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Re: problem with new iterators in 1.31 Release candidate # 2
by Robert Ramey 01 Feb '04

01 Feb '04

Robert Ramey <ramey(a)rrsd.com> writes: > I have a problem with the latest version of the new iterators. > This is illustrated in the following example. > > #include <strstream> > #include <iterator> > #include <boost/iterator/counting_iterator.hpp> > > main(){ > std::istrstream is("abcdefg"); > typedef boost::counting_iterator<std::istream_iterator<char> > ci; > const ci end = std::istream_iterator<char>(); // note the const !!! I don't see why the const should be relevant. >From looking at the code for counting iterator it seems to me that it is implemented for non - random access iterators by incrementing one iterator until it equals the other and return the number of times the increment occured. (I concede that I've had difficulty following the implementation so I could be wrong). So if one of the iterators is const - that one can't be the one that's incremented. > ci begin = std::istream_iterator<char>(is); Hmm, the implicit conversions from istream_iterator to the counting_iterator above are troubling. I think those constructors should be explicit. Hmmm - From looking at the documentation and the code, I get absolutly no indication that the counting iterator requires a randome access iterator. In fact, looking at the code suggests that there is code especially included to handle any forward transversal iterators. And the first invocation below DOES work - I can't believe that's an accident. > unsigned int size; > > // the following should fail at compilation ? Why? OK, maybe it would be better to make it fail because the iterator is not in fact a random-access iterator. > // in fact it compiles are returns a value of -7 !!! > size = begin - end; > > // the following should compile and return a value of 7 > // in fact, it compiles but goes into an infinite loop > size = end - begin; > } My mistake - I wrongly presumed that only the second iterator would be incremented and since its const it should fail. It looks like the code intends to select which iterator to increment depending on const. So this first case looks ok to me now. I don't see why you think the first should compile but the second should not. If they're not random-access iterators, it seems to me that there's no reason you should be able to subtract them in any order. If they were random-access iterators, it would be unreasonable to expect the compiler to detect which one had an earlier position and disallow one subtraction. So my position is that both compile (as they should). The first works as one would expect while the second results in an infinite loop. I'm sorry but I don't see how this can be correct. > Note that this problem did not appear with the first release > candidate. > > Also, if one follows the links from the main documentation page, one > is directed to the documentation of the old iterators. This is > extremely confusing. This has been pointed out before. That's a serious problem which I'll fix immediately. Robert Ramey

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mpl lambda question
by Eyal Farago 01 Feb '04

