April 2005 - Boost-users - lists.preview.boost.org

Need a method to compare types of data objects at runtime
by Stephen Torri 26 Apr '05

26 Apr '05

If I have a abstract class with two classes that implement it how can I make a check that tests for the type of the implementation classes? For example: class Base { public: virtual void run (){} virtual void stop (){} }; class Gas_Pedal : public Base { public: virtual void run (){} void set_rate (unsigned int); private: unsigned int m_rate; }; class Brake_Pedal : public Base { public: virtual void stop (){} void set_pressure (unsigned int); private: unsigned int m_pressure; }; When I have a client that receives a Base object I want to be able to check at run-time. So that if I am expecting a Gas_Pedal object and I receive something else I can perform some recovery action. The software I am designing contains an untold number of arrangements of items. Each item expect a distinctive input type. If it receives something that it does not know how to handle or need I want to throw an error. In order to do this I would like to do something like: void process (Base* sobj) { if (! (isExpectedType(sobj)) { throw NotForMeException (); } Brake_Pedal* bp = dynamic_cast<Brake_Pedal>(sobj); bp.set_pressure (50); } So perhaps my design is flawed that I am running into this situation. I am attempting to keep the interface for the Base class simple. The underlying types could have different data and access methods because they differ so widely in what they will do. This example was given to keep things simple. Stephen

3 2

Problems with boost::filesystem::path
by Johnson, Donald W MVK Contractor 26 Apr '05

26 Apr '05

Boost::filesystem::path is failing to create any paths. If always throws and exception stating invalid path. In the main function I call boost::filesystem::path::default_name_check( boost::filesystem::native ); boost::filesystem::initial_path(); The attempts to construct paths are in the pattern boost::filesystem::path(some_path_name); Specificly the error occurs here in constructing a path void path::m_path_append( const std::string & src, name_check checker ) { // convert backslash to forward slash if checker==native // allow system-specific-root if checker==no_check || checker==native assert( checker ); assert( src.size() == std::strlen( src.c_str() ) ); // no embedded 0 if ( src.size() == 0 ) return; std::string::const_iterator itr( src.begin() ); // [root-filesystem] # ifdef BOOST_WINDOWS if ( (checker == no_check || checker == native) && src.size() >= 2 ) // This fails { ... Since fore some reasion it seemed to be failing to get the native checker I tired this instead boost::filesystem::path(some_path_name,boost::filesystem::native); But the above test still fails. This seems to be related to the filesystem code being used in the main application and a DLL. I added this line to boost/config/user.hpp #define BOOST_FILESYSTEM_DYN_LINK So the library should be dynamicly linked and it being used in two places shouldn't be a problem. If I trace the function in a debugger all calls to the filesystem library look like this > FESMLibDebug.dll!boost::filesystem::path::default_name_check(bool (const std::basic_string<char,std::char_traits<char>,std::allocator<char> > &)* new_check=0x004573e2) > FESMLibDebug.dll!boost::filesystem::path::m_path_append(const std::basic_string<char,std::char_traits<char>,std::allocator<char> > & src={...}, bool (const std::basic_string<char,std::char_traits<char>,std::allocator<char> > &)* checker=0x004573e2) So it doesn't look like im getting 2 copies of boostfile system. I previously was getting calls to $(APPNAME)!boost::filesystems and $(DLLNAME)!boost::filesystems. However, if I incluede the source files of the dll directly into the application the problem dissapears. Anyone know what I missed? This is with Visual C++ 2003 and Windows XP. Thanks Donald Johnson

2 1

Thread Pool Qs
by Olenhouse, Jason 26 Apr '05

26 Apr '05

In poking around Boost I've noticed the Thread Pool code, but I haven't been able to find much current information on it. I've found a link mentioning it being in the next major version of Boost.Threads, but that was nearly three years ago: http://lists.boost.org/MailArchives/boost-users/msg01157.php <http://lists.boost.org/MailArchives/boost-users/msg01157.php> I've found the "Attic" in SourceForge, but I'm unsure of what the Attic is or for and how it relates to Boost in general as well as Boost Thread Pool: http://cvs.sourceforge.net/viewcvs.py/boost/boost/libs/thread/src/Attic/thr… og Basically, I'm just looking for some status information about Boost Thread Pools, specifically if there is any progress on the Thread Pool code, what version I'm to use, where to get the most current stable code, why it's not released, and when it will be released, but any other information would useful as well. Of course, if there's anyway I or my co-workers can contribute to help get things going we'd be more than happy to help. Thank you, -Jason

