <http://www.boostpro.com/vault/index.php?action=downloadfile&filename=bitfie…> Boost Sandbox: https://svn.boost.org/svn/boost/sandbox/bitfield Documentation: https://svn.boost.org/svn/boost/sandbox/bitfield/libs/bitfield/doc/index.ht… Html doc also included the Vault package Categories: Portability, Integer Description: Portable bitfields traits. Boost.Bitfield consists of: * a generic bitfield traits class providing generic getter and setter methods. * a BOOST_BITFIELD_DCL macro making easier the definition of the bitfield traits and the bitfield getter and setter functions. Example declaration: struct Rgb565 { uint16_t storage; BOOST_BITFIELD_DCL(uint16_t, storage, unsigned char, red, 0, 4); BOOST_BITFIELD_DCL(uint16_t, storage, unsigned char, green, 5, 10); BOOST_BITFIELD_DCL(uint16_t, storage, unsigned char, blue, 11,15); }; Example usage: Rgb565 r; r.storage= 0xffff; // Write to a bitfield. Note that parenthesis are needed around the bitfield r.red() = 23; // Read from a bitfield unsigned char b = r.blue(); In a near future the library could add the following if the users consider it useful. * Add bitfields group * Used to easily manipulate groups of bitfields the same way as does C bitfields, but in a portable manner. Example declaration: struct Rgb565 { struct red {}; struct green {}; struct blue {}; typedef bitfields<mpl::vector< member<unsigned char, red, 5>, member<unsigned char, green, 6>, member<unsigned char, blue, 5> > > type; }; Example usage: Rgb565::type r = make_bitfields<Rgb565::type, 1,2,3>; // Write to a bitfield. r.get<Rgb565::red>() = 23; //or r.set<Rgb565::red>(23); // Read from a bitfield Rgb565::at<Rgb565::blue>::value_type b = r.get<Rgb565::blue>(); * Add pointer_plus_bits * Based on a.. The article of Joaquin Optimizing red-black tree color bits, b.. the implementation of Ion pointer_plus_bits from Boost.Intrusive , and c.. Clang's QualType smart pointer This class will allows to use the unsused bits of a pointer to reduce the size of the nodes containing pointers and bits and sometimes improving also the performances. I have not reached yet the interface I would like to have. For the moment we can do typedef pointer_plus_bits<int*,1,bool>::type pint_and_bool; int i=0; pint_and_bool v1; ASSERT_EQUALS(v1.pointer(),0); ASSERT_EQUALS(v1.small_int(),false); pint_and_bool v2(&i, true); ASSERT_EQUALS(v2.pointer(),&i); ASSERT_EQUALS(v2.small_int(),true); v1.pointer()=v2.pointer(); v1.small_int()=true; ASSERT_EQUALS(v1.pointer(),&i); ASSERT_EQUALS(v1.small_int(),true); typedef pointer_plus_bits< pointer_plus_bits<int*,1,bool>::type ,1, bool>::type pint_and_bool_bool pint_and_bool_bool v1; ASSERT_EQUALS(v1.small_int(),false); ASSERT_EQUALS(v1.pointer().get_pointer(),0); ASSERT_EQUALS(v1.get_pointer().get_pointer(),0); ASSERT_EQUALS(v1.get_pointer().small_int(),false);

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[interthreads] Pre-review request
by vicente.botet 19 Oct '09

