October 2003 - Boost-users - lists.preview.boost.org

mpl + enum + VC = error
by nagual 06 Oct '03

06 Oct '03

Hello, All! I write simple code: =============mpl_enum.cpp============= #include <boost/mpl/range_c.hpp> #include <boost/mpl/for_each.hpp> #include <iostream> enum test_e {ONE, TWO, THREE}; void f(test_e e) { const char* names[] = {"ONE", "TWO", "THREE"}; std::cout<<names[e]<<std::endl; } typedef boost::mpl::range_c< test_e, ONE, static_cast<test_e>(THREE + 1) > range; int main() { boost::mpl::for_each<range>(f); return 0; } =============mpl_enum.cpp============= MSVC 7 (ver 13.00.9466) =============Command Line============== c:\cl /EHsc /GR /Zc:wchar_t /Zc:forScope /nologo mpl_enum.cpp =============Command Line============== =============Output===================== mpl_enum.cpp C:\Lang\Projects\boost\boost\mpl\aux_\integral_wrapper.hpp(78) : error C2440: 'return' : cannot convert from '' to 'test_e' Conversion to enumeration type requires an explicit cast (static_cast, C-style cast or function-style cast) C:\Lang\Projects\boost\boost\mpl\aux_\integral_wrapper.hpp(78) : while compiling class-template member function 'boost::mpl::integral_c<T,N>::operator`T'(void) const' with [ T=test_e, N=ONE ] C:\Lang\Projects\boost\boost\mpl\aux_\range_c\iterator.hpp(34) : see reference to class template instantiation 'boost::mpl::integral_c<T,N>' being compiled with [ T=test_e, N=ONE ] C:\Lang\Projects\boost\boost\mpl\for_each.hpp(70) : see reference to class template instantiation 'boost::mpl::range_c_iterator<N>' being compiled with [ N=boost::mpl::range_c<test_e,ONE,3>::start ] C:\Lang\Projects\boost\boost\mpl\for_each.hpp(101) : see reference to function template instantiation 'void boost::mpl::aux::for_each_impl<done>::execute(Iterator *,last *,transform_op *,void (__cdecl *)(test_e))' being compiled with [ done=false, Iterator=first ] C:\Lang\Projects\boost\boost\mpl\for_each.hpp(111) : see reference to function template instantiation 'void boost::mpl::for_each(F,range *,boost::mpl::identity<T> *)' being compiled with [ F=void (__cdecl *)(test_e), T=boost::mpl::void_ ] mpl_enum.cpp(15) : see reference to function template instantiation 'void boost::mpl::for_each(F,range *)' being compiled with [ F=void (__cdecl *)(test_e) ] =============Output===================== However gcc v3.2.3, icl v 7.1, bcc32 v5.6.4 compile it. (bcc32 show 3 equivalent warning). How use it in MSVC 7?

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remove_pointer
by Leo Landa 05 Oct '03

05 Oct '03

Good day to everyone, I am trying to find a portable enough implementation of remove_pointer (MSVC 6, MSVC 7.1, G++ 2.95.3, G++ 2.96). The "usual" template technique relies on partial template specialization, which MSVC 6.0 does not support. As far as I can tell, Boost's version of remove_pointer is a little bit of a "cheat" - i.e. it becomes predefined only for primitive types. Am I right about that? I'm a bit of a newb in these parts of London ;-) If this is true, then I'm screwed - and I can't convert a generic pointer type to the pointee type. If it is not true, then what is the technique? Leo. P.S. Just in case - I know how to figure out _whether_ the type is a pointer, and now just trying to strip it.

