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[boost exception]complaint
by Robert Ramey 22 Aug '08

22 Aug '08

In the course of investigating some issues with the serialization library I had occasion to investigate boost/throw exception.hpp . I understood the original purpose of this header was to provide support for throw for both compilers which implemented exceptions and those that didn't (e.g. some embedded systems environment). Looking through this header - it seems that its function has changed completely. It now drags in a lot of machinery that no one who was using it before will need. It seems that the whole purpose of the header has been changed. I did review the documentation for boost exception and indeed, it now seems that boost/throw_exception does implement a different purpose. Besides imposing the requirement for RTTI - I have no idea what else this might break. Should all users of throw_exception be advised to recode? Could we not restore the orginal boost/throw_exception and make a differently named file like boost/exception/???.hpp. This would provide all the benefits of the new library to those who want and require them without requiring changes all over the rest of boost. Robert Ramey

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Documentation Redux (was Re: Boost 1.36.0 release notice)
by Dean Michael Berris 22 Aug '08

22 Aug '08

On Mon, Aug 18, 2008 at 4:17 PM, John Maddock <john(a)johnmaddock.co.uk> wrote: > Robert Ramey wrote: >> >> LOL - of course it does. If regression testing were setup for >> boost tools, they would be demonstrated to be functioning as >> expected before they were used in the actual release process. >> Had this been procedure been in place, the issue raised >> above would not have occurred. > > This is a good point, in fact is there any reason why the doc build > shouldn't be part of the regression tests? > > Ah.... but it requires external tools that might not be available > (especially now that accumulators has introduced a dependency on Latex and > Ghostscript) :-( > I think this may be something that should be solved by policy rather than technical solutions. For instance, libraries follow a certain set of guidelines regarding how the code is organized (namespaces, macro names, type names, directory structure, directory naming, etc.). Why shouldn't there be guidelines regarding the documentation of these libraries? I know the guidelines are minimal by design (for example should be in HTML and/or PDF) but right now it's getting quite unwieldy -- and arguably, the documentation is becoming as important as the actual code is. I understand that documentation is largely an author/maintainer domain, and that currently the choice of documentation tools used is left to the author/maintainer. If we can somehow standardize on a tool set and help authors/maintainers convert their documentation from their current format to another then maybe we can make some progress regarding fixing the documentation-building/generation process and "improvement" of the library documentation. This also allows interested contributors to (more easily) learn the tools required and help out in the "improvement" of the documentation effort. Traditionally, Wiki's have worked well for other projects. Should Boost start doing this too, and just export documentation from the Wiki into properly cross-linked HTML pages in release builds? I understand Trac has the Wiki functionality already available -- should we start using it for documentation? Another option (that I think Dave Abrahams has been doing) is to use RST [0] to make writing/reading the source documentation easier than having to rely on Boostbook+XSLT (which I personally think is a brittle tool-chain). Quickbook is also a nice documentation language to use, but the reliance on Boostbook+XSLT makes it harder to pull-off. I don't know though if Quickbook can be made to generate HTML directly instead of XML. Joel? I understand there's also a Boost Documentation project. Anything happening in that front? [0] - http://docutils.sourceforge.net/rst.html -- Dean Michael C. Berris Software Engineer, Friendster, Inc.

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[md5] Try out optimizations
by Daryle Walker 21 Aug '08

21 Aug '08

In revision 48279 at <http://svn.boost.org/svn/boost/sandbox/md5>, I added a class that will submit bytes to a MD5-processor byte-wise if CHAR_BIT was a factor of the hash block size, 512 bits. (This satisfies most computers since they have CHAR_BIT as 8.) I was wondering if anyone would like to try out the library, both people who have a system with CHAR_BIT == 8 and those who not, including those who have a system with 512 % CHAR_BIT == 0 even when CHAR_BIT isn't 8. I also need help checking little- vs. big-endian systems (if CHAR_BIT == 8). This will test all the optimizations. There are two preprocessor flags controlling optimizations, so try all qualifying combinations of those settings too. I hope this code is as speedy as C-based MD5 code. -- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT hotmail DOT com

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wacky async_read?_write behavior!
by Abu Amar 21 Aug '08

