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

[iostreams] skip bug (repost)
by Phillip Seaver 01 Jun '07

01 Jun '07

I ran into a problem when using restrict on a file_source. The problem was that it decided that the stream wasn't seekable and called the version of skip that reads a character at a time until it gets to the requested offset, instead of just calling seek. The code was similar to this: namespace io = boost::iostreams; std::string filename; io::filtering_istream rstr(io::restrict(io::file_source(filename), 10, 100)); I've attached a patch that solved my problem. It was checking to see if the device was seekable (which means input_seekable and output_seekable), but since it was an input device, it was just input_seekable. Phillip Seaver --- skip.hpp.orig 2007-03-20 16:20:55.253000000 -0400 +++ skip.hpp 2007-03-20 16:11:51.096750000 -0400 @@ -67,7 +67,17 @@ void skip(Device& dev, stream_offset off) { typedef typename mode_of<Device>::type mode; - detail::skip(dev, off, is_convertible<mode, seekable>()); + typedef mpl::or_< + mpl::and_< + is_convertible<mode, input>, + is_convertible<mode, input_seekable> + >, + mpl::and_< + is_convertible<mode, output>, + is_convertible<mode, output_seekable> + > + > can_seek; + detail::skip(dev, off, can_seek()); } template<typename Filter, typename Device>

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Problem with 1.34 Regex Package
by Jeffery Cavallaro 01 Jun '07

01 Jun '07

Hi, all! I am a bit of a newbie, so forgive if this has already been covered. The 1.34 regex package (or at least my build of it on FC6) appears to be broken. Please consider the following: #include <iostream> #include <iomanip> #include <boost/regex.hpp> int main(int argc, char *argv[]) { boost::regex rl("ab"); boost::regex ru("AB"); bool pass = regex_search("ab", rl); std::cout << std::boolalpha << pass << std::endl; pass = regex_search("AB", ru); std::cout << std::boolalpha << pass << std::endl; return EXIT_SUCCESS; } When built with 1.33 (as delivered with FC6), both tests return true. When built under 1.34 (downloaded and built), the uppercase test returns false. Yuck. Am I missing something? (probably...) -- Jeffery Cavallaro POSTINI Engineering Group 650-486-8342 ----------------------------------------------------------- This message may contain confidential and/or privileged information. This information is intended to be read only by the individual or entity to whom it is addressed. If you are not the intended recipient, you are on notice that any review, disclosure, copying, distribution or use of the contents of this message is strictly prohibited. If you have received this message in error, please notify the sender immediately and delete or destroy any copy of this message.

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newbie ordering question for boost::multi_index::ordered_non_unique
by Kevin McMahon 01 Jun '07

01 Jun '07

I'd like to pop items in my data set ordered by a key, but if the key is identical then ordered in the order I inserted them. Is there a good way to do that? I guess I could make a composite key using an increasing id. -kevin

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[Boost.Test 1.34] Multiple instances of unit_test_log_t singleton
by Kolya 01 Jun '07

01 Jun '07

Hi, All! I am using Boost.Test library in my own application and I have included boost/test/unit_test.hpp in many my cpp-files. When I used boost version 1.33.1 all works fine. But in version 1.34 I have following compiler error: file1.obj : error LNK2005: "class unit_test_log_t::boost::unit_test_log_t & boost::unit_test::`anonymous namespace'::unit_test_log" (?unit_test_log@?A0xa35d3712@unit_test@boost@@3AAVunit_test_log_t@23@A) already defined in file2.obj After including boost/test/unit_test.hpp class unit_test_log has multiple instances. See boost/test/unit_test_log.hpp for details: BOOST_TEST_SINGLETON_INST( unit_test_log ) It means that following code will be included in many cpp-files! namespace { unit_test_log_t & inst = unit_test_log_t::instance(); } When I replace BOOST_TEST_SINGLETON_INST( unit_test_log ) in boost/test/unit_test_log.hpp with namespace {extern unit_test_log_t & unit_test_log;} and in one of my cpp-files add: namespace boost { namespace unit_test { BOOST_TEST_SINGLETON_INST( unit_test_log ) } } all works fine May be I do not understand something? Is there any legal workaround from this situation? I do not like touch boost core files by myself. Thank you! VC++ 7.1, boost 1.34, xp sp2.

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Bind: more convenience operators?
by Arno Schoedl 01 Jun '07

01 Jun '07

Bind has operator! overloaded to allow convenient notting of bound functions. Is there a specific reason not to overload all other operators in a similar way, for example for defining an AND of two predicates f and g as boost::bind( f, _1 ) && boost::bind( g, _1 )? Arno

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[TR1] Configuration macros
by Scott Meyers 01 Jun '07

