- Boost - lists.preview.boost.org

Temporary objects
by DE 03 Nov '09

03 Nov '09

hi all unfortunately i'm totally out of time now so i only write my proposal and an example forgive me for that the code #include <algorithm> template<typename type> class temporary : public type { temporary() : type() {} temporary(temporary &a) : type() { using std::swap; swap(static_cast<type&>(*this), static_cast<type&>(a)); } template<typename other> temporary(const other &a) : type(a) {} temporary &operator=(temporary &a) { using std::swap; swap(static_cast<type&>(*this), static_cast<type&>(a)); return *this; } template<typename other> temporary &operator=(const other &a) { type::operator=(a); return *this; } }; example1 temporary<huge_type> foo(const huge_type &a) {//returning temporary object temporary<huge_type> ret; //or even 'ret(a)' //doing something... return ret; } //... huge_type result; result = foo(bar); //somewhere in code only one copy operation -- assignment operator return by value copying overhead is eliminated with help of swap() example2 struct my_type { //... my_type(temporary<my_type> &a) { this->swap(a); } //... my_type &operator=(temporary<my_type> &a) { this->swap(a); return *this; } //... }; temporary<my_type> process(const my_type &item) { temporary<my_type> ret; //processing item... return ret; } //... my_type result = process(item); //somewhere in code //or result = process(item); no temporary object handling overhead at all return by value, copy-construct and assign from temporary objects for free! thank you for attention

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[interval container (itl)] A pretty large bitset
by Joachim Faulhaber 03 Nov '09

03 Nov '09

Dear list! In thread http://lists.boost.org/Archives/boost/2009/06/152786.php Zachary Turner posted an article about a compressed bitset, that uses run-length defined intervals to achieve a compact representation of large bitsets that are useful for managing huge file allocation tables. As I mentioned in a reply to this article, Zach's compressed bitsets, in their basic ideas, are quite similar to itl::interval_sets: They allow for compression of large quantities of elements as long as they occur in (large) uninterrupted chunks. As Zach pointed out, this nice behavior is completely spoiled, if we would want to handle a set like {1,3,5,7,9,...,2(k-1)} or as bitset '0101010101...01' Here, the capability of usual bitsets to compress elements that are distributed over only small ranges can neither be applied to Zach's compressed bitset nor to an itl::interval_set of the Interval Template Library. As a new use case of interval containers I have developed a *large_bitset* class template on top of itl::interval_map that is able to combine interval compression *and* bitset compression. It is, for instance, capable of representing the bitset mentioned above '01010101...010' a b a: bit 0 b: bit 2^64-1 containing 2^63 bits (or elements) with just *one* internal interval associated to only *one* value of 64bit length ;) Curious?? Find the documented example code in my updated library docs at http://www.herold-faulhaber.de/boost_itl/doc/libs/itl/doc/html/boost_itl/pr… While the documented class template 'large_bitset', for reasons of a short presentation, is only a minimal one, you can find a more elaborated version as 'interval_bitset' in the sandbox at https://svn.boost.org/svn/boost/sandbox/itl/boost/itl_xt/interval_bitset.hpp I'd like to ask Zachary Turner to comment on the use case. Can this be useful in your field? Moreover I'd like to encourage everyone to give feedback on my interval container library, report problems, bugs and share suggestions. If you find this stuff useful please volunteer as review manager for the submitted library Boost Interval Containers. Note, that the new example on 'large_bitsets' is not yet included in the library submitted for review in the vault but it is contained in the sandbox. I am currently preparing an update of the review version of the itl, that is adjusted and corrected for the feedback, suggestions and patches that I have received during the last weeks. I will integrate further feedback and account for bug reports if you have any. Best regards Joachim

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[tree?] STL like tree data structure in boost?
by Nil Geisweiller 03 Nov '09

03 Nov '09

hi, any idea if there is in boost a similar tree data structure such as Kasper Peeters's tree.hh http://tree.phi-sci.com/ ? thanks Nil