1 0

Boost Serialization & VC8 link problems
by Flavio Antonioli 25 Apr '05

25 Apr '05

Hi, I wrote earlier about linking problems with Boost & Microsoft VC8 beta 2. I realized I hadn't built Boost with VC8, I thought I did but apparently the build system was confused by the fact that both Visual Studio 2003 and 2005 where installed and defaulted to the older version. I was finally able to build renaming the Visual Studio 2003 folder. I was suprised to see that the Boost Serialization library was correctly built only in the release version, the debug version reported compilation errors. I've narrowed them down to actually the _DEBUG macro being defined or not. When it is defined compilation errors appear when compiling for example xml_grammar.cpp I'm using the v1 build system as I wasn't able to understand how v2 works, I managed only to make it build a dll version of the Serialization lib. Follows is a command line that compiles the file. Switching from /MD to /MDd breaks the compilation. /MDd /U_DEBUG works, as it undefines _DEBUG. C:\swap\boost2\boost_1_32_0\libs\serialization\build>"c:\Program Files (x86)\Microsoft Visual Studio 8\Common7\Tools\..\..\VC\bin\cl" /Zm800 -nologo /EHsc -c -DBOOST_TEST_NO_AUTO_LINK=1 /MD /Z7 /Od /Ob0 /EHsc /GR /Zc:forScope /Zc:wchar_t -I"..\..\..\bin\boost\libs\serialization\build" -I"C:\swap\boost2\boost_1_32 _0" -Fo"..\..\..\bin\boost\libs\serialization\build\libboost_serialization.lib\vc-8_0\debug\threading-multi\xml_grammar.obj" -Tp"C:\swap\boost2\boost_1_32_0\ libs\serialization\build\../src/xml_grammar.cpp" Needless to say I'm lost. Thanks to anyone who could shed some on this. Flavio.

