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Re: [Boost-users] enable_shared_from_this - or an alternative..
by Nat Goodspeed 21 Mar '06

21 Mar '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of Felipe Magno de Almeida > Sent: Monday, March 20, 2006 8:53 PM > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] enable_shared_from_this - or an alternative.. > > On 3/20/06, Nat Goodspeed <ngoodspeed(a)solidworks.com> wrote: > > > Indeed, for our purposes, we don't WANT smart pointers in the registry. > > Couldnt be a weak_ptr ? [Nat] It could. But AFAICT the big advantage of a weak_ptr over a dumb base* pointer is that a weak_ptr can detect when the referenced object has been deleted. Since our base-class destructor unregisters the object, deleting the registered pointer, that becomes a non-issue. So for this use case, I see no particular advantage to using weak_ptr rather than a dumb pointer. Indeed, for this use case, there appear to be a couple of advantages to using a dumb pointer. It's cheaper than a weak_ptr. But more importantly, it works regardless of whether the referenced object is allocated on the heap, on the stack or in static storage. That's useful to us, as we do have a number of tracked objects declared statically.

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Re: [Boost-users] how to use shared_ptr to wrap std::vector andreturnfrom function?
by Sohail Somani 21 Mar '06

21 Mar '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > David Abrahams > Sent: Tuesday, March 21, 2006 4:25 AM > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] how to use shared_ptr to wrap > std::vector andreturnfrom function? > > "Sohail Somani" <s.somani(a)fincad.com> writes: > > >> -----Original Message----- > >> From: boost-users-bounces(a)lists.boost.org > >> [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > >> kdsfinger(a)gmail.com > >> Sent: Monday, March 20, 2006 9:59 AM > >> To: Boost-users(a)lists.boost.org > >> Subject: [Boost-users] how to use shared_ptr to wrap > >> std::vector and returnfrom function? > >> > >> hi, Boost users > >> > >> Suppose I created a large data in a function and want to > >> return it back to where the function was called. I want to > >> return the pointer so that the deep copy of the large data is > >> not needed and memory leak is nicely handled. Can someone let > >> me know how to do it? > > > > This is what auto_ptr is for, shared_ptr is overkill as far as I can > > tell > > unless you have to cross DLL boundaries, or you need a custom deletion > routine, or a base class of the object pointed to might not have a > virtual destructor, ... As far as I can tell! Sheesh :)

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Re: [Boost-users] lexical_cast and string to wstring!
by Andrew Holden 21 Mar '06

21 Mar '06

> -----Original Message----- > From: Thomas Gulbrandsen [mailto:thomas@tansa.no] > Sent: Tuesday, March 21, 2006 11:30 AM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] lexical_cast and string to wstring! > > Hello! > > I have to convert a std::wstring to a std::string and tried the following > small test program. > But this will not compile on MSVC8.0 or MSVC7.1. > Is the boost::lexical_cast suppost to handle this conversion? As far I know, it's not (corrections, anybody?). My usual method to perform this conversion on Windows is to use WideCharToMultiByte, found in the Windows Platform SDK. Note, however, this function is designed to work with C-style strings and/or fixed-width. You might consider a function similar to the following (warning: untested code): #include <string> #include <windows.h> std::string NarrowString (const std::wstring &src) { //A temporary buffer to store the converted string. //It must be large enough to store the string. char buffer[100]; //Convert the string to UTF-8 and store it in the local buffer. //If you're looking for your native encoding, replace //CP_UTF8 with CP_ACP and look into the dwFlags, lpDefaultChar, and //lpUsedDefaultChar parameters to WideCharToMultiByte. int narrowWidth = WideCharToMultiByte (CP_UTF8, 0, src.data(), src.length(), buffer, sizeof buffer, NULL, NULL); //Convert the buffer to a string and return it return std::string (buffer, narrowWidth); } Other platforms have a similar facility. If you're looking for a cross-platform solution, I would recommend the ICU library. Also, as I understand it, ICU is the "similar facility" for several variants of Unix.

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Boost Regex 'Split' Question
by admin＠geocodenet.com 21 Mar '06

21 Mar '06

Hi all, I have Boost 1.33.1 and VC++ 7.1. I'm currently writing some apps that perform splitting, searching, replacing, etc. using Boost Regex++. I've nailed the searching, but am having trouble with the splitting. Basically I need to know how to convert the result of a regex_token_iterator to a C-style string (don't ask...) that I can display using the old-style printf() function. Can anyone out there give me an idea how to implement such a beast? Thanks in advance.

