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iterator_adaptor: disguise iterator as const_iterator?
by Martin Wartens 03 Dec '04

03 Dec '04

Hi all, I am trying to disguise a std container non-const iterator as a const_iterator. My guess is that iterator_adaptor could be useful for this, but I can't figure it out myself. I am trying to solve an old problem with the standard library, which is that you can't convert a const_iterator into an iterator. [There are two "solutions" to that problem, one uses distance and is expensive, the other one does a brutal conversion on bitlevel which breaks for several std implementations.] My use case: I have written a wrapper class mymap for std::map. I only want to give map::const_iterators to the users of this class. If the user wants to erase an element from the map, he must pass a const_iterator back to the wrapper class and call "mymap::erase(const_iterator)". The problem is that mymap has no way to convert the const_iterator into an iterator to call "map::erase(iterator)" in turn [there is no "map::erase(const_iterator)"]. So my idea was to write a iterator_adaptor for iterator that lets it behave like a const_iterator. Unfortunately I didn't get very far. I have to say that the documentation was not of much help to me. There are lots of complicated implementation details but only small examples. So any help is appreciated. How can I solve my problem? Side note: In the following code sample, iterator_adaptor accidentally turns a const_iterator into a non-const iterator. (Seemingly, some bit-level casting is done somewhere). Is this a bug? #include <boost/iterator/iterator_adaptor.hpp> #include <map> template <class Value> class node_iter :public boost::iterator_adaptor<node_iter<Value>, Value> { public: node_iter() : node_iter::iterator_adaptor_(0) {} node_iter(Value p) : node_iter::iterator_adaptor_(p) {} }; int main() { typedef std::map<int, int> mymap_type; mymap_type testmap; node_iter<mymap_type::const_iterator> ni(testmap.begin()); ni->second = 42; //this works, not a const_iterator anymore } ___________________________________________________________________________ Die einen haben es, die anderen werden es! http://my-mail.ch/?redirect=9905 So macht schenken richtig Freude! Schenken und Helfen mit World Vision! http://www.my-mail.ch/?redirect=1958

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Re: newbie boost sample compile program
by Brian Gaber 02 Dec '04

02 Dec '04

Martin Lemieux <lemieux<at>cae.com> writes: 1) You describe to much path information in the #include directive in simple_ls.cpp . Like the Boost's .hpp, just start with "boost/(...).hpp". I fixed the path information in the #include directive to be "boost/filesystem/... 2) Then make sure your compiler command line at least mention "-I /user/local/include" or "-I $(INC)" where INC ~includes~ "/user/local/include". I get further, here is the new AIX compiler error: xlc++ -o simple_ls simple_ls.cpp -I /usr/local/include ld: 0711-317 ERROR: Undefined symbol: .boost::filesystem::initial_path() ld: 0711-317 ERROR: Undefined symbol: boost::filesystem::native(const std::basic_string<char,std::char_traits<char>,std::allocator<char> >&) ld: 0711-317 ERROR: Undefined symbol: .boost::filesystem::path::path(const char*,bool(*)(const std::basic_string<char,std::char_traits<char>,std::allocator<char> >&)) ld: 0711-317 ERROR: Undefined symbol: .boost::filesystem::system_complete(const boost::filesystem::path&) ld: 0711-317 ERROR: Undefined symbol: .boost::filesystem::exists(const boost::filesystem::path&) ld: 0711-317 ERROR: Undefined symbol: .boost::filesystem::path::native_file_string() const ld: 0711-317 ERROR: Undefined symbol: .boost::filesystem::is_directory(const boost::filesystem::path&) ld: 0711-317 ERROR: Undefined symbol: .boost::filesystem::path::native_directory_string() const ld: 0711-317 ERROR: Undefined symbol: .boost::filesystem::path::leaf() const ld: 0711-317 ERROR: Undefined symbol: .boost::filesystem::detail::dir_itr_init(boost::shared_ptr<boost::filesystem::detail::dir_itr_imp>&,const boost::filesystem::path&) ld: 0711-317 ERROR: Undefined symbol: .boost::filesystem::detail::dir_itr_dereference(const boost::shared_ptr<boost::filesystem::detail::dir_itr_imp>&) ld: 0711-317 ERROR: Undefined symbol: .boost::filesystem::detail::dir_itr_increment(boost::shared_ptr<boost::filesystem::detail::dir_itr_imp>&) ld: 0711-345 Use the -bloadmap or -bnoquiet option to obtain more information. 2a) On AIX, look inside your makefile. What am I looking for? > [...] MS Visual C++ 6 > generates the following similar error when attempting to compile > simple_ls.cpp > > c:\boost\include\boost-1_32\boost\filesystem\operations.hpp(18) : fatal > error C1083: Cannot open include file: 'boost/filesystem/path.hpp': No such file or directory 2b) On MSDEV6, add "c:\boost\include\boost-1_32" in your project settings. More specifically in the "C++" tab, under "Preprocessor" category (drop-down list), and at "Additional include directories:". I did this and I can now build, but I get a linker error: LINK : fatal error LNK1104: cannot open file "libboost_filesystem-vc6-sgd-1_32.lib" Thanks.

