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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 !

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[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

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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

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[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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