21 Aug '08

Hi, I am trying to do a simple POP3S client. I am using the boost::asio sockets and SSL wrapper. Somehow, the output from the sock read is directed to the input of the sock write. Any idea? The code snippet is below, but here is the output of my program first (I replaced the IP with x's) -bash# ./main 209.85.199.111 995 foo.bar(a)gmail.com pass_in_plain_text Got RES (66) bytes +OK Gpop ready for requests from xxx.xxx.xxx.xxx c20pf1156691rvf.3 Sent REQ: APOP foo.bar(a)gmail.com pass_in_plain_text Got RES (36) bytes -ERR bad command c20pf1156691rvf.3 Sent REQ: STAT Read failed: End of file Exception: End of file and here is the code snippet that produced this input enum { max_length = 8192 }; class client { public: client(boost::asio::io_service& io_service, boost::asio::ssl::context& context, boost::asio::ip::tcp::endpoint& endpoint) : socket_(io_service, context) { //connect to the pop3 server socket_.lowest_layer().async_connect(endpoint, boost::bind(&client::handle_connect, this, boost::asio::placeholders::error)); } ~client() { socket_.lowest_layer().close(); } void handle_connect(const boost::system::error_code& error) { if (!error) { //do the SSL handshake socket_.async_handshake(boost::asio::ssl::stream_base::client, boost::bind(&client::handle_handshake, this, boost::asio::placeholders::error)); } else { std::cerr << "Connection failed: " << error << "\n"; boost::asio::detail::throw_error(error); } } void handle_handshake(const boost::system::error_code& error) { if (error) { std::cerr << "SSL Handshaking failed: " << error << "\n"; boost::asio::detail::throw_error(error); } } void write(std::string buffer) { str_req=buffer; boost::asio::async_write(socket_, boost::asio::buffer(str_req), boost::bind(&client::handle_write, this, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); } void handle_write(const boost::system::error_code& error, size_t bytes) { if (!error) { std::cout << "Sent REQ: " << str_req <<std::endl; try{ boost::asio::async_read_until(socket_, buff_, "\r\n", boost::bind(&client::handle_read_until, this, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); }catch(const boost::system::system_error &err){ std::cerr << " code: " << err.code().value() << " :" << err.code().message() << std::endl; } } else { std::cerr << "Write failed: " << error.message() << "\n"; boost::asio::detail::throw_error(error); } } void read() { try{ boost::asio::async_read_until(socket_, buff_, "\r\n", boost::bind(&client::handle_read_until, this, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); }catch(const boost::system::system_error &err){ std::cerr << " code: " << err.code().value() << " :" << err.code().message() << std::endl; } } void handle_read_until(const boost::system::error_code& error, size_t bytes_transferred) { if (!error) { std::cout << "Got RES (" << bytes_transferred<<") bytes\n"; std::cout << &buff_; std::cout << "\n"; } else { std::cout << "Read failed: " << error.message() << "\n"; boost::asio::detail::throw_error(error); } } private: boost::asio::ssl::stream<boost::asio::ip::tcp::socket> socket_; boost::asio::streambuf buff_; //for receiving std::string str_req; //for sending }; int main(int argc, char* argv[]) { try { if (argc != 5) { std::cerr << "Usage: " << argv[0] << " <host> <port> <user> <pass>\n"; return 1; } boost::asio::io_service io_service; boost::asio::ssl::context ctx(io_service, boost::asio::ssl::context::sslv23); ctx.set_verify_mode(boost::asio::ssl::context::verify_none); boost::asio::ip::tcp::endpoint endpoint( boost::asio::ip::address::from_string(argv[1]), atoi(argv[2])); client c(io_service, ctx, endpoint); io_service.run(); //should execute till handshake completes //read the pop3 greeting io_service.reset(); io_service.post(boost::bind(&client::read,&c)); io_service.run(); //send the authentication command std::string str_cmd="APOP " + std::string(argv[3]) + " " + std::string(argv[4]) +"\r\n"; io_service.reset(); io_service.post(boost::bind(&client::write,&c,str_cmd)); io_service.run(); //get how many messages are in the inbox str_cmd="STAT\r\n"; io_service.reset(); io_service.post(boost::bind(&client::write,&c,str_cmd)); io_service.run(); //quit the pop3 session str_cmd="QUIT\r\n"; io_service.reset(); io_service.post(boost::bind(&client::write,&c,str_cmd)); io_service.run(); } catch (std::exception& e) { std::cerr << "Exception: " << e.what() << "\n"; } return 0; }

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[bigint] Integer data type larger than 64 bits?
by Simonson, Lucanus J 21 Aug '08

