November 2006 - Boost-users

Solving boost version issues
by Daniel Krügler 02 Nov '06

02 Nov '06

Hello, I apologize in advance, if this contribution is slightly off-topic, but I assume that the discussed problem is of general interest for most boost users. Not rarely one stumbles across the problem that even your most favourite 3rd party library has an implementation error, and you need a fix for that. And the good thing: Those highly motivated guys have already found the error and fixed it - in cvs. Well, that is actually all very fine, especially if you are able to handle with cvs (who of the programmers can not?) and you could use this fixed version, but there remains one big problem: The 3rd party library has not been released and you want to prevent nasty effects, if your fixed version meets the older version - the have all the same lib names. OK, end of the scenario, I assume that I describe here a well-known and well-feared problem ;-) Actually everything is fine, besides...: I would like to modify the lib names and which place would be more reasonable than the bjam configuration? First, because the described problem just hits me in the moment concerning a boost fix and I would like to influence the current bjam, such that all libraries are build as usual, but with an additional user-defined (or even hard-coded(!) string constant (aka "build id") at the end of each name. I have to confess that I have little experience with bjam and I don't understand the way how I can modify the related file(s) to reach the wanted effect: I can only assume that one has to change the file Jamfile.v2, probably the "function" rule tag beginning with line 95. Please, is someone willing to help me in that situation? Second I would like to propose that the current bjam script is generally modified to allow the addition of such a user-defined build-id simply attached after the normal naming scheme described on http://boost.org/more/getting_started.html#Results libboost_date_time-gcc-mt-d-1_31-your_build_id.a with a new, to be defined bejam option, which allows such an addition. Sorry for the noise and thank you for your patience! With Greetings from Bremen, Daniel Krügler

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[Boost.Parameter] How to Use Named Parameters in a Class Hierarchy?
by Wu Yinghui, Freddie 02 Nov '06

02 Nov '06

Dear all, I'm implementing a hierarchy of classes to handle different types of objects. The characteristics of these objects are mostly similar (so I can put them into a container that knows only about the pure abstract base interface type), but some properties are specific to each object types. I plan to use Boost.Parameter for its capability of providing named parameter to these object types. However, I have one problem in this approach: Since Boost.Parameter requires that the function processing the ArgumentPack to be a template, I cannot make it virtual (a member function template cannot be virtual) in my pure abstract base interface. Furthermore, due to the lack of "virtual" member function, I cannot use the base class pointer to provide these named parameters to some subclasses. So my question is: Is there a way to tackle this problem? (Use Boost.Parameter with virtual member functions? Or avoid using Boost.Parameter, but provide a way to access subclass properties that are not know directly via the base class?) Any suggestion is welcomed! Cheers, Freddie -- Wu Yinghui, Freddie Research & Development Senior Software Engineer Volume Interactions Pte Ltd 1 Kim Seng Promenade, #12-01 Great World City East Tower Singapore 237994 Tel: +65 62226962 (Ext 216) Fax: +65 62226215 Email: yhwu(a)volumeinteractions.com URL: http://www.volumeinteractions.com Important: This message is intended for the recipient(s) addressed above. It contains privileged and confidential information. If you are not the intended recipient, please notify the sender immediately by replying to this message and then delete it from your system. You must not read, copy, use, or disseminate this communication in any form. Thank you.

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[boost::concept_check] Question about possible feature
by Ovanes Markarian 02 Nov '06

02 Nov '06

Hi! Thanks for the great library. Currently I have to deal with constants as template parameters and I wonder, why there is no library to model constant concepts. Like: template<class T, size_t MAX_SIZE> struct Allocator { Allocator()throw(); }; template<class T, size_t MAX_SIZE> Allocator<T,MAX_SIZE>::Allocator()throw() { boost::function_requires<ConstGreaterThen<MAX_SIZE,O> >(); } I understand I could model it with BOOST_MPL_ASSERT etc. But would not it be better to unite all these features in one lib? With Kind Regards, Ovanes Markarian

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Compiling with VC8 gives libraries and DLLs with vc71
by Javier Estrada 02 Nov '06