01 Feb '04

hi, I'm trying to use mpl lambda on vc.6.5, it seems that for some reason when applying lambda on the expression the compiler tries to instantiate the wrong specialisation(the one with the boost::mpl::arg<1> as a template parameter. this is the test program: #include <boost/mpl/lambda.hpp> #include <boost/tuple/tuple.hpp> template< class T_ > struct head_type { typedef typename T_::head_type type; BOOST_MPL_AUX_LAMBDA_SUPPORT( 1, head_type, ( T_ ) ); }; void main() { typedef boost::tuples::tuple< int > int_tuple_t; typedef head_type< int_tuple_t >::type head_of_int_tuple_t; typedef head_type< boost::mpl::_1 > exp_t; typedef boost::mpl::lambda< exp_t >::type exp_lambda_t; //this line causes the compilation error typedef boost::mpl::apply1< exp_lambda_t, int_tuple_t >::type int_tuple_head_type; } and this is the compiler's output: --------------------Configuration: boost_tests - Win32 Debug-------------------- Compiling... main.cpp C:\c++\boost_tests\main.cpp(7) : error C2039: 'head_type' : is not a member of 'arg<1>' c:\c++\boost_1_30_0\boost\mpl\aux_\preprocessed\msvc60\arg.hpp(28) : see declaration of 'arg<1>' c:\c++\boost_1_30_0\boost\type_traits\is_convertible.hpp(64) : see reference to class template instantiation 'head_type<struct boost::mpl::arg<1> >' being compiled c:\c++\boost_1_30_0\boost\type_traits\is_convertible.hpp(80) : see reference to class template instantiation 'boost::detail::does_conversion_exist<struct head_type<struct boost::mpl::arg<1> > &>::result_<struct boost::detail::int_convertible >' being compiled c:\c++\boost_1_30_0\boost\type_traits\is_convertible.hpp(184) : see reference to class template instantiation 'boost::detail::is_convertible_basic_impl<struct head_type<struct boost::mpl::arg<1> > &,struct boost::detail::int_convertible>' be ing compiled c:\c++\boost_1_30_0\boost\type_traits\is_convertible.hpp(239) : see reference to class template instantiation 'boost::detail::is_convertible_impl<struct head_type<struct boost::mpl::arg<1> > &,struct boost::detail::int_convertible>' being co mpiled c:\c++\boost_1_30_0\boost\type_traits\is_enum.hpp(54) : see reference to class template instantiation 'boost::is_convertible<struct head_type<struct boost::mpl::arg<1> > &,struct boost::detail::int_convertible>' being compiled c:\c++\boost_1_30_0\boost\type_traits\is_enum.hpp(91) : see reference to class template instantiation 'boost::detail::is_enum_helper<0>::type<struct head_type<struct boost::mpl::arg<1> > &>' being compiled c:\c++\boost_1_30_0\boost\type_traits\is_enum.hpp(108) : see reference to class template instantiation 'boost::detail::is_enum_impl<struct head_type<struct boost::mpl::arg<1> > >' being compiled c:\c++\boost_1_30_0\boost\type_traits\is_scalar.hpp(30) : see reference to class template instantiation 'boost::is_enum<struct head_type<struct boost::mpl::arg<1> > >' being compiled c:\c++\boost_1_30_0\boost\type_traits\is_scalar.hpp(50) : see reference to class template instantiation 'boost::detail::is_scalar_impl<struct head_type<struct boost::mpl::arg<1> > >' being compiled c:\c++\boost_1_30_0\boost\type_traits\is_class.hpp(78) : see reference to class template instantiation 'boost::is_scalar<struct head_type<struct boost::mpl::arg<1> > >' being compiled c:\c++\boost_1_30_0\boost\type_traits\is_class.hpp(93) : see reference to class template instantiation 'boost::detail::is_class_impl<struct head_type<struct boost::mpl::arg<1> > >' being compiled c:\c++\boost_1_30_0\boost\mpl\aux_\has_rebind.hpp(32) : see reference to class template instantiation 'boost::is_class<struct head_type<struct boost::mpl::arg<1> > >' being compiled c:\c++\boost_1_30_0\boost\mpl\aux_\preprocessed\msvc60\template_arity.hpp(27) : see reference to class template instantiation 'boost::mpl::aux::has_rebind<struct head_type<struct boost::mpl::arg<1> > >' being compiled c:\c++\boost_1_30_0\boost\mpl\aux_\preprocessed\msvc60\lambda_no_ctps.hpp(150) : see reference to class template instantiation 'boost::mpl::aux::template_arity<struct head_type<struct boost::mpl::arg<1> > >' being compiled C:\c++\boost_tests\main.cpp(17) : see reference to class template instantiation 'boost::mpl::lambda<struct head_type<struct boost::mpl::arg<1> >,1>' being compiled Error executing cl.exe. boost_tests.exe - 1 error(s), 0 warning(s) eyal.

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ICE with is_abstract on VC 7.0
by Robert Ramey 01 Feb '04

01 Feb '04

When I compile anything that includes is_abstract.hpp I get a compiler ICE with VC 7.0 since is_abstract.hpp is included by type_traits.hpp it means that a large part of boost 1.31 release candidate 2 is now uncompilable on this platform. is_abstract was known to test the limits of many platforms. It is incredible to me that this could be dropped into "release candidate # 2" without having been part of the development tree for a reasonable amount of time. When can we expect 1.31 release candidate # 3? Robert Ramey

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1.31.0 Release candidate 2 available
by Beman Dawes 01 Feb '04

01 Feb '04

Release candidate 2 is available at http://www.esva.net/~beman/boost_1_31_0_rc2.zip Feedback appreciated! Boost developers should limit changes to the RC_1_31_0 branch to fixes for showstoppers. Anything less should go in the next release. --Beman

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problem with new iterators in 1.31 Release candidate # 2
by Robert Ramey 01 Feb '04

01 Feb '04

I have a problem with the latest version of the new iterators. This is illustrated in the following example. #include <strstream> #include <iterator> #include <boost/iterator/counting_iterator.hpp> main(){ std::istrstream is("abcdefg"); typedef boost::counting_iterator<std::istream_iterator<char> > ci; const ci end = std::istream_iterator<char>(); // note the const !!! ci begin = std::istream_iterator<char>(is); unsigned int size; // the following should fail at compilation ? // in fact it compiles are returns a value of -7 !!! size = begin - end; // the following should compile and return a value of 7 // in fact, it compiles but goes into an infinite loop size = end - begin; } Note that this problem did not appear with the first release candidate. Also, if one follows the links from the main documentation page, one is directed to the documentation of the old iterators. This is extremely confusing. This has been pointed out before. This above example is using 1.31. "release candidate" #2 compiled with VC 7.0 Robert Ramey