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Parallel Tree Merge
by Biddiscombe, John A. 03 Nov '09

03 Nov '09

If I have a representation of a tree and I have sub-portions of it spread across a number of processes (but the whole tree represents a well-formed and simple tree structure). Is there a reasonably straightforward way of doing this using BGL or PBGL. I had hoped that it might be as simple as defining some templated tree structure and using the add operator after gathering pieces onto one node. (The tree structure could be represented as XML where the root would exist on all processes, different sub-nodes and leaves and would occur on different processes - a simple xml merge would probably suffice for my needs right now). If examples using boost libraries ((p)BGL/MPI) or other similar combination exist and anyone can point me to resources I'd be most grateful. (I'm not an expert with BGL so will need some do some learning...) Thanks JB -- John Biddiscombe, email:biddisco @ cscs.ch http://www.cscs.ch/ CSCS, Swiss National Supercomputing Centre | Tel: +41 (91) 610.82.07 Via Cantonale, 6928 Manno, Switzerland | Fax: +41 (91) 610.82.82

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Cross-platform date/time problems
by Zachary Turner 03 Nov '09

03 Nov '09

Hello list, Apologies for the cross-posting, this originally went to the boost-users list but it got no responses, and then I also realized it was actually more appropriate here. Suppose I have a cross-platform agent that communicates with a server. Agent from platform X sends a message to the server which contains a date/time. Server sends a message to another agent running platform Y with the same date/time. In practice X/Y are always either windows/linux or linux/windows. The server always tells the agent which platform's native format the time is represented in, so there should be no problem. Ideally I'd like to write the following code: ptime time; if (msg.is_from_windows()) { time = from_ftime<ptime>(msg.time()); } else { time = from_time_t(msg.time()); } But this doesn't work because from_ftime<> is not defined on linux. If from_ftime<> is already templated on the FILETIME type, is there any reason it needs to be #ifdef'd out on non-windows platforms? I mean, a FILETIME is really just a uint64, can't the templated function also just operate on a boost::uint64_t? Zach

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#3541 Support <boost/ptr_map.hpp>
by Olaf van der Spek 02 Nov '09

02 Nov '09

Hi, https://svn.boost.org/trac/boost/ticket/3541 Could a forward header file be created such that #include <boost/ptr_map.hpp> works? The extra ptr_container directory is hard to remember..., I always have to look it up. boost/ptr_* looks much more natural. Greetings, Olaf

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Re: [boost] loglite - A logging library (JD) (Zachary Turner)
by Tan, Tom (Shanghai) 02 Nov '09

02 Nov '09

>I've always found it was easiest to do something like: >namespace boost { namespace filesystem { >#if defined(_WIN32) || defined(WIN64) > typedef wpath npath; >#else > typedef path npath; >#endif >} } >and then use boost::filesystem::npath everywhere. Performance isn't >generally the bottleneck when dealing with the filesystem, but why even >bother with so many behind-the-scenes conversions when you can just as >easily store everything in the type the O/S is expecting in the first place >with a simple typedef? That's handy when only OS API is involved, but if you have to use it other Libraries which are only string-ready, e.g. LIGLITE, you have no choice. Even Some popular Boost libraries are only for strings, Boost.Test is one.

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The C++ Post-Processor
by Christian Schladetsch 02 Nov '09