02 Nov '06

I'm running into a problem when compiling with VC8 regarding the library names that are produced. The names come out with an infix of 'vc71' (e.g., libboost_thread-vc71-mt-1_33_1.lib). I gathered that this infix comes from some of the macros that are defined, but have been unable to uncover why the name is not picked up correctly, given that the compiler version is correct. I'm quite sure I've followed the installation instructions correctly, open the right command prompt and the vcvars batch file, etc. Ultimately, the problem I'm experiencing is that when porting a VC71 project to VC8, the names of the libraries required have changed :-) Regards, Javier

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Boost ROCKS !!!!!
by Nindi Singh 02 Nov '06

02 Nov '06

For the past few months I have been making more and more use of Boost, in fact I would say becoming more and more reliant on Boost, every so often introducing myslef to a new library. But discovering the MPL, well that was awsome. The first time I applied it was to implement a factory. I would NEVR have though of doing it this way WITHOUT the MPL. Any comments on my use ( or indeed abuse !) of Boost would be more than apprieciated. <Factory.h> #ifndef FACTORY_HEADER_GUARD #define FACTORY_HEADER_GUARD #include<string> #include<map> #include"Singleton.h" #include<boost/shared_ptr.hpp> #include<boost/mpl/size.hpp> #include<boost/mpl/list.hpp> #include<boost/mpl/at.hpp> //Constructors of different Hierachies take a different humber fo parameters , so we set up //some helper macros, for constructirs taking up to 10 parameters. More can be defined if required #define PARAM_0 #define PARAM_1 typename boost::mpl::at_c<typename BaseClass::Constructor_TypeList,0>::type P1 #define PARAM_2 PARAM_1 , typename boost::mpl::at_c<typename BaseClass::Constructor_TypeList,1>::type P2 #define PARAM_3 PARAM_2 , typename boost::mpl::at_c<typename BaseClass::Constructor_TypeList,2>::type P3 #define PARAM_4 PARAM_3 , typename boost::mpl::at_c<typename BaseClass::Constructor_TypeList,3>::type P4 #define PARAM_5 PARAM_4 , typename boost::mpl::at_c<typename BaseClass::Constructor_TypeList,4>::type P5 #define PARAM_6 PARAM_5 , typename boost::mpl::at_c<typename BaseClass::Constructor_TypeList,5>::type P6 #define PARAM_7 PARAM_6 , typename boost::mpl::at_c<typename BaseClass::Constructor_TypeList,6>::type P7 #define PARAM_8 PARAM_7 , typename boost::mpl::at_c<typename BaseClass::Constructor_TypeList,7>::type P8 #define PARAM_9 PARAM_8 , typename boost::mpl::at_c<typename BaseClass::Constructor_TypeList,8>::type P9 #define PARAM_10 PARAM_9 , typename boost::mpl::at_c<typename BaseClass::Constructor_TypeList,9>::type P10 #define Q0 #define Q1 P1 #define Q2 Q1, P2 #define Q3 Q2, P3 #define Q4 Q3, P4 #define Q5 Q4, P5 #define Q6 Q5, P6 #define Q7 Q6, P7 #define Q8 Q7, P8 #define Q9 Q8, P9 #define Q10 Q9, P10 // One Registration object per class in a hireachy, this is the template blue print for the base classes of // the registration objects template < class BaseClass, typename Key = std::string, unsigned long = boost::mpl::size<typename BaseClass::Constructor_TypeList>::value > struct RegistraBase {}; // This is the template blue print for the concrete classes of // the registration objects template < class BaseClass, class Derived, typename Key = std::string, unsigned long n = boost::mpl::size<typename BaseClass::Constructor_TypeList>::value > struct Registra :public RegistraBase<BaseClass,Key,n>{}; // This is the factory template blue print of the Factory class template < class BaseClass, typename Key = std::string , unsigned long n = boost::mpl::size<typename BaseClass::Constructor_TypeList>::value > class Factory {}; // This is the Factory 'concrete' class for Hireachies where the constrcutors tales no parameters template < class BaseClass, typename Key > class Factory<BaseClass,Key,0> { public: bool Register(const Key & theKey,RegistraBase<BaseClass,Key,0> *theRegistra){ return theInnerMap.insert(InnerMap::value_type(theKey,theRegistra)).second; } boost::shared_ptr<BaseClass> RetrieveObject(const Key &id )const { InnerMapIterator theIterator (theInnerMap.find(id)); if(theIterator==theInnerMap.end())return boost::shared_ptr<BaseClass>(static_cast<BaseClass *>(0)); return theIterator->second->RetrieveObject(Q0); } private: typedef typename