August 2006 - Boost - lists.boost.org

Re: [boost] library for type erasure
by Steven Watanabe 03 Aug '06

03 Aug '06

AMDG Alexander, > >Steven, do you have a document that describes your approach in more details? Does it support multimethods for binary operations? > >-- >Alexander Nasonov > > No I don't have such a document so here are the main benefits and drawbacks of my approach. I didn't know about your library until yesterday so I only understand it in general but I will try to primarily note the differences: I am using a table of function pointers and an unchecked variant type(like Boost.Function) instead of using virtual functions. Thus I avoid a heap allocation for objects that are small enough and are correctly aligned. On the other hand this implementation requires the cast methods to only convert to the exact type put in - not to any of it's base classes. The class template erasure is declared as template<class Operations, class Policy = default_policy, class Derived = my_own_type> class erasure; Operations is a composite tree of operations to allow groups of operations to behave the same as single operations. So all three of these are equivalent typedef combine_operations<boost::mpl::vector<isreamable, ostreamable> > ops; erasure<ops> any; typedef combine_operations<istreamable> ops; erasure<boost::mpl::vector<ops, ostreamable> > any; erasure<boost::mpl::vector<isreamable, ostreamable> > any; Policy specifies the details of the object structure. I have implemented a policy that simulates a virtual function based approach but this seems to put excessive strain on the compiler because of the extra dependencies it introduces. Derived is to allow members like assignment which return(*this) to cast to the correct type. Because of the two other parameters I don't allow things like erasure<istreamable, ostreamable> like of Boost.Variant although I think I could add support for it(with some ugly metafunctions and more coupling). I have provided support for Boost.Ref int i; erasure<...> any(boost::ref(i)); int& iref = erasure_cast<int&>(any); assert(&i == &iref); const int* iptr = erasure_cast<const int*>(*any); assert(iptr == & iref); The price of allowing the addition of const(or volatile) is a very repetitive section of code and 1-2 extra integer comparisons. One final optimization I have implemented is for conversions from one type to a subset. I think that this will slow down the assignment(especially in a multi-threaded program) but will speed up subsequent operations on the result. erasure<istreamable, ostreamable> any_io(1); erasure<ostreamable> any_out(any_io); assert(erasure_cast<const int&>(any_out) == 1); I do not support multi-methods. Unfortunately, there is no way to implement a binary operation that takes two arbitrary types. The closest I can get is to have an operation that takes one arbitrary type and one type from some fixed set which may depend on the first type. I didn't even think of this possibility until you mentioned it so I havn't actually tried to implement it. Finally, here is an example of how I am defining operations: struct addition1 : operation<addition1> { template<class T, class Any> struct static_impl : implementation<void (T&, const Any&)> { static void execute(T& arg, const Any& other) { arg += erasure_cast<const T&>(other); //throws bad_erasure_cast } }; template<class Base> struct partial_interface : Base { typename Base::erasure_full_t& operator+=(const typename Base::erasure_full_t& other) { erasures::call<addition1>(*this, other); //throws object_is_empty return(*erasures::full(this)); } }; }; From the above you can see that the syntax for defining operations is somewhat less than ideal. The main problem I know of is that defining overloaded functions requires a workaround to prevent the derived class version from hiding the base class one. Thus the preceeding example becomes: struct addition1 : operation<addition1> { template<class T, class Any> struct static_impl : implementation<void (T&, const Any&)> { static void execute(T& arg, const Any& other) { arg += erasure_cast<const T&>(other); } }; template<class Base> struct partial_interface_impl : Base { typename Base::erasure_full_t& operator+=(const typename Base::erasure_full_t& other) { erasures::call<addition1>(*this, other); return(*erasures::full(this)); } }; template<class Base> struct partial_interface : partial_interface_impl<Base> { using partial_interface_impl<Base>::operator+=; }; }; If you have any furthur questions I would be glad to answer them. In Christ, Steven Watanabe

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Re: [boost] Boost.Operators base class chaining
by Steven Watanabe 03 Aug '06

03 Aug '06

AMDG Daniel, > >Sure, but this a known and solved problem. Just use addable1 directly, >as documented in the "Caveat" at ><http://boost.org/libs/utility/operators.htm#chaining>. > I guess I should have read the documentation more carefully. Thank you again. In Christ, Steven Watanabe

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[filesystem] very minor request
by Gennaro Prota 02 Aug '06

02 Aug '06

Hi, I don't know if this has been discussed in the LWG but I'd like to make basic_path(const string_type& s); // (*) explicit. I'm right now working on the inspect tool, trying to cut down some of its dependencies. After eliminating boost::bind, which looks overkill to me in this case, I came upon a ironical situation: I modified the function contains_dot() to take a reference to path instead of a reference to string. The intent was to have a stricter type checking: bool contains_dot( /*std::string const& x */ path const & p) { return p.string().find( '.' ) != std::string::npos; } On the invoking code however, I forgot to remove ".string()", so I was still passing a string to it, except that the converting constructor (*) made everything compile anyway. As a result I was converting the path twice, from string and then again to string. This doesn't seem an unusual situation to me, especially when refactoring. What do you think? -- [ Gennaro Prota, C++ developer for hire ]

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[endian] Comments on Endian 0.5
by Dave Dribin 02 Aug '06

