July 2006 - Boost-users - lists.preview.boost.org

Re: [Boost-users] [iterator] reverse_iterator from iterators thatreturn references to data in self.
by Seb Martel 17 Jul '06

17 Jul '06

"David Abrahams" <dave(a)boost-consulting.com> wrote in message news:<uwtafgdi0.fsf(a)boost-consulting.com>... > "Seb Martel" <smartel(a)real.com> writes: > > > Hello, > > > > given something like: > > > > class ProxyIterator > > : public boost::iterator_facade<ProxyIterator, Costly, boost::random_access_traversal_tag> > > { > > public: > > ProxyIterator(FactoryOfCostly* pF, int i ) : m_pFactory( pF ), m_index( i ) > > {} > > private: > > friend class boost::iterator_core_access; > > void decrement() {--m_index;} > > // ... and others > > > > Costly& dereference() const > > { > > m_value = m_pFactory->MakeCostlyAtIndex( m_index ); > > return m_value; > > } > > private: > > FactoryOfCostly* m_pFactory; > > int m_index; > > mutable Costly m_value; > > }; > > You might need to do something to prevent this from being reported as > a valid random access (or even forward) iterator. 24.1.3: > > --- If a and b are both dereferenceable, then a == b if and only if *a > and *b are the same object. > As in &(*a) == &(*b) ? That's just cruel. But then again, vector<bool> comes to mind... Which reminds me: Is http://boost.org/libs/iterator/doc/new-iter-concepts.html making any progress ? > > You could build a reverse_iterator like the one you propose by storing > the inner iterator within a boost::optional wrapper, and only > initializing it upon dereference. > I might just name it the DamnYou2413ReverseIterator. Tx! -seb

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Macro to contruct/allocate a shared_ptr?
by bringiton bringiton 17 Jul '06

17 Jul '06

I'm trying to define a MACRO that creates a shared_ptr and hides memory allocation. Here is what i have so far: #define NEW0(T) boost::shared_ptr<T>(new T()); #define NEW1(T, p1) boost::shared_ptr<T>(new T(p1)); #define NEW2(T, p1, p2) boost::shared_ptr<T>(new T(p1, p2)); #define NEW3(T, p1, p2, p3) boost::shared_ptr<T>(new T(p1, p2, p3)); --------------------------------- Example of usage for the type Test: class Test { public: Test() {;} Test(int p1) {;} Test(int p1, char p2) {;} Test(int p1, char p2, std::string p3) {;} }; boost::shared_ptr<Test> p0 = NEW0(Test); boost::shared_ptr<Test> p1 = NEW1(Test, 100); boost::shared_ptr<Test> p2 = NEW2(Test, 100, 'a'); boost::shared_ptr<Test> p3 = NEW3(Test, 100, 'a', "hello"); --------------------------------- Is there a better way to do this? I would prefer to use a function instead of a MACRO. But I don't think it is possible because it is not know how many paramaters are in T's constructor. // not sure how to do this (or whether possible) // i am not sure how to implement the variable parameters // (hense the .. in my syntax) template <class T> boost::shared_ptr<T> New(...) { boost::shared_ptr<T> p(new T(...)); return p; } Any ideas? I often have problems with the c++ syntax when creating my own containers because i want to allocate T within the implementation (instead of passing pointers and having the user manage the memory).

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Regex build problem using g++ under cygwin
by Nindi Singh 16 Jul '06

16 Jul '06

Hi Darren .... I had problems with Boost Python which i think which were similar to yours .... i managed to get around them .... take a look at the subject 'Boost Python not linking under Cygwin' posted 16 Jul 14:16 let me know if indeed it is the same problem .. and if the soltuion works for you N

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Fw: [regex]How to get Content-Type's parameter pairs using boost.regex?
by Mockey Chen 16 Jul '06