std::map<Key,RegistraBase<BaseClass,Key,0> *> InnerMap; typedef typename std::map<Key,RegistraBase<BaseClass,Key,0> *>::const_iterator InnerMapIterator; std::map<Key,RegistraBase<BaseClass,Key,0> *> theInnerMap; }; // This is ta Macro definition Factory 'concrete' class for Hireachies where the constrcutors take // a non xero number of parameters #define FACTORY(NnN) \ template \ < \ class BaseClass, \ typename Key \ > \ class Factory<BaseClass,Key,NnN> { \ public: \ bool Register(const Key & theKey,RegistraBase<BaseClass,Key,NnN> *theRegistra){ \ return theInnerMap.insert(InnerMap::value_type(theKey,theRegistra)).second; \ } \ \ boost::shared_ptr<BaseClass> RetrieveObject(const Key &id,PARAM_##NnN )const { \ InnerMapIterator theIterator (theInnerMap.find(id)); \ if(theIterator==theInnerMap.end())return boost::shared_ptr<BaseClass>(static_cast<BaseClass *>(0)); \ return theIterator->second->RetrieveObject(Q##NnN ); \ } \ private: \ typedef typename std::map<Key,RegistraBase<BaseClass,Key,NnN> *> InnerMap; \ typedef typename std::map<Key,RegistraBase<BaseClass,Key,NnN> *>::const_iterator InnerMapIterator; \ std::map<Key,RegistraBase<BaseClass,Key,NnN> *> theInnerMap; \ }; FACTORY(1) FACTORY(2) FACTORY(3) FACTORY(4) FACTORY(5) FACTORY(6) FACTORY(7) FACTORY(8) FACTORY(9) FACTORY(10) // The macro defintions of the Registration Objects #define REGISTRA(NnN) \ template<class BaseClass,typename Key> struct RegistraBase<BaseClass,Key,NnN> { \ virtual boost::shared_ptr<BaseClass> RetrieveObject(PARAM_##NnN)const=0; \ }; \ template<class BaseClass,class Derived,typename Key> \ struct Registra<BaseClass,Derived,Key,NnN>:public RegistraBase<BaseClass,Key,NnN> { \ Registra(const Key & theKey){Singleton<Factory<BaseClass,Key,NnN> >::instance().Register(theKey,this);} \ boost::shared_ptr<BaseClass> RetrieveObject(PARAM_##NnN)const{return boost::shared_ptr<BaseClass>(new Derived(Q##NnN));} \ virtual ~Registra(){} \ }; REGISTRA(0) REGISTRA(1) REGISTRA(2) REGISTRA(3) REGISTRA(4) REGISTRA(5) REGISTRA(6) REGISTRA(7) REGISTRA(8) REGISTRA(9) REGISTRA(10) #endif ----------------------------- end of Factory.h <main.cpp> #include<vector> #include<iostream> #include"Factory.h" using namespace std; struct MyClassVoid { typedef boost::mpl::list<> Constructor_TypeList; MyClassVoid(){} virtual void f()const=0; virtual ~MyClassVoid(){}; }; struct MyClassVoidDerived :public MyClassVoid { MyClassVoidDerived(){} virtual void f()const{cout << " I am in MyClassVoidDerived \n";} virtual ~MyClassVoidDerived(){}; }; namespace { Registra<MyClassVoid,MyClassVoidDerived> theRegistraVoid(std::string("MyClassVoidDerived")); } struct MyClassDouble { typedef boost::mpl::list<double> Constructor_TypeList; MyClassDouble(double){} virtual void f(){cout << " I am in MyClassDouble \n";} virtual ~MyClassDouble(){}; }; struct MyClassDoubleDerived :public MyClassDouble { MyClassDoubleDerived(double x):MyClassDouble(x){} virtual void f(){cout << " I am in MyClassDoubleDerived \n";} virtual ~MyClassDoubleDerived(){}; }; namespace { Registra<MyClassDouble,MyClassDouble> theRegistra(std::string("MyClassDouble")); Registra<MyClassDouble,MyClassDoubleDerived> theRegistraD(std::string("MyClassDoubleDerived")); } struct MyClassMultiple { typedef boost::mpl::list<std::string,std::vector<double>,double,MyClassDoubleDerived > Constructor_TypeList; MyClassMultiple(std::string,std::vector<double>,double,MyClassDoubleDerived){} virtual void f(){cout << " I am in MyClassMultiple \n";} virtual ~MyClassMultiple(){}; }; namespace { Registra<MyClassMultiple,MyClassMultiple> theRegistraM(std::string("MyClassMultiple")); } int main() { boost::shared_ptr<MyClassVoid> thePtrVoid(Singleton<Factory<MyClassVoid> >::instance().RetrieveObject("MyClassVoidDerived")); thePtrVoid->f(); boost::shared_ptr<MyClassDouble> thePtrDoubleDerived(Singleton<Factory<MyClassDouble> >::instance().RetrieveObject("MyClassDoubleDerived",1.0)); thePtrDoubleDerived->f(); boost::shared_ptr<MyClassDouble> thePtrDouble(Singleton<Factory<MyClassDouble> >::instance().RetrieveObject("MyClassDouble",1.0)); thePtrDouble->f(); boost::shared_ptr<MyClassMultiple> thePtrM(Singleton<Factory<MyClassMultiple> >::instance().RetrieveObject("MyClassMultiple",std::string("String"),std::vector<double>(2),1.0,MyClassDoubleDerived(1.0))); thePtrM->f(); } Send instant messages to your online friends http://uk.messenger.yahoo.com