1 0

Link problems with VC8 Beta 2
by Flavio Antonioli 25 Apr '05

25 Apr '05

I'm trying to build my application with Visual Studio 2005 Beta 2 and I'm having the following horrilbe linking problems. I'm using Boost 1.32.0, which I've rebuilt with VS2005 using the vc-8_0 tools option. The errors are in 2 groups, "already defined" and unresolved external symbols. I don't get any errors or warnings with VS .Net 2003 7.1 compiler. Help! Thanks, Flavio. 1>Linking... 1>msvcprtd.lib(MSVCP80D.dll) : error LNK2005: "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl std::operator<<<char,struct std::char_traits<char>,class std::allocator<char> >(class std::basic_ostream<char,struct std::char_traits<char> > &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (<mailto:??$?6DU?$char_traits@D@std@@V?$allocator@D@1@@std@@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@0@AAV10@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@0@@Z>??$?6DU?$char_traits@D@std@@V?$allocator@D@1@@std@@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@0@AAV10@ABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@0@@Z) already defined in libboost_serialization-vc71-mt-gd.lib(xml_oarchive.obj) 1>msvcprtd.lib(MSVCP80D.dll) : error LNK2005: "class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __cdecl std::operator+<char,struct std::char_traits<char>,class std::allocator<char> >(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,char const *)" (<mailto:??$?HDU?$char_traits@D@std@@V?$allocator@D@1@@std@@YA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@0@ABV10@PBD@Z>??$?HDU?$char_traits@D@std@@V?$allocator@D@1@@std@@YA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@0@ABV10@PBD@Z) already defined in libboost_serialization-vc71-mt-gd.lib(xml_oarchive.obj) 1>msvcprtd.lib(MSVCP80D.dll) : error LNK2005: "class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __cdecl std::operator+<char,struct std::char_traits<char>,class std::allocator<char> >(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (<mailto:??$?HDU?$char_traits@D@std@@V?$allocator@D@1@@std@@YA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@0@ABV10@0@Z>??$?HDU?$char_traits@D@std@@V?$allocator@D@1@@std@@YA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@0@ABV10@0@Z) already defined in libboost_serialization-vc71-mt-gd.lib(xml_oarchive.obj) 1>msvcprtd.lib(MSVCP80D.dll) : error LNK2005: "class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > __cdecl std::operator+<char,struct std::char_traits<char>,class std::allocator<char> >(char const *,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (<mailto:??$?HDU?$char_traits@D@std@@V?$allocator@D@1@@std@@YA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@0@PBDABV10@@Z>??$?HDU?$char_traits@D@std@@V?$allocator@D@1@@std@@YA?AV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@0@PBDABV10@@Z) already defined in libboost_serialization-vc71-mt-gd.lib(xml_oarchive.obj) 1>msvcprtd.lib(MSVCP80D.dll) : error LNK2005: "public: __thiscall std::allocator<char>::allocator<char>(void)" (<mailto:??0?$allocator@D@std@@QAE@XZ>??0?$allocator@D@std@@QAE@XZ) already defined in libboost_serialization-vc71-mt-gd.lib(basic_text_oprimitive.obj) 1>msvcprtd.lib(MSVCP80D.dll) : error LNK2005: "public: __thiscall std::allocator<char>::allocator<char>(class std::allocator<char> const &)" (<mailto:??0?$allocator@D@std@@QAE@ABV01@@Z>??0?$allocator@D@std@@QAE@ABV01@@Z) already defined in libboost_serialization-vc71-mt-gd.lib(basic_text_oprimitive.obj) 1>msvcprtd.lib(MSVCP80D.dll) : error LNK2005: "public: unsigned int __thiscall std::allocator<char>::max_size(void)const " (<mailto:?max_size@?$allocator@D@std@@QBEIXZ>?max_size@?$allocator@D@std@@QBEIXZ) already defined in libboost_serialization-vc71-mt-gd.lib(basic_text_oprimitive.obj) 1>libboost_serialization-vc71-mt-gd.lib(basic_text_oprimitive.obj) : warning LNK4217: locally defined symbol <mailto:?_Addfac@_Locimp@locale@std@@AAEXPAVfacet@23@I@Z>?_Addfac@_Locimp@locale@std@@AAEXPAVfacet@23@I@Z (private: void __thiscall std::locale::_Locimp::_Addfac(class std::locale::facet *,unsigned int)) imported in function "public: __thiscall std::locale::locale<class boost::archive::codecvt_null<char> >(class std::locale const &,class boost::archive::codecvt_null<char> *)" (<mailto:??$?0V?$codecvt_null@D@archive@boost@@@locale@std@@QAE@ABV01@PAV?$codecvt_null@D@archive@boost@@@Z>??$?0V?$codecvt_null@D@archive@boost@@@locale@std@@QAE@ABV01@PAV?$codecvt_null@D@archive@boost@@@Z) 1>libboost_serialization-vc71-mt-gd.lib(basic_text_iprimitive.obj) : warning LNK4049: locally defined symbol <mailto:?_Addfac@_Locimp@locale@std@@AAEXPAVfacet@23@I@Z>?_Addfac@_Locimp@locale@std@@AAEXPAVfacet@23@I@Z (private: void __thiscall std::locale::_Locimp::_Addfac(class std::locale::facet *,unsigned int)) imported 1>libboost_serialization-vc71-mt-gd.lib(basic_text_oprimitive.obj) : warning LNK4217: locally defined symbol <mailto:??0_Locimp@locale@std@@AAE@ABV012@@Z>??0_Locimp@locale@std@@AAE@ABV012@@Z (private: __thiscall std::locale::_Locimp::_Locimp(class std::locale::_Locimp const &)) imported in function "public: __thiscall std::locale::locale<class boost::archive::codecvt_null<char> >(class std::locale const &,class boost::archive::codecvt_null<char> *)" (<mailto:??