02 Nov '09

Hello, This is a general post about C++. Why is it that the pre-processor (PP) is the source of so much disdain, and yet it is the first resource exploited to 'fix' problems with C++? Why has the PP received so little attention over the years, from its early use as M4? This is a message to the powers that be: the PP is a powerful tool. It provides a 'context-cutting' mechanism for creating and extending solutions. It is a true "meta-programming" system built right into C++. No other language I can think of has a PP. This is often viewed as being a good thing, but I wonder more and more as I get older that a good PP is in fact needed to span some otherwise very difficult boundaries. Other languages are "dynamic" inasmuch as they reflect classes and allow for runtime changes to types and instances. I think we all here agree that this ability is counter to building firm, safe and efficient software. But the PP is similar to that, allowing a degree of dynamicy not otherwise available. Specifically, by exposing concepts to the PP we can leverage reflection and synthesis while building on inheritance and conglomeration. I don't have a point as such; I just wanted to raise the idea of developing M4 and the PP past where it is. There is a lot of low-hanging fruit there. This is evidenced by the fact that a lot of other languages are or can be transliterated to C++. Rather than thinking of C++ as the output, we could be thinking of C++ as the input. Perhaps a way forward for C++ is a good PP and a standards-based implementation of C++ in C++ so it can embed itself. I've written a number of languages, and in each I've had to address the issue of pre-processing. The latest attempts have resulted in a system where it parses and executes via AST input to produce an output that is then parsed by the same system to produce an AST that is then walked to eventually produce machine code. I think this model is best, and would be delighted to see some similar movements in the PP/C++. We have Boost.Wave to start with... Why not give it real Expressions? Loops? Scopes? Classes? Templates? memory management? IO? Is there any interest in a Boost.C++ ? Regards, Christian

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[optional] layout
by Domagoj Saric 01 Nov '09

01 Nov '09

why is boost::optional laid out so that the bool comes before the object's placeholder/storage? this takes up to 7 extra bytes of storage with default alignement and, more importantly, it forces pointer offset adjustment/calculation when accessing a boost::optional<> through a pointer (and trying to access the actual contained object)... it also makes life harder for those of us keen to hackery ;) because it makes the address of an optional different from the address of the actual object within the optional... ps. it would be 'cool' if all of the functionality from boost::optional<> not related to the 'is initialized' bool (conditional destruction, etc...) could be extracted into a separate class (usefull for cases where you have to delay/in-place construct an object but are certain that you will construct it by the point where it needs to be used or destroyed...so you do not need the 'conditional' overhead)... -- "That men do not learn very much from the lessons of history is the most important of all the lessons of history." Aldous Huxley

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Re: [boost] loglite - A logging library (JD)
by Tan, Tom (Shanghai) 01 Nov '09

01 Nov '09

> Please have a look and let me know what you think could be improved. The first thing I notice is that it does not support std::wstring directly. It's a big problem in my case I use wide-character in all my applications, which simplifies dealing with UTF-16 adopted by Modern Windows platforms. If I need to any string info from my program, I'll have to convert from UTF16(represented as std::wstring) to UTF8 so that it could be working well with LOGLITE. That's inconvenient. Offtopic, I am expecting boost::filesystem V3 for this very same reason.

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[ANN] CLI command line interface compiler for C++
by Boris Kolpackov 29 Oct '09

29 Oct '09

Hi, I am pleased to announce the first public release of CLI. CLI is an open-source (MIT license), cross-platform command line interface compiler for C++. It allows you to specify the options that your program supports, their types, and default values. For example: include <string>; class options { bool --help; std::string --name = "example"; unsigned int --level | -l = 5; }; This specification can then be automatically translated to C++ classes that implement parsing of the command line arguments and provide a convenient and type-safe interface for accessing the extracted data. For example: #include <string> class options { public: options (int argc, char** argv); options (int argc, char** argv, int& end); bool help () const; const std::string& name () const; unsigned int level () const; ... }; int main (int argc, char* argv[]) { options o (argc, argv); if (o.help ()) print_usage (); if (o.level () > 4) cerr << "name is " << o.name () << endl; ... } It is easy to start using CLI in your application since there are no external dependencies. You can compile your command line interface to C++ and simply add the generated files to your project's source code. For a five minute introduction to CLI, see the "Hello World" example in the CLI Getting Started Guide: http://www.codesynthesis.com/projects/cli/doc/guide/#2 More information, documentation, and source code distributions are available from the project's web page: http://www.codesynthesis.com/projects/cli/ Enjoy, Boris -- Boris Kolpackov, Code Synthesis Tools http://codesynthesis.com/~boris/blog Open-source XML data binding for C++: http://codesynthesis.com/products/xsd XML data binding for embedded systems: http://codesynthesis.com/products/xsde

