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Re: [Boost-users] Re: gregoran::year_based_generator and mingw-3.4.2
by Antonio Coralles 18 Jan '05

18 Jan '05

boost-users(a)lists.boost.org wrote: > > "Antonio Coralles" <noche.suapie(a)reflex.at <mailto:>> wrote in message > news:41EBE2F0.7020003@reflex.at... >> i'm writing on a programm which uses the boost date_time library >> [boost-version = 1.32.0] heavily; while i normally programm in linux > using >> gcc-3.3.5 i also need to compile my program in windows from time to > time. >> because it makes life easier with another library [gtkmm-2.4.8] i'm > using >> mingw-3.4.2; everthing worked fine (my code contains about 10 000 lines >> using boost_date_time) until i started using a >> boost::gregorian::year_based_generator. while gcc-3.3.5 in liux > accepts my >> code without even a single warning [with -Wall], mingw-3.4.2 complains - >> it seems that the compiler has problems with year_based_generator: >> >> calendar.hpp:60: error: variable or field `insertGenerator' declared void >> calendar.hpp:60: error: expected `;' before '(' token >> calendar.hpp:92: error: expected `)' before '*' token >> calendar.hpp:95: error: using-declaration for non-member at class scope >> calendar.hpp:95: error: expected `;' before '*' token >> >> here is the header: >> > ...snip... >> maybe somebody can give me a hint - or maybe point out an error in this >> header which is ignored by gcc-3.3.5. >> thanks, >> antonio > > I don't have mingw 3.4 available to me (I have 3.2). I do know the > regressions tests are passing for date_generators and 3.4 though. > > Are you able to build the print_holidays example? It uses pointers to > year_base_generators. > > It's in libs/date_time/example/gregorian. > > Bart > i'll try that in the next time and post the results of this experiment; be the way, i've now compiled my app in win succesfully by putting evrything which is somehow connected to year_based_generator into #ifndef WIN32_COMPILE .... #endif. that isn't too bad for the moment, because i don't use these methods by now in other parts of my prog [except unit tests]. but sooner or later i will ... antonio

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boost::tokenizer problems with Sun CC 5.3
by Debajit Adhikary 18 Jan '05

18 Jan '05

For the following code: // start of code #include <iostream> #include <string> #include <boost/tokenizer.hpp> int main() { using namespace std; using namespace boost; string s = "first second third"; tokenizer<> tok(s); for(tokenizer<>::iterator i = tok.begin(); i != tok.end(); ++i) cout << *i << "\n"; } // end of code With the Sun CC compiler (Sun WorkShop 6 update 2 C++ 5.3), I get the following error message: "/usr/include/boost/iterator/iterator_facade.hpp", line 623: Error: Could not find a match for boost::iterator_core_access::equal<boost::iterator_core_access::Facade1, boost::iterator_core_access::Facade2>(const boost::token_iterator<boost::char_delimiters_separator<char, std::char_traits<char>>, const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, const boost::token_iterator<boost::char_delimiters_separator<char, std::char_traits<char>>, const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, boost::is_convertible<boost::token_iterator<boost::char_delimiters_separator<char, std::char_traits<char>>, const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, boost::token_iterator<boost::char_delimiters_separator<char, std::char_traits<char>>, const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>>). "t.cpp", line 15: Where: While instantiating "boost::operator!=<boost::token_iterator<boost::char_delimiters_separator<char, std::char_traits<char>>, const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, std::basic_string<char, std::char_traits<char>, std::allocator<char>>, boost::forward_traversal_tag, const std::basic_string<char, std::char_traits<char>, std::allocator<char>>&, int, boost::token_iterator<boost::char_delimiters_separator<char, std::char_traits<char>>, const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, std::basic_string<char, std::char_traits<char>, std::allocator<char>>, boost::forward_traversal_tag, const std::basic_string<char, std::char_traits<char>, std::allocator<char>>&, int>(const boost::iterator_facade<boost::token_iterator<boost::char_delimiters_separator<char, std::char_traits<char>>, const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, std::basic_string<char, std::char_traits<char>, std::allocator<char>>, boost::forward_traversal_tag, const std::basic_string<char, std::char_traits<char>, std::allocator<char>>&, int>&, const boost::iterator_facade<boost::token_iterator<boost::char_delimiters_separator<char, std::char_traits<char>>, const char*, std::basic_string<char, std::char_traits<char>, std::allocator<char>>>, std::basic_string<char, std::char_traits<char>, std::allocator<char>>, boost::forward_traversal_tag, const std::basic_string<char, std::char_traits<char>, std::allocator<char>>&, int>&)". "t.cpp", line 15: Where: Instantiated from non-template code. 1 Error(s) detected. What could be the problem here? If Sun CC 5.3 doesnt support boost::tokenizer at all, are there any workarounds that I could use?