$?0V?$codecvt_null@D@archive@boost@@@locale@std@@QAE@ABV01@PAV?$codecvt_null@D@archive@boost@@@Z>??$?0V?$codecvt_null@D@archive@boost@@@locale@std@@QAE@ABV01@PAV?$codecvt_null@D@archive@boost@@@Z) 1>libboost_serialization-vc71-mt-gd.lib(basic_text_iprimitive.obj) : warning LNK4049: locally defined symbol <mailto:??0_Locimp@locale@std@@AAE@ABV012@@Z>??0_Locimp@locale@std@@AAE@ABV012@@Z (private: __thiscall std::locale::_Locimp::_Locimp(class std::locale::_Locimp const &)) imported 1>libboost_serialization-vc71-mt-gd.lib(basic_text_oprimitive.obj) : error LNK2019: unresolved external symbol <mailto:__imp_?_Xran@_String_base@std@@QBEXXZ>__imp_?_Xran@_String_base@std@@QBEXXZ referenced in function "public: class std::basic_string<char,struct std::char_traits<char>,class std::_DebugHeapAllocator<char> > & __thiscall std::basic_string<char,struct std::char_traits<char>,class std::_DebugHeapAllocator<char> >::assign(class std::basic_string<char,struct std::char_traits<char>,class std::_DebugHeapAllocator<char> > const &,unsigned int,unsigned int)" (<mailto:?assign@?$basic_string@DU?$char_traits@D@std@@V?$_DebugHeapAllocator@D@2@@std@@QAEAAV12@ABV12@II@Z>?assign@?$basic_string@DU?$char_traits@D@std@@V?$_DebugHeapAllocator@D@2@@std@@QAEAAV12@ABV12@II@Z) 1>libboost_serialization-vc71-mt-gd.lib(basic_text_iprimitive.obj) : error LNK2001: unresolved external symbol <mailto:__imp_?_Xran@_String_base@std@@QBEXXZ>__imp_?_Xran@_String_base@std@@QBEXXZ 1>libboost_serialization-vc71-mt-gd.lib(basic_text_oprimitive.obj) : error LNK2019: unresolved external symbol <mailto:__imp_?_Xlen@_String_base@std@@QBEXXZ>__imp_?_Xlen@_String_base@std@@QBEXXZ referenced in function "protected: bool __thiscall std::basic_string<char,struct std::char_traits<char>,class std::_DebugHeapAllocator<char> >::_Grow(unsigned int,bool)" (<mailto:?_Grow@?$basic_string@DU?$char_traits@D@std@@V?$_DebugHeapAllocator@D@2@@std@@IAE_NI_N@Z>?_Grow@?$basic_string@DU?$char_traits@D@std@@V?$_DebugHeapAllocator@D@2@@std@@IAE_NI_N@Z) 1>libboost_serialization-vc71-mt-gd.lib(basic_text_iprimitive.obj) : error LNK2001: unresolved external symbol <mailto:__imp_?_Xlen@_String_base@std@@QBEXXZ>__imp_?_Xlen@_String_base@std@@QBEXXZ 1>libboost_serialization-vc71-mt-gd.lib(xml_iarchive.obj) : error LNK2019: unresolved external symbol <mailto:__imp_?begin@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE?AViterator@12@XZ>__imp_?begin@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE?AViterator@12@XZ referenced in function "protected: void __thiscall boost::archive::basic_xml_iarchive<class boost::archive::xml_iarchive>::load_end(char const *)" (<mailto:?load_end@?$basic_xml_iarchive@Vxml_iarchive@archive@boost@@@archive@boost@@IAEXPBD@Z>?load_end@?$basic_xml_iarchive@Vxml_iarchive@archive@boost@@@archive@boost@@IAEXPBD@Z) 1>libboost_serialization-vc71-mt-gd.lib(xml_grammar.obj) : error LNK2001: unresolved external symbol <mailto:__imp_?begin@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE?AViterator@12@XZ>__imp_?begin@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE?AViterator@12@XZ 1>libboost_serialization-vc71-mt-gd.lib(xml_iarchive.obj) : error LNK2019: unresolved external symbol <mailto:__imp_?end@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE?AViterator@12@XZ>__imp_?end@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE?AViterator@12@XZ referenced in function "protected: void __thiscall boost::archive::basic_xml_iarchive<class boost::archive::xml_iarchive>::load_end(char const *)" (<mailto:?load_end@?$basic_xml_iarchive@Vxml_iarchive@archive@boost@@@archive@boost@@IAEXPBD@Z>?load_end@?$basic_xml_iarchive@Vxml_iarchive@archive@boost@@@archive@boost@@IAEXPBD@Z) 1>libboost_serialization-vc71-mt-gd.lib(xml_grammar.obj) : error LNK2001: unresolved external symbol <mailto:__imp_?end@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE?AViterator@12@XZ>__imp_?end@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAE?AViterator@12@XZ 1>libboost_serialization-vc71-mt-gd.lib(xml_grammar.obj) : error LNK2019: unresolved external symbol <mailto:__imp_?append@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAEAAV12@Vconst_iterator@12@0@Z>__imp_?append@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@QAEAAV12@Vconst_iterator@12@0@Z referenced in function "public: void __thiscall boost::archive::`anonymous namespace'::append_string<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator>::operator()(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator)const " (<mailto:??R?$append_string@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@Vconst_iterator@12@@?A0x6748d6fd@archive@boost@@QBEXVconst_iterator@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@0@Z>??R?$append_string@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@Vconst_iterator@12@@?A0x6748d6fd@archive@boost@@QBEXVconst_iterator@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@0@Z)

