April 2005 - Boost-users - lists.preview.boost.org

How to get type given pointer to base?
by Delfin Rojas 02 May '05

02 May '05

Hello all, I hope somebody can help me with this. What I want to do is the following: Let's say I have a templated class called Foo template<class U> class Foo { public: Foo(U * p) : m_p(p) {} ~Foo() {} U* getP() const { return m_p; } private: U* m_p; }; Now let's say I want to have a collection of pointers to Foo. What should I do? The possibilities I can think of are the following: 1) Create a class FooBase and have Foo inherit from FooBase. FooBase is non-templated so there should be no problem with having a collection of pointers to FooBase where I can put instances of Foo. The problem with this approach is that given a FooBase* in that collection I could not use the getP method because I would not know what type of Foo it holds. 2) Create a boost::variant of all the possible types of Foo<U>* I want to have. Then have a collection of this FooVariant. Using static visitation I can obtain the original type of Foo<U>* in a given FooVariant. The problem with this approach is that I get an ICE from VC++ 7.1 when the type of U gets too complex (shared_ptr to another type for example). Have I overlooked something? Is there a better technique for what I want to achieve? Any help would be great, Thanks Delfin Rojas

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Re: [Boost-users] Re: pimpl and boost
by Gottlob Frege 30 Apr '05

30 Apr '05

> Date: Fri, 29 Apr 2005 10:56:14 +0200 > From: David Gruener <gruenedd(a)idmt.fraunhofer.de> > Subject: Re: [Boost-users] Re: pimpl and boost > To: boost-users(a)lists.boost.org > Message-ID: <4271F6AE.20509(a)idmt.fraunhofer.de> > Content-Type: text/plain; charset=us-ascii; format=flowed > > Pavel Antokolsky aka Zigmar wrote: > > auto_ptr - compiled with warning about destroying incomplete type > > As i already mentioned, > very little to no benefit here over plain pointer. > > > shared_ptr - compiled and worked - the destructor of > > Yes, but you still have to provide assignment and copy > constructor for your standard cases. So, as i stated, little > benefit here over plain pointer too and an ideological problem that > shared_ptr used in this way, as serveral times suggested, > isn't a shared pointer anymore. > Again, whats needed is a pointer like Griffiths's grin_ptr > or Peter's impl_ptr. I'm looking forward to the > policy pointers. > > --David > I agree, if/when the need next arises, I will find/write an impl_ptr<>. I will also go with the technique mentioned earlier of ONLY putting the data in the impl_ptr, and not forwarding all the functions. (Still think it should be part of the language though. C++ proclaims to enable data-hiding, but it really doesn't. The speed/data-hiding trade-off that C++ originally made was fine for the times, but now that trade-off isn't so necessary...)

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Re: pimpl and boost
by Peter Dimov 30 Apr '05

30 Apr '05

Kyle Alons wrote: >> I wrote such a pointer several years ago: >> >> http://lists.boost.org/MailArchives/boost/msg21930.php >> http://groups.yahoo.com/group/boost/message/15313 >> http://groups.yahoo.com/group/boost/files/impl_ptr/impl_ptr.html >> >> but I never proposed it for Boost. >> >> The reason that I didn't propose it is that I don't use it. :-) > > Is the source code for this still available anywhere? I get > 'document not found' for the links on > http://groups.yahoo.com/group/boost/files/impl_ptr/impl_ptr.html. > Thanks. It's there: http://groups.yahoo.com/group/boost/files/impl_ptr/

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[Mac OS X] Problem compiling boost
by Daniel Lidström 29 Apr '05

29 Apr '05

Hello, I get linking errrors while trying to compile the program_options. Here is the output: Daniels-Monster:/Users/daniellidstrom/Desktop/boost_1_32_0> bjam --with-program_options stage ...found 468 targets... ...updating 4 targets... gcc-Link-action bin/boost/libs/program_options/build/libboost_program_options.dylib/ gcc/debug/shared-linkable-true/libboost_program_options-gcc-d -1_32.dylib g++: unrecognized option `-shared' ld: Undefined symbols: _main set -e DYLD_LIBRARY_PATH=bin/boost/libs/program_options/build/ libboost_program_options.dylib/gcc/debug/shared-linkable- true:$DYLD_LIBRARY_PATH export DYLD_LIBRARY_PATH "g++" -g -fPIC -shared -o "bin/boost/libs/program_options/build/libboost_program_options.dylib/ gcc/debug/shared-linkable-true/libboost_program_options-gcc-d -1_32.dylib" "bin/boost/libs/program_options/build/libboost_program_options.dylib/ gcc/debug/shared-linkable-true/cmdline.o" "bin/boost/libs/program_options/build/libboost_program_options.dylib/ gcc/debug/shared-linkable-true/config_file.o" "bin/boost/libs/program_options/build/libboost_program_options.dylib/ gcc/debug/shared-linkable-true/options_description.o" "bin/boost/libs/program_options/build/libboost_program_options.dylib/ gcc/debug/shared-linkable-true/parsers.o" "bin/boost/libs/program_options/build/libboost_program_options.dylib/ gcc/debug/shared-linkable-true/variables_map.o" "bin/boost/libs/program_options/build/libboost_program_options.dylib/ gcc/debug/shared-linkable-true/value_semantic.o" "bin/boost/libs/program_options/build/libboost_program_options.dylib/ gcc/debug/shared-linkable-true/positional_options.o" "bin/boost/libs/program_options/build/libboost_program_options.dylib/ gcc/debug/shared-linkable-true/utf8_codecvt_facet.o" "bin/boost/libs/program_options/build/libboost_program_options.dylib/ gcc/debug/shared-linkable-true/convert.o" "bin/boost/libs/program_options/build/libboost_program_options.dylib/ gcc/debug/shared-linkable-true/winmain.o" ...failed gcc-Link-action bin/boost/libs/program_options/build/libboost_program_options.dylib/ gcc/debug/shared-linkable-true/libboost_program_options-gcc-d -1_32.dylib... ...skipped <@boost!lib>libboost_program_options-gcc-d-1_32.dylib for lack of <@boost!libs!program_options!build/libboost_program_options.dylib/gcc/ debug/shared-linkable-true>libboost_program_options-gcc-d-1_32.dylib... I'm using gcc 3.2 (the one that came with XCode 1.5). Strange thing is the man page says -static is an option for both gcc and g++. How can I successfully compile the dynamic-link library? The static-link library was compiled successfully though. Also, I added -Wno-long-double to the g++ options, to get rid of an annoying warning. The gcc bjam file says there is no gcc or g++ on Darwin, but there certainly is for me. I'm using Mac OS X 10.3.9 with gcc 3.2 from XCode 1.5 installation. -- Daniel SBG AB