16 Jul '06

Hi, experts, I using boost.regex parse the content-type header's value in MIME. A typical content-type's BNF like following: Content-Type = "Content-Type:" SP media-type media-type = type "/" subtype *( ";" gen-param ) type = token subtype = token gen-param = pname [ "=" pval ] pname = token pval = token / quoted-string An example content-type as following: multipart/mixed; boundary="theboundary" ;id=33 There may be zero or one more parameters in content-type. My parse code as following: #include <boost/regex.hpp> #include <iostream> #include <string> #define COUT(x) std::cout << x << std::endl #define VAR(v) std::cout << #v << ": " << v << std::endl #define TOKEN "[a-zA-Z0-9]+" #define TYPE "(" TOKEN ")" #define SUBTYPE "(" TOKEN ")" #define PNAME "(" TOKEN ")" #define PVALUE "(" TOKEN ")" #define PARAM "(;" PNAME "=" PVALUE ")" #define CONTENT_TYPE_EXPRESS TYPE "/" SUBTYPE PARAM "*" int main() { std::string ct("multipart/mixed;boundary=theboundary;id=33"); COUT(CONTENT_TYPE_EXPRESS); boost::regex regex_content_type(CONTENT_TYPE_EXPRESS); boost::smatch result; if (boost::regex_match(ct, result, regex_content_type)) { VAR(result.size()); for (unsigned int i=0; i<result.size(); ++i) { if (result[i].matched) { COUT("result[" << i << "] = " << result[i]); } } } else { COUT("match failed."); } return 0; } /** output: ([a-zA-Z0-9]+)/([a-zA-Z0-9]+)(;([a-zA-Z0-9]+)=([a-zA-Z0-9]+))* result.size(): 6 result[0] = multipart/mixed;boundary=theboundary;id=33 result[1] = multipart result[2] = mixed result[3] = ;id=33 result[4] = id result[5] = 33 */ I want to get the parameter "boundary" and its value. Any way to do it? Sebastian Redl said: Not really. Regex doesn't support getting each submatch in a repeated expression. Xpressive does, but in this case, I think you'd be better off modelling the content-type grammar in Spirit and using that. Anyway, this question should have gone to boost-users, so I forward this to boost-users. Thanks in advance. -- Regards. Mockey Chen

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Boost Python not linking uder Cygwin
by Nindi Singh 16 Jul '06

