February 2007 - Boost-users - lists.preview.boost.org

Filesystem library questions
by Manish Motwani 26 Feb '07

26 Feb '07

Hi, We're creating a new cross-platform dispersed storage technology. Backing up a file from one platform and restoring to another (or the same) is a requirement. We have found boost to be very useful for threads, date/time, program options, etc. We're also currently using the boost filesystem libarary, but we can't figure out why many of the file-metadata query and modifier functions are missing. Can someone from boost let us know if there's any way of querying complete file-metadata (including read/write/execute permissions on windows and linux, ACLs, creation-time in windows, etc.). I found only the following function in version 1.32 (the one we're using): last_write_time (read and write modification time). symbolic_link_exists (check if a file is a sym link). And these new functions have been added since: create_hard_link create_symlink .. and some functionality to get the type of file is also there in the trunk version. But what about the rest of metadata filesystems (POSIX, NTFS, FAT32, HFS, etc) provide? Is this ever going to be included in the library? Is there a way to access this information any other way? I suspect these questions may have been asked by others, so can someone point me to where I can find code to complement the boost filesystem library to handle file-metadata? Thanks, Manish

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Boost date time and MinGW
by Franck Guillaud 25 Feb '07

25 Feb '07

Hello World, I'm doing some experiments to use boost (1.33.1) under Win XP and with MinGW (5.1.3) environment. Boost was compiled with bjam with no particular options. I'm facing some problems on linking with boost_date_time. Here is the simple test program: #include <iostream> #include <string> #include <boost/date_time/posix_time/posix_time.hpp> using namespace std; using namespace boost::posix_time; int main (int argc, char** argv) { char dummy; ptime d1(min_date_time); ptime d2(max_date_time); cout << "min:" << to_simple_string(d1) << endl; cout << "max:" << to_simple_string(d2) << endl; cin.get(dummy); return 0; } Compiling lines are : g++ -DUSE_DATE_TIME_PRE_1_33_FACET_IO -I"E:\dev\boost_1_33_1" -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"main.d" -MT"main.d" -o"main.o" "../main.cpp" g++ -L"E:\dev\boost_1_33_1\stage\lib" -o"TestBOOST.exe" ./main.o -lboost_date_time-mgw-mt-d-1_33_1 I get the error (simplified output) : E:/dev/boost_1_33_1/boost/date_time/gregorian/greg_weekday.hpp: undefined reference to `boost::gregorian::greg_month::as_long_string() const' If I remove the lines with *to_simple_string*, I get no error. From the docs [*] it seems there may be a problem for streams support for some compilers, so I tryed to define USE_DATE_TIME_PRE_1_33_FACET_IO in my project, but with no effect. Does it needs to be done when compiling boost ? Is there any other way to solve my link problem ? (appart not using string output for dates :-) ) Thanks for any help. Franck,e- [*] http://www.boost.org/doc/html/date_time/details.html#date_time.buildinfo

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Any reasons why an exception would not be caught by BOOST_CHECK_THROW?
by Stephen Torri 25 Feb '07

25 Feb '07

I have an exception class that is not getting caught my BOOST_CHECK_THROW. Here is a similar setup to what I have: class Base_Exception : public virtual std::exception { public: virtual ~Base_Exception() throw{} virtual const char* what () const throw() = 0; virtual const char* name () const throw() = 0; boost::uint32_t const& id () const throw(); private: boost::uint32_t id; }; class Child_Exception : public virtual Base_Exception { public: enum ERROR_ID { INVALID_API_INPUT, CANNOT_FIND_TARGET, INTERNAL_LIBRARY_ERROR, }; Child_Exception ( ERROR_ID message_id ); virtual ~Child_Exception () throw () {} virtual const char* what () const throw(); virtual const char* name () const throw(); private: static const char* m_exception_name; static const char* m_messages[]; }; I find that when I use the BOOST_CHECK_THROW ( expression, Child_Exception ) that I still get the test crashing with an uncaught exception. Here is the actual output: terminate called after throwing an instance of 'libreverse::errors::API_Exception' what(): Internal library error has occurred. At this point consider the library unreliable. unknown location(0): fatal error in "test_wrong_sources": signal: SIGABRT (application abort requested) *** errors detected in test suite "Architecture Type Detector suite"; see standard output for details FAIL: test_arch_type_detector I can send the whole test file but I hope this is enough to understand the nature of the problem. Is there a FAQ about BOOST_CHECK_THROW? Stephen

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[graph] birected -> directed adapter?
by Jens Müller 25 Feb '07

25 Feb '07

http://www.boost.org/libs/graph/doc/reverse_graph.html reverses edge directions. Is there an adapter (i.e., has someone written such a thing) that combines in and out edges in a bidirected graph and gives a view as if the graph were undirected? I'd need this for doing BFS independent of edge directions in a bidirected graph.

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Bug in options_description.cpp when offer a long program options to boost::program_options
by Jack Shi 25 Feb '07

25 Feb '07

If you provide a long program options description while using boost, you will encounter such issue, if you using debug version, you will see a debug assertion failed alert, if you using release version, your program will be crashed. following codes can be used to reproduce this issue #include <iostream> #include <boost/program_options.hpp> using namespace std; int main(int argc, char* argv[]) { namespace po = boost::program_options; po::options_description desc("supported options"); desc.add_options() ("help,h", "display this help message,this help will be printed out if you not provide option here!"); std::cout << desc << "\n"; } I have trace this issue, it is located in function format_paragraph in the file options_description.cpp, namespace { void format_paragraph(std::ostream& os, std::string par, unsigned first_column_width, unsigned line_length) { ...... // prevent chopped words // if (lastchar != ' ') && // ((exists(lastchar + 1) && (lastchar + 1 != ' ')) if ((*(line_end - 1) != ' ') && ((line_end < par_end) && (*line_end != ' '))) { // find last ' ' in the second half of the current paragraph line string::const_iterator last_space = find(reverse_iterator<string::const_iterator>(line_end - 1), reverse_iterator<string::const_iterator>(line_begin - 1), ' ') .base(); if (last_space != line_begin - 1) { ...... } if option description is long enough, the find function will be called, and "reverse_iterator<string::const_iterator>(line_begin - 1)" will lead to this issue, may "line_begin - 1" access a invalid space. If there have some guys to confirm it was a bug in boost?

