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

Boost on HPC system
by John Fletcher 06 Sep '06

06 Sep '06

I have been having a discussion with the system maintainer as to how boost should be installed on a cluster system. He has it installed as /apps/gnu64/boost which makes the include files /apps/gnu64/boost/include/boost and the example sources not installed where he expects users to go. It appears not convenient to use /usr/include or /usr/local/include as these are replicated across all the nodes. Can anyone say what has been done at other locations? My ideal is one where it is easy to pick up the header files when needed without having to make complicated provision. Thanks John Fletcher

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[MPL] Help with delayed placeholder expression evaluation
by Thyfate 06 Sep '06

06 Sep '06

Hello ! I have been trying to work with the MPL but I have some problems with the composition and argument binding concepts. 1/ Here is a problem I cannot find a solution for: I would like to have a placeholder expression (S) which takes a single argument which is itself a placeholder expression of 2 arguments (A). I want S when invoked with mpl::apply to return a lambda expression (B) of 1 argument which when invoked on (x) would yield the same result than applying the pair (x, x) to (A). This means I expect apply<S, A> == B and apply<B, x> == apply<A, x, x>. Could someone tell me if this is possible? (I know how to do this without a placeholder expression for (S) but I would like to improve my understanding of them) Typedef int_<1> one; Typedef plus<_1, _2> A; Typedef . S; Typedef typename apply<S, A>::type B; BOOST_STATIC_ASSERT(apply<B, one>::type::value == apply<A, one, one>::type::value) 2/ Why doesn't bind take a placeholder expression ? If I want to remap a placeholder expression, I can do for example: bind<typename lambda<plus<_1, _2>::type, _1, _1> but why doesn't the library invoke lambda by itself ? (bind< plus<_1, _2>, _1, _1> wont work) Is the combination bind/lambda the only way to remap placeholder expressions? 3/ What is the use of protect? Where can I find some examples? Thanks in advance, Charles

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assign shared_ptr to 0 in initialization list
by Scott Amort 06 Sep '06

06 Sep '06

Hello, I am in the process of converting an application that uses raw pointers to boost::shared_ptr. For example: ErrorWriter *writer_; now becomes: typedef boost::shared_ptr<ErrorWriter> ErrorWriterPtr; ErrorWriterPtr writer_; The problem is that, with raw pointers I was able to use 0-value pointers in the constructor, like so: Parser(ErrorWriter *writer) : writer_(writer) { } Parser testParser(0); So it was possible to initialize the class with an empty writer pointer, and then later in some other Parser code do this: if (writer_ == 0) { /* create default error writer */ } But now, with shared_ptr, I cannot assign or evaluate to 0. I understand that the default ErrorWriterPtr constructor and ErrorWriterPtr.reset() will provide me with an empty pointer that I can check like so: if (writer_.get() == 0) { /* create default error writer */ } But how do I rewrite the Parser constructor to fit this new idiom? If I have: Parser(ErrorWriterPtr writer) : writer_(writer) { } What is the equivalent to: Parser testParser(0); Thank you for any assistance! Best, Scott

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graph search algorithm
by kellygp 06 Sep '06

06 Sep '06

I have a undirected graph set on a 2D plane. Imagine the graph looking something like the USA where the edges form the borders of the states. I would like to automatically recognise all of the enclosed regions (the states) by searching the graph and store each state as a subgraph. How can I search the graph returning only the enclosed regions? Thanks, any suggestions appreciated.

