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[review] Formal Fast-Track review of the Boost.Functional/Factory library - extended until sunday
by John Torjo 22 Dec '07

22 Dec '07

Hi all, I've extended the review until Sunday (inclusive). I'm hoping for more reviews. So far, we've had only two. If you are interested in the library (you should be :)), please take some time to review it. This is the info you need to do a review on: *Description* Factories are callback mechanisms for constructors, so we provide two function objects, boost::value_factory and boost::factory, that encasulate object construction through direct application of the constructor or operator new, respectively. These templates make other facilities that operate on function objects (such as standard algorithms, Boost.Bind, Boost.Function, or Fusion functional adapters) applicable to constructors. *Author* Tobias Schwinger *Download* Get it from here: http://www.boost-consulting.com/vault/index.php?action=downloadfile&filenam… Read documentation online here: http://torjo.com/tobias/ What to include in Review Comments ================================== Your comments may be brief or lengthy, but basically the Review Manager needs your evaluation of the library. If you identify problems along the way, please note if they are minor, serious, or showstoppers. Here are some questions you might want to answer in your review: * What is your evaluation of the design? * What is your evaluation of the implementation? * What is your evaluation of the documentation? * What is your evaluation of the potential usefulness of the library? * Did you try to use the library? With what compiler? Did you have any problems? * How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? * Are you knowledgeable about the problem domain? And finally, every review should answer this question: * Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Best, John Torjo - Review Manager - -- http://John.Torjo.com -- C++ expert ... call me only if you want things done right

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Re: [Boost-users] [review] Formal Fast-Track review of the Boost.Functional/Factory library - extended until sunday
by Tobias Schwinger 22 Dec '07

22 Dec '07

shunsuke wrote: > John Torjo wrote: >> Hi all, >> >> I've extended the review until Sunday (inclusive). I'm hoping for more reviews. So far, we've had only two. >> If you are interested in the library (you should be :)), please take some time to review it. This >> is the info you need to do a review on: >> >> *Description* >> >> Factories are callback mechanisms for constructors, so we provide two >> function objects, boost::value_factory and boost::factory, that >> encasulate object construction through direct application of the >> constructor or operator new, respectively. These templates make other >> facilities that operate on function objects (such as standard >> algorithms, Boost.Bind, Boost.Function, or Fusion functional adapters) >> applicable to constructors. > > Is there any difference to lambda::constructor/new_ptr? Yes, those components are designed to only work with the Lambda library. Functional/Factory OTOH provides standard compliant (they work with result_of and the libraries built upon it) function objects. Regards, Tobias

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vector slice for other containers
by abir basak 22 Dec '07

22 Dec '07

Hi, can I use vector_slice / vector_range from uBLAS for std::vector or std::deque ? Or any other library can do it? I can't use iterator based libs (like boost::range or boost::range + step_iterator) as I want to hold view even after a few push_back & pop_front , as long as no element gets remove from within my view window. If elements gets removed from view window,any behavior is fine for me .. but if the case is not so , I want the range/slice view to hold the proper elements irrespective of iterator invalidation due to push_back/pop_front. Thanks abir

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[review] Formal Fast-Track review of the Boost.Functional/Factory library - 2 days left
by John Torjo 22 Dec '07

