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covariance of shared_ptr types
by Vaclav Vesely 16 Feb '03

16 Feb '03

Hi, in C++ it's possible to write this: class A {}; class B: public A {}; class X { virtual A* f() { ... }; }; class Y: public X { virtual B* f() { ... }; // B* is covariant from A* }; However it is NOT possible to write that with shared_ptr: class X { shared_ptr<A> f() { ... }; }; class Y: public X { virtual shared_ptr<B> f() { ... }; // Error: shared_ptr<B> is NOT covariant from shared_ptr<A> }; I don't know C++ standard very well (in fact I've never read it). So my question is: it's possible to adjust shared_ptr to allow such constructions? Thank you, Wasek [Non-text portions of this message have been removed]

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Problems building RegExp3
by kekogomez <kekogomez＠yahoo.es> 15 Feb '03

15 Feb '03

Hello to all, I have tried to build the RegExp3 library... but I get some errors... I'm using Vc++ Net. I execute the command nmake vc7.mak and I get the nexts error results... could someone help me? .... .... .... link kernel32.lib user32.lib gdi32.lib winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib uuid.lib odbc32.lib odbccp32.lib /nologo /dll /incremental:yes /pdb:"vc7/boost_regex_vc7_m did.pdb" /debug /machine:I386 /out:"vc7/boost_regex_vc7_mdid.dll" /imp lib:"vc7/boost_regex_vc7_mdid.lib" /LIBPATH:\lib vc7/boost_regex_vc7_mdid/c_regex_traits.obj vc7/boost_regex_vc7_mdid/c_regex_traits_common.obj vc7/boost_regex_vc7_mdid/cpp_regex_traits.obj vc7/boost_regex_vc7_mdid/cregex.obj vc7/boost_regex_vc7_mdid/fileiter.obj vc7/boost_regex_vc7_mdid/instances.obj vc7/boost_regex_vc7_mdid/posix_api.obj vc7/boost_regex_vc7_mdid/regex.obj vc7/boost_regex_vc7_mdid/regex_debug.obj vc7/boost_regex_vc7_mdid/regex_synch.obj vc7/boost_regex_vc7_mdid/w32_regex_traits.obj vc7/boost_regex_vc7_mdid/wide_posix_api.obj vc7/boost_regex_vc7_mdid/winstances.obj Creating library vc7/boost_regex_vc7_mdid.lib and object vc7/boost_regex_vc7_mdid.exp regex_synch.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp w32_regex_traits.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp wide_posix_api.obj : error LNK2019: unresolved external symbol __RTC_CheckEsp referenced in function _regerrorW@16 winstances.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp fileiter.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp instances.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp posix_api.obj : error LNK2019: unresolved external symbol __RTC_CheckEsp referenced in function _regerrorA@16 regex.obj : error LNK2019: unresolved external symbol __RTC_CheckEsp referenced in function "public: __thiscall boost::match_results<char const *,class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >::match_results<char const *,class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> >(class boost::detail::allocator_adapter<char,class boost::detail::simple_alloc> const &)" (??0?$match_results@PBDV? $allocator_adapter@DVsimple_alloc@detail@boost@@@detail@boost@@@boost@ @QAE@ABV?$allocator_adapter@DVsimple_alloc@detail@boost@@@detail@1@@Z) c_regex_traits.obj : error LNK2019: unresolved external symbol __RTC_CheckEsp referenced in function "unsigned int __cdecl `anonymous namespace'::re_get_message(unsigned short *,unsigned int,unsigned int)" (?re_get_message@?A0xc953bc5d@@YAIPAGII@Z) c_regex_traits_common.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp cpp_regex_traits.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp cregex.obj : error LNK2001: unresolved external symbol __RTC_CheckEsp regex_synch.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 w32_regex_traits.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 wide_posix_api.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 winstances.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 fileiter.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 instances.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 posix_api.obj : error LNK2019: unresolved external symbol @_RTC_CheckStackVars@8 referenced in function _regerrorA@16 regex.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 c_regex_traits.obj : error LNK2019: unresolved external symbol @_RTC_CheckStackVars@8 referenced in function "unsigned int __cdecl `anonymous namespace'::re_get_message(unsigned short *,unsigned int,unsigned int)" (?re_get_message@?A0xc953bc5d@@YAIPAGII@Z) c_regex_traits_common.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 cpp_regex_traits.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 cregex.obj : error LNK2001: unresolved external symbol @_RTC_CheckStackVars@8 regex_synch.obj : error LNK2001: unresolved external symbol __RTC_Shutdown w32_regex_traits.obj : error LNK2001: unresolved external symbol __RTC_Shutdown wide_posix_api.obj : error LNK2001: unresolved external symbol __RTC_Shutdown winstances.obj : error LNK2001: unresolved external symbol __RTC_Shutdown fileiter.obj : error LNK2001: unresolved external symbol __RTC_Shutdown instances.obj : error LNK2001: unresolved external symbol __RTC_Shutdown posix_api.obj : error LNK2019: unresolved external symbol __RTC_Shutdown referenced in function _regerrorA@16 regex.obj : error LNK2001: unresolved external symbol __RTC_Shutdown c_regex_traits.obj : error LNK2001: unresolved external symbol __RTC_Shutdown c_regex_traits_common.obj : error LNK2001: unresolved external symbol __RTC_Shutdown cpp_regex_traits.obj : error LNK2019: unresolved external symbol __RTC_Shutdown referenced in function "public: __thiscall boost::re_detail::message_data<char>::message_data<char>(class std::locale const &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??0? $message_data@D@re_detail@boost@@QAE@ABVlocale@std@@ABV? $basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@4@@Z) cregex.obj : error LNK2001: unresolved external symbol __RTC_Shutdown regex_synch.obj : error LNK2001: unresolved external symbol __RTC_InitBase w32_regex_traits.obj : error LNK2001: unresolved external symbol __RTC_InitBase wide_posix_api.obj : error LNK2019: unresolved external symbol __RTC_InitBase referenced in function _regerrorW@16 winstances.obj : error LNK2001: unresolved external symbol __RTC_InitBase fileiter.obj : error LNK2001: unresolved external symbol __RTC_InitBase instances.obj : error LNK2001: unresolved external symbol __RTC_InitBase posix_api.obj : error LNK2001: unresolved external symbol __RTC_InitBase regex.obj : error LNK2001: unresolved external symbol __RTC_InitBase c_regex_traits.obj : error LNK2001: unresolved external symbol __RTC_InitBase c_regex_traits_common.obj : error LNK2001: unresolved external symbol __RTC_InitBase cpp_regex_traits.obj : error LNK2019: unresolved external symbol __RTC_InitBase referenced in function "public: __thiscall boost::re_detail::message_data<char>::message_data<char>(class std::locale const &,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (??0? $message_data@D@re_detail@boost@@QAE@ABVlocale@std@@ABV? $basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@4@@Z) cregex.obj : error LNK2001: unresolved external symbol __RTC_InitBase vc7/boost_regex_vc7_mdid.dll : fatal error LNK1120: 4 unresolved externals