21 Aug '08

I have encountered the need for an integer data type larger than 64 bits to prevent overflow when doing algebra on 32 bit integer data. I notice that there is mention of a couple proposed boost big int libraries in the archive. Is there a boost library that provides this currently, or is there a library nearing acceptance level quality that I should use? I am not eager to take on a non-boost/non-stl dependency because I intend to submit the geometry library I need this for to boost. Thanks, Luke

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GIL: how to convert an any_image_view to its const equivalent?
by Philipp Reh 21 Aug '08

21 Aug '08

Dear list, I think GIL is not able to convert an any_image_view to its const equivalent or I don't know how to do it. The variant class checks in its constructor if it can hold the given type but it doesn't have a constructor to convert an any_image_view from one to another. Here is a simple piece of code declaring two any_image_views: typedef boost::gil::any_image_view< boost::mpl::vector< boost::gil::rgba8_view_t > > image_view; typedef boost::gil::any_image_view< boost::mpl::vector< boost::gil::rgba8c_view_t > > const_image_view; Now when I try to construct a const_image_view from an image_view I get an std::bad_cast exception. What can I do about it? Cheers, Philipp -- View this message in context: http://www.nabble.com/GIL%3A-how-to-convert-an-any_image_view-to-its-const-… Sent from the Boost - Dev mailing list archive at Nabble.com.

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[1.35] using binary_oarchive instead of text_oarchive
by Alexander Dong Back Kim 21 Aug '08

21 Aug '08

Dear members, I'm trying to use binary_oarchive instead of text_oarchive because I expect using binary may decrease the size of archive compare to using text_oarchive. std::ostreamstream ostr; boost::archive::text_oarvhice oa (ostr); oa & foo; The codes above works fine and I could do deserialization as well without any problem. In this case if I want to use binary_oarchive, what codes should I have to add? Any suggestion or advice will be appreciated. Thank you very much at all time. regards, -- Alexander Dong Back Kim

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[Important] Server outage on Thursday, August 21st
by Doug Gregor 21 Aug '08

21 Aug '08

There will be a server outage on Thursday, August 21st from 8:00AM-9:00AM EDT while we upgrade Boost's Subversion repository to Subversion 1.5. The Boost Subversion repository, Trac, and mailing - Doug

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[extension] Check if basic_type_map is empty
by Boris 21 Aug '08

21 Aug '08

When a library is loaded the return type of shared_library::open() or shared_library::is_open() can be used to detect whether the library was loaded successfully. When shared_library::call() is called the return type can be used to detect whether the exported map function could be called. But is there another function like is_open() which could be called afterwards to check if the map function was called successfully? The datatype basic_type_map only provides get() and no empty(). It would be required to call get() first and operate on the returned std::map type to see if it contains any factories? Boris

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[unordered] Compiler warnings in VC++ 9 SP1
by Boris 21 Aug '08

21 Aug '08

I just replaced a std::map with a boost::unordered_map and got many compiler warnings (not only me as it seems like: http://www.boost.org/development/tests/release/developer/output/RW_WinXP_VC…) Is anyone working already on the code to get rid of the warnings? Boris

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[smart_ptr] make_shared usage
by Daniel Frey 21 Aug '08

21 Aug '08

Hi, I have a question on make_shared. Consider a class which intends to force all instances to be handled via a shared_ptr. I used to do this by putting the ctors into the private section and adding static create()-methods in the public section. Example: class X { private: X( int, double ); public: static shared_ptr<X> create( int i, double d ) { return shared_ptr<X>( new X( i, d ) ); } }; Replacing the returned expression with make_shared<X>( i, d ) wouldn't work, since it requires a public ctor. Is there any solution to this or do I have to make a decision between efficiency and a safe interface for X? Regards, Daniel

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[PATCH: MPL] Compiling with gcc 4.4.0 -std=c++0x
by Chris Fairles 21 Aug '08

21 Aug '08

Due to pre-processor changes in gcc 4.4.0, MPL fails to compile given -std=c++0x or -std=gnu++0x on the command line. The attached patch addresses this issue. This is a works-for-me solution, YMMV. Chris

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Where does make_shared.hpp come from?
by Boris 20 Aug '08