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shipping software depending on boost
by Wieger Wesselink 29 Apr '05

29 Apr '05

Hi, I have written some code for a software package that my group at the university is distributing, and it has dependencies on boost. Now my boss is getting very worried about the extra complications this brings for a user to install the software (note that the dependencies are not only header files). The package is currently installed using an autoconf script. I wonder how others deal with this situation. Is it best to ship the complete boost library as part of the installation, and handle the compilation of the used boost libraries by autoconf? Thanks, Wieger -- _______________________________________________ Surf the Web in a faster, safer and easier way: Download Opera 8 at http://www.opera.com Powered by Outblaze

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pimpl and boost
by David Gruener 29 Apr '05

29 Apr '05

Hi, i'm wondering if there is a nice smart pointer in boost to implement PImpl. I found an implementation here: [1]. So, does boost provide a smart pointer which does play nice with pimpl, so that one doesn't need to provide a destructor, copyconstructor and assignment operator for the default cases? --David [1] http://www.octopull.demon.co.uk/arglib/TheGrin.html.

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redefinition of `class boost::algorithm::iterator_range<IteratorT>'
by Michael Garriss 28 Apr '05

28 Apr '05

this program: #include <boost/algorithm/string.hpp> #include <boost/range.hpp> produces this error: In file included from /home/mgarriss/dev/tp-compiled/include/boost-1_32_0/boost/range.hpp:20, from range.cxx:2: /home/mgarriss/dev/tp-compiled/include/boost-1_32_0/boost/range/iterator_range.hpp:79: error: redefinition of `class boost::algorithm::iterator_range<IteratorT>' /home/mgarriss/dev/tp-compiled/include/boost-1_32_0/boost/algorithm/string/iterator_range.hpp:50: error: previous definition of `class boost::algorithm::iterator_range<IteratorT>' /home/mgarriss/dev/tp-compiled/include/boost-1_32_0/boost/range/iterator_range.hpp:380: error: `template<class IteratorT> boost::algorithm::iterator_range<IteratorT> boost::make_iterator_range(IteratorT, IteratorT)' conflicts with previous using declaration `template<class IteratorT> boost::algorithm::iterator_range<IteratorT> boost::algorithm::make_iterator_range(IteratorT, IteratorT)'

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bgl question: in which namespace to put the functions
by Andreas Fabri 28 Apr '05

28 Apr '05

Hello, Developping code so that BGL algorithms can run on the vertices and edges of CGAL triangulations, I am wondering if there are rules or recommendations for in which namespace the functions source, target, vertices, out_edges ... shall go. In boost, because it is boostish code, or in CGAL, because that is the namespace where the triangulation lives in? thank's in advance, andreas

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Re: pimpl and boost
by Gottlob Frege 28 Apr '05

28 Apr '05

> Today's Topics: > > 1. Re: pimpl and boost (Gennadiy Rozental) > 2. Re: Re: Re: pimpl and boost (David Gruener) > 3. Re: Re: Re: pimpl and boost (Jeff Flinn) > > ---------------------------------------------------------------------- > I so wish that pimpl was somehow part of the language. ie you don't worry about or see the pointer at all, nor do you have to forward all the function calls. I don't see why the compiler couldn't implement pimpl for me. (Of course, for cases where you want multiple implementations at run time, etc, you still do that yourself, but the typical case the compiler could do). Maybe: // h file class Foo interface { void GetX(); }; // cpp file: class Foo continue // some keyword { int x; }; Foo::GetX() { return x; } And just like implementing the same function twice, the linker could warn about 2 implementations of the same class. P.S. this could also allow you to keep some members defined in the h file, (and others in the cpp impl) if you wanted the speed of inlines for some variables, or public/protected variables, etc. Just a thought. Maybe I should complain elsewhere...

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Program_options and XML
by Jason Stewart 28 Apr '05

28 Apr '05

Has anyone implemented an XML parser for boost::program_options? I have just started looking into using this library but I need to read/write XML files. Before digging in and doing it myself I thought I'd ask if anyone has looked at the problem. Thanks, Jason Stewart

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