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Re: [boost] [Boost-users] at_thread_exit() never getting called
by vicente.botet 29 Oct '09

29 Oct '09

Hi, ----- Original Message ----- From: "cowwoc" <cowwoc(a)bbs.darktech.org> To: <boost-users(a)lists.boost.org> Sent: Wednesday, October 28, 2009 7:33 PM Subject: Re: [Boost-users] at_thread_exit() never getting called > > > I think https://svn.boost.org/trac/boost/ticket/2739 prevents it from > working. > > Gili > > > Steven Watanabe-4 wrote: >> >> AMDG >> >> cowwoc wrote: >>> I am registering boost::this_thread::at_thread_exit() against one of my >>> threads. When the main thread exits using "return 0" the at_thread_exit >>> hook >>> never gets invoked. Is this normal? >> >> It's supposed to work for the main thread... For me yes, but it dosn't works. The example attached to the ticket show the problem. >>> Is there a way to hook the main thread >>> shutting down? >>> >> >> On windows you can use on_thread_exit(). >> The patch worked when I summited it. Anthony, I've see that you have started to integrate the patch for the thread attributes. Do you plan to integrate this patch also? Thanks, Vicente

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what is the interest of In Place factory
by rodrigue pons 29 Oct '09

29 Oct '09

Hello, I was looking about the boost In Place Factory to resolve a problem i got, and there is something i don't understand: what is the advantage of this lib? For example: I get a class A, wich constructor is: A( int, const string& ); And an another class, C, that contains an A*. C provides a method to construct this A*: void C::BuildA( int i, const string & str ); wich will be called this way: instance_of_C.BuildA( 1, "test" ); If now i use the boost In Place Factory, the member function C::BuildA will become: template<class InPlaceFactoryT> void C::BuildA( InPlaceFactoryT const& factory ) wich will be called this way: instance_of_C.BuildA( 1, "test" ); We can see here that with or wothout the In Place Factory, the code is exactly the same. So i guess there is something i didn't understand. But what?

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boost.math
by rodrigue pons 29 Oct '09

29 Oct '09

Hello, i need to implement the computation of huges series. These series are made of floats, and thus the error propagates. The problem is that the main constrain is the execution time, thus i must use the more "native" type possible. Is boost.math offer a solution to minimize this error? Which type of float (float, double, any structure?) must i use? Thanks.

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[spirit][regex] rxstrlit/regex_p with wchar_t strings
by Adam Badura 29 Oct '09

29 Oct '09

Is it possible to use rxstrlit/regex_p with wide character strings (wchar_t based)? Or even better, with arbitrary char type/char traits pair? I tried this with suggested example (http://www.boost.org/doc/libs/1_40_0/libs/spirit/classic/example/fundamenta…) and after converting to wchar_t what was required and compiling it run successfully. But it generated a lot of warnings about converting wchar_t to char in headers that looked like regex headers. So I guess it worked only because the wchar_ts in the example are actually chars. If I changed the example to use wchar_t which have no corresponding char values the example would likely fail. In the end I have a string with templated char type and traits type (just like with string and iostream library). And I want to match it against grammar build from (among others) strings with the same char type and traits type. Can I force regex in Spirit to do that? Adam Badura

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Why BOOST_HAS_DECLSPEC is not defined under MingW?
by Artyom 29 Oct '09

29 Oct '09

Hello, I've noticed following lines under boost/config/platform/win32.hpp #if !defined(__GNUC__) && !defined(BOOST_HAS_DECLSPEC) # define BOOST_HAS_DECLSPEC #endif Why? GCC provides support of declspec, Why it is specifically undefined? It can auto-export symbols but it does not work when static members involved. Thanks, Artyom

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Re: [boost] New boost packaging suggestion for windows
by Julian Bangert 29 Oct '09