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gregoran::year_based_generator and mingw-3.4.2
by Antonio Coralles 18 Jan '05

18 Jan '05

i'm writing on a programm which uses the boost date_time library [boost-version = 1.32.0] heavily; while i normally programm in linux using gcc-3.3.5 i also need to compile my program in windows from time to time. because it makes life easier with another library [gtkmm-2.4.8] i'm using mingw-3.4.2; everthing worked fine (my code contains about 10 000 lines using boost_date_time) until i started using a boost::gregorian::year_based_generator. while gcc-3.3.5 in liux accepts my code without even a single warning [with -Wall], mingw-3.4.2 complains - it seems that the compiler has problems with year_based_generator: calendar.hpp:60: error: variable or field `insertGenerator' declared void calendar.hpp:60: error: expected `;' before '(' token calendar.hpp:92: error: expected `)' before '*' token calendar.hpp:95: error: using-declaration for non-member at class scope calendar.hpp:95: error: expected `;' before '*' token here is the header: /* This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #ifndef CL_CALENDAR #define CL_CALENDAR #include "boost/date_time/gregorian/gregorian.hpp" #include <stdexcept> #include <vector> #include <map> #ifndef BG #define BG boost::gregorian #endif /*!@brief besides of providing you with information if the day you are looking at is a * working day / saturday / sunday you can also store and retrieve additional * information about specific dates */ class calendar { public: enum dayChar { NORMAL_DAY = 0, SATURDAY = 1, SUNDAY = 2, PUBLIC_HOLIDAY = 3, SPECIAL_DAY = 4 }; /*!@brief obtain a calendar for a given context*/ static calendar& get(unsigned context=0); /*!@brief remove all calendar instances which have been created so far*/ static void removeAll(); /*!@brief remove the instance for a given context * * @remark you should call this function if you don't need the instance associated with * with context any more to avoid memory leaks ! */ static void remove(unsigned context); /*!@param[in] tDay the day to mark * @param[in] character the new character * @return true if the operation was succesfull * @note you cant lower the default character of a given day - e.g. you can't * give a sunday the character of a normal working day*/ bool markDay(const BG::date& tDay, dayChar character); /*!@return true if succesfull*/ bool unmarkDay(const BG::date& tDay); /*!@brief mark a day for every year using a partial_date * * @param[in] pDate a partial date * @param[in] character the new character*/ void markDay(const BG::partial_date& pDate, dayChar character); /*!@return true if succesfull*/ bool unmarkDay(const BG::partial_date& tDate); /*!@brief use this function to define more sophisticated (holi)days * * @param[in] gen a pointer to a year_based_generator optained from new * @param[in] manage if true the calendar is responsible for deleting*/ void insertGenerator(BG::year_based_generator *gen, dayChar character, bool manage=true); /*!@brief removes all generators inserted with insertGenerator*/ void removeGenerators(); /*!@brief get information from our calendar*/ dayChar getDayCharacter(const BG::date& thatDay) const; void reset(); int getRegularWorkingDaysWithin(const BG::date_period& tPeriod) const; /*!@remark this function can be usefull to dump our calendar to a file */ const std::map<BG::date, dayChar>& getDateMap() const { return _dMap; } /*!@remark this function can be usefull to dump our calendar to a file */ const std::map<BG::partial_date, dayChar>& getPartialDateMap() const { return _pMap; } private: calendar() {}; ~calendar(); //no copy-construction, no assignement calendar(const calendar&); calendar& operator=(const calendar&); static dayChar getDefaultCharacter(const BG::date& tDate); //data std::map<BG::date, dayChar> _dMap; std::map<BG::partial_date, dayChar> _pMap; struct hlp { hlp(BG::year_based_generator *gen, dayChar tChar, bool man) : generator(gen), character(tChar), manage(man) {} BG::year_based_generator *generator; dayChar character; bool manage; }; std::vector<hlp> _genVec; static std::map<unsigned, calendar*> _sc_calMap; }; std::ostream& operator<<(std::ostream& os, calendar::dayChar dChar); std::istream& operator>>(std::istream& is, calendar::dayChar& dChar); #endif maybe somebody can give me a hint - or maybe point out an error in this header which is ignored by gcc-3.3.5. thanks, antonio

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spirit (boost 1.32.0) grammar.ipp won't compile
by Sergey Skorniakov 18 Jan '05