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Re: [Boost-users] Thread pool
by Sohail Somani 02 Nov '06

02 Nov '06

Ooh, there is a bunch of stuff in here. Thanks! > -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > Oliver.Kowalke(a)qimonda.com > Sent: Wednesday, November 01, 2006 9:37 PM > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] Thread pool > > Hello Sohail, > take a look at defer library in the vault (section 'Concurrent > Programming'). > Oliver

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Failure to compile the Boost library on Win XP with MinGW
by Colin Smith 02 Nov '06

02 Nov '06

Hi, I'm running into some large frustrations with trying to compile the Boost library on WinXP using MinGW 3.4.2 (I would like to compile it so that I can use the project_options). I can't get the library to compile and I'm finding that the opaqueness of the error messages and the lack of troubleshooting documentation are very well effectively preventing me from making progress. Either this gets resolved quickly, or I'll have to drop Boost from my project and implement the functionality I need with other libraries or by hand. It seems that every compilation rule inexplicably fails when I run the jam script. I'm using the command "bjam -sTOOLS=mingw install". All the compiling rules fail and then the header files get copied. A sample of the failure messages are below. Unfortunately, the error messages do not give me any useful clues as to what is going wrong. I've also tried the command "bjam -sTOOLS=mingw stage" and received equally unimpressive results. Any help on this would be very much appreciated. -- Colin gcc-C++-action bin\boost\libs\date_time\build \boost_date_time.dll\mingw\debug\gr eg_month.obj g++: no input files "c:\MinGW\bin\g++" -c -Wall -ftemplate-depth-255 -DBOOST_ALL_DYN_LINK=1 -D USE_DATE_TIME_PRE_1_33_FACET_IO -g -O0 -fno-inline -mno-cygwin -I"bin\boost\lib s\date_time\build" -I "c:\MinGW\include\" -I "C:\boost_1_33_1" -o "bin\boost\lib s\date_time\build\boost_date_time.dll\mingw\debug\greg_month.obj" "C:\boost_1_33 _1\libs\date_time\build\../src/gregorian/greg_month.cpp" ...failed gcc-C++-action bin\boost\libs\date_time\build\boost_date_time.dll\ming w\debug\greg_month.obj... gcc-C++-action bin\boost\libs\date_time\build\boost_date_time.dll\mingw\debug\gr eg_weekday.obj g++: no input files "c:\MinGW\bin\g++" -c -Wall -ftemplate-depth-255 -DBOOST_ALL_DYN_LINK=1 -D USE_DATE_TIME_PRE_1_33_FACET_IO -g -O0 -fno-inline -mno-cygwin -I"bin\boost\lib s\date_time\build" -I "c:\MinGW\include\" -I "C:\boost_1_33_1" -o "bin\boost\lib s\date_time\build\boost_date_time.dll\mingw\debug\greg_weekday.obj" "C:\boost_1_ 33_1\libs\date_time\build\../src/gregorian/greg_weekday.cpp" ...failed gcc-C++-action bin\boost\libs\date_time\build\boost_date_time.dll\ming w\debug\greg_weekday.obj... gcc-C++-action