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compile error with Boost Function object and templated function (Intel C++ compiler)
by Faheem Mitha 06 Sep '06

06 Sep '06

Hi, The following bit of code using Boost Function compiles fine with gcc 3.3 or later, but has problems with the Intel C++ compiler version 9.1, which produces the following error message. Is this a compiler bug, or is there something wrong with the code? If the former, I'd be grateful for suggestions of a workaround, and if the latter, please tell me what I'm doing wrong. Note that the corresponding version with no templates compiles without problems. Thanks in advance. Faheem. ************************************************************************** icpc -o foo.o -c -Wall -Werror -g -wd383,810,981,1418 cxxlib-icc -DBOOST_RAND -I/usr/local/include/boost-1_33_1 \foo.cpp foo.cpp(12): error: no operator "=" matches these operands operand types are: boost::function<int (), std::allocator<void>> = <unknown-type> choice = &rchoice<dim>; ^ ************************************************************* #include <boost/function.hpp> template<int dim> int rchoice() { return 1; } template<int dim> int foo(void) { boost::function<int ()> choice; choice = &rchoice<dim>; return choice(); } int main() { return foo<2>(); } ***************************************************************

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how to pass pointer to boost.python function in python?
by Qinfeng(Javen) Shi 06 Sep '06

06 Sep '06

Dear all, I wraped a v_varray class into python by boost. I called it in python, most of its attributes work well. Only when I call a.push(1.0),it crashed due to not match type.The problem is that my input argument in c++ is float*(for passing an array) while python has no pointer type. How can I pass a variable in python to a.push() to make sure it work correctly? Many thanks for help! Javen /*************************running result in python:****************/ >>> a.push(1.0) Traceback (most recent call last): File "<stdin>", line 1, in ? Boost.Python.ArgumentError: Python argument types in array_floatstar.push(array_floatstar, float) did not match C++ signature: push(v_array<float*> {lvalue}, float*) >>> /*************************v_array def in stack.h:****************/ #ifndef _STACK_H #define _STACK_H #include <stdlib.h> template<class T> class v_array{ public: int index; int length; T* elements; T last() { return elements[index-1];} void decr() { index--;} v_array() { index = 0; length=0; elements = NULL;} T& operator[](unsigned int i) { return elements[i]; } void push(const T &new_ele) { while(index >= length) { length = 2*length + 3; elements = (T *)realloc(elements,sizeof(T) * length); } this->elements[index++] = new_ele; } void alloc(int newLength) { elements = (T *)realloc(elements, sizeof(T) * newLength); length = newLength; } T pop() { if (index > 0) return this->elements[--index]; else return T(); } }; #endif /*************************stack.cpp for boost.python(bjam need it to build a stack.so file):****************/ // Boost Includes ============================================================== #include <boost/python.hpp> #include <boost/cstdint.hpp> // Includes ==================================================================== #include "stack.h" // Using ======================================================================= using namespace boost::python; // Declarations ================================================================ BOOST_PYTHON_OPAQUE_SPECIALIZED_TYPE_ID(float) // Module ====================================================================== BOOST_PYTHON_MODULE(stack) { class_< v_array<float*> >("array_floatstar", init< >()) .def(init< const v_array<float*>& >()) .def_readwrite("index", &v_array<float*>::index) .def_readwrite("length", &v_array<float*>::length) .def_readwrite("elements", &v_array<float*>::elements) .def("last", &v_array<float*>::last, return_value_policy< return_opaque_pointer >()) .def("decr", &v_array<float*>::decr) .def("push", &v_array<float*>::push) .def("alloc", &v_array<float*>::alloc) .def("pop", &v_array<float*>::pop, return_value_policy< return_opaque_pointer >()) ; } -- Qinfeng(Javen) Shi Research School of Information Sciences and Engineering Australian National University Locked Bag 8001 Canberra ACT 2601

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portable way to determine return type from class member function
by Peter Piehler 05 Sep '06