20 Aug '08

I stumbled over boost::make_shared() in Andrey's logging library. I checked the smart pointers documentation at http://www.boost.org/doc/libs/1_36_0/libs/smart_ptr/smart_ptr.htm but couldn't find any reference to boost::make_shared(). The header file make_shared.hpp contains the link http://www.boost.org/libs/smart_ptr/make_shared.html but the webpage doesn't exist either. Is boost::make_shared() not yet documented? Boris

2 1

[log] Questions for Andrey
by Boris 20 Aug '08

20 Aug '08

I've been converting a program from John's logging library to Andrey's logging library. I have to continue playing around with Andrey's library but in the moment I prefer it over John's library. I can't say really that this or that is better - it's more the overall handling of Andrey's logging library which feels more natural for me. Maybe it's also Andrey's documentation which is rather good (the definitions and design overview really help to understand the big picture before you dive into all the details). I've some questions though for Andrey: * Where is the connection between a source and a sink? In the basic_usage example there are two sinks registered (console and file). There is then one source created which is used to log a message. The message is then sent to both the console and the file. But what if I want to use for example two sources and want messages from each source to be sent to a different sink? Do I understand correctly that I need to use attributes somehow and filter records based on attribute values? I guess I would need to add an attribute to each source and set a filter in each sink to make sure only messages with a certain attribute are written? * If I want to format a message and add a timestamp why do I need to write boost::log::formatters::date_time("TimeStamp") and can't write boost::log::formatters::attr("TimeStamp")? Doesn't the attribute value know how to be serialized (or isn't it written to a std::ostream)? If I use boost::log::formatters::attr("TimeStamp") nothing is written to the log file. It's not a problem to use boost::log::formatters::date_time("TimeStamp") of course. But I still wonder why the library can't figure out to write the timestamp if I use boost::log::formatters::attr("TimeStamp"). * I've been reading http://boost-log.sourceforge.net/libs/log/doc/html/advanced/advanced.html#a… a few times but still don't understand why I can't (or shouldn't) instantiate a global logger with "boost::log::sources::logger logger;". I actually did this and everything works (or at least seems to work :). Must the macro BOOST_LOG_DECLARE_GLOBAL_LOGGER really be used when a global logger is created? Maybe I better understand if I ask differently: What is so special about a logger that I need to use a macro to define it globally while I can create for example a global std::string instance without a macro? * By default there is a newline appended to every message written? By the way, looking at the TODO list: I would be very much interested in Windows NT event log support. I'm sure it would also convince more developers to use a logging library as writing texts to files in some fancy ways can also be done without a logging library. :) Boris

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[log] More questions for Andrey (how to add function signature to messages)
by Boris 20 Aug '08

20 Aug '08

Currently I'm writing messages to a file with: BOOST_LOG(mylogger) << __FUNCSIG__ << " message text"; I'd prefer if the function signature (let's assume for now that the macro is supported by all compilers) is written automatically without me having to add __FUNCSIG__ everywhere. From what I understand I can't simply add an attribute to the logger as __FUNCSIG__ would then be used in another function (and thus a different function signature would be written). Looking around in the documentation I found BOOST_LOG_WITH_PARAMS (see http://boost-log.sourceforge.net/libs/log/doc/html/BOOST_LOG_WITH_PARAMS.ht…) It makes me think that I could define my own BOOST_LOG macro somehow like this: #define BOOST_LOG_FUNCSIG(logger)\ BOOST_LOG_WITH_PARAMS((logger), (::boost::log::sources::keywords::funcsignature = (__FUNCSIG__))) I see that the macro BOOST_LOG_SEV is defined similarly in severity_logger.hpp. However I also see that some more code has to be added to the logger to make the logger understand what to do with the keyword. For example in the severity logger in open_record() the appropriate attribute is set if the severity keyword is found. That means I would need to create a new logger and check for my new funcsignature attribute in open_record() if I want the function signature to be written automatically? Is there another way to do this more easily? Boris

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[exception] missing workarounds for msvc 4265 warning
by Jürgen Hunold 20 Aug '08

20 Aug '08

Hi ! My coworkers found some more annoying msv 4265 warnings. (missing virtual destructor. The attached patch adds the necessary workaround (analog to gcc). Okay to commit ? Yours, Jürgen -- * Dipl.-Math. Jürgen Hunold ! Ingenieurgesellschaft für * voice: ++49 511 262926 57 ! Verkehrs- und Eisenbahnwesen mbH * fax : ++49 511 262926 99 ! Lister Straße 15 * juergen.hunold(a)ivembh.de ! www.ivembh.de * * Geschäftsführer: ! Sitz des Unternehmens: Hannover * Prof. Dr.-Ing. Thomas Siefer ! Amtsgericht Hannover, HRB 56965 * PD Dr.-Ing. Alfons Radtke !