bin\boost\libs\date_time\build\boost_date_time.dll\mingw\debug\da te_generators.obj g++: no input files "c:\MinGW\bin\g++" -c -Wall -ftemplate-depth-255 -DBOOST_ALL_DYN_LINK=1 -D USE_DATE_TIME_PRE_1_33_FACET_IO -g -O0 -fno-inline -mno-cygwin -I"bin\boost\lib s\date_time\build" -I "c:\MinGW\include\" -I "C:\boost_1_33_1" -o "bin\boost\lib s\date_time\build\boost_date_time.dll\mingw\debug\date_generators.obj" "C:\boost _1_33_1\libs\date_time\build\../src/gregorian/date_generators.cpp" ...failed gcc-C++-action bin\boost\libs\date_time\build\boost_date_time.dll\ming w\debug\date_generators.obj... ...skipped <@boost!libs!date_time!build\boost_date_time.dll\mingw\debug>boost_da te_time-mgw-d-1_33_1.dll for lack of <@boost!libs!date_time!build\boost_date_tim e.dll\mingw\debug >greg_month.obj... ...skipped <@boost!libs!date_time!build\boost_date_time.dll\mingw\debug>boost_da te_time-mgw-d-1_33_1.lib for lack of <@boost!libs!date_time!build\boost_date_tim e.dll\mingw\debug>greg_month.obj... ...skipped <@boost!lib>boost_date_time-mgw-d-1_33_1.dll for lack of <@boost!libs !date_time!build\boost_date_time.dll\mingw\debug>boost_date_time-mgw-d-1_33_1.dl l... ...skipped <@boost!lib>boost_date_time-mgw-d-1_33_1.lib for lack of <@boost!libs !date_time!build\boost_date_time.dll\mingw\debug>boost_date_time-mgw-d-1_33_1.li b... gcc-C++-action bin\boost\libs\date_time\build\boost_date_time.dll\mingw\debug\th reading-multi\greg_month.obj g++: no input files "c:\MinGW\bin\g++" -c -Wall -ftemplate-depth-255 -DBOOST_ALL_DYN_LINK=1 -D USE_DATE_TIME_PRE_1_33_FACET_IO -g -O0 -fno-inline -mthreads -mno-cygwin -I"bin \boost\libs\date_time\build" -I "c:\MinGW\include\" -I "C:\boost_1_33_1" -o "bin \boost\libs\date_time\build\boost_date_time.dll\mingw\debug\threading-multi\greg _month.obj" "C:\boost_1_33_1\libs\date_time\build\../src/gregorian/greg_month.cp p" ...failed gcc-C++-action bin\boost\libs\date_time\build\boost_date_time.dll\ming w\debug\threading-multi\greg_month.obj... gcc-C++-action bin\boost\libs\date_time\build\boost_date_time.dll\mingw\debug\th reading-multi\greg_weekday.obj g++: no input files "c:\MinGW\bin\g++" -c -Wall -ftemplate-depth-255 -DBOOST_ALL_DYN_LINK=1 -D USE_DATE_TIME_PRE_1_33_FACET_IO -g -O0 -fno-inline -mthreads -mno-cygwin -I"bin \boost\libs\date_time\build" -I "c:\MinGW\include\" -I "C:\boost_1_33_1" -o "bin \boost\libs\date_time\build\boost_date_time.dll\mingw\debug\threading-multi\greg _weekday.obj" "C:\boost_1_33_1\libs\date_time\build\../src/gregorian/greg_weekda y.cpp" ...failed gcc-C++-action bin\boost\libs\date_time\build\boost_date_time.dll\ming w\debug\threading-multi\greg_weekday.obj... gcc-C++-action bin\boost\libs\date_time\build\boost_date_time.dll\mingw\debug\th reading-multi\date_generators.obj g++: no input files -- ********************************* Colin Smith smithco(a)gmail.com *********************************