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boost::thread and MinGW
by Russ 14 Feb '03

14 Feb '03

Hi, I was previously using the threading library with MinGW (latest release version) with no problems. Yesterday I came across a segfault that occurred when accessing a shared pointer so I updated the boost-cvs version I was using to see if it was a known problem that had been fixed; however when attempting to build the new version it appeared that threading had been disabled for MinGW? Is this the case or is it a problem with the way I'm building my code. Any help greatly appreciated, Russ

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RE: [Boost-Users] Re: Why scoped_ptr dost provide custom dealloca tion?
by bjorn.karlsson＠readsoft.com 14 Feb '03

14 Feb '03

> From: Peter Dimov [mailto:pdimov@mmltd.net] [snip] > A zero-overhead scoped_ptr<X, D> would require a helper class here: Yes, and I shouldn't have said scoped_ptr<X,D>, but scoped_ptr<X> with custom deallocation capabilities... I'd be willing to pay for the increase in size, but I realize not everyone would. The case is real, however. > scoped_ptr<void, void (*) (void *)> p(hPrinter, &ClosePrinter); > > that would increase sizeof(scoped_ptr) and is of questionable > utility. :-) Actually, I kind of like it. :-) > There is always the option to define a dedicated printer > class, of course. Yep, but there are hundreds of cases like this, which is why the feature would be useful. One could argue the same for the resource management of any type, right? ;-) Bjorn Karlsson

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RE: [Boost-Users] Re: Why scoped_ptr dost provide custom dealloca tion?
by bjorn.karlsson＠readsoft.com 14 Feb '03