16 Jul '06

Apologies for resending this email ... but for some reason my last email ended up as a reply for a completely disconnected subject.... TWICE. I am able to build my Python Extension Module under MSVC 7.1, MSVC 8.0 and GCC (LINUX). However I cannot seem to build it under Cygwin gcc. The output of uname is CYGWIN_NT-5.1 The output of gcc -v is : Reading specs from /usr/lib/gcc/i686-pc-cygwin/3.4.4/specs Configured with: /gcc/gcc-3.4.4/gcc-3.4.4-1/configure --verbose --prefix=/usr --exec-prefix=/usr --sysconfdir=/etc --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/ info --enable-languages=c,ada,c++,d,f77,java,objc --enable-nls --without-included-gettext --enable-version-specific-runtime-libs --without-x --enable-libgcj --disable-java-awt --with-system-zlib ble-interpreter --disable-libgcj-debug --enable-threads=posix --enable-java-gc=boehm --disable-win32-registry --enable-sjlj-exceptions --enable-hash-synchronization --enable-libstdcxx-debug : (r gured) Thread model: posix gcc version 3.4.4 (cygming special) (gdc 0.12, using dmd 0.125) My compile command line is : g++ -o /cygdrive/c/Build/cygwin/gcc/3.4.4/Debug/Intermediate/PythonPapa/PythonPapa.dll -shared /cygdrive/c/Build/cygwin/gcc/3.4.4/Debug/Intermediate/PythonPapa/main.os /cygdrive/c/Build/cygwin/gcc/3. .4/Debug/Intermediate/PythonPapa/StdVector.os -L/cygdrive/c/Build/cygwin/gcc/3.4.4/Debug -L/usr/local/lib -L/lib/python2.4/config -lPapaGateWay -lboost_python-gcc-mt-d-1_33_1 -lpython2.4 -lPapaGa eWay Then there are ALOT of errors .. here are the last few lines : /usr/local/include/boost-1_33_1/boost/python/object/make_ptr_instance.hpp:(.text$_ZN5boost6python7objects14pointer_holderIPSt6vectorIdSaIdEES5_ED1Ev[boost::python::objects::pointer_holder<std::vector< double, std::allocator<double> >*, std::vector<double, std::allocator<double> > >::~pointer_holder()]+0x16): undefined reference to `__imp___ZN5boost6python15instance_holderD2Ev' /usr/local/include/boost-1_33_1/boost/python/object/make_ptr_instance.hpp:(.text$_ZN5boost6python7objects14pointer_holderIPSt6vectorIdSaIdEES5_ED0Ev[boost::python::objects::pointer_holder<std::vector< double, std::allocator<double> >*, std::vector<double, std::allocator<double> > >::~pointer_holder()]+0x16): undefined reference to `__imp___ZN5boost6python15instance_holderD2Ev' /usr/local/include/boost-1_33_1/boost/python/object/make_ptr_instance.hpp:(.text$_ZN5boost6python7objects14pointer_holderIPSt6vectorImSaImEES5_ED1Ev[boost::python::objects::pointer_holder<std::vector< unsigned long, std::allocator<unsigned long> >*, std::vector<unsigned long, std::allocator<unsigned long> > >::~pointer_holder()]+0x16): undefined reference to `__imp___ZN5boost6python15instance_holde rD2Ev' /usr/local/include/boost-1_33_1/boost/python/object/make_ptr_instance.hpp:(.text$_ZN5boost6python7objects14pointer_holderIPSt6vectorImSaImEES5_ED0Ev[boost::python::objects::pointer_holder<std::vector< unsigned long, std::allocator<unsigned long> >*, std::vector<unsigned long, std::allocator<unsigned long> > >::~pointer_holder()]+0x16): undefined reference to `__imp___ZN5boost6python15instance_holde rD2Ev' /usr/local/include/boost-1_33_1/boost/python/object/make_ptr_instance.hpp:(.text$_ZN5boost6python7objects14pointer_holderIPSt6vectorIN17__papa__namespace16pTemplateVariantINS4_14pTemplateArrayIdEENS4_ 15pTemplateMatrixIdEEEESaISA_EESC_ED1Ev[boost::python::objects::pointer_holder<std::vector<__papa__namespace::pTemplateVariant<__papa__namespace::pTemplateArray<double>, __papa__namespace::pTemplateMa trix<double> >, std::allocator<__papa__namespace::pTemplateVariant<__papa__namespace::pTemplateArray<double>, __papa__namespace::pTemplateMatrix<double> > > >*, std::vector<__papa__namespace::pTemplat eVariant<__papa__namespace::pTemplateArray<double>, __papa__namespace::pTemplateMatrix<double> >, std::allocator<__papa__namespace::pTemplateVariant<__papa__namespace::pTemplateArray<double>, __papa__ namespace::pTemplateMatrix<double> > > > >::~pointer_holder()]+0x16): undefined