2 1

boost libraries dependecies?
by Sandor 25 Apr '05

25 Apr '05

Hi, Is there a dependency tree available of boost libraries? I mean what other boost libraries are used by a specific boost library. thanks in advance, Sandor

3 2

Boost Logging Library?
by Matthias Kaeppler 25 Apr '05

25 Apr '05

Hello, on http://www.torjo.com/ is a "Boost logging library" available for download, but it doesn't exist on the official boost website. Will this library be in a future release of boost, or has someone just abused the well-known name for pushing his work? A logging library would be a very nice thing to have in boost, but before I use this one, I want to make sure it will be available publicly in the official boost packages. -- Matthias Kaeppler

4 3

Compatibility between shared_ptr and Rational RoseRT
by Dave.Ware＠seleniacomms.com 25 Apr '05

25 Apr '05

Does anyone know of a compatibility problem between the use of the Boost shared_ptr class and Rational RoseRT (real-time version of Rational Rose). We are having problems with intermittent crashes (not repeatable), and the crash dump debugger always indicates a problem while destroying objects that were held in existence by a shared_ptr - The underlying objects are of many different classes. We are never destroying the objects explicitly, but let the shared_ptr object take care of this when the last pointer to an object is deleted. When running the executable under Rational Purify, it reports many FIM errors (Freeing Invalid Memory), and all of these are again due to the deletion of objects that were owned by a shared_ptr. Any help would be very much appreciated Dave ------------------------------------------------------------ This email and any attached files contains company confidential information which may be legally privileged. It is intended only for the person(s) or entity to which it is addressed and solely for the purposes set forth therein. If you are not the intended recipient or have received this email in error please notify the sender by return, delete it from your system and destroy any local copies. It is strictly forbidden to use the information in this email including any attachment or part thereof including copying, disclosing, distributing, amending or using for any other purpose. In addition the sender excludes all liabilities (whether tortious or common law) for damage or breach arising or related to this email including but not limited to viruses and libel.

2 1

RE: [Boost-users] RE: Mutexes (Was: (no subject))
by Sliwa, Przemyslaw (London) 25 Apr '05

25 Apr '05

Sorry, I cannot. This is my corporate client. I am not allowed to change it. It is MS Outlook. Perhaps you will know some tricks. Thanks Pshemek -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Vladimir Prus Sent: 25 April 2005 07:32 To: boost-users(a)lists.boost.org Subject: [Boost-users] RE: Mutexes (Was: (no subject)) Sliwa, Przemyslaw (London) wrote: > Volodya, > > Thanks for answer. > Right I have forgotten to put the subject->it was stupid. > But the try_mutex and scoped_tyy_lock cause that both processors are > used properly. > > Can you explain? Ben has already given the answer to your question. I can only mention that you use mail client or NNTP client that does not preserve threading. So, every message from you is shows as a separate thread for me, making reading very inconvenient. Can you consider using some better client? On Windows, Thunderbird is known to work. On Linux, pretty much every mailer works fine, Thunderbird and KMail being two examples. You can also use gmane.org for posting. - Volodya _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users -------------------------------------------------------- If you are not an intended recipient of this e-mail, please notify the sender, delete it and do not read, act upon, print, disclose, copy, retain or redistribute it. Click here for important additional terms relating to this e-mail. http://www.ml.com/email_terms/ --------------------------------------------------------

4 3

RE: [Boost-users] Need a method to compare types of data objects atruntime
by Marcin Tustin 25 Apr '05

25 Apr '05

const type_info& type = typeid(*v); Comparable based on string representation. Part of standard. Header <typeinfo>. > -----Original Message----- > From: Stephen Torri [mailto:storri@torri.org] > Sent: 24 April 2005 19:46 > To: boost > Subject: [Boost-users] Need a method to compare types of data > objects atruntime > > If I have a abstract class with two classes that implement it > how can I make a check that tests for the type of the > implementation classes? > > For example: > > class Base { > public: > virtual void run (){} > virtual void stop (){} > }; > > class Gas_Pedal : public Base { > public: > virtual void run (){} > void set_rate (unsigned int); > private: > unsigned int m_rate; > }; > > class Brake_Pedal : public Base { > public: > virtual void stop (){} > void set_pressure (unsigned int); > private: > unsigned int m_pressure; > }; > > When I have a client that receives a Base object I want to be > able to check at run-time. So that if I am expecting a > Gas_Pedal object and I receive something else I can perform > some recovery action. The software I am designing contains an > untold number of arrangements of items. Each item expect a > distinctive input type. If it receives something that it does > not know how to handle or need I want to throw an error. > > In order to do this I would like to do something like: > > void process (Base* sobj) > { > if (! (isExpectedType(sobj)) > { > throw NotForMeException (); > } > > Brake_Pedal* bp = dynamic_cast<Brake_Pedal>(sobj); > bp.set_pressure (50); > } > > So perhaps my design is flawed that I am running into this > situation. I am attempting to keep the interface for the Base > class simple. The underlying types could have different data > and access methods because they differ so widely in what they > will do. This example was given to keep things simple. > > Stephen > > >

1 0