14 Feb '03

> From: Peter Dimov [mailto:pdimov@mmltd.net] [snip] > (An example of a convincing case: "In my project I have > encountered the > following situation: <description with real(istic sounding) > identifiers> and > I believe that scoped_ptr<X, D> would be a perfect fit." Some > non-examples: > "Someone might find it useful." "Wouldn't it be cool if...") In my project I have encountered the following situation: A lot of the code needs to handle (no pun intended) resources that are represented by indiscriminate types, such as void* or long. Different resources (and different functions for allocation/deallocation) use this handle type, so specialization is not an option. It's possible to use shared_ptr to handle lifetime management of the resource: HANDLE hPrinter=0; OpenPrinter(_T("Some printer"),&hPrinter,0); if (boost::shared_ptr<void> p(hPrinter,&ClosePrinter)) { } While this works, it doesn't convey the intent of the code (nor preserve it): the resource should typically not be shared, only scoped, and I believe that scoped_ptr<X,D> would be a perfect fit. There are other tools in Boost (outside too, of course) for solving this type of problem, but I think it would be more than cool for scoped_ptr to have this feature; I'd definitely use it in real code. Bjorn Karlsson

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[BGL] Strange result with internal graph properties
by yg-boost-users＠m.gmane.org 13 Feb '03

13 Feb '03

I have the following code in one of my header files: struct vertex_type_t { typedef boost::vertex_property_tag kind; }; enum vtype { ROOT, INNER, LEAF }; typedef boost::property<vertex_type_t, enum vtype> vertex_type; typedef boost::property<boost::vertex_index_t, int, vertex_type> vertex_index; typedef boost::property<boost::vertex_name_t, std::string, vertex_type> vertex_property; typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, vertex_property, edge_property> tree; Notice the error: The vertex properties are not chained together. Rather, the actual vertex property that is added to the graph points to vertex_type, and the vertex_index /also/ points to the vertex_type! Now the strange thing: I have been running this and using all of the vertex properties, including vertex_index, without any problems, but when I noticed this, and tried setting the last template parameter of vertex_property to vertex_index instead I get segmentation faults. I have no idea why this is. Björn

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regex_match() Division By Zero
by Glover Barker 13 Feb '03

13 Feb '03

I am using boost::regex (1.29.0) under MSVC++ 6.0. Whenever I call regex_match(), I get: "Unhandled exception in filename.exe: 0xC0000094: Integer Divide by Zero." I have tried various ways to make the call (including the snippets posted on www.boost.org) Even this simple example fails: regex expression("abc"); cmatch what; if ( regex_match("xyz", what, expression) ) { // Whatever ... } Breakpoints reveal that after expression is set, the value of _expression_len is still 0. So when regex_match() is called, it in turn sends the value of expression.size() (which is just _expression_len) to re_detail::_priv_match_data(), which sends this value to estimate_max_state_count(). Then estimate_max_state_counts(), which calls this value "states", does the following: states *= states; // and later ... if(dist > (difference_type)(lim / states)) Since states is 0, this last expression causes division by 0, and the resulting exception. In case my environment matters, I am building my program under MSVC++ 6.0, running with boost_regex.dll. I am defining BOOST_REGEX_NO_LIB and BOOST_REGEX_USE_CPP_LOCALE, and linking in boost_regex.lib. What am I doing wrong? Glover Barker

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Compile problem with regex.hpp and VS6SP5
by soulofsealion <dworthem＠symyx.com> 13 Feb '03