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[filesystem] unable to parse file path
by Küppers, Ben 02 Nov '06

02 Nov '06

Greetings, I posted this topic on the boost mailing list but believe this is a better place to discuss it. I am trying to write some cross-platform code that processes a Windows provided file path. The file path is of the form .\filename.ext (i.e. Windows style relative to current directory). Using the construct boost::filesystem::path path( ".\\filename.ext", boost::filesystem::native ) I have been able to successfully parse this path on Windows. However, I can't seem to find a construct that yields similar results on Linux. I have tried using default and explicit name checkers which result in either a filesystem_error exception or the obscurely named hidden file .\filename.ext. The library contains the logic to do this right otherwise the Windows version wouldn't work either. However, it seems the necessary code is excluded from compilation for systems other than Windows. I am trying to understand why this decision is made at compile time and is not accessible at runtime. Ideally, I would like to be able to tell the path class to use Windows path parsing (regardless of the platform the app is running on). Something in the style of: boost::filesystem::path path( ".\\filename.ext", boost::filesystem::windows ) There is a windows_name checker but it doesn't support the ".". Neither would the library be able to parse the path because of the compile-time exclusion mentioned above. At the moment, I don't see any other option than to process the path string manually before passing it to the path constructor (kind-a defeats the whole purpose of using this class). Anybody have any ideas? Also, am I really trying to do something that exotic or is this library missing some essential functionality? Ben This e-mail and any attachment is for authorised use by the intended recipient(s) only. It may contain proprietary material, confidential information and/or be subject to legal privilege. It should not be copied, disclosed to, retained or used by, any other party. If you are not an intended recipient then please promptly delete this e-mail and any attachment and all copies and inform the sender. Thank you.

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Re: [Boost-users] Boost ROCKS !!!!!
by Sohail Somani 02 Nov '06

02 Nov '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Nindi Singh > Sent: Wednesday, November 01, 2006 5:06 PM Dude, please stop posting html email :)

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Re: [Boost-users] Boost ROCKS !!!!!
by Nindi Singh 02 Nov '06