19 Oct '09

Hi, I have requested the Review Wizards to include Boost.Interthreads library on the review schedule. Even if there were not too much interest for this library on this ML, there were more than 1000 dowloads from the Boost Vault. I'm open to reduce the scope of the library, if there are some parts that are not enough generic. I would appreciate it if people could participate to this Pre-review, reading the documentation, testing on their compiler, .... Every comment will help me a lot to improve the library. BTW, I'm looking for a review manager. Thanks in advance, Vicente InterThreads __________ :Author: Vicente J. Botet Escribá :Review Manager: ??? :Download: `Boost Vault: <http://www.boostpro.com/vault/index.php?action=downloadfile&filename=intert…> Boost Sandbox: https://svn.boost.org/svn/boost/sandbox/interthreads Documentation: https://svn.boost.org/svn/boost/sandbox/interthreads/libs/interthreads/doc/… Html doc also included the Vault package :Description: Boost.InterThreads extends Boost.Threads adding thread setup/cleanup decorator, thread specific shared pointer, thread keep alive mechanism and thread tuples. * thread decorator: thread_decorator allows to define setup/cleanup functions which will be called only once by thread: setup before the thread function and cleanup at thread exit. * thread specific shared pointer: this is an extension of the thread_specific_ptr providing access to this thread specific context from other threads. As it is shared the stored pointer is a shared_ptr instead of a raw one. * thread keep alive mechanism: this mechanism allows to detect threads that do not prove that they are alive by calling to the keep_alive_point regularly. When a thread is declared dead a user provided function is called, which by default will abort the program. * thread tuple: defines a thread groupe where the number of threads is know statically and the threads are created at construction time. * set_once: a synchonizer that allows to set a variable only once, notifying to the variable value to whatever is waiting for that. * thread_tuple_once: an extension of the boost::thread_tuple which allows to join the thread finishing the first, using for that the set_once synchronizer. * thread_group_once: an extension of the boost::thread_group which allows to join the thread finishing the first, using for that the set_once synchronizer. (thread_decorator and thread_specific_shared_ptr) are based on the original implementation of threadalert written by Roland Schwarz.

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[spirit] Support for one-pass iterators?
by Andrey Semashev 19 Oct '09

19 Oct '09

Hi, I'm trying to use Boost.Spirit.Classic to parse a text file content (or, to be more generic, a content that is read from an STL stream). I created a grammar that would fit the content, but I'm not sure which iterator I should pass to the parse function. The parser does not guarantee that it will read the content only in one pass, and I'm sure my actors will want to read the content themselves as they are called. So, obviously, istream_iterator/istreambuf_iterator will not work. Is there a tool in Boost.Spirit that would provide content buffering during the parse? If not, what can be suggested to solve this problem? BTW, the content is line-aligned, i.e. each line is syntactically distinct from others. I was thinking about writing a loop of readline/parse combo but I'm not sure how efficient it would be with regard to the grammar definition construction/destruction within the parse function. Are these concerns valid? Thanks.

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Re: [boost] C# LINQ-like library: Boost.Qlang.
by Germán Diago 18 Oct '09

18 Oct '09

> Hi, > I read you mail on boost concerning QLang. I just wanted to say I was > wondering (not very seriously) how to do such system, and you come with a > very clean first try. > Basically it's done with some metaprogramming to get the exact return type of a query. For example, if I put as an argument in a select a pointer to member data, I extract that pointer to member's type and put it in a tuple, without const, volatile and removing the reference. I also use filter_iterator and transform_iterator from boost to filter sequences based on the where lambda. Just a suggestion : it would be great if the user of the qlang could select > a tuple of value as a return value. (let's say I want to select the string > member "_name", a copy of the pointeur "this", and an int "_age" for example > from a set of objects. I suppose returning a tuple for example (or some > other type than those of the members) could be very interesting. > I don't know very well what you mean by returning a tuple of value as a return value. For now, what the libraries does is, if you write: from(somerange).select(full_object); it will return a select_ object which will generate a copy of the full object. if you write: from(somerange).select(&MyStruct::a_, &MyStruct::b_); it will return a select_ object which will return a std::tuple<type of a_ without const and without reference, type of b_ without const and without reference>. Boost.Qlang allows you to return tuples right now, the problem is that those tuples (for now) are just 1-element tuples. But in the future they will be arbitrary tuples. A copy of the this pointer does not make sense I think. Since every piece of data is immutable (data is always generated based on the select arguments), if you want the this pointer, you will have to return full_object (a copy). So you cannot get the this pointer directly. You can manipulate that query and write it back where it belongs if you want to modify some object.

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[filesystem] truncate() function?
by Beman Dawes 18 Oct '09

18 Oct '09

There was a request on the users list for a file truncate() function similar to the POSIX function of the same name. Since Windows provides a function with virtually identical semantics, this seems like a reasonable request. The POSIX spec includes: "If the request would cause the file size to exceed the soft file size limit for the process, the request shall fail and the implementation shall generate the SIGXFSZ signal for the process." I have no knowledge of or experience with POSIX signals, so need advice. Does the POSIX implementation need to do anything to cope with the possibility of a SIGXFSZ signal? If so what? Thanks, --Beman

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