05 Sep '06

Hello, i look for a portable way to determine the return-type of a member function: #include <boost/utility/result_of.hpp> #include <boost/type_traits/function_traits.hpp> class CMyClass { public: int method( void ) {return 5;} }; template< typename T > struct result_of {}; template< typename R, typename A > struct result_of< R(*)(A) > { typedef R type; }; template< typename R > struct result_of< R(*)(void) > { typedef R type; }; template< typename R, typename C > struct result_of< R(C::*)(void) > { typedef R type; }; template< typename R, typename C, typename A > struct result_of< R(C::*)(A) > { typedef R type; }; /*...some other specialisations...*/ /* (1) OK, but I must now return-type and signature */ //typedef int (CMyClass::*fnPointer_t)(void); /* (2) OK, but I must now return-type and signature */ //typedef typeof(int(CMyClass::*)(void)) fnPointer_t; /* (3) OK, compiler determine return-type and signature if CMyClass::method non-ambiguous */ typedef typeof(&CMyClass::method) fnPointer_t; int main( ) { fnPointer_t p = &CMyClass::method; /* (4) OK */ result_of< fnPointer_t >::type i; /* (5) OK, if CMyClass::method non-ambiguous */ result_of< typeof(&CMyClass::method) >::type i2; /* (6) Failure, type expected */ //result_of< p >::type i3; /* (7) OK */ result_of< typeof(p) >::type i4; /* (8) Failure, no function pointer support */ //boost::result_of< fnPointer_t >::type i5; /* (9) Failure, no function pointer support */ //boost::result_of< typeof(&CMyClass::method) >::type i6; /* (10) Failure, no function pointer support */ //boost::function_traits< fnPointer_t >::result_type i7; /* (11) Failure, no function pointer support */ //boost::function_traits< typeof(&CMyClass::method) >::result_type i8; } Which is a portable way? My prefered solution is number 5, but i dont now whether typeof(&CMyClass::method) is portable. Why function pointer are not supported by boost::result_of and boost::function_traits templates? Thanks and Greetings, Peter

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Building Tests With Boost Test
by Eric Lemings 05 Sep '06

05 Sep '06

Hi, Can anyone point me to the documentation for writing Jamfiles to build tests that use the Boost Test library? All that I can find in the Boost Test documentation is source code. Thanks, Eric.

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[variant] MSVC7.1 produces an Internal Compiler error when variant gets too complicated
by Eoin 05 Sep '06

05 Sep '06

Hello I am developing a library which uses a variant like this one class my_class {}; typedef boost::make_recursive_variant< my_class, int , std::string, boost::posix_time::ptime, std::vector<boost::recursive_variant_>, std::map<std::string, boost::recursive_variant_> >::type param; Under a Debug build when the type my_class is not present everything compiles perfectly, however with my_class I get internal compiler errors such as the ones below; G:\Program Files (x86)\Microsoft Visual Studio .NET 2003\Vc7\include\xstring(827) : fatal error C1001: INTERNAL COMPILER ERROR (compiler file 'msc1.cpp', line 2701) Please choose the Technical Support command on the Visual C++ Help menu, or open the Technical Support help file for more information c1xx : fatal error C1063: INTERNAL COMPILER ERROR Please choose the Technical Support command on the Visual C++ Help menu, or open the Technical Support help file for more information While playing around with the code and making adjustments (like reordering the types for the variant) I once got the compiler to display this error; fatal error C1067: compiler limit : debug information module size exceeded Searchs on the net pointed to using the #pragma component (mintypeinfo, on ) around the offending code, but even when I include this pragam enclosing the entire header containing my variant type I continue to get the Internal Compiler Error for some files, though it does go away for others. As hinted to by searches on the net this problem seems to be related to debug information and indeed everything does work fine under a release build. However as I am developing a library for use by others I cannot force them to avoid debug builds :^) . Everything works fine with the lastest MinGW debug or release. Any suggestions would be very much appreciated. Kind Regards, Eoin.