02 Nov '06

OK did it . <Phactory.h> #ifndef PHACTORY_HEADER_GUARD #define PHACTORY_HEADER_GUARD #include<string> #include<map> #include<cassert> #include<boost/shared_ptr.hpp> #include<boost/variant.hpp> #include<boost/utility.hpp> #include<boost/static_assert.hpp> #include<boost/mpl/size.hpp> #include<boost/mpl/list.hpp> #include<boost/mpl/at.hpp> template<unsigned long i> struct unsigned_long {enum {value=i};}; template<class BaseClass> struct PhRegistraBase { typedef typename boost::make_variant_over<typename BaseClass::variant_type_list::type>::type variant; typedef std::map<std::string,variant> ParameterMap; virtual boost::shared_ptr<BaseClass> RetrieveObject(const std::string &theKey,const ParameterMap& theMap )const=0; }; template<class BaseClass> class Phactory { public: typedef typename boost::make_variant_over<typename BaseClass::variant_type_list::type>::type variant; typedef std::map<std::string,variant> ParameterMap; bool Register(const std::string &theKey, const PhRegistraBase<BaseClass>* theRegistra){ return theInnerMap.insert(InnerMap::value_type(theKey,theRegistra)).second; } boost::shared_ptr<BaseClass> RetrieveObject(const std::string &id, const ParameterMap & theMap)const { InnerMapIterator theIterator (theInnerMap.find(id)); if(theIterator==theInnerMap.end())return boost::shared_ptr<BaseClass>(static_cast<BaseClass *>(0)); return theIterator->second->RetrieveObject(id,theMap); } private: typedef typename std::map<std::string,const PhRegistraBase<BaseClass> *> InnerMap; typedef typename std::map<std::string,const PhRegistraBase<BaseClass> *>::const_iterator InnerMapIterator; std::map<std::string,const PhRegistraBase<BaseClass> *> theInnerMap; }; #define CPARAM_1 boost::get<const boost::mpl::at_c<signature,0>::type &>(theMap.find(theVarNames[0])->second) #define CPARAM_2 CPARAM_1, boost::get<const boost::mpl::at_c<signature,1>::type &>(theMap.find(theVarNames[1])->second) #define CPARAM_3 CPARAM_2, boost::get<const boost::mpl::at_c<signature,2>::type &>(theMap.find(theVarNames[2])->second) #define CPARAM_4 CPARAM_3, boost::get<const boost::mpl::at_c<signature,3>::type &>(theMap.find(theVarNames[3])->second) #define CPARAM_5 CPARAM_4, boost::get<const boost::mpl::at_c<signature,4>::type &>(theMap.find(theVarNames[4])->second) #define CPARAM_6 CPARAM_5, boost::get<const boost::mpl::at_c<signature,5>::type &>(theMap.find(theVarNames[5])->second) #define CPARAM_7 CPARAM_6, boost::get<const boost::mpl::at_c<signature,6>::type &>(theMap.find(theVarNames[6])->second) #define CPARAM_8 CPARAM_7, boost::get<const boost::mpl::at_c<signature,7>::type &>(theMap.find(theVarNames[7])->second) #define CPARAM_9 CPARAM_8, boost::get<const boost::mpl::at_c<signature,8>::type &>(theMap.find(theVarNames[8])->second) #define CPARAM_10 CPARAM_9, boost::get<const boost::mpl::at_c<signature,9>::type &>(theMap.find(theVarNames[9])->second) #define INNER_RETRIVE_OBJECT(Nb) \ template<> boost::shared_ptr<BaseClass> InnerRetrieveObject< Nb >(const std::string &theKey,const ParameterMap& theMap)const{ \ CheckMap(theMap); \ return boost::shared_ptr<BaseClass>(new DerivedClass( CPARAM_##Nb ) \ ); \ } template < class BaseClass, class DerivedClass > class PhRegistra:public PhRegistraBase<BaseClass>{ public: typedef typename DerivedClass::constructor_signature_typelist signature; typedef typename boost::make_variant_over<typename BaseClass::variant_type_list::type>::type variant; typedef std::map<std::string,variant> ParameterMap; enum {ssize = boost::mpl::size<signature>::value}; template<unsigned long i> PhRegistra(const std::string &theKey, const char *theVariableNames[],const unsigned_long<i> *p=0) { BOOST_STATIC_ASSERT(i==ssize); // Must have ONE variable name for each paramter of the constructor for(unsigned long i(0);i<ssize;++i) theVarNames[i]=std::string(theVariableNames[i]); Singleton<Phactory<BaseClass> >::instance().Register(theKey,this); } boost::shared_ptr<BaseClass> RetrieveObject(const std::string &theKey,const ParameterMap& theMap)const{ return InnerRetrieveObject<ssize>(theKey,theMap); } template<int i> boost::shared_ptr<BaseClass> InnerRetrieveObject(const std::string &theKey,const ParameterMap&)const; INNER_RETRIVE_OBJECT(1) INNER_RETRIVE_OBJECT(2) INNER_RETRIVE_OBJECT(3) INNER_RETRIVE_OBJECT(4) INNER_RETRIVE_OBJECT(5) INNER_RETRIVE_OBJECT(6) INNER_RETRIVE_OBJECT(7) INNER_RETRIVE_OBJECT(8) INNER_RETRIVE_OBJECT(9) INNER_RETRIVE_OBJECT(10) private: void CheckMap(const ParameterMap& theMap)const { assert(theMap.size()==ssize); for(unsigned long i(0);i<ssize;++i)assert(theMap.find(theVarNames[i])!