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Question on ptr_vector class
by Sebastien Fortier 21 Mar '06

21 Mar '06

I would like to define two different sorting predicates for a class but I do not understand how to do this. //meteorlogicalObj.hpp class meteorlogicalObj { public: meteorlogicalObj(int val, Point pt) : val_(val), pt_(pt){} virtual ~meteorlogicalObj() {} // how would I go about creating these sorting functions that would work with the ptr_vector class bool sortOnValue(const meteorlogicalObj&, const meteorlogicalObj&); bool sortOnPoint(const meteorlogicalObj&, const meteorlogicalObj&); // ... private: int val_; Point pt_; }; //meteorlogicalObj.cpp #include "meteorlogicalObj.h" bool meteorlogicalObj::sortOnValue(const meteorlogicalObj& metObj, const meteorlogicalObj& other) { return (metObj.val_ < other.val_); } bool meteorlogicalObj::sortOnPoint(const meteorlogicalObj& metObj, const meteorlogicalObj& other) { return (metObj.pt_ < other.pt_); } //main.cpp boost::ptr_vector<meteorlogicalObj> metObjVec; //... fill vector metObjVec.sort( sortOnValue() ); // this does not work, what is missing??? metObjVec.sort( sortOnPoint() ); // this does not work, what is missing??? I can see that I probably need the indect_fun but I do not know how to wrap my sorting function to pass them to the sorting function Thank you for your assistance!

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Newbie Question: Boost Regex
by admin＠geocodenet.com 21 Mar '06

21 Mar '06

Hi, I have a newbie question here. I'm trying to use the Boost regex in an application, but I keep getting strange errors. How can I compile the regex code into a DLL or LIB that I can link to from my app -- I'm looking for the path of least resistance here. The version is 1.33.1, the platform is VC++ 7.1. The most recent error is the following: xp_regex_match error LNK2019: unresolved external symbol "private: class boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > & __thiscall boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >::do_assign(char const *,char const *,unsigned int)" (?do_assign@?$basic_regex@DU?$regex_traits@DV?$w32_regex_traits@D@boost@@@boost@@@boost@@AAEAAV12@PBD0I@Z) referenced in function "public: class boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > & __thiscall boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >::assign(char const *,char const *,unsigned int)" (?assign@?$basic_regex@DU?$regex_traits@DV?$w32_regex_traits@D@boost@@@boost@@@boost@@QAEAAV12@PBD0I@Z) xp_regex_match error LNK2019: unresolved external symbol "public: bool __thiscall boost::re_detail::perl_matcher<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator,class std::allocator<struct boost::sub_match<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator> >,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >::find(void)" (?find@?$perl_matcher@Vconst_iterator@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V?$allocator@U?$sub_match@Vconst_iterator@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@boost@@@3@U?$regex_traits@DV?$w32_regex_traits@D@boost@@@boost@@@re_detail@boost@@QAE_NXZ) referenced in function "bool __cdecl boost::regex_search<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator,class std::allocator<struct boost::sub_match<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator> >,char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator,class boost::match_results<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator,class std::allocator<struct boost::sub_match<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator> > > &,class boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > const &,enum boost::regex_constants::_match_flags,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator)" (??$regex_search@Vconst_iterator@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V?$allocator@U?$sub_match@Vconst_iterator@?$basic_string@DU?$char_t xp_regex_match error LNK2019: unresolved external symbol "public: __thiscall boost::re_detail::perl_matcher<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator,class std::allocator<struct boost::sub_match<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator> >,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >::perl_matcher<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator,class std::allocator<struct boost::sub_match<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator> >,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator,class boost::match_results<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator,class std::allocator<struct boost::sub_match<class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator> > > &,class boost::basic_regex<char,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > const &,enum boost::regex_constants::_match_flags,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >::const_iterator)" (??0?$perl_matcher@Vconst_iterator@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V?$allocator@U?$sub_match@Vconst_iterator@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@boost@@@3@U?$regex_traits@DV?$w32_regex_traits@D@boost@@@boost@@@re_detail@boost@@QAE@Vconst_iterator@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@0AAV?$match_results@Vconst_iterator@?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@V?$allocator@U?$sub_match@Vconst_iterator@?$basic_string@DU?$ xp_regex_match fatal error LNK1120: 3 unresolved externals Any feedback is appreciated. Thanks!