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Q: W4003 with vc7 boost=1.32 in date_time lib
by Dan Dimerman 02 Dec '04

02 Dec '04

Hello, I just wanted to see if there are others getting this warning in VC7 with Boost 1.32, or it's just me doing something wrong with the #include order or forgetting a #define. The warning reads: C:\Boost\include\boost-1_32\boost\date_time\gregorian\greg_facet.hpp(293) : warning C4003: not enough actual parameters for macro 'max' thanks for any help... Dan --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com) Version: 6.0.802 / Virus Database: 545 - Release Date: 26-Nov-04

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GCC and precompiling headers containing anonymous namspaces (i.e. bind/placeholders.hpp)
by Matthew Gruenke 02 Dec '04

02 Dec '04

Like a number of other compilers, GCC (version 3.4.3) appears to have problems related to precompiled headers that contain anonymous namespaces - such as the one in bind/placeholders.hpp. There appears to be some consensus that GCC currently does have issues in this area (see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10591) I noticed the workarounds in bind/placeholders.hpp (Boost version 1.32.0) for other compilers, and tried them with the above version of GCC. I discovered that only the work-around using static inline wrapper functions (i.e. the one for Borland compilers) seems to work. Can anyone confirm this? Should I file a bug to have that workaround apply for GCC, as well? Are anonymous/unnamed namespaces used in any other BOOST headers (which should presumably also have the workaround)? Matt Gruenke Software Engineer IntelliVid Corporation

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boost::lambda without 'use namespace'
by Agoston Bejo 01 Dec '04

01 Dec '04

Hi all, is there a way to use the boost::lambda library without having to use boost::lambda; ? I would like to use lambda expressions in a header file, therefore without 'use'-ing the namespace. Thx, Agoston

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newbie boost sample compile program
by Brian Gaber 01 Dec '04

01 Dec '04

I have installed boost on both Windows and AIX and get the same problem when I try to compile the simple_ls.cpp program that boost provides. In AIX the boost hpp files get installed in /usr/local/include/boost-1_32/boost/... I created /usr/local/include/boost/... with this command: ln -s /usr/local/include/boost-1_32/boost /usr/local/include/boost In Windows the boost hpp files get installed C:\boost-1_32\boost\... In AIX when I try to compile simple_ls.cpp I get the following: "/usr/local/include/boost/filesystem/operations.hpp", line 18.10: 1540-0836 (S) The #include file <boost/filesystem/path.hpp> is not found. "/usr/local/include/boost/filesystem/operations.hpp", line 19.10: 1540-0836 (S) The #include file <boost/shared_ptr.hpp> is not found. "/usr/local/include/boost/filesystem/operations.hpp", line 21.10: 1540-0836 (S) The #include file <boost/iterator.hpp> is not found. "/usr/local/include/boost/filesystem/operations.hpp", line 22.10: 1540-0836 (S) The #include file <boost/cstdint.hpp> is not found. "/usr/local/include/boost/filesystem/operations.hpp", line 27.10: 1540-0836 (S) The #include file <boost/config/abi_prefix.hpp> is not found. "/usr/local/include/boost/filesystem/operations.hpp", line 149.10: 1540-0836 (S) The #include file <boost/config/abi_suffix.hpp> is not found. my simple_ls.cpp currently has the following include statements: #include "/usr/local/include/boost/filesystem/operations.hpp" #include "/usr/local/include/boost/filesystem/path.hpp" #include <iostream> simple_ls.cpp came with the following include statements which generate similar errors to those above: #include "boost/filesystem/operations.hpp" #include "boost/filesystem/path.hpp" #include <iostream> MS Visual C++ 6 generates the following similar error when attempting to compile simple_ls.cpp c:\boost\include\boost-1_32\boost\filesystem\operations.hpp(18) : fatal error C1083: Cannot open include file: 'boost/filesystem/path.hpp': No such file or directory Thanks for any tips.