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Too stupid to install Boost
by Thomas 05 Sep '06

05 Sep '06

Hi, I would like to use the Boost RegEx Library. Somehow I failed installing it (WinXP, VC6). Is there a step by step instruction to get boost running under this configuration? The steps I took so far: 1) Set the MSDevDir and MSVCDir EnvVars by hand. 2) Compiled BJam and copied it to the boost root. 3) Execute bjam "-sTOOLS msvc" install 4) Set the path for include files and libraries in Tools->Options->Directories to the folder I unzipped Boost to. Got the following error messages while trying to compile a simple regex example :( Thanks in advance, Thomas --------------------Configuration: trwetst - Win32 Release-------------------- Compiling... trwetst.cpp C:\BOOST\boost/regex/v4/perl_matcher_common.hpp(129) : error C2664: '__thiscall boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,struct boost::re gex_traits<char,class boost::w32_regex_traits<char> > > >::boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > >(class boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > > *,bool (__thiscall T::*)(void ))' : cannot convert parameter 2 from 'bool (__thiscall boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >::*' to 'bool (__ thiscall T::*)(void)' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast C:\BOOST\boost/shared_ptr.hpp(246) : while compiling class-template member function 'bool __thiscall boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,struct boost::regex_traits<char,cla ss boost::w32_regex_traits<char> > >::protected_call(bool (__thiscall boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,struct boost::regex_traits<char,class boost::w32_regex_traits<char> > >::* )' C:\BOOST\boost/regex/v4/perl_matcher_common.hpp(129) : error C2664: '__thiscall boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,class boost::cpp _regex_traits<char> > >::boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,class boost::cpp_regex_traits<char> > >(class boost::re_detail::perl_ma tcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,class boost::cpp_regex_traits<char> > *,bool (__thiscall T::*)(void))' : cannot convert parameter 2 from 'bool (__thiscall boost::re_detail::perl_matcher<char const *,cl ass std::allocator<struct boost::sub_match<char const *> >,class boost::cpp_regex_traits<char> >::*' to 'bool (__thiscall T::*)(void)' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast C:\BOOST\boost/shared_ptr.hpp(246) : while compiling class-template member function 'bool __thiscall boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,class boost::cpp_regex_traits<char> >::protected_call(bool (__thiscall boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,class boost::cpp_regex_traits<char> >::*)' C:\BOOST\boost/regex/v4/perl_matcher_common.hpp(129) : error C2664: '__thiscall boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,struct boost::c_ regex_traits<char> > >::boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,struct boost::c_regex_traits<char> > >(class boost::re_detail::perl_matc her<char const *,class std::allocator<struct boost::sub_match<char const *> >,struct boost::c_regex_traits<char> > *,bool (__thiscall T::*)(void))' : cannot convert parameter 2 from 'bool (__thiscall boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,struct boost::c_regex_traits<char> >::*' to 'bool (__thiscall T::*)(void)' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast C:\BOOST\boost/shared_ptr.hpp(246) : while compiling class-template member function 'bool __thiscall boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,struct boost::c_regex_traits<char> >::protected_call(bool (__thiscall boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,struct boost::c_regex_traits<char> >::*)' C:\BOOST\boost/regex/v4/perl_matcher_common.hpp(129) : error C2664: '__thiscall boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,class boost::w32 _regex_traits<char> > >::boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,class boost::w32_regex_traits<char> > >(class boost::re_detail::perl_ma tcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,class boost::w32_regex_traits<char> > *,bool (__thiscall T::*)(void))' : cannot convert parameter 2 from 'bool (__thiscall boost::re_detail::perl_matcher<char const *,cl ass std::allocator<struct boost::sub_match<char const *> >,class boost::w32_regex_traits<char> >::*' to 'bool (__thiscall T::*)(void)' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast C:\BOOST\boost/shared_ptr.hpp(246) : while compiling class-template member function 'bool __thiscall boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,class boost::w32_regex_traits<char> >::protected_call(bool (__thiscall boost::re_detail::perl_matcher<char const *,class std::allocator<struct