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iterators
by Witz 05 Oct '03

05 Oct '03

Hi, I would like to raise a couple of points about the iterator adaptors. Firstly, is it really necessary to have the predicate as part of the template specification for the filter_iterator? Surely it can be assumed that it will always be convertible to boost::function<bool (const value_type&)> ? Secondly, by allowing the return type of the function used by the transform_iterator to be a reference can we not use it to implement a more generic form of indirect_iterator? The code below gives a flavour of the idea. struct dereference { typedef int result_type; int* data_; dereference(int* data):data_(data){} int operator()(int i) const { return data_[i]; } }; int main() { int data[] = { 1,2,3,4,5,6,7,8 }; int keys[] = { 0,3,1,6,5,4,2,7 }; typedef boost::transform_iterator_generator<dereference, int*>::type indirect_iterator; indirect_iterator i(keys, dereference(data)), i_end(keys+8,dereference(data)); while(i != i_end) std::cout << *i++ << ' '; return 0; } The output is: 1 4 2 7 6 5 3 8 Witz

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boost library build consistency
by Thomas S. Urban 03 Oct '03

03 Oct '03

Is there any definition of how libraries are supposed to build? I've integrated the building of required boost libraries into the build system for our projects. There seems to be some inconsistency in what gets built and where it gets put. In particular, for the thread and regex libs, boost builds both shared and static versions of the libraries and puts them in a bin-stage subdirectory under the library build directory. However, for the filesystem library, only the static library gets built and the bin-stage/ directory is not used. Is there a standard behavior library developers are supposed to follow in this regard? Can I count on the bin-stage/ as a short-named location for the most recent build of any library? Are the boost or boost_filestsystem maintainers interested in the simple fix to the Jamfile to make that library behave like the other two I mentioned? Thanks Scott Urban

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parse error in format library
by Alan Stewart 03 Oct '03

03 Oct '03

I've been successfully using the tokenizer library for some time, and am very grateful for it. The format library looks very userful - I need to convert a bunch of old printf's to ostreams. However, in attempting to compile with gcc 2.96 I'm finding that there are many substitutions that need to be made, such as replacing "char_traits" with "basic_string". I'm using Boost 1.30.0 in production, but have also tried 1.30.2 with the same results. I see that the format library headers include the header file "boost/config.hpp". Is it likely that I have some sort of configuration error? Where do I find information on toolset compatabiliy for specific Boost libraries, since this one does not seem to be compatible with mine? -- D. Alan Stewart Senior Software Developer Layton Graphics, Inc. 155 Woolco Drive Marietta, GA 30065 Voice: 770/973-4312 Fax: 800/367-8192 http://www.layton-graphics.com

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Problem using Boost.thread : Class destructor called several times!
by Huck finn 02 Oct '03

02 Oct '03

Hi there, still a newbie question for you guys... I changed a bit the sample example from thread.cpp : here's the new code i'm trying: ----------------- boost::mutex io_mutex; // The iostreams are not guaranteed to be thread-safe! class FakeClass { public: FakeClass(int NewID):ID(NewID) { boost::mutex::scoped_lock scoped_lock(io_mutex); std::cout<<"FakeClass #"<<ID<<" says : "<<"I'm alive!"<<std::endl; } ~FakeClass() { boost::mutex::scoped_lock scoped_lock(io_mutex); std::cout<<"FakeClass #"<<ID<<" says : "<<"I'm being destroyed!"<<std::endl; } void operator()() { boost::mutex::scoped_lock scoped_lock(io_mutex); std::cout<<"Thread for FakeClass #"<<ID<<" has been started!"<<std::endl; } private: int ID; }; void main () { boost::thread_group group; FakeClass item1(1),item2(2); group.create_thread(item1); group.create_thread(item2); group.join_all(); std::cout<<" main ending..."<<std::endl; } ----------------------------- here's what I get when executing : FakeClass #1 says : I'm alive! FakeClass #2 says : I'm alive! FakeClass #1 says : I'm being destroyed! FakeClass #1 says : I'm being destroyed! FakeClass #1 says : I'm being destroyed! Thread for FakeClass #1 has been started! FakeClass #2 says : I'm being destroyed! FakeClass #1 says : I'm being destroyed! FakeClass #2 says : I'm being destroyed! FakeClass #2 says : I'm being destroyed! Thread for FakeClass #2 has been started! FakeClass #2 says : I'm being destroyed! main ending... FakeClass #2 says : I'm being destroyed! FakeClass #1 says : I'm being destroyed! Press any key to continue 1- I'm wondering why the destructor of my FakeClass is called 4 times for each items ??? 2- It says in the doc that the function that creates a thread "copies the function wrapped by threadfunc" and threadfunc would be in this case item1 and item2, does this means that the copy constructor is called every time a thread is created with an object? Thanks all! Simon _________________________________________________________________ MSN Messenger : discutez en direct avec vos amis ! http://messenger.fr.msn.ca/

