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RE: [Boost-Users] Re: Why isn't the "last access time" part of the filesystem library?
by Ben Hutchings 09 May '03

09 May '03

richard_fanta <richard.fanta(a)morganstanley.com>: > --- In Boost-Users(a)yahoogroups.com, "Ben Hutchings" > <ben.hutchings@b...> wrote: > > richard_fanta <richard.fanta@m...> wrote: > > > Beman Dawes <bdawes@a...> wrote: > > > > At 01:02 AM 5/6/2003, richard_fanta wrote: > > > > >Looking at the filesystem library and the attributes work in > > > > >boost-sandbox, I don't immediately see "last access time" > > > > >being available for a file or directory. > > > > > > > > > >"Last access time" was included in Dietmar Kuehl's original > > > > >dir_it. > > > > > > > > > >Can someone kindly tell me why this was removed? It's highly > > > > >useful, and part of every filesystem that I've seen. <snip> > > > > Perhaps we should do more to support attribute query within the > > > > main library, but I don't really think we should include any > > > > that aren't reliably supported by at least POSIX, Windows, and > > > > ISO-9660 systems. > > > > > > Your point is well made. However, it does seem odd that a > > > feature that is useful for >95% of all typical usage shouldn't be > > > in the library. > > > > What does that figure refer to, if anything? > > Typical application usage. Yes, mileage can vary. > > Out of the last 50 apps you wrote that did file access, how many > involved CD-ROMS/DVDs that were ISO 9660 filesystems? I think most of them could quite happily have worked with files on CD-ROMs, but then I tend to write general-purpose code rather than very specific applications. A few of them needed to know file modification times. <snip> > > and updates to them may be disabled because the volume is read- > > only (whether or not the underlying medium is read-only) or > > purely to avoid the cost of updating them. > > Even if the volume is read-only from one machine, it might still > help to know when the file was last altered. > > > Note that Windows NT maintains > > access times at quite a low resolution, to reduce this cost. > > Low resolution or not, it's there. When the file changes, the > timestamp is updated. That's information that many applications > would find useful. <snip> What you're talking about is the modification time, not the access time. I agree that *that* is useful and widely supported, but it's not what you were originally asking for!

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combinations of boost::condition
by Joshua Napoli 09 May '03

09 May '03

Is there any way to wait for one of several condition objects to become ready? Is there some reason that this capability is omitted from the thread library? I would like to do something like this: mutex monitorA, monitorB; condition conditionA, conditionB; double_condition conditionAB(conditionA,conditionB); void executeNextEvent() { lock lkA(monitorA); lock lkB(monitorB); //Wait for either conditionA or conditionB to become ready. conditionAB.wait(lkA,predicateA,lkB,predicateB); if(predicateA()) { executeEventA(); } else { executeEventB(); } } [Non-text portions of this message have been removed]

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RE: [Boost-Users] Re: Why isn't the "last access time" part of the filesystem library?
by Ben Hutchings 09 May '03

09 May '03

richard_fanta <richard.fanta(a)morganstanley.com> wrote: > Beman Dawes <bdawes@a...> wrote: > > At 01:02 AM 5/6/2003, richard_fanta wrote: > > > > >Looking at the filesystem library and the attributes work in boost- > > >sandbox, I don't immediately see "last access time" being available > > >for a file or directory. > > > > > >"Last access time" was included in Dietmar Kuehl's original dir_it. > > > > > >Can someone kindly tell me why this was removed? It's highly useful, > > >and part of every filesystem that I've seen. > > > > ISO/IEC 9660:1999 filesystems don't supply a "last access" time stamp, > > perhaps because the original uses were on write-once media. > > Which filesystems adhere to this spec other than CD-ROMs? Many DVDs use this too, but for most purposes they're basically just higher-capacity CDs. > > Perhaps we should do more to support attribute query within the main > > library, but I don't really think we should include any that aren't > > reliably supported by at least POSIX, Windows, and ISO-9660 systems. > > Your point is well made. However, it does seem odd that a feature > that is useful for >95% of all typical usage shouldn't be in the > library. What does that figure refer to, if anything? > Other options: > -For ISO 9660 filesystems, use the time created as the "last > access" time stamp. > -Throw a "FeatureNotSupportedException" or somesuch. Then the feature won't be at all portable, and might as well not be supported at all. Access times are far from a universal OS feature, and updates to them may be disabled because the volume is read-only (whether or not the underlying medium is read-only) or purely to avoid the cost of updating them. Note that Windows NT maintains access times at quite a low resolution, to reduce this cost.