boost::sub_match<char const *> >,class boost::w32_regex_traits<char> >::*)' C:\BOOST\boost/regex/v4/perl_matcher_common.hpp(129) : error C2664: '__thiscall boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const * > >,struct boost::regex_traits<unsigned short,class boost::w32_regex_traits<unsigned short> > > >::boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<uns igned short const *> >,struct boost::regex_traits<unsigned short,class boost::w32_regex_traits<unsigned short> > > >(class boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,s truct boost::regex_traits<unsigned short,class boost::w32_regex_traits<unsigned short> > > *,bool (__thiscall T::*)(void))' : cannot convert parameter 2 from 'bool (__thiscall boost::re_detail::perl_matcher<unsigned short const *,class std::allocato r<struct boost::sub_match<unsigned short const *> >,struct boost::regex_traits<unsigned short,class boost::w32_regex_traits<unsigned short> > >::*' to 'bool (__thiscall T::*)(void)' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast C:\BOOST\boost/shared_ptr.hpp(246) : while compiling class-template member function 'bool __thiscall boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,struct boost::r egex_traits<unsigned short,class boost::w32_regex_traits<unsigned short> > >::protected_call(bool (__thiscall boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,struct boost:: regex_traits<unsigned short,class boost::w32_regex_traits<unsigned short> > >::*)' C:\BOOST\boost/regex/v4/perl_matcher_common.hpp(129) : error C2664: '__thiscall boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const * > >,class boost::cpp_regex_traits<unsigned short> > >::boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,class boost::cpp_rege x_traits<unsigned short> > >(class boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,class boost::cpp_regex_traits<unsigned short> > *,bool (__thiscall T::*)(void))' : cannot convert parameter 2 from 'bool (__thiscall boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,class boost::cpp_regex_traits<unsigned short> >::*' to 'bool (__thiscall T::*)(v oid)' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast C:\BOOST\boost/shared_ptr.hpp(246) : while compiling class-template member function 'bool __thiscall boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,class boost::cp p_regex_traits<unsigned short> >::protected_call(bool (__thiscall boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,class boost::cpp_regex_traits<unsigned short> >::*)' C:\BOOST\boost/regex/v4/perl_matcher_common.hpp(129) : error C2664: '__thiscall boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const * > >,struct boost::c_regex_traits<unsigned short> > >::boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,struct boost::c_regex_ traits<unsigned short> > >(class boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,struct boost::c_regex_traits<unsigned short> > *,bool (__thiscall T::*)(void))' : cannot co nvert parameter 2 from 'bool (__thiscall boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,struct boost::c_regex_traits<unsigned short> >::*' to 'bool (__thiscall T::*)(void) ' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast C:\BOOST\boost/shared_ptr.hpp(246) : while compiling class-template member function 'bool __thiscall boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,struct boost::c _regex_traits<unsigned short> >::protected_call(bool (__thiscall boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,struct boost::c_regex_traits<unsigned short> >::*)' C:\BOOST\boost/regex/v4/perl_matcher_common.hpp(129) : error C2664: '__thiscall boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const * > >,class boost::w32_regex_traits<unsigned short> > >::boost::re_detail::concrete_protected_call<class boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,class boost::w32_rege x_traits<unsigned short> > >(class boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,class boost::w32_regex_traits<unsigned short> > *,bool (__thiscall T::*)(void))' : cannot convert parameter 2 from 'bool (__thiscall boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,class boost::w32_regex_traits<unsigned short> >::*' to 'bool (__thiscall T::*)(v oid)' Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast C:\BOOST\boost/shared_ptr.hpp(246) : while compiling class-template member function 'bool __thiscall boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,class boost::w3 2_regex_traits<unsigned short> >::protected_call(bool (__thiscall boost::re_detail::perl_matcher<unsigned short const *,class std::allocator<struct boost::sub_match<unsigned short const *> >,class boost::w32_regex_traits<unsigned short> >::*)' Error executing cl.exe. trwetst.exe - 8 error(s), 0 warning(s)

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