18 Jan '05

Hello, All! I had tryed to compile some code with Microsoft (R) C/C++ Optimizing Compiler Version 14.00.2207 for AMD64 (from Server 2003 DDK) and got an error: C:\boost_1_32_0\boost\spirit\core\non_terminal\impl\grammar.ipp(308) : error C2784: 'std::mem_fun_t<_R,_Ty> std::mem_fun(_R (__cdecl _Ty::* ) (void))' : could not deduce template argument for 'T1 (__cdecl T2::* )(void)' from 'int (__cdecl boost::spirit::impl::grammar_helper_base<GrammarT>::* )(GrammarT *)' with [ GrammarT=boost::spirit::grammar<boost::archive::basic_xml_grammar<wchar_t>>::self_t ] Just changing std::mem_fun(&helper_base_t::undefine) to std::mem_fun1(&helper_base_t::undefine) resolves this problem. Modified successfully compiles under VC7.1, too. With best regards, Sergey.

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Have anyone used boost on ARM platform?
by Vyacheslav E. Andrejev 17 Jan '05

17 Jan '05

Hello All. I'm interested in possibility of using boost library on ARM9 platform. Does anyone do it before? Any pitfalls and hidden dangers? What toolchain for compilation is better to use? Is there some performance drawbacks when using boost compared with pure C? -- Vyacheslav E. Andrejev System Architect, Excelsior, LLC

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counting_iterator and iterator_adaptor problem
by Felipe Magno de Almeida 17 Jan '05

17 Jan '05

I'm trying to create an iterator from a class that is almost an iterator, it worked fine for const iterator with counting_iterator, but when I needed to dereference it, it complained about this: error C2440: 'return' : cannot convert from 'const xmlmanager::xml_basic_node<T>' to 'boost::iterator_facade<Derived,Value,CategoryOrTraversal,Reference,Difference>::reference' I think it is because it is still a const iterator... But I need a mutable iterator, and I have no clue in how to do it... I've tried the documentation, but it just explains what it is, but not ho to do it. The way I'm doing the iterator is: template <typename T> class xml_basic_node : public xml_basic_container<T>, public boost::iterator<boost::iterator_archetypes::readable_lvalue_iterator_t, xml_basic_node<T> > { public: // some specifics constructors bool operator == (xml_basic_node<T> const &n) const { // compares equality } xml_basic_node<T> &operator ++() { // advances... return *this; } }; and the iterator through counting_iterator: template <typename T> class acontainer { typedef boost::counting_iterator<xml_basic_node<T> > iterator; }; If someone could, please point me where I am getting wrong... I am days already trying to figure out how to do it... Sorry for the size of the mail and thanks in advance. -- Felipe Magno de Almeida UIN: 2113442 email: felipe.almeida@ic unicamp br, felipe.m.almeida@gmail com I am a C, modern C++, MFC, ODBC, Windows Services, MAPI developer from synergy, and Computer Science student from State University of Campinas(UNICAMP). To know more about: Unicamp: http://www.ic.unicamp.br Synergy: http://www.synergy.com.br current work: http://www.mintercept.com

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Environment variable library?
by Aaron W. LaFramboise 17 Jan '05

17 Jan '05

Is there a Boost library that supports manipulating process environment variables? I realize that accessing environment variables in the normal way is typically trivial, but it would be nice to have the entire thing wrapped up in a system-independent interface that is natural for C++. Aaron W. LaFramboise

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shared_from_this and custom deleters
by Niklas Wiberg 17 Jan '05

17 Jan '05

Hi, I have the following situation: In the constructor body of class A, I need to call functions that take a shared_ptr<A> as a parameter. These functions do not store the shared_ptr<A>, but in some situations a weak_ptr<A>. There is not yet any shared_ptr owning the A instance, since this is during A construction... At first, I thought using a shared_ptr<A> tmpThis(this, NullDeleter()) was a good idea. But when I later on (when another shared_ptr actually owns the A instance) want to use shared_from_this on A, I get an exception since the use_count of the internal weak_ptr is based on the first temporary shared_ptr that I used during construction (with the NullDeleter). Am I correct in my assumption that the internal weak_ptr in enable_shared_from_this is initialized by the first shared_ptr and that will prevent any later use of shared_from_this when I have another shared_ptr (with a default deleter) owning the element? I guess that a static create function would solve the problem, but changing that would be quite a big undertaking in this particular case so I thought I'd check if someone knows a simple solution to this... I added a small example code snipped below... Best regards, Niklas Example: void foo(shared_ptr<A> a); void otherFunction(shared_ptr<A> a); class A : public enable_shared_from_this<A> { A() { // Can't use shared_from_this since no shared_ptr owns this yet shared_ptr<A> thisTmp(this, NullDeleter()); foo(thisTmp); } bar() { otherFunction(shared_from_this()); // Throws exception... } }; int main() { shared_ptr<A> a(new A()); a->otherFunction(); ... }