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[conversion] lexical_cast behaviour changed from 1_33_1
by Paul O'Neill 25 Feb '07

25 Feb '07

Compiling the following code on MSVC80, sp1 has different behaviour in the latest CVS head compared to 1_33_1? double dbl(88.8); std::cout << boost::lexical_cast<std::string>(dbl) << std::endl; boost1.33.1 = 88.8 boost::CVS = 88.799999999999997 Any ideas as I prefer the old behaviour? Thanks.

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boost RegEx problem: Invalid content of repeat range
by Michael Radzewitz 25 Feb '07

25 Feb '07

Hello everyone, i have a problem with libboost_regex-gcc-mt-1_33_1.a on a debian Linux and a simple function to test some Names: bool is_valid_name(const char *s) { if(!s) return false; const char* re = "^[a-zA-Z][.*0-9a-zA-Z._-]{4,60}$"; static const boost::regex e(re); return regex_match(s,e); } Everything works well when i put this Funtion in a simple Programm and run it. When I put the same Function in my cgi which is wrapped through fastCgi and handled by an apache webserver i get the following Error message: Invalid content of repeat range so in a simple programm the range check {4,60} in boost regex works but in a more complex program it didd'nt. I have testet the same function on Linux using: libboost_regex-gcc-mt-1_33_1.a and free BSD using: libboost_regex.so.3 and get with both libs the same error message. It would be nice if someone can help me find a solution or tell me what went wrong here. Thanks in advance!

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Boost Preprocessor Question
by Eric Lemings 24 Feb '07

24 Feb '07

Greetings, I was wondering if the following can be done with Boost Preprocessor. Given a list of preprocessor macro names, write a simple program that prints whether each macro is defined and its value if it is defined. In particular, I'd like to know if the following example program could be reduced/simplified with Boost: #include <iostream> using namespace std; #define STRING(x) #x #define STRINGIZE(x) STRING(x) #define IS " is " #define NOT "not " #define DEFINED "defined." #define VALUE " Its value is " extern int main () { #if defined __mips cout << STRING(__mips) IS DEFINED; cout << VALUE STRINGIZE(__mips) << endl; #else cout << STRING(__mips) IS NOT DEFINED << endl; #endif #if defined __unix cout << STRING(__unix) IS DEFINED; cout << VALUE STRINGIZE(__unix) << endl; #else cout << STRING(__unix) IS NOT DEFINED << endl; #endif #if defined __sgi cout << STRING(__sgi) IS DEFINED; cout << VALUE STRINGIZE(__sgi) << endl; #else cout << STRING(__sgi) IS NOT DEFINED << endl; #endif #if defined _COMPILER_VERSION cout << STRING(_COMPILER_VERSION) IS DEFINED; cout << VALUE STRINGIZE(_COMPILER_VERSION) << endl; #else cout << STRING(_COMPILER_VERSION) IS NOT DEFINED << endl; #endif #if defined __GNUC__ cout << STRING(__GNUC__) IS DEFINED; cout << VALUE STRINGIZE(__GNUC__) << endl; #else cout << STRING(__GNUC__) IS NOT DEFINED << endl; #endif return 0; } Thanks, Eric.

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Error in using boost lambda in a template
by Meryl Silverburgh 24 Feb '07

24 Feb '07

Hi, I have code which uses Boost lambda in a template like this: template<class T> bool lessThanXY( T& src, T& dest ) { return (src.getY() < dest.getY()); } template<class T1, class T2> void sortXY(T1& list) { ::sort( list.begin(), list.end(), bind(::lessThanXY<T2>, *(_1), *(_2) ) ); } But when I instantiate the template like this, I get the following compile error: class Rect; typedef list<Rect*> RectList; void sortXYRectList(RectList& rl) { sortXYWithThreshold<RectList, Rect>(rl); } /usr/include/boost/lambda/detail/lambda_traits.hpp:389: error: ignoring 'const' qualifiers added to function type 'bool ()(Rect&, Rect&)const' gmake[5]: *** [RectUtils.o] Error 1 Can you please tell me how to fix my problem ? I did not use 'const' anywhere in my template, why I get this error: error: ignoring 'const' qualifiers added to function type 'bool ()(Rect&, Rect&)const'

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[graph] internal predecessor map
by Jens Müller 24 Feb '07

24 Feb '07

Can I store an edge_descriptor of a predecessor edge as an internal/bundled property? I am currently doing this: struct EdgeProperties; struct VertexProperties { double x; double y; double weight; int dist; boost::graph_traits< boost::adjacency_list<boost::vecS, boost::vecS, boost::bidirectionalS, VertexProperties, EdgeProperties> >::edge_descriptor pred; int app_height; bool mark; }; struct EdgeProperties { double length; }; int main() { using namespace boost; typedef adjacency_list<vecS, vecS, bidirectionalS, VertexProperties, EdgeProperties> Graph; } This is legal, isn't need? Obviously the definition of EdgeProperties is not needed where it is first used. But is this the proper way to do it, or is there a more elegant way?

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