22 Dec '07

Hi all, There are only 2 days left from the formal Fast-Track review of the Boost.Functional/Factory library. We've had just one review, and we need more. If you are interested in the library (you should be :)), please take some time to review it. This is the info you need to do a review on: *Description* Factories are callback mechanisms for constructors, so we provide two function objects, boost::value_factory and boost::factory, that encasulate object construction through direct application of the constructor or operator new, respectively. These templates make other facilities that operate on function objects (such as standard algorithms, Boost.Bind, Boost.Function, or Fusion functional adapters) applicable to constructors. *Author* Tobias Schwinger *Download* Get it from here: http://www.boost-consulting.com/vault/index.php?action=downloadfile&filenam… Read documentation online here: http://torjo.com/tobias/ What to include in Review Comments ================================== Your comments may be brief or lengthy, but basically the Review Manager needs your evaluation of the library. If you identify problems along the way, please note if they are minor, serious, or showstoppers. Here are some questions you might want to answer in your review: * What is your evaluation of the design? * What is your evaluation of the implementation? * What is your evaluation of the documentation? * What is your evaluation of the potential usefulness of the library? * Did you try to use the library? With what compiler? Did you have any problems? * How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? * Are you knowledgeable about the problem domain? And finally, every review should answer this question: * Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Best, John Torjo - Review Manager - -- http://John.Torjo.com -- C++ expert ... call me only if you want things done right

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[review][unordered] Review summary
by Ion Gaztañaga 21 Dec '07

21 Dec '07

Hi to all, This post tries to summarize the review of the new Boost.Unordered library. In general, there were no serious implementation change requests and most reviewers had only documentation issues. Here we go: * * * begin of summary * * * Thosten Ottosen's review: ---------------------- (http://lists.boost.org/Archives/boost/2007/12/131372.php) Thorsten questioned about the convenience of supporting throwing hash or predicates. This started a thread about the exception safety guarantees of STL containers and Daniel explained the thread-safety guarantees of Unordered. Basically, Daniel's implementation uses an smart double-buffering technique to obtain strong safety guarantees (stricter than the requirements of the standard) in some operations. There's an slight size overhead (the container must allocate space for two equality functors and hashers) but according to Daniel, speed should not suffer. Chung Ping Wang's review: ---------------------- (http://lists.boost.org/Archives/boost/2007/12/131372.php) The only complain was the packaging of the library (there was an "unordered" directory at the top). Since the library has been accepted it will be packaged as the rest of Boost libraries so the problem disappears. Mathias Gaunard's comment: ---------------------- (http://lists.boost.org/Archives/boost/2007/12/131426.php) Mathias suggested adding move semantics and in-place construction. Daniel said that these features were likely to be added in the future. He pointed that we have no standard move emulation library in Boost so we'll need to push that first. Regarding in-place construction, there is a problem with allocators, since containers are now required to call allocator::construct() to construct values. Hervé Brönnimann's review: ---------------------- (http://lists.boost.org/Archives/boost/2007/12/131435.php) Hervé praised the library and suggested adding operator==(). Daniel replied that he was trying to limit himself to obvious design decisions for extensions so he didn't want to go into this area. He also cited some problems with non-unique key unordered containers. Hervé suggested extending the prime number list and Daniel agreed. Daniel also agreed to correct some documentation issues. "Swap" semantics wrt allocators was also discussed. "Swap" and its effect on containers is an active issue in the committee, so Daniel is free to implement what he thinks best until we have a firm resolution. John Torjo's review: ---------------------- (http://lists.boost.org/Archives/boost/2007/12/131557.php) A concise and positive review with no comments. Jamie Allsop's review: ---------------------- (http://lists.boost.org/Archives/boost/2007/12/131762.php) Documentation suggestions that Daniel found interesting and a request to include a comparison with other implementations. Steven Watanabe's comments ---------------------- (http://lists.boost.org/Archives/boost/2007/12/131817.php) Several implementation comments regarding (ADL, BOOST_DEDUCED_TYPENAME, warnings...). See the post for details. Cromwell Enage's review ---------------------- (http://lists.boost.org/boost-users/2007/12/32706.php) Suggested the addition of local_cbegin() and similar, and some documentation suggestions Daniel agreed to solve. Paul A Bristow's review ---------------------- (http://lists.boost.org/Archives/boost/2007/12/131545.php) A brief and positive review with no comments. * * * end of summary * * * Regards, Ion

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BOOST_PP_COUNTER compiler errors (MSVC8)
by Robert Dailey 21 Dec '07