29 Oct '09

Hello, > Sadly, the only point being discussed so far is the online registration. > What I find to be at least as annoying is the size of the package. And > by that I'm not (only) referring to the memory or bandwidth. The most > important issue is the burden of having to deal with such an amount of > data, even if I'm only interested into a relatively small part of boost. > My package contains everything in one archive. These 37MB offer quite good compression and you can choose what you wish to extract. > I wonder whether there is still any thought or even effort spent on > breaking boost up into individual components that can be built, tested, > and ultimately also packaged separately. Any news on that ? > > Thanks, > Stefan > Well, a lot of Linux distributions already have this ( all the libboost- packages in debian for examples ) . In W32 it is possible even with BoostPro and in my distribution you can selectively extract libs. Tell me if this is wanted/appreciated and I can write a GUI frontend to automatically install components. I just uploaded the files to 2 sites for distribution, at least one of which should be up at any given time: 1) ( the mirror, but the preferred location ) http://boost-win-bin.googlecode.com/files/boost_1_40_0-vc9-preview.7z* 2) ( main site, but not on a good machine) https://obliviononline.com/pub/boost/ *After a few people confirm that this works for them they should be considered stable and I would build for other C versions as well. Then they could also be mentioned in getting started. * *Thanks, Julian Bangert __________ Information from ESET NOD32 Antivirus, version of virus signature database 4553 (20091028) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com

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[dbc] Interest in Design By Contract for C++?
by Lorenzo Caminiti 29 Oct '09

29 Oct '09

Hello all, Is there any interest in a library that supports Design By Contract (DBC) for C++? All DBC features of the Eiffel programming language are supported by this library, among others: 1) Optional compilation and runtime checking of preconditions, postconditions, and invariants. 2) Subcontracting for derived classes. 3) Use of "old" in postconditions. 4) Automatic contract documentation (integrated with doxygen or similar tools). EXAMPLE This is part of the Stack4 DBC example presented for Eiffel in the book "Object Oriented Software Construction", B. Meyer, 1997. It has been coded for C++ using this library. #include <dbc.hpp> // This library. template<typename T> class Stack4 DBC_INHERIT_OBJECT(Stack4<T>) { public: Stack4(const int& n): capacity_(0), count_(0), representation_() DBC_CONSTRUCTOR( (private) (template)(Stack4)( (const int&) (n) ), { // Constructor preconditions. DBC_ASSERT(n >= 0, "non negative capacity"); }, { // Constructor postconditions. DBC_ASSERT(self.now.capacity() == n.now, "capacity set"); DBC_ASSERT(self.now.empty(), "is empty"); }, { // Constructor body. capacity_ = n; representation_.resize(capacity_); }) virtual ~Stack4() DBC_DESTRUCTOR( (public) (virtual) (template)(Stack4)(), { // Destructor body (do nothing). }) void remove() DBC_MEM_FUN( (public) (void) (template)DBC_COPYABLE(Stack4) (remove)(), { // Member function preconditions. DBC_ASSERT(!self.empty(), "not empty"); }, { // Member function postconditions. DBC_ASSERT(!self.now.full(), "not full"); DBC_ASSERT(self.now.count() == (self.old.count() - 1), "count decreased"); }, { // Member function body. --count_; }) ... // The rest of the Stack4 class. private: int capacity_; int count_; std::vector<T> representation_; DBC_INVARIANT(Stack4, { DBC_ASSERT(self.count() >= 0, "count non negative"); DBC_ASSERT_STREAM(self.count() <= self.capacity(), "count no greater than capacity", err << "count " << self.count() << " bounded by capacity " << self.capacity()); DBC_ASSERT( self.capacity() == int(self.representation_.capacity()), "capacity consistent with vector capacity"); DBC_ASSERT(self.empty() == (self.count() == 0), "empty when no elements"); if (self.count() > 0) DBC_ASSERT( self.representation_.at(self.count() - 1) == self.item(), "if positive count, item at top"); }) }; Example Notes: a) The somewhat strange syntax of the macro-based API (i.e., DBC_CONSTRUCTOR(), DBC_DESTRUCTOR(), and DBC_MEM_FUN()) uses a C++ preprocessor sequence of tokens "(public) (void) (template) ..." (this library internally uses Boost.Preprocessor to implement these macros). This library also provides a code-based API (dbc::fun::constr<>, dbc::fun::destr<>, and dbc::fun::mem<>) that can be used instead of the macro-based API but more setup code needs to be written by the programmers. b) This library also internally uses Boost.MPL mainly for typetraits, to support "old" in postconditions but only for types marked DBC_COPYABLE(), and for static assertions checking for library missuses (e.g., incorrect preprocessor sequence of tokens passed to the macro-based API). c) This library requires contracts to be written together with the class declaration (as contracts are part of the class specification). The class definition (function body) instead can either be written together with the contracts in the class declaration (like in the example above) or it can be written separately from the class declaration (i.e., this library maintains for function bodies the same C++ feature that allows to separate function's declaration and definition). Cheers, Lorenzo