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RE: [Boost-Users] call_traits and MSVC 7.1
by Randy Bowen 08 May '03

08 May '03

Thanks for the info. This is illegal code. That it compiled in MSVC 7.0 was a bug. The template parameter '_Source' can not be deduced from the callsite of doSomething. 14.8.2.4 in the ISO/IEC 14882 lists the forms in which template parameters can be deduced, but a qualified name involving nested types is not one of them. I suspect it's because of something like this: [Non-text portions of this message have been removed]

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Compiling smart_ptr library
by l＠lo 08 May '03

08 May '03

Hi everybody! I'm trying to compile the smart_ptr library using the Jamfile in the test directory. Some of the test *.cpp files are compiled successfully, but some of them drops the following error: sunpro-Link-action ../../../libs/smart_ptr/test/bin/shared_ptr_alloc_ test.test/sunpro/debug/runtime-link-dynamic/shared_ptr_alloc_test Undefined first referenced symbol in file boost::__RTTI__1nFboostPchecked_deleter4nBZ___ /rest/proj/users/kercsoj/boost/boost_1_30_0/libs/s mart_ptr/test/bin/shared_ptr_alloc_test.test/sunpr o/debug/runtime-link-dynamic/ SunWS_cache/CC_obj__/_iANwWXwaw2nbnjBybyL.o [Hint: static member boost::__RTTI__1nFboostPchecked_deleter4nBZ___ must be defined in the program] It's seems, it is a common error, because it appears several times in the error output of the compiler. Has anybody any ideea, why this error message comes, and how could be corrected? Thanks, lalo

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Indirect Iterator Adaptor, std::set and MSVC 6.5
by Joaquín Mª López Muñoz 08 May '03

08 May '03

The following produces an internal compiler crash in MSVC 6.5 #include <set> #include <boost/iterator_adaptors.hpp> int main() { typedef std::set<int *> type0; typedef boost::indirect_iterator_generator< type0::iterator,const int>::type type1; type0 s; type1 it(s.begin()); return 0; } This happens for std::set only, using say std::vector instead works fine. Is some workaround known? TIA Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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Regex issue under Visual Studio 2003
by Frank Schwab 08 May '03

08 May '03

I have an inherited VC++ program that I am trying to port to Microsoft Visual Studio 2003 (it compiles and runs fine in Visual Studio 6.0). I've downloaded the 1.30.0 release, and the following problem still occurs. The (exceptionally) verbose error message I receive from the compiler is: error C2664: 'bool boost::regex_match<std::char_traits<char>,std::allocator<_Ty>,Allocator,char ,boost::regex_traits<charT>,std::allocator<_Ty>>(const std::basic_string<_Elem,_Traits,_Ax> &,boost::match_results<iterator,Allocator> &,const boost::reg_expression<charT,traits,Allocator> &,unsigned int)' : cannot convert parameter 2 from 'boost::cmatch' to 'boost::match_results<iterator,Allocator> &' with [ _Ty=char, Allocator=std::allocator<char>, charT=char, _Elem=char, _Traits=std::char_traits<char>, _Ax=std::allocator<char>, iterator=std::basic_string<char,std::char_traits<char>,std::allocator<char>> ::const_iterator, traits=boost::regex_traits<char> ] and [ iterator=std::basic_string<char,std::char_traits<char>,std::allocator<char>> ::const_iterator, Allocator=std::allocator<char> ] The Code fragment I get the error on is: // lpcszDeviceName is a function parameter defined as LPCTSTR lpcszDeviceName TSTRING strName = lpcszDeviceName; boost::regex expr("IW\\s+[A-Za-z]+\\s+([0-9]+)"); boost::cmatch matches; if (boost::regex_match(strName, matches, expr)) { ... } with the error message pointing to: if (boost::regex_match(strName, matches, expr)) This may be related to a Microsoft note: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vccore/html /vclrfsomeiteratorsarenolongersameaspointers.asp but, then again, it may not. Anyone have any suggestions? I am well out of my depth in trying to understand the incantations here, and have a dozen spots in the code where this occurs. TIA, /frank