21 Dec '07

Hi, I'm currently compiling my code in Visual Studio 2005. Below is the code that utilizes BOOST_PP_COUNTER. Note that the goal here is to increment the counter 1 time each time the CHECK_MATCH_AND_RETURN macro is used. This allows me to make sure that I've got one macro call per enumeration member. The problem I'm having is that I'm getting page after page of compiler error and as far as I can tell I'm using the counter system as it was shown in the code examples. Below I've also listed some of the compiler errors I'm getting: Compiler Errors: error C2162: expected macro formal parameter error C2065: 'include' : undeclared identifier error C2882: 'boost' : illegal use of namespace identifier in expression Code: #include <boost/static_assert.hpp> #include <boost/preprocessor/slot/counter.hpp> /// Various camera actions that may be performed. /// These actions are usually a result of input events. enum CameraAction { MOVE_FORWARD = 0 , MOVE_BACKWARD , MOVE_LEFT , MOVE_RIGHT , MOVE_UP , MOVE_DOWN , ROTATE_RIGHT , ROTATE_LEFT , ROTATE_UP , ROTATE_DOWN , ROLL_LEFT , ROLL_RIGHT , INCREASE_ACCEL , DECREASE_ACCEL , ENABLE_LOOK , TOGGLE_LOOK , ENABLE_AUTO_MOVE , TOGGLE_AUTO_MOVE /// @cond , NUM_CAMERAACTIONS , CAMERAACTION_NONE /// @endcond }; //========================================================================================= CameraAction StringToCameraAction( const std::string& str ) { // I'm using a macro here because I need the stringizing preprocessor operator (#) // to make the conditionals more manageable. By using this macro, I never have to explicitly // update the string comparison itself if the enumeration names ever change. #define CHECK_MATCH_AND_RETURN( action ) if( str == #action ) { return action; } #include BOOST_PP_UPDATE_COUNTER() CHECK_MATCH_AND_RETURN( ROTATE_LEFT ) CHECK_MATCH_AND_RETURN( ROTATE_RIGHT ) CHECK_MATCH_AND_RETURN( ROTATE_UP ) CHECK_MATCH_AND_RETURN( ROTATE_DOWN ) CHECK_MATCH_AND_RETURN( MOVE_UP ) CHECK_MATCH_AND_RETURN( MOVE_DOWN ) CHECK_MATCH_AND_RETURN( MOVE_LEFT ) CHECK_MATCH_AND_RETURN( MOVE_RIGHT ) CHECK_MATCH_AND_RETURN( MOVE_FORWARD ) CHECK_MATCH_AND_RETURN( MOVE_BACKWARD ) CHECK_MATCH_AND_RETURN( ROLL_RIGHT ) CHECK_MATCH_AND_RETURN( ROLL_LEFT ) CHECK_MATCH_AND_RETURN( INCREASE_ACCEL ) CHECK_MATCH_AND_RETURN( DECREASE_ACCEL ) CHECK_MATCH_AND_RETURN( ENABLE_LOOK ) CHECK_MATCH_AND_RETURN( TOGGLE_LOOK ) CHECK_MATCH_AND_RETURN( ENABLE_AUTO_MOVE ) CHECK_MATCH_AND_RETURN( TOGGLE_AUTO_MOVE ) // This helps me remember to add/remove items above. BOOST_STATIC_ASSERT( (BOOST_PP_COUNTER)+1 != NUM_CAMERAACTIONS ); return CAMERAACTION_NONE; }

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multi_index_container: modification of a non-key member of a value_type
by Venikov, Andy 21 Dec '07

21 Dec '07

Let say we have struct A {...}; struct B {...}; struct C {...}; And we define a container of objects that hold these three structures: struct Whole { A a; B b; C c; }; multi_index_container<Whole, indexed_by< ordered_unique< member<Whole, A, &Whole::a> > >, indexed_by< ordered_unique< member<Whole, A, &Whole::b> > > > container; As you can see only a and b are the keys, c is just a member. Let's also say that we've got an iterator "it" pointing to an element in the container (through what index the iterator has been retrieved is immaterial at this point). And we want to modify "c" member of that element. Is this safe: *const_cast<C **>(&it->c) = <new value of c> ??? I know that one can use "modify" member function, but it seems an overkill to have to create a separate functor just to update a non-key element. Plus, member does additional checks on collision, and the performance may suffer as a result. Thanks, Andy.