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[integer] Compilation failed in Visual Studio
by Adam Badura 28 Oct '09

28 Oct '09

Following simple program: #include <boost/integer_fwd.hpp> int main() { return 0; } does not compile in Visual Studio 2008 with Boost 1.40.0. Compilation errors are following: 1>d:\libraries\boost_1_40_0\boost\integer_fwd.hpp(70) : error C2039: 'long_long_type' : is not a member of 'boost' 1>d:\libraries\boost_1_40_0\boost\integer_fwd.hpp(70) : error C2065: 'long_long_type' : undeclared identifier 1>d:\libraries\boost_1_40_0\boost\integer_fwd.hpp(70) : error C2913: explicit specialization; 'boost::integer_traits' is not a specialization of a class template 1>d:\libraries\boost_1_40_0\boost\integer_fwd.hpp(73) : error C2913: explicit specialization; 'boost::integer_traits' is not a specialization of a class template Adam Badura

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[thread][thread_specific_ptr]
by Sid Sacek 28 Oct '09

28 Oct '09

In VC++ and GCC a user creates global TLS like this: VC++ __declspec( thread ) int tls_1; GCC __thread int tls_2; But using the boost library boost::thread_specific_ptr< int > tls_3; doesn't provide an initialized global variable as one would expect from thread-local-storage. Using tls_3 crashes the program if it's not pre-initialized to some object. The implication is that every time a new thread is created, it needs to first instantiate all global TLS objects. Am I not understanding the intentions of this class? Is there a proper or intended way of using this class? I couldn't find any example code in the boost archives. Thanks, -Sid

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Can we suppress integer_traits warnings?
by John Maddock 27 Oct '09

27 Oct '09

If you have a program that simply includes boost/integer_traits.hpp and is compiled with g++ -pedantic you get a bunch of warnings: ./boost/integer_traits.hpp:164:57: warning: use of C99 long long integer constant ./boost/integer_traits.hpp:164:73: warning: use of C99 long long integer constant ./boost/integer_traits.hpp:170:62: warning: use of C99 long long integer constant ./boost/integer_traits.hpp:170:62: warning: use of C99 long long integer constant And no matter where I insert __extension__ I can't seem to get gcc to suppress these:-( Any ideas? BTW I'm asking because this came to me as a - somewhat misplaced - bug report: https://svn.boost.org/trac/boost/ticket/1451. Thanks, John.