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Problem with is_class and is_enum
by Romain Lerallut 02 Oct '03

02 Oct '03

In the following code, struct foo2 is mistakenly taken for an enum, which breaks is_class, which leads to some unfortunate problems in boost::python. Problem appears on both Boost 1.30.0 and a one-month old CVS checkout, using gcc 3.3.2 and 2.95 and Intel icc 7.1 for linux. I have tried specializing 'is_enum', setting it by hand to return 'false', but though it works for this simple case, it does no good when the call to is_enum is buried deep inside boost. I rely heavily on being able to do these implicit conversions for foo2, so if anyone has an idea on how to make this work, it would be great. Thanks in advance, Romain ---------------------------------------------------------------- #include <boost/type_traits/is_enum.hpp> #include <iostream> struct foo1 // this one is not detected as an enum { operator int() { return 0; } }; struct foo2 // this one *is* detected as an enum { template<typename T> operator T(){return 0;} }; int main() { std::cout<<boost::is_enum<int>::value<<"\n"; std::cout<<boost::is_enum<foo1>::value<<"\n"; std::cout<<boost::is_enum<foo2>::value<<"\n"; } -------------------------------------------------------------- Expected Result: 0 0 0 Actual Result: 0 0 1

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compilation on Win64 platform with MSVC7.1 for 64 bit
by bart.tanghe＠skynet.be 02 Oct '03

02 Oct '03

Hi, we're using Boost 1.30.0 with MSVC7.1 on a Win32 platform. Currently where working on a port to a Win64 platform using the MSVC7.1 for IA64 compiler. (13.10.2240.8 for IA64) I just compiled the code as is and unfortunately I encountered errors in boost headers. This probably is because of missing/bad defines for this 'unknown' platform in the config headers... I was wondering if somebody already tried to compile boost on a 64 bit platform, and if he/she succeeded? Or if there are known implementation details which would cause boost 'never' to work on 64 bit platforms? If there are no known 'showstoppers' then I suppose I'll have to go through the Boost Configuration Reference or should I look somewhere else? Thanks, Bart

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Compile Boost.thread libraries has a static library (.lib) with msvc 6 ?
by Huck finn 01 Oct '03

01 Oct '03

Hi everyone, I'm a total newbie to boost, but I've got to developp a project that could use some of the powerful boost libraries, so I'm trying to make a move in that way... Ok, most of the boost libraries I can build in a static way and create (.lib) files with Microsoft Visual Studio 6.0 for my partners to use . But I am having a problem doing the same thing with the Boost.Thread libraries... First question : Is it possible to build this librairy in a (.lib) file with msvc 6.0? I'm getting tons of warnings concerning "dllexport" problems, but the (.lib) are still created. I was wondering if someone could help me understanding/fixing the warning problems : warning C4275: non dll-interface class 'boost::noncopyable' used as base for dll-interface class 'boost::detail::condition_impl' c:\wrk\common\boost-1.30.2\boost\noncopyable.hpp(22) : see declaration of 'noncopyable' warning C4273: 'thread::thread' : inconsistent dll linkage. dllexport assumed. I really need to avoid using .dll in this project, so builing this static library is very important to me... Thanks in advance, Simon _________________________________________________________________ MSN Search, le moteur de recherche qui pense comme vous ! http://fr.ca.search.msn.com/

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