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State machine throws std exception in an action
by Andreas Huber 21 Dec '07

21 Dec '07

Forwarded private email: --- Ankorus wrote: > Subject: State machine throws std exception in an action > Date: Mon, 10 Dec 2007 15:08:01 -0800 > > Andreas, > > The state machine I am using for boost statechart playground is as > simple as it gets. > Stopped -> Started > where Started state has 2 sub states: > Passive (default) -> Active. > I started with simple_state, found that it does not have sm context > in constructor, moved to state, added some actions. > Everything was looking good so far. > Now the action called transitioning from Passive to Active throws > std exception. > I am expecting Started state to transit to Exception but it is not > happenning... > Any comments appreciated... > > Thanks, > Ankorus > > // StateDefines.h > #pragma once > #include <boost/statechart/event.hpp> > #include <boost/statechart/state_machine.hpp> > namespace sc = boost::statechart; > // Events > struct EvStart : sc::event<EvStart> {}; > struct EvStop : sc::event<EvStop> {}; > struct EvActivate : sc::event<EvActivate> {}; > struct EvDeactivate : sc::event<EvDeactivate> {}; > // States > struct Started; > struct Stopped; > struct Active; > struct Passive; > struct Exception; > > // States.h > #pragma once > #include <boost/statechart/state.hpp> > #include <boost/statechart/simple_state.hpp> > #include <boost/statechart/transition.hpp> > #include <boost/statechart/exception_translator.hpp> > #include <boost/mpl/list.hpp> > #include "SomeClass.h" > namespace mpl = boost::mpl; > struct Started : sc::simple_state<Started, SomeClass, Passive> > { > typedef mpl::list > < > sc::transition<EvStop, Stopped, SomeClass, &SomeClass::Shutdown>, > sc::transition<sc::exception_thrown, Exception> > > reactions; > Started(); > ~Started(); > }; > struct Stopped : sc::state<Stopped, SomeClass> > { > typedef sc::transition<EvStart, Started, SomeClass, > &SomeClass::Startup> reactions; > Stopped(my_context ctx); > ~Stopped(); > }; > struct Active : sc::simple_state<Active, Started> > { > typedef sc::transition<EvDeactivate, Passive, SomeClass, > &SomeClass::Deactivate> reactions; > Active(); > ~Active(); > }; > struct Passive : sc::simple_state<Passive, Started> > { > typedef sc::transition<EvActivate, Active, SomeClass, > &SomeClass::Activate> reactions; > Passive(); > ~Passive(); > }; > struct Exception : sc::simple_state<Exception, Started> > { > //typedef sc::transition<EvStart, Started, SomeClass, > &SomeClass::Startup> reactions; > Exception(); > ~Exception(); > }; > > // States.cpp > #include "StdAfx.h" > #include "States.h" > Stopped::Stopped(my_context ctx) > : sc::state<Stopped, SomeClass>(ctx) > { > std::cout << __FUNCTION__ << std::endl; > context<SomeClass>().SomeFun(); > }; > Stopped::~Stopped() > { > std::cout << __FUNCTION__ << std::endl; > }; > Started::Started() > { > std::cout << __FUNCTION__ << std::endl; > }; > Started::~Started() > { > std::cout << __FUNCTION__ << std::endl; > }; > Active::Active() > { > std::cout << __FUNCTION__ << std::endl; > }; > Active::~Active() > { > std::cout << __FUNCTION__ << std::endl; > }; > Passive::Passive() > { > std::cout << __FUNCTION__ << std::endl; > }; > Passive::~Passive() > { > std::cout << __FUNCTION__ << std::endl; > }; > Exception::Exception() > { > std::cout << __FUNCTION__ << std::endl; > }; > Exception::~Exception() > { > std::cout << __FUNCTION__ << std::endl; > }; > > > // SomeClass.h > #pragma once > #include "StatesDefines.h" > class SomeClass : public sc::state_machine<SomeClass, Stopped> > { > public: > SomeClass(); > ~SomeClass(); > void SomeFun() > { > std::cout << __FUNCTION__ << std::endl; > } > public: > void Activate(const EvActivate& e) > { > std::cout << "Action: "__FUNCTION__ << std::endl; > throw std::exception("Activation exception"); > } > void Deactivate(const EvDeactivate& e) { std::cout << __FUNCTION__ > << std::endl; } > void Startup(const EvStart& e) { std::cout << __FUNCTION__ << > std::endl; } > void Shutdown(const EvStop& e) { std::cout << __FUNCTION__ << > std::endl; } > }; > > // SomeClass.cpp > #include "StdAfx.h" > #include "States.h" > SomeClass::SomeClass() > { > initiate(); > } > SomeClass::~SomeClass() > { > } > > // main.cpp > #include "stdafx.h" > #include "SomeClass.h" > int main(int argc, char* argv[]) > { > //try > //{ > SomeClass sc; > sc.process_event(EvStart()); > sc.process_event(EvActivate()); > sc.process_event(EvStop()); > //} > //catch(std::exception& e) > //{ > // std::cout << e.what() << std::endl; > //} > return 0; > }