13 Feb '03

When I included regex.hpp into my project: #include <boost\regex.hpp> I received the following errors c:\cvsprojectsroot\renaissance\3rdpartyfiles\boostlibrary\boost\regex. hpp(860) : error C2899: typename cannot be used outside a template declaration c:\cvsprojectsroot\renaissance\3rdpartyfiles\boostlibrary\boost\regex. hpp(440) : error C2899: typename cannot be used outside a template declaration So at lines 440-2 template <class iterator, class Allocator = #if !(defined(BOOST_MSVC) && (BOOST_MSVC <= 1300)) BOOST_DEFAULT_ALLOCATOR(typename re_detail::def_alloc_param_traits<iterator>::type) > I Tried the following: //This section was altered to handle the problem of the VS6 compiler not handling of a typename in a macro for a template parameter-DWW 02/06/2003 template<class iterator> class def_alloc_param_traits_fixclass { public: typedef typename re_detail::def_alloc_param_traits<iterator>::type def_alloc_param_traits_fix; }; template <class iterator, class Allocator = #if !(defined(BOOST_MSVC) && (BOOST_MSVC <= 1300)) //BOOST_DEFAULT_ALLOCATOR(typename re_detail::def_alloc_param_traits<iterator>::type) > BOOST_DEFAULT_ALLOCATOR (def_alloc_param_traits_fixclass<iterator>::def_alloc_param_traits_fix ) > //End of section altered to handle the problem of the VS6 compiler not handling of a typename in a macro for a template parameter-DWW 02/06/2003 And at lines 858-862 namespace re_detail{ template <class iterator, class Allocator = BOOST_DEFAULT_ALLOCATOR (typename def_alloc_param_traits<iterator>::type) > class match_results_base { I tried: namespace re_detail{ //This section was altered to handle the problem of the VS6 compiler not handling of a typename in a macro for a template parameter-DWW 02/06/2003 template<class iterator> class def_alloc_fixclass { public: typedef typename def_alloc_param_traits<iterator>::type def_alloc_fix; }; //template <class iterator, class Allocator = BOOST_DEFAULT_ALLOCATOR (typename def_alloc_param_traits<iterator>::type) > template <class iterator, class Allocator = BOOST_DEFAULT_ALLOCATOR(def_alloc_fixclass<iterator>::def_alloc_fix) > //End of section altered to handle the problem of the VS6 compiler not handling of a typename in a macro for a template parameter-DWW 02/06/2003 class match_results_base { This compiled OK, has any one else had this problem and any comments on this fix or is there anything else that I missed so I do nto have to change the regex.hpp file? it appeared to me that the VS6 compile has a problem with a typename as a parameter in a macro that is in turn a template parameter. Thank you for any help.

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Ah.......Boost Socket.....
by hjlee＠hurim.net 12 Feb '03

12 Feb '03

Anyone who knows when boost socket library is comming and where I can get beta version..? [Non-text portions of this message have been removed]

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boost::bind/function and C function pointers
by Thomas Pollinger 12 Feb '03

12 Feb '03

Apologies if this topic has already been discussed. I have looked around on various mailing lists, in addition I have tried to make it work with the current C++ STL standard with std::mem_fun and std::bind1st but with no success. The problem is basically to bind a member function pointer with an instance of its declaring class and to assign the result to an existing C library function that expects a C style function pointer. This certainly works for ordinary C functions and static C++ functions, however fails for bound member function pointers. Here is what I am trying to achieve: #include <boost/bind.hpp> // C function declared in some library struct E; extern void setCallBack(void (*callback_fct)(E*)); class A { public: void init(); void callBack(E *e); .... }; void A::init() {setCallBack(boost::bind(&A::callBack, this));} void A::callBack(E *e) {...} I tried also using the STL calls, but without success either: ... setCallBack(std::bind1st(std::mem_fun(&A::callBack), this)); I like the elegant approach of boost::bind and would like to use it for this case. The workaround would be to declare a static function and to store the instance somewhere to access the other members of the A instance - but I'd prefer the other way if there is a solution to make it work. BTW, I am using gcc v 3.2 on Linux/i386 - but I guess that this is a more general problem than a specific compiler issue. The error I've gotten is /opt/src/boost/boost/bind.hpp: In instantiation of `boost::_bi::result_traits<boost::_bi::unspecified, void (A::*)(E*)>': /opt/src/boost/boost/bind/bind_template.hpp:16: instantiated from `boost::_bi::bind_t<boost::_bi::unspecified, void (A::*)(E*), boost::_bi::list1<boost::_bi::value<A*> > >' controller.cpp:28: instantiated from here /opt/src/boost/boost/bind.hpp:59: `void (A::*)(E*)' is not a class, struct, or union type Chaning boost::bind(...) to boost::bind<void>(...) to explicitly delclare the return type yields: controller.cpp:28: cannot convert `boost::_bi::bind_t<void, void (A::*)(E*), boost::_bi::list1<boost::_bi::value<A*> > >' to `void (*)(E*)' for argument `1' to `void setCallBack(void (*)(E*))' which probably reveals the root of the problem, that of not being able to cast a boost function pointer type to a regular C function type. I tried applying some cast operators, but that failed already in the syntactical stage of the parser, e.g. static_cast<void (*)(E*)>. -Thomas

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