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[task in sandbox] memory leak?
by Jeffrey Hellrung 27 Oct '09

27 Oct '09

All: A colleague of mine is trying to use the proposed Boost.Task library in the sandbox, but he is observing some memory leaks. See forwarded email below and attached cpp file. Does anyone have any information or suggestions for him? I agreed to query the list for him, but if this becomes too involved, I'll ask him to subscribe and communicate directly. Thanks! - Jeff -------- Original Message -------- Subject: Boost.task memory leak Date: Tue, 27 Oct 2009 15:14:44 -0700 From: Paul Jones <pajones(a)gmail.com> To: Jeffrey Hellrung <jhellrung(a)ucla.edu> References: <7f0a1570910271324o3dcb2d9xb361501267b7a5db(a)mail.gmail.com> This code leaks memory on my system: - gcc version 4.4.1 (Ubuntu 4.4.1-4ubuntu8) - Boost 1.40 - boost.task-0.3.0 When this code is run you can observe the program's allocated memory steadily increasing in the system monitor. The output displays the number of (undestroyed) functor objects when all the pool has completed all of its tasks. This seems to be capped at 64, so this isn't the source of the leak. The maintainer's name is Oliver Kowalke. But I couldn't find his email address. Paul

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asio library
by Peter Foelsche 27 Oct '09

27 Oct '09

Out of curiousity (reading somebody comment here regarding socket calls) I looked into the asio library and found the following example code below. My question is: What is the use of the socket object created in the first line? I think this line must always be followed by some more code. Because of this it does not make sense, that a library exports this functionality. boost::asio::ip::tcp::socket socket(io_service); boost::system::error_code ec; socket.open(boost::asio::ip::tcp::v4(), ec); if (ec) { // An error occurred. }

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Proposal for Library to perform dependency injection
by Adam Young 27 Oct '09

27 Oct '09

Having had a career that has bounced me between a few languages, I have had the opportunity to work with a couple of tools in the Java world that didn't see, to have analogues in C++. One of these is the inversion of control containers, of which Spring is one of the best known. Ken Fowler suggested the term "Dependency Injection" as a way to better describe how inversion of control is performed, and I prefer his term. I've written a fairly simple dependency injection framework in C++ that seems to make proper use of the C++ Language. It is not attempting to do any COM like component model. Rather, it allows the developer the ability to cleanly separate the Object usage from the construction policy. I've posted the code on Sourceforge at https://sourceforge.net/projects/cpp-resolver/. I have not yet taken the time to get it into proper format for a Sandbox project, but will do that next if there seems to be enough interest in the project. I wrote up the philosophy behind the design here: http://adam.younglogic.com/?p=146 The code is currently g++ only, although I've attempted to use only core language constructs. It has no dependencies on other libraries other than stl collections. Any constructive feed back will be most appreciated. Adam

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[conversion] Release v0.4: Replace function template specialization by ADL
by vicente.botet 27 Oct '09

27 Oct '09

Hi, I have just released the version 0.4 of Boost.Conversion , which includes since my last publicly announced version 0.3: Replace function template specialization by ADL A Source class is convertible to a Target class if: * Either: A function with the signature convert_to<Target>(Source const&, boost::dummy::type_tag<To> const&) is available via argument dependent lookup * Or: A template specialization of boost::conversion::convert_to<Target, Source> exists for Target and Source * Or: Target is copy constructible from Source (default implementation) The template function convert_to allows to convert a source type to a target type, using argument dependent lookup to select a specialized convert_to function if available. If no specialized convert_to function is available, boost::conversion::convert_to is used. The generic convert_to function requires that the elements to be converted are assignable and copy constructible. It is implemented using the Target copy construction from a Source or the Source conversion operator Target - this is sometimes unavailable. For standard types, we can not add a specialized convert_to function on the namespace std. The alternative to using argument dependent lookup in this situation is to provide a template specialization of boost::conversion::convert_to for every pair of standard types that requires a specialized convert_to. You can found all the detail for dowloading, documentation, ... in http://svn.boost.org/trac/boost/wiki/LibrariesUnderConstruction#Boost.Conve… I'd appreciate it if people could take a look, test it on their compiler and give me some feedback. Thanks to Edward Diener for showing me that multiple assignments should be taken in account. Thanks also to Jeffrey Hellrung and Robert Stewart for showing me that Boost.Conversion should use also ADL. BTW, I'm looking for a review manager. Anyone around here who would like to volunteer? Best regards, _____________________ Vicente Juan Botet Escribá

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