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FStream compile problem in VC6
by Adam 01 Dec '04

01 Dec '04

Hi, I'm trying to compile the following in Visual C++6.0 #include "boost/config.hpp" #include "boost/filesystem/operations.hpp" // includes boost/filesystem/path.hpp #include "boost/filesystem/fstream.hpp" // ditto #include <iostream> // for std::cout using namespace boost::filesystem; int main(int argc, char* argv[]) { remove_all( "foobar" ); create_directory( "foobar" ); boost::filesystem::ofstream file( "foobar/cheeze" ); file << "tastes good!\n"; file.close(); if ( !exists( "foobar/cheeze" ) ) std::cout << "Something is rotten in foobar\n"; return 0; } and I keep getting an error saying that c:\program files\microsoft visual studio\vc98\include\boost\filesystem\fstream.hpp(95) : error C2504: 'basic_ofstream<char,struct std::char_traits<char> >' : base class undefined C:\Program Files\Microsoft Visual Studio\MyProjects\boost_filesystem\boost_filesystem.cpp(17) : see reference to class template instantiation 'boost::filesystem::basic_ofstream<char,struct std::char_traits<char> >' being compiled which I think means that it can't find the implementation for std::basic_ofstream<charT,traits> . I'm not sure how to get around this because I can define a std::basic_ofstream, without problem. Thanks for help, Adam

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Format Library - Asterisk Support
by Barak Simon 01 Dec '04

01 Dec '04

Hi, I have noticed that the format library does not support at present the printf asterisk for providing dynamic width as an extra parameter. Unfortunately my users need to use this widely and I would really hate to revert back to a non-typesafe solution. a. Are there any plans to support it in near future? b. If not, is there an easy way to add that to parsing.hpp, parse_printf_directive method, parse_width & parse_precision sections? currently the asterisk is ignored, and the library throws an exception thinking it has an extra parameter. c. Is there any workaround I miss which may give me the same expected result of providing say "%*s, width, charPtr" ? (I have 'width' and a non-null-terminated char pointer and need to construct the correct string from them without doing unnecessary copying...) Many thanks, Barak ________________________ Barak Simon GED IT Core Platform Deutsche Bank 190 George St. Sydney, 2000 Phone +61 2 925 85070 Fax +61 2 925 95050 -- This e-mail may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.

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Q: VC7 boost1.32 date_time\time_system_counted.hpp(57) : warning C4244: 'initializing'
by Dan Dimerman 01 Dec '04

01 Dec '04

Hello, >From the department of unexplained warnings... I found this one which I hope someone out there could help me kill. The warning reads: C:\Boost\include\boost-1_32\boost\date_time\time_system_counted.hpp(57) : warning C4244: 'initializing' : conversion from 'boost::date_time::counted_time_rep<config>::int_type' to 'boost::date_time::gregorian_calendar_base<ymd_type_,date_int_type_>::date_int_type', possible loss of data What can I do to get rid of this one? many thanks Dan --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com) Version: 6.0.803 / Virus Database: 546 - Release Date: 30-Nov-04

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abort when constructing filesystem::path object
by Richard Wolf 01 Dec '04

01 Dec '04

Hi I'm trying to use the filesystem library, and I get an abort when trying to initialise a path object with a string containing a space. #include <boost/filesystem/path.hpp> #include <iostream> int main() { boost::filesystem::path p1("hello"); std::cout << p1.string(); boost::filesystem::path p2("hello world"); std::cout << p2.string(); } when run, this prints: helloAborted I couldn't find anything saying that the string path constructor can't contain a space. Am I doing something wrong, or is this a bug? Using gcc 3.3.4 on Debian. thanks, Richard

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