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[config] disabling hash_map/set by #define BOOST_NO_HASH
by Juergen Hunold 20 Aug '08

20 Aug '08

Hi ! After upgrading to gcc-4.3 I got annoyed by the myriads of deprecated warnings about "hash_map" and "hash_set" especially from the BGL code. I tried to get rid of those by simply adding #define BOOST_NO_HASH to the command line and it worked. Unfortunately, it seems that trunk config does not detect hash support with msvc-8.0 and this compiler then bailed out with a macro redefinition error at config/suffix.hpp :-(( Patch to add a check for an already defined BOOST_NO_HASH (and for BOOST_NO_SLIST) attached. Comments ? Ok to commit ? Better ideas to disable hash support ? Yours, Jürgen -- * Dipl.-Math. Jürgen Hunold ! Ingenieurgesellschaft für * voice: ++49 511 262926 57 ! Verkehrs- und Eisenbahnwesen mbH * fax : ++49 511 262926 99 ! Lister Straße 15 * juergen.hunold(a)ivembh.de ! www.ivembh.de * * Geschäftsführer: ! Sitz des Unternehmens: Hannover * Prof. Dr.-Ing. Thomas Siefer ! Amtsgericht Hannover, HRB 56965 * PD Dr.-Ing. Alfons Radtke !

2 2

[integer] Recent changes introduced failures on many platforms
by Markus Schöpflin 20 Aug '08

20 Aug '08

The two tests integer_mask_test and integer_test have been broken by the recent commits to integer on nearly all platforms. (Probably all but Windows) The error message is: In file included from ../libs/integer/test/integer_test.cpp:29: ../boost/integer.hpp:154:39: error: invalid suffix "ui64" on integer constant ../libs/integer/test/integer_test.cpp:115:39: error: invalid suffix "ui64" on integer constant ../libs/integer/test/integer_test.cpp:215:39: error: invalid suffix "ui64" on integer constant Regards, Markus

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[fsm review] Comparison with ad-hoc FSM coding
by Phil Endecott 20 Aug '08

20 Aug '08

Dear All, I have just spent a few minutes comparing an ad-hoc FSM implementation with an implementation using the proposed library. The example that I've used is the USB device state machine, which I recently had to understand for an embedded application, and I've put an image of the state graph here: http://chezphil.org/tmp/fsm.png For more info, google("USB 2.0 spec") (you'll find a zip file with a PDF in it) and see the start of chapter 9. Note that it seems to me that the "power interruption" transition is wrong and should go to "attached" rather than "powered", and that I have ignored the "suspended" states. The behaviour is essentially as follows: a device is "attached" until the hub supplies power, when it becomes "powered". It then waits for a reset, at which point it starts listening for messages at the "default address" (zero); the host ensures that only one device is in this state at any time. When the host sends a set_address message it changes to the "address" state, and when the host sends a set_configuration message it changes to the "configured" state for normal operation. Here is my ad-hoc implementation (note that I haven't tried to even compile any of this code): struct usb_device { enum state_t { Attached, Powered, Default, Address, Configured }; state_t state; int addr; int configuration; usb_device(): state(Attached), addr(0), configuration(0) {} void power_on() { state = Powered; } void power_off() { state = Attached; } void reset() { state = Default; addr = 0; configuration = 0; } void set_address(int addr_) { addr = addr_; state = (addr==0) ? Default : Configured; } void set_configuration(int configuration_) { configuration = configuration_; state = (configuration==0) ? Address : Configured; } }; In comparison, here's what I've come up with using Boost.FSM: struct Attached; struct Powered; struct Default; struct Address; struct Configured; typedef mpl::vector<Attached, Powered, Default, Address, Configured>::type StateList; struct PowerOn; struct PowerOff; struct Reset; struct SetAddress { int addr; SetAddress(int addr_): addr(addr_) {} }; struct SetConfiguration { int configuration; SetConfiguration(int configuration_): configuration(configuration_) {} }; struct Common { int addr; int configuration; }; struct Attached: fsm::state<Attached,StateList>, Common { void on_process(const PowerOn&) { switch_to<Powered>(); } }; struct Powered: fsm::state<Powered,StateList>, Common { void on_process(const PowerOff&) { switch_to<Attached>(); } void on_process(const Reset&) { switch_to<Default>(); } }; struct Default: fsm::state<Default,StateList>, Common { void on_enter_state() { addr = 0; } void on_process(const PowerOff&) { switch_to<Attached>(); } void on_process(const Reset&) { } void on_process(const SetAddress& set_address) { addr = set_address.addr; if (addr != 0) { switch_to<Address>(); } } }; struct Address: fsm::state<Address,StateList>, Common { void on_process(const PowerOff&) { switch_to<Attached>(); } void on_process(const Reset&) { switch_to<Default>(); } void on_process(const SetAddress& set_address) { addr = set_address.addr; if (addr == 0) { switch_to<Default>(); } } void on_process(const SetConfiguration& set_configuration) { configuration = set_configuration.configuration; if (configuration != 0) { switch_to<Configured>(); } } }; struct Configured: fsm::state<Configured,StateList>, Common { void on_process(const PowerOff&) { switch_to<Attached>(); } void on_process(const Reset&) { switch_to<Default>(); } void on_process(const SetConfiguration& set_configuration) { configuration = set_configuration.configuration; if (configuration == 0) { switch_to<Address>(); } } }; The latter is clearly more verbose than the former. Some of the verbosity would go if I put the common events (e.g. PowerOff) into a base class, but that adds verbosity of its own. There are a few characteristics of this particular design that favour the ad-hoc code. Firstly, the device's behaviour is allowed to be undefined if an unexpected event occurs. Secondly, many events have the same effect irrespective of the state (e.g. power off). Finally, the effect of events often depends on their data (i.e. zero has a special meaning). I would also say that the turnstile example given in the library documentation could be implemented more concisely using an ad-hoc approach (would someone like to try?). Perhaps more complex FSMs would benefit more from what this library offers. In that case, can we see an example? I note that this library is targeted at simpler FSMs than Boost.Statechart (which I have not used). Is there a category of FSMs that are simple enough that Boost.Statechart's features are not needed (e.g. hierarchy) yet too complex for an ad-hoc implementation? Regards, Phil.