reference to `__imp___ZN5boost6python15instance_holderD2Ev' /cygdrive/c/Build/cygwin/gcc/3.4.4/Debug/Intermediate/PythonPapa/StdVector.os:/usr/local/include/boost-1_33_1/boost/python/object/make_ptr_instance.hpp:(.text$_ZN5boost6python7objects14pointer_holderI PSt6vectorIN17__papa__namespace16pTemplateVariantINS4_14pTemplateArrayIdEENS4_15pTemplateMatrixIdEEEESaISA_EESC_ED0Ev[boost::python::objects::pointer_holder<std::vector<__papa__namespace::pTemplateVar iant<__papa__namespace::pTemplateArray<double>, __papa__namespace::pTemplateMatrix<double> >, std::allocator<__papa__namespace::pTemplateVariant<__papa__namespace::pTemplateArray<double>, __papa__name space::pTemplateMatrix<double> > > >*, std::vector<__papa__namespace::pTemplateVariant<__papa__namespace::pTemplateArray<double>, __papa__namespace::pTemplateMatrix<double> >, std::allocator<__papa__n amespace::pTemplateVariant<__papa__namespace::pTemplateArray<double>, __papa__namespace::pTemplateMatrix<double> > > > >::~pointer_holder()]+0x16): more undefined references to `__imp___ZN5boost6pytho n15instance_holderD2Ev' follow /cygdrive/c/Build/cygwin/gcc/3.4.4/Debug/Intermediate/PythonPapa/StdVector.os: In function `_ZN5boost6python7objects17make_ptr_instanceIN17__papa__namespace16pTemplateVariantINS3_14pTemplateArrayIdEEN S3_15pTemplateMatrixIdEEEENS1_14pointer_holderIPS9_S9_EEE9constructISB_EEPSC_PvP7_objectRT_': /usr/local/include/boost-1_33_1/boost/python/object/make_ptr_instance.hpp:(.text$_ZN5boost6python7objects14pointer_holderIPSt6vectorIN17__papa__namespace16pTemplateVariantINS4_14pTemplateArrayIdEENS4_ 15pTemplateMatrixIdEEEESaISA_EESC_E5holdsENS0_9type_infoEb[boost::python::objects::pointer_holder<std::vector<__papa__namespace::pTemplateVariant<__papa__namespace::pTemplateArray<double>, __papa__nam espace::pTemplateMatrix<double> >, std::allocator<__papa__namespace::pTemplateVariant<__papa__namespace::pTemplateArray<double>, __papa__namespace::pTemplateMatrix<double> > > >*, std::vector<__papa__ namespace::pTemplateVariant<__papa__namespace::pTemplateArray<double>, __papa__namespace::pTemplateMatrix<double> >, std::allocator<__papa__namespace::pTemplateVariant<__papa__namespace::pTemplateArra y<double>, __papa__namespace::pTemplateMatrix<double> > > > >::holds(boost::python::type_info, bool)]+0xea): undefined reference to `__imp___ZN5boost6python7objects17find_dynamic_typeEPvNS0_9type_info ES3_' /usr/local/include/boost-1_33_1/boost/python/object/make_ptr_instance.hpp:(.text$_ZN5boost6python7objects14pointer_holderIPSt6vectorImSaImEES5_E5holdsENS0_9type_infoEb[boost::python::objects::pointer_ holder<std::vector<unsigned long, std::allocator<unsigned long> >*, std::vector<unsigned long, std::allocator<unsigned long> > >::holds(boost::python::type_info, bool)]+0xea): undefined reference to ` __imp___ZN5boost6python7objects17find_dynamic_typeEPvNS0_9type_infoES3_' /usr/local/include/boost-1_33_1/boost/python/object/make_ptr_instance.hpp:(.text$_ZN5boost6python7objects14pointer_holderIPSt6vectorIdSaIdEES5_E5holdsENS0_9type_infoEb[boost::python::objects::pointer_ holder<std::vector<double, std::allocator<double> >*, std::vector<double, std::allocator<double> > >::holds(boost::python::type_info, bool)]+0xea): undefined reference to `__imp___ZN5boost6python7obje cts17find_dynamic_typeEPvNS0_9type_infoES3_' collect2: ld returned 1 exit status Also I expected to see an import library build for the boost_python.dll, but i can't see that it is .. this is the contents of my /usr/local/lib libboost_python-gcc-1_33_1.a libboost_python-gcc-d-1_33_1.dll libboost_python-gcc-mt-1_33_1.dll libboost_python-gcc-mt-d.a libcppunit.a libboost_python-gcc-1_33_1.dll libboost_python-gcc-d.a libboost_python-gcc-mt-d-1_33_1.a libboost_python-gcc-mt.a libcppunit.la libboost_python-gcc-d-1_33_1.a libboost_python-gcc-mt-1_33_1.a libboost_python-gcc-mt-d-1_33_1.dll libboost_python-gcc.a I cannot see any .dll.lib or .dll.a I would appricate any comments on this problems. Thanx Ninds