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How to create a compilation warning
by Remi Ricard 21 Dec '07

21 Dec '07

Hi, I want to warn user about a possible miss use of a function. Now I'm only able to stop the compilation with the following code template <typename ValueType> class simVec3 { ......... /// Unary multiply by scalar. /// @param rsh The scalar to multiply the vector with template<class T> simVec3<ValueType>& operator *= (const T& rhs) { // The function should not be use like this // simVec<int> vec(1, 1, 1); // a *= 0.3; // since what a will contain is [0, 0, 0] BOOST_MPL_ASSERT_NOT(( boost::mpl::and_< \ boost::is_floating_point<T>, \ boost::is_integral<ValueType> > )); ValueType s=static_cast<ValueType>(rhs); vec[0]*=s; vec[1]*=s; vec[2]*=s; return *this; } What I would want is something like #if A_meta_function_returning_1_if_int_double #pragma message("simVec::Possible type truncation") #endif instead of the BOOST_MPL_ASSERT_NOT I also tried something like: template <bool x> struct AA; template <> struct AA<true> { enum {value = 1 }; }; template <> struct AA<false> { enum {value = 0}; }; template <typename U, typename V> double myfct(U u, V v) { #if ( AA< boost::mpl::and_< boost::is_integral<U>, \ boost::is_floating_point<V> > > ::value ) #pragma message("****** Hellop *********") #endif return u + v; } But the compilation is complaining about an unmatched parenthesis Remi

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[Boost.Spirit] Cannot negate a parser with action?
by Smith, Lloyd 20 Dec '07

20 Dec '07

The following negation gives the error messages below (VS2005). Negation is OK if no action is given. Is there any way to enable an action on a negated character parser? +(~ch_p(L';')[push_back_a(variableName)]) error C2678: binary '~' : no operator found which takes a left-hand operand of type 'boost::spirit::action<ParserT,ActionT>' (or there is no acceptable conversion) Lloyd Smith Senior Architect, Development CA, Inc. tel: +1 858 625-6869 tel: +1 858 538-1189 (home) mailto:lloyd.smith@ca.com <mailto:lloyd.smith@ca.com>

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