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Re: [boost] [filesystem] On POSIX, any reliable way to find file size?
by Beman Dawes 31 Jan '04

31 Jan '04

At 01:29 PM 1/31/2004, Christoph Ludwig wrote: >I don't know whether there is a solution within any formally defined >Unix or Posix standard. But according to >http://www.suse.de/~aj/linux_lfs.html the Linux 2.4 kernel supports >the Large File Support (LFS) interface. There is also a link to the >LFS specification: >http://ftp.sas.com/standards/large.file/x_open.20Mar96.html Thanks. I think that is a bit dated, but Jens' reply seems reflect actual practice and that should be enough to get started with. --Beman

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boost_1_31_0_rc2 - Missing files,
by Joe Gottman 31 Jan '04

31 Jan '04

I discovered that there are a couple of missing html files in the rc2: \boost_1_31_0_rc2\libs\iterator\doc\iterator_traits.html and \boost_1_31_0_rc2\libs\iterator\doc\interoperable.html Joe Gottman

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Linux RC_1_31_0 regression test questions
by Beman Dawes 31 Jan '04

31 Jan '04

Looking at http://boost.sourceforge.net/regression-logs/cs-Linux-RC_1_31_0.html to make sure we are in good shape for RC2 from the Linux perspective, I've got some (probably dumb) questions: * gcc 3.4 20040124 (prerelease) has 21 errors compared to 3 errors for gcc 3.3.1 and 3.3.2. Has anyone looked at the 3.4 errors and reported them to the appropriate gcc or Boost lists? Here are the three tests failing gcc 3.3.1 and 3.3.2: * iterator interoperable_fail * python embedding * type_traits is_abstract_test Do any of these raise alarm bells? Or are they all to be expected? --Beman

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Re: [Type Traits] is_array and remove_bounds bug
by Jonathan Turkanis 31 Jan '04

31 Jan '04

"John Maddock" <john(a)johnmaddock.co.uk> wrote in message news:005801c3e27a$a6c4d1f0$4b580352@fuji... > > I have noticed that is_array and remove_bounds do not seem to work > > with array types of unknown bounds; e.g., > > > > BOOST_STATIC_ASSERT(!boost::is_array< int[] >::value); > > BOOST_STATIC_ASSERT((boost::is_same< boost::remove_bounds< int[] > > >::type, int[]>::value)); > > > > compile on GCC 3.2 and VC7.1. Is this the desired behavior? > > No, not at all. > > Thanks for the patches, No trouble. > ... this seems to be a strange corner case: VC7.1 > doesn't need the patches (it does the right thing without them), but gcc > does, while Borland doesn't compile the patched version, or do the right > thing without the patches... sigh. That's funny. My installation of VC7.1 defintely doesn't work with the unpatched version. > > Anyway, I've patched the headers and extended the test cases on my local cvs > copy, I've got the type traits regression tests running now, assuming > everything is OK, then I'll commit your patches when cvs comes back online. > How did the regressions turn out? BTW, while we're on the subject of remove_bounds, I think the documentation is slightly misleading. All the remove_xxx traits have a note under 'compiler requirements' essentially stating that the traits don't work correctly without partial specialization, 'except as noted below'. AFAICT, the note refers to the use of the macro BOOST_BROKEN_COMPILER_TYPE_TRAITS_SPECIALIZATION; however, this macro does not provide specializations of remove_bounds (and probably can't, efficiently). I therefore think it might be appropriate to remove 'except as noted below' from the remove_bounds documentation. I am I wrong? Thanks. Jonathan

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Re: [boost] Re: Re: BOOST_STD_EXTENSION_NAMESPACE and dinkumware stdlib313
by John Maddock 31 Jan '04

31 Jan '04

> That's interesting. Since the compiler is determined before the > standard library, it would still be possible to put the definition in > boost/config/stdlib/dinkumware.hpp, like so > > #if defined(BOOST_MSVC) && (BOOST_MSVC >= 1310) > #define BOOST_STD_EXTENSION_NAMESPACE stdext > #endif > > Maybe one should check _CPPLIB_VER for good measure. This sounds > reasonable. What do you think? That sounds reasonable, I'll commit the changes to the main development branch when I get a chance, Intel uses Microsoft's headers (at least I think they do), so it'll be the same for them, but other vendors that use Dinkumware don't necessarily do the same thing (although again it's hard to be definitive). Thanks, John

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