01 Jun '07

I'm having trouble understanding the information at http://www.boost.org/doc/html/boost_tr1/config.html, and having already spent a fair amount of time running test programs and pouring over the output of the preprocessor for various compilers, I'm hoping that somebody in the know can just explain things to me. My goal is simple: use Boost.TR1 such that if my compiler ships with a library with support for whatever TR1 component I want to use, I'll get that native support. But if the library that ships with the compiler lacks support for the TR1 component I need, I want to fall back on the Boost implementation, if there is one. And I want to uniformly refer to TR1 components as if they are in the namespace std::tr1. My reading of the above-referenced page leads me to believe that this is the behavior I'm supposed to get by default. And it's consistent with the tests I've performed using VC8 and g++ 4.1. But then I read this: > The configuration macros used by each TR1 component are documented in each library section (and all together in the Boost.Config documentation), but defining BOOST_HAS_TR1 will turn on native TR1 support for everything (if your standard library has it), which can act as a convenient shortcut. This kind of suggests that I should define BOOST_HAS_TR1. Should I? So far I have not. And then I read this: > Boost.TR1 does not currently enable gcc's native TR1 implementation as this is currently in an early stage of development. However, you may choose to do so by defining BOOST_HAS_GCC_TR1. This pretty clearly suggests that I should define BOOST_HAS_GCC_TR1. Should I? So far, I have. I've also found that unless I define it like this, > #ifdef __GNUC__ > #define BOOST_HAS_GCC_TR1 > #endif compilation with VC8 fails, which I find kind of strange. Here's an error I get: > D:\C++\Boost\Current\boost/tr1/type_traits.hpp(11): fatal error C1083: Cannot open include file: 'type_traits': No such file or dire > ctory Why should defining BOOST_HAS_GCC_TR1 have any effect on a VC8 compilation? All clarification about the correct settings of TR1 configuration macros for at least VC8 and g++ 4.1 would be much appreciated. Thanks, Scott

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[bind] Convenience operator overloads
by Arno Schödl 01 Jun '07

01 Jun '07

Hello, are there any plans to provide more convenience operator overloads, such as operator! which is already implemented? I don't see any reason why not to overload all operators in that fashion. Thanks, Arno -- Arno Schoedl · aschoedl(a)think-cell.com Technical Director think-cell Software GmbH · Invalidenstr. 34 · 10115 Berlin, Germany http://www.think-cell.com · phone +49-30-666473-10 · fax +49-30-666473-19 Geschäftsführer: Dr. Markus Hannebauer, Arno Schoedl · Amtsgericht Charlottenburg, HRB 85229

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[tokenizer] position of tokenizer
by Seweryn Habdank-Wojewódzki 01 Jun '07

01 Jun '07

Hi Is that possible to take actual position of the tokenizer in the parsed string? The question is motivated by such a case: 1. there is a line with data separated by e.g. "\t' sign 1 23 3.45 21 2093 494 3.4 2. important is only some of them let say from 2nd token to 5th token, but after parsing them I want to pass tokens from 6th to the end to the other string. Now I am iterating tokenizer to the end, and concatenate it. If I have had a position of tokenizer on the string I can simply create new substring with out iteration. Maybe there is other solution for that. Regards. -- |\/\/| Seweryn Habdank-Wojewódzki \/\/

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Bind & Memory Leakage
by Sudhir Parikh 01 Jun '07

01 Jun '07

BoundsChecker is reporting a memory leak for every 'bind' call. I am using the threadpool includes, v 0.2.3, with "libboost_thread-vc71-mt-gd-1_33_1.lib", MSVC 7.1. Any help is appreciated. The usage is similar to the following working example: void task(int param1) { // performs some task printf("%d : Param1 : %d\n", GetCurrentThreadId(), param1); Sleep(1000); } void foo() { boost::threadpool::pool tp(5); // Threadpool with 5 threads while (1) { for (int i = 0; i < 10; i++) { // Seems like there is memory allocation which is not // deallocated after returning from the function call. tp.schedule(boost::bind(task, i)); } tp.wait(); // wait to finish off the remaining tasks Sleep(5000); // sleep for 5 seconds } }

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[Unit Test] default FPC_STRONG limtations when checking close to 0.
by Chris Fairles 01 Jun '07

01 Jun '07

After wondering why my BOOST_CHECK_CLOSE(some_number_close_to_zero, 0.0) hadn't been working, I found that the default comparison type is FPC_STRONG which means the ration between the abs val of the difference and BOTH values must be < tolerance but this doesn't turn out to be true (running through what safe_fpt_division outputs atm ... difference between 0.0{0} and 0.0 std::numeric_limits<double>::epsilon(){-2.2204460492503131e-16} exceeds 0.01% It should work using FPC_WEAK but I can't find a way through the test_tools to easily change this. I have three solutions at this time. 1) Use BOOST_CHECK_SMALL. However, I have code that loops through matrix indicies like: for (int j = 0; j < matrix.col; j++) for (int i = 0; i < matrix.row; i++) BOOST_CHECK_CLOSE(matrix(i,j), data(i,j), tolerance); I'm going to have to use an if statement for the special case where I'm testing against 0 and it doesn't use the tolerance anyway so the test is completely different. Theres another number to determine "how small" the number should be. 2) Use check_is_close explicitly and change the default comparison type to FPC_WEAK. This means going outside the nice auto-unit-test and test-tools framework which although I'm fine with, other programmers writing test cases on my team might not be. 3) Define my own macro to simplify solution 2. Something along the lines of: CHECK_IS_CLOSE_WEAK(x,y,t) { check_is_close(x ,y,t, FPC_WEAK); } Are there any other recommended solutions?

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