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How to pass a member variable with boost::ref() in boost::bind()?
by tom gee 17 Jan '05

17 Jan '05

Here is the work around: class A { ... private: typedef struct _ONE_RECORD_ { string sGUID; string sID; string sName; string sSupport; string sModify; } ONE_RECORD; vector<ONE_RECORD> m_v; private: void FillOneLine(const ONE_RECORD& one_line); void FillAllLines(); }; void A::FillAllLines() { ... // method 1 for_each(m_v.begin(), m_v.end(), boost::bind(&A::FillOneLine, this,_1)); // OK // method 2 for_each(m_v.begin(), m_v.end(), boost::bind(&A::FillOneLine, this, ref(_1))); // error ... } Since ONE_RECORD can be large, I prefer to calling bind() as method 2, but, compiled under VC7.1 it generates such an error: e:\Boost\include\boost-1_32\boost\bind.hpp(285): error C2664: 'R boost::_mfi::mf1<R,T,A1>::operator ()<A>(U & ,A1) const' : cannot convert parameter 2 from 'boost::arg<I>' to 'A::ONE_RECORD' with [ R=void, T=A, A1=A::ONE_RECORD, U=A * ] and [ I=1 ] Can any body help to explain why and give a solution? Thanks.

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Smart pointers
by Kercso Jozsef 17 Jan '05

17 Jan '05

Hi! I would have several questions regarding to smart pointers. They are completely new for me, and I'm not sure if my design is the best. Feel free to comment it. :) The "safe" pointer problem: There is a class Data, whom instances are used by many other Processor objects. It can happen, that a Manager object deletes the Data object, so the Processors have invalid pointers. It must be made such a design, where the Processors can check the Data pointers before using it, if it is still valid or not. My solution: class Handler; class Data { boost::shared_ptr< Data > m_sharedPtr; //shared pointer to myself public: Data(); ~Data() {}; Handler getHandler(); int aMethod(); .... }; class Handler { boost::weak_ptr< CTrain > m_weakPtr; //weak pointer to the handled Data public: Handler(boost::shared_ptr< Data > data) bool aMethod(int& result); ... }; Data::Data() : m_sharedPtr(this) {} Data::~Data() {} Handler Data::getHandler() { return Handler(m_sharedPtr); } int Data::aMethod() { return 1; } Handler::Handler(boost::shared_ptr< Data > data) : m_weakPtr(train) {} bool Handler::aMethod(int& result) { bool retVal = !m_weakPtr.expired(); if (retVal) { boost::shared_ptr< Data > p = m_weakPtr.lock(); result = p->aMethod(); } return retVal; } When somebody wants to access a Data object, it gets only a Handler to it. The Handler can check with its weak pointer, if the corresponding shared pointer is expired (data object deleted) or not. Thus it can be assured, that no invalid pointer of the Data object will be used by the Processors. If the Manager object (who has a container of Data* ) deletes a data object, the corresponding Handler gives false back, because m_weakPtr.expired() returns false. So everything seems to be OK, but there are several problems and questions: 1. the destructor of the Data object will be called twice, when the Manager calls 'delete data;': - Once, when by the delete. - Once by the m_sharedPtr. After this the use_count() method returns -1 (!!!) and the m_weakPtr.expired() returns true (!!!). To eliminate this problem I initialize the m_sharedPtr in the Data constructor in the following way: m_sharedPtr(this, emptyDeleter), where emptyDeleter is an empty method: void emptyDeleter(Data* data) { } 2. What happens, if one of the Processors locks its m_weakPtr to obtain a shared pointer to acces the Data, but after obtaining the shared pointer the manager deletes the corresponding data object? If the Processor tries to acces again the (deleted) data object --> core dump. I have found the following solution to this problem: - before deletion the Manager somehow checks if data->m_sharedPtr.unique() returns true. If not, it refuses to delete the data object. 3. The Data object will be accessed many times by many Processors, and by every access the following construction will be used: if (!m_weakPtr.expired()) { boost::shared_ptr< Data > p = m_weakPtr.lock(); // do job on p ... } My question is: how "expensive" is such a construction? How fast is to obtain a shared pointer from a weak pointer unsing lock()? If you already met the problem of these "safe" pointers and have an other solution, please share it with us. Or if you have a comment to my solution, then say it too. :) Thanks, Jozsef Kercso

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