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call_traits and MSVC 7.1
by Randy Bowen 08 May '03

08 May '03

We have been using call_traits from Boost version 1.29.0 in conjunction with MSVC 7.0. When attempting to recompile this code under MSVC 7.1, using either Boost 1.29.0 or 1.30.0, we now encounter compilation errors. A simple example of the usage pattern is: ############################################################### #include <boost/call_traits.hpp> class A { public: template<typename _Source> void doSomething ( typename boost::call_traits<_Source>::param_type value ) { } }; class B { public: explicit B(double d = 1.0, int i = 42) : _d(d), _i(i) {} B(B const& b) : _d(b._d), _i(b._i) {} private: double _d; int _i; }; extern "C" int main(int argc, char* argv[]) { A a; B b; a.doSomething(b); return 0; } ############################################################# The new compiler generates the error message: c:\Documents and Settings\rbowen\My Documents\Projects\CallTraitsTest\CallTraitsTest.cpp(34) : error C2783: 'void A::doSomething (boost::call_traits<_Source>::param_type)' : could not deduce template argument for '_Source' c:\Documents and Settings\rbowen\My Documents\Projects\CallTraitsTest\CallTraitsTest.cpp(11) : see declaration of 'A::doSomething' As an experiment, I manually included the older logic for call_traits by cutting and pasting the relevant classes into my source from 'detail/ob_call_traits.hpp' and still encountered the same error. Has anyone else experienced this? Is this (yet another) MS compiler bug?

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Static thread library missing in 1_30_0
by yss15632 08 May '03

08 May '03

Hi, I am using boost on a linux system. I upgraded from boost_1_29_0 to 1_30_0. However, if I build the library just by typing "bjam" I cannot find the static library libboost_thread.a, in contrary to version 1_29_0. How can I generate it? Thank you very much, Stefan

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date_time link or compile problem
by Jimmy Pritts 08 May '03

08 May '03

I have boost 1.29 and gcc 3.2.2 on Linux. Here is the simple code I am trying to compile: #include <string> #include "boost/date_time/gregorian/gregorian.hpp" int main() { using namespace std; using namespace boost::gregorian; string ds("2002/1/25"); date d1(from_string(ds)); return 0; } I get the following link error: make g++ main.cc -lstdc++ -o test /tmp/ccph1inq.o(.gnu.linkonce.t._ZN5boost9date_time4dateINS_9gregorian4dateENS2_18gregorian_calendarENS0_13date_durationIlEEEC2ERKNS0_19year_month_day_baseINS2_9greg_yearENS2_10greg_monthENS2_8greg_dayEEE+0x11): In function `boost::date_time::date<boost::gregorian::date, boost::gregorian::gregorian_calendar, boost::date_time::date_duration<long> >::date[not-in-charge](boost::date_time::year_month_day_base<boost::gregorian::greg_year, boost::gregorian::greg_month, boost::gregorian::greg_day> const&)': : undefined reference to `boost::date_time::gregorian_calendar_base<boost::date_time::year_month_day_base<boost::gregorian::greg_year, boost::gregorian::greg_month, boost::gregorian::greg_day>, unsigned long>::day_number(boost::date_time::year_month_day_base<boost::gregorian::greg_year, boost::gregorian::greg_month, boost::gregorian::greg_day> const&)' collect2: ld returned 1 exit status make: *** [test] Error 1 The missing symbol does not seem to be in the static library libboost_date_time.a, so I don't think I need to link to that. Any suggestions? Thanks in advance, Jimmy.

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