=theMap.end()); } std::string theVarNames[ssize]; }; #define PARAM_NAMES(n) n , static_cast<unsigned_long<sizeof(n)/sizeof(char*)> *>(0) #endif ----------------- end of Phactory.h <main,cpp> #include<vector> #include<iostream> #include"Phactory.h" using namespace std; template<class Object> //Quick liitle singletone just to demonstrate class Singleton { public: static Object & instance(){static Object theObject;return theObject;} virtual ~Singleton(){} private: Singleton(); Singleton(const Singleton<Object> & illegal); Singleton<Object> & operator=(const Singleton<Object> & illegal){return *this;} }; struct Dummy{}; struct Base { typedef boost::mpl::list<double,int,unsigned long,std::string,std::vector<double>,float,Dummy> variant_type_list; Base(){} virtual void f()const=0; virtual ~Base(){}; }; struct Derived :public Base { typedef boost::mpl::list<double,int,std::string,std::vector<double> > constructor_signature_typelist; Derived(double x_,int n_,const std::string &s_,const std::vector<double>&v_): x(x_),n(n_),s(s_),v(v_){} virtual void f()const{ cout << "My Double is " << x << "\n" << "My int is " << n << "\n" << "My String is " << s << "\n" << "My Vector Size is " << v.size() << "\n"; } private: double x; int n; std::string s; std::vector<double> v; }; namespace { const char * theVarNames[]={"Double","Int","String","Vector"}; PhRegistra<Base,Derived> thePhRegistra(std::string("DerivedObject"),PARAM_NAMES(theVarNames)); } int main() { std::map<std::string,typename boost::make_variant_over<typename Base::variant_type_list::type>::type> theMap; theMap["Double"]=1.0; theMap["Int"]=1; theMap["String"]="hello"; theMap["Vector"]=std::vector<double>(10); boost::shared_ptr<Base> thePtrSM(Singleton<Phactory<Base> >::instance().RetrieveObject("DerivedObject",theMap)); thePtrSM->f(); } ----- Original Message ---- From: Nindi Singh <nindi73(a)yahoo.co.uk> To: boost-users(a)lists.boost.org Sent: Wednesday, 1 November, 2006 8:59:31 PM Subject: Re: [Boost-users] Boost ROCKS !!!!! Cool ! Actualy I am now working another factory implementation. In the new implementation, the Base Class will hold a typedef for a Boost Variant, and then the derived objects can be instantiated by the factory by being given a std::map of the variants and stripping out the values to make a call to the constructor of the derived class. The ONLY intrusion on the classes would be a typelist in the Base class to type the appropriate Boost::Variant and a typelist in the derived class identifing the signature of the constructor to be called by the factory, similar to the factory i have posted previously. The MPL really is VERY cool, and I think I have JUST touched the surface !!!. In fact I put my order in for 'C++ Template Metaprogramming: Concepts, Tools, and Techniques from Boost and Beyond' at Amazon this afternoon !!!! ----- Original Message ---- From: Sohail Somani <s.somani(a)fincad.com> To: boost-users(a)lists.boost.org Sent: Wednesday, 1 November, 2006 8:46:28 PM Subject: Re: [Boost-users] Boost ROCKS !!!!! > -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Nindi Singh > > For the past few months I have been making more and more use > of Boost, in fact I would say becoming more and more reliant > on Boost, every so often introducing myslef to a new library. > But discovering the MPL, well that was awsome. The first time > I applied it was to implement a factory. I would NEVR have > though of doing it this way WITHOUT the MPL. Any comments on > my use ( or indeed abuse !) of Boost would be more than apprieciated. [snip code] Actually, I've been thinking of doing something similar and I am also interested in what people say! PS: Boost does rock _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users All new Yahoo! Mail "The new Interface is stunning in its simplicity and ease of use." - PC Magazine _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users Send instant messages to your online friends http://uk.messenger.yahoo.com

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