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lexical_cast and string to wstring!
by Thomas Gulbrandsen 21 Mar '06

21 Mar '06

Hello! I have to convert a std::wstring to a std::string and tried the following small test program. #include <iostream> #include <string> #include <boost/lexical_cast.hpp> int main(int argc, char** argv) { std::wstring ws(L"Hello"); std::string s(boost::lexical_cast<std::string>(ws); std::cout << s << std::endl; return 0; } But this will not compile on MSVC8.0 or MSVC7.1. Is the boost::lexical_cast suppost to handle this conversion? Thanks, Thomas Gulbrandsen

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Re: [Boost-users] Question on ptr_vector class
by David Klein 21 Mar '06

21 Mar '06

boost-users-bounces(a)lists.boost.org wrote: > I would like to define two different sorting predicates for a class > but I do not understand how to do this. > > //meteorlogicalObj.hpp > class meteorlogicalObj { > public: > meteorlogicalObj(int val, Point pt) : val_(val), pt_(pt){} > virtual ~meteorlogicalObj() {} > > // how would I go about creating these sorting functions that would > work with the ptr_vector class > bool sortOnValue(const meteorlogicalObj&, const meteorlogicalObj&); > bool sortOnPoint(const meteorlogicalObj&, const meteorlogicalObj&); > // ... > private: > int val_; > Point pt_; > }; > > //meteorlogicalObj.cpp > #include "meteorlogicalObj.h" > > bool meteorlogicalObj::sortOnValue(const meteorlogicalObj& metObj, > const meteorlogicalObj& other) > { > return (metObj.val_ < other.val_); > } > > > bool meteorlogicalObj::sortOnPoint(const meteorlogicalObj& metObj, > const meteorlogicalObj& other) > { > return (metObj.pt_ < other.pt_); > } > > //main.cpp > boost::ptr_vector<meteorlogicalObj> metObjVec; > > //... fill vector > > metObjVec.sort( sortOnValue() ); // this does not work, what is > missing??? metObjVec.sort( sortOnPoint() ); // this does not work, > what is missing??? > > I can see that I probably need the indect_fun but I do not know how to > wrap my sorting function to pass them to the sorting function > > > > Thank you for your assistance! > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users hi sebastien, try the following changes... 1) make the sort function static class meteorlogicalObj { ... static bool sortOnValue(const meteorlogicalObj&, const meteorlogicalObj&); ... }; 2) call sort like this metObjVec.sort(&meteorlogicalObj::sortOnValue); HTH dave

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[date_time] How to create a date from string with specific format?
by Christian Henning 21 Mar '06

21 Mar '06

Hi there, I would like to create a date object from a string with a specific format ( mm-dd-yyyy ). How to I do that? Thanks ahaed, Christian

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Re: [Boost-users] Question on ptr_vector class
by David Klein 21 Mar '06

21 Mar '06

boost-users-bounces(a)lists.boost.org wrote: > I would like to define two different sorting predicates for a class > but I do not understand how to do this. > > //meteorlogicalObj.hpp > class meteorlogicalObj { > public: > meteorlogicalObj(int val, Point pt) : val_(val), pt_(pt){} > virtual ~meteorlogicalObj() {} > > // how would I go about creating these sorting functions that would > work with the ptr_vector class > bool sortOnValue(const meteorlogicalObj&, const meteorlogicalObj&); > bool sortOnPoint(const meteorlogicalObj&, const meteorlogicalObj&); > // ... > private: > int val_; > Point pt_; > }; > > //meteorlogicalObj.cpp > #include "meteorlogicalObj.h" > > bool meteorlogicalObj::sortOnValue(const meteorlogicalObj& metObj, > const meteorlogicalObj& other) > { > return (metObj.val_ < other.val_); > } > > > bool meteorlogicalObj::sortOnPoint(const meteorlogicalObj& metObj, > const meteorlogicalObj& other) > { > return (metObj.pt_ < other.pt_); > } > > //main.cpp > boost::ptr_vector<meteorlogicalObj> metObjVec; > > //... fill vector > > metObjVec.sort( sortOnValue() ); // this does not work, what is > missing??? metObjVec.sort( sortOnPoint() ); // this does not work, > what is missing??? > > I can see that I probably need the indect_fun but I do not know how to > wrap my sorting function to pass them to the sorting function > > > > Thank you for your assistance! > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users hi sebastien, try the following changes... 1) make the sort function static class meteorlogicalObj { ... static bool sortOnValue(const meteorlogicalObj&, const meteorlogicalObj&); ... }; 2) call sort like this metObjVec.sort(&meteorlogicalObj::sortOnValue); HTH dave

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