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[asio] Resolving Aliases
by Dean Michael Berris 20 Aug '08

20 Aug '08

Hi Guys, While writing the HTTP client in the C++ Networking Library, I ran into a bizarre problem: resolving virtual hosts. For example, given a host named 'bucket.s3.amazonaws.com', trying to resolve it with Boost.Asio (in 1.35) causes a 'Host not found (authoritative)' error. Is this a known issue, and if so what's my alternative? TIA -- Dean Michael C. Berris Software Engineer, Friendster, Inc.

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Need opinion on implementation issue
by Daryle Walker 19 Aug '08

19 Aug '08

I have a class that has the cool pubic member access without "()", like "left" and "right" for boost::bimap. In my case, it's meant to simulate a function object, so it can be passed to functions like std::for_each, and the return value from said functions (the updated function object) can be assigned back to the special member. This function object forwards to the actual computation object within my class object. I implemented this by making a special inner private class and have the auxiliary function object be a public data member of that private type. The actual computation object isn't directly in my class object, but within the public auxiliary member. So the auxiliary function object can be passed by copy or assignment and everything works. The problem is in a class derived from my first one. It also has a public auxiliary function object data member. However, it forwards to the SAME actual computation object as the base class's auxiliary member. I implemented this by the derived class's auxiliary keeping a pointer to the computation object within the base's auxiliary. The issue is when I create temporary derived-auxiliaries for use in std::for_each. I have to create a copy of the computation object with new and delete on destruction. The derived-auxiliary keeps a bool flag indicating whether the pointer points to a contained object or a heap one. I was thinking of making a boost::variant<CompObj, CompObj*> instead, but trades use of the heap for temporaries for making all derived-auxiliaries huge (if sizeof(CompObj) > sizeof (CompObj*)): Current: base's CompObj + derived's CompObj* and bool New: base's CompObj + derived's variant -> base's CompObj + derived's max(CompObj, CompObj*) -> 2 * CompObj (None of these include the various administrative padding or "otherwise empty" bytes.) I haven't changed it yet because I suspect this is a bad trade-off. But what happens on systems with low/no heaps? Should this be some sort of macro switch? -- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT hotmail DOT com

1 0

I need someone with a little-endian system to test an optimization.
by Daryle Walker 19 Aug '08