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[shmem] error while closing the segment
by Sascha Lumma 16 Jul '06

16 Jul '06

Hi, I get an error when I try to close the shared memory segment. My destructor calls simply mysegm.close(). I get the message below, but I can't interpret it so that I can do anything with it. It happens only if before a child process, that works in this segment too, is terminated erroneous and subsequently a faultless run was done. But to close the segment should be possible after errors too and at any time. When I restart my application without deleting the segment by hand it hangs in the constructor and I can wait forever, without any message. Thanks a lot, Sascha boost/shmem/detail/segment_manager.hpp:698: bool boost::shmem::detail::segment_manager<CharType, MemoryAlgorithm, IndexType>::priv_generic_named_destroy(const CharT*, typename boost::shmem::detail::segment_manager<CharType, MemoryAlgorithm, IndexType>::index_traits<CharT>::index_type&) [with T = std::pair<int, int>, CharT = char, CharType = char, MemoryAlgorithm = boost::shmem::simple_seq_fit<boost::shmem::shared_mutex_family, boost::shmem::offset_ptr<void, boost::shmem::offset_1_null_ptr> >, IndexType = boost::shmem::flat_map_index]: Assertion `0' failed. Program received signal SIGABRT, Aborted. [Switching to Thread 1076082048 (LWP 6141)] 0xffffe410 in ?? () (gdb) backtrace #0 0xffffe410 in ?? () #1 0xbfffead0 in ?? () #2 0x00000006 in ?? () #3 0x000017fd in ?? () #4 0x4014d7a1 in raise () from /lib/tls/libc.so.6 #5 0x4014ef79 in abort () from /lib/tls/libc.so.6 #6 0x40146fe3 in __assert_fail () from /lib/tls/libc.so.6 #7 0x41b6f53e in priv_generic_named_destroy<std::pair<int, int>, char> (this=0x30000008, name=Variable "name" is not available. ) at lock.hpp:85 #8 0x41b64c45 in ~Mosilapy (this=Variable "this" is not available. ) at segment_manager.hpp:432

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templates for class member functions
by bringiton bringiton 15 Jul '06

15 Jul '06

sorry this is not a boost question, but wondering whether you guys could help with templates. I want to place template parameters on a class's member function. however it does not work: class Test { public: template <class T> void DoTest(T t) { cout << t; } }; Test t; t.DoTest<int>(2); //error C2062: type 'int' unexpected is it possible to do this?

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enable thread safety
by Winson Yung 15 Jul '06

15 Jul '06

Hello, I am building boost regex using VC6, and I am not sure BOOST_HAS_THREADS is enabled by default or not. Reading http://www.boost.org/libs/regex/doc/thread_safety.html, it doesn't tell me which file to look, and how to enable it under VC6 if disabled by default. Could somebody help me on this please? Thanks! /Winson

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Linking libboost...
by Martin Kardigen 15 Jul '06

15 Jul '06

Hello, I'm using test test libraries from boost to testing my code. I want to create Makefile.am rules for my project but I don't know how to define needed libboost libraries because all of boost libraries have -gcc suffix. What I have to do if I want to have code that would be compiled and linked in other compilers then gcc ??? Where can I find some clues about linking BOOST?

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[mpl] Help with simple algorithm needed
by Stephan Tolksdorf 15 Jul '06

15 Jul '06

Hi I'm trying to build a mpl::vector which looks like [(a,1),(a,2),...,(a,a),(a+1,1),...,(b,b)], where a < b are int's and (x,y) stands for mpl::pair< int_<x>, int_<y> >. The following code does not compile with MSVC 8. Could somebody tell me what's wrong with my code? Does someone have an idea how to solve this problem more elegantly with MPL? Any help is much appreciated. Code snippet with the vector named "ListofNMPairs": template <typename N> struct NPush : mpl::lambda< mpl::push_front< mpl::_1, mpl::pair<N, mpl::_2> > >::type { }; template <typename S> struct MyRange : mpl::reverse_fold< mpl::range_c<int, 1, S::value + 1>, mpl::vector< >, NPush<S> >::type { }; typedef mpl::reverse_fold< mpl::range_c<int, 16, 66>, // a=16, b=65 mpl::vector< >, mpl::insert_range< mpl::_1, mpl::begin<mpl::_1>, MyRange<mpl::_2> > >::type ListofNMPairs; Regards, Stephan

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