19 Aug '08

I just added an optimization to some code for systems with octet- sized bytes. I have such a system; so I tested that code. I added a further optimization for little-endian systems. Unfortunately, my computer is big-endian, so I have no way to test the second change. So if you have access to a computer with octet-sized bytes (CHAR_BIT == 8) and larger integers in little-endian format, can you help? The code is on our Subversion server, in the sandbox section, just checked in as revision 48224. Check-out or export the <http:// svn.boost.org/svn/boost/sandbox/md5> directory. The headers are in the "boost" subdirectory, of course. There is one mandatory source file at "libs/coding/src/md5.cpp". There are three test files at "libs/coding/test/md5*test.cpp". Compile all those together with our Unit Test and Serialization libraries. (On my system, I made a project file with a three sub-targets: Boost.Test unit-test, Boost.S11N, and md5.cpp; which the target with the test files compiled linked to.) The "md5.cpp" has the optimized code. The optimized code doesn't activate unless CHAR_BIT is 8 and the file's BOOST_CONTROL_OPTIMIZE_OCTET_BYTES macro is set (or overridden) to 1. The little-endian extra optimization is activated with the BOOST_LITTLE_ENDIAN macro and is mandatory (if valid). I added three now-commented-out #error lines to test which case was activated, which confirmed I'm using a not-little endian system. You can un- comment those to check for yourself. Let me know if the little endian code works, or tell me how to fix it (if not). If you want, you can comment-out the little endian code to test the endian- agnostic code, and then redefine or override BOOST_CONTROL_OPTIMIZE_OCTET_BYTES to be 0 to test the octet-agnostic code (which explodes the packed array into a bool array before combining). Thanks in advance.... -- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT hotmail DOT com

1 0

[Units+Lambda+Math] Functor wrappers for overloaded cmath functions to avoid static_cast in boost::lambda::bind calls
by Torsten Maehne 19 Aug '08

19 Aug '08

Hello, nearly three months ago, I started a thread <http://thread.gmane.org/gmane.comp.lib.boost.devel/175774> on Boost-devel to propose a header, which interfaces Boost.Units with Boost.Lambda. An improved version <boost/units/lambda.hpp> became official part of Boost.Units. However, this header only addresses the mathematical operators (+, -, *, /, ...) and not the common mathematical functions defined cmath (overloaded for boost::units::quantity<Unit, Y> in <boost/units/cmath.hpp>). In an lambda expression, their invocation needs to be postponed till the execution of the whole lambda expression, using boost::lambda::bind to bind the function arguments to the function pointer. The problem is that for overloaded functions, a lengthy static_cast is required to avoid an "unresolved overloaded function type" error as for example in the following code fragment taken from <libs/units/example/lambda.cpp>: using namespace boost::units; using namespace boost::units::si; using boost::function; using boost::lambda::bind; using boost::lambda::_1; function<quantity<current> (quantity<time>) > i = iamp * bind(static_cast<quantity<dimensionless, double> (*)( const quantity<plane_angle>&)>(sin), 2.0 * M_PI * radian * f * _1) + i0; Steven Watanabe proposed in <http://thread.gmane.org/gmane.comp.lib.boost.devel/175774> to create functor wrappers for each cmath function to allow Boost.Lambda to automatically determine the return type of the overloaded functions. As this solution is not Boost.Units specific, he proposed to put the functor wrappers under a more general place like boost::math::functional. I implemented his proposal in the attached header "boost/units/math_functional.hpp" for all the functions overloaded in <boost/units/cmath.hpp>. There is also a unit test "libs/units/test/test_math_functional.cpp" and example "libs/units/examples/math_functional_lambda.cpp". In the latter, the above code snippet simplifies down to: using namespace boost::units; using namespace boost::units::si; using boost::function; using boost::lambda::bind; using boost::lambda::_1; using boost::math::functional; using boost::units::functional; function<quantity<current> (quantity<time>) > i = iamp * bind(sin_t(), 2.0 * M_PI * radian * f * _1) + i0; The functor wrappers include either a sig template or a result_type typedef, which allows Boost::Lambda's bind to choose the correct overloaded function depending on the types passed through the lambda placeholders. The cmath function calls are not prefixed by a namespace qualifier thus allowing argument dependent lookup (ADL, a.k.a. Koenig lookup). All functor wrappers have a '_t' prefix to avoid interference with the ADL. The functor wrappers for functions from <cmath> are defined in namespace boost::math::functional (to anticipate a generalization of this header). Functor wrappers for Boost.Units specific functions are defined in boost::units::functional (for boost::units::pow<long>, boost::units::pow<Rat>, boost::units::root<long>, boost::units::root<Rat>). The implementation has still some issues: * TODO: Functor wrappers for fma, nearbyint, rint (the boost::units implementations are unfinished in trunk). * TODO: Remove limitation of functor wrapper nexttoward to only boost::units::nexttoward, which is currently implemented in terms of boost::math::nextafter because boost::math::nexttoward is not yet available. * Is there a way to organize the code to allow dropping the _t prefix of the functor wrappers so that it would not interfere with the ADL to find the correct overloaded function in the namespaces of the function arguments? The only solution I came up with was by putting using declarations for each function defined in <cmath> and <boost/units/cmath.hpp> in a cmath_ namespace and prefix the function call inside functor wrapper with this namespace, e.g.: namespace cmath_ { using std::sin; using boost::units::sin; } struct sin { template<typename Args> class sig { private: typedef typename boost::tuples::element<1, Args>::type arg1_type; BOOST_TYPEOF_NESTED_TYPEDEF(nested, \ cmath_::sin(typeof_::make<arg1_type>()))) public: typedef typename nested::type type; }; template<typename T> typename sig<typename boost::tuples::tuple<sin, T> >::type operator()(const T& arg) const { return cmath_::sin(arg); } }; However, this has the drawback, that ADL is bypassed and only functions imported into cmath_ are found. * Is there a way to merge the functors for pow<long>, pow<Rat> and root<long>, root<Rat>? Currently, they have rather long names to disambiguate between the template arguments: static_rational_pow_t<Rat>, static_integer_pow_t<long>, static_rational_root_t<Rat>, and static_integer_root_t<long>. I'm looking for comments on this solution, especially, how it can be improved and how it should be restructured to maybe become part of Boost itself. Best regards, Torsten Maehne

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[shifted_ptr] QA
by Phil Bouchard 19 Aug '08

19 Aug '08

Hello, If anybody is able to make shifted_ptr<> break, please share the replication test. It looks to be working fine but the possibility of having something I forgot could still be present. To give everybody a quick idea on the different states both the pointer and the pointee will have are defined as such: shifted_ptr<> (pointer): - part of the pool (local heap) - part of anything else (stack, data, system heap) shifted<> (pointee): - initialized - uninitialized When the shifted<> is initialized it means it knows what "set" it belongs to. If it is uninitialized it means it is still part of a construction sequence that is not yet finalized, hence not yet attached to any "set". Please disregard anything related to shifted_allocator<> because this is of pure shifted_ptr<> concerns. Some test examples can be found at: https://svn.boost.org/svn/boost/sandbox/shifted_ptr/libs/smart_ptr/example/ Regards, -Phil

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Re: [boost] "SuperC"
by Phil Bouchard 19 Aug '08

19 Aug '08

"David Abrahams" <dave(a)boostpro.com> wrote in message news:877iae4oeq.fsf@mcbain.luannocracy.com... [...] >> Let's put it this way. All new "unordered" and multiset containers could >> easily be implemented as: >> 1) superc1st<double, list, vector> s1; >> 2) superc2nd<string, double, map, vector> s2; >> 3) superc2nd<string, double, map, map> s3; > > Sounds reminiscent of boost::graph::adjacency_list. It's a n-th dimensional container as opposed to adjacent_list. All in all we will benefit from: - "unordered" when list is part of the container. Ex.: superc<char, _map<char>, _list> s; - multisets or unordered multisets. Ex.: superc<employee, _map<string>, _map<string>, _map<double>, _map<double>, list> s; - the vector O(1) access when fragmentation is minimal - accessing sorted nodes (using map) but still adjacent in memory (vector). Ex.: superc<char, _map<char>, _vector> s = (_node<_map<char>, _vector> []) {'T', 'h', 'i', 's', ' ', 'i', 's', ' ', 'a', ' ', 't', 'e', 's', 't', '.'}; - interchanging vector iterators to map iterators. Ex.: superc<char, _map<char>, _vector> s; superc<char, _map<char>, _vector>::iterator i = s[10]; // if new _vector<>::operator [] returns: _node<> & s.find(i, s.end()); // O(log n) find from within a range of iterators only - STL code reuse - easy implementation - easy to use -Phil

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