02 Aug '06

Hello, I started a thread on Boost-users about the proposed endian library, but it's probably more suitable on the dev list. Here's a link to the thread in the archives: <http://lists.boost.org/boost-users/2006/07/20887.php> I see two issues with the library as of 0.5. First, the endian classes cannot be used in unions. And, second the classes cannot be used in variable argument lists. I'm attaching a patch to help resolve both of these issues. In order to be used in a union, a class must not have any constructors. However, removing constructors breaks the following code: big4_t x = 42; My solution was to provide a static init() method to help in these situations: big4_t x = big_t::init(42); The second problem shows up using varargs. For example, this will not compile: printf("x = %d\n", x); The solution I came up with is to use operator() to get the native value: printf("x = %d\n", x()); In my patch, I've also added a check_unions() function to endian_test.cpp that tests the sizes of unions. Thanks, -Dave

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interest in sorted vector containers?
by Lewis Hyatt 02 Aug '06

02 Aug '06

Hi Everyone- Is there any interest in providing Boost container classes with the same functionality as set/map implemented with sorted vectors? I have four simple classes vset, vmap, vmultiset, vmap which do this. It seems like it would be quite useful, especially since, in my experience, set and map are heavily overused because of their convenience even when the insertion efficiency and iterator invalidation guarantees are not necessary. My classes provide the same interface as the STL equivalent, with additional functions such as nth_element() that take advantage of the random access iterators, and some conveniences like key-only and value-only iterators for vmap and vmultimap. I can post the code with a first attempt at making it appropriate for Boost if people think it is worth it? -Lewis

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Is there any interest in a UTF-8 library?
by Nemanja Trifunovic 02 Aug '06

02 Aug '06

Hello everybody. I have just released Beta 2 version of a small (one header file) generic library for handling UTF-8 encoded strings - you can read more about it at http://utfcpp.sourceforge.net/ . Is there any interest in adding this library too Boost? Either as a separate library or maybe as an addition to some of existing ones. Thanks. Nemanja Trifunovic --------------------------------- See the all-new, redesigned Yahoo.com. Check it out.

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[Boost-bugs] [ boost-Support Requests-1533386 ] 10/2002 version
by SourceForge.net 02 Aug '06

02 Aug '06

Support Requests item #1533386, was opened at 2006-08-02 14:02 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1533386&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Building Boost Group: None Status: Open Resolution: None Priority: 5 Submitted By: piratefan (gregmolnar) Assigned to: Nobody/Anonymous (nobody) Summary: 10/2002 version Initial Comment: I need boost 10/2002 for a project i was just assigned on. I've never used boost before or this environment. I was told to build regex . Where can I get the 10/200 version. Thanks. gregmolnar(a)yahoo.com ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1533386&group_… ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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Boost regression notification (2006-08-02 [RC_1_34_0])
by Douglas Gregor 02 Aug '06

02 Aug '06

Boost Regression test failures Report time: 2006-08-02T06:38:31Z This report lists all regression test failures on release platforms. Detailed report: http://engineering.meta-comm.com/boost-regression/CVS-RC_1_34_0/developer/i… 268 failures in 24 libraries algorithm/string (1) concept_check (1) filesystem (4) graph (5) io (1) iostreams (10) mpl (6) numeric/conversion (4) numeric/interval (1) numeric/ublas (7) parameter (22) program_options (9) python (85) random (1) rational (4) regex (1) serialization (25) signals (16) spirit (1) test (2) tr1 (51) typeof (9) utility (1) xpressive (1) |algorithm/string| regex: borland-5_6_4 |concept_check| class_concept_check_test: vc-7_1-stlport |filesystem| mbcopy: sun-5.8 operations_test: vc-7_1-stlport operations_test_dll: vc-7_1-stlport wide_test: sun-5.8 |graph| adjacency_matrix_test: vc-7_0 csr_graph_test: sun-5.8 graphviz_test: msvc-8.0 msvc-8.0 vc-7_1-stlport |io| ios_state_unit_test: gcc-4.1.0_linux_x86_64 |iostreams| bzip2_test: msvc-7.1 msvc-8.0 compose_test: borland-5_6_4 example_test: vc-6_5-stlport filtering_stream_test: vc-7_1-stlport finite_state_filter_test: cw-9.4 gzip_test: msvc-7.1 msvc-8.0 zlib_test: msvc-7.1 msvc-8.0 |mpl| multiset: gcc-4.0.3_linux gcc-4.1.0_linux gcc-4.1.0_linux_x86_64 gcc-4.1.1_sunos_i86pc gcc-4_0_3_tru64 vector_c: sun-5.8 |numeric/conversion| converter_test: borland-5_8_2 traits_test: borland-5_8_2 udt_example_0: borland-5_8_2 udt_support_test: borland-5_8_2 |numeric/interval| test_float: vc-7_1-stlport |numeric/ublas| concepts: vc-7_1-stlport vc-7_1-stlport test1: vc-7_1-stlport test2: vc-7_1-stlport test4: vc-7_1-stlport test5: vc-7_1-stlport vc-7_1-stlport |parameter| basics: borland-5_6_4 borland-5_8_2 duplicates: borland-5_6_4 borland-5_8_2 maybe: vc-6_5 vc-6_5-stlport vc-7_0 preprocessor: borland-5_6_4 borland-5_8_2 sun-5.8 vc-6_5 vc-6_5-stlport python-parameter-test: vc-6_5 vc-6_5-stlport vc-7_0 sfinae: borland-5_8_2 vc-6_5-stlport singular: borland-5_6_4 borland-5_8_2 unnamed_fail: vc-6_5 vc-6_5-stlport vc-7_0 |program_options| cmdline_test_dll: cw-9.4 options_description_test_dll: cw-9.4 parsers_test_dll: cw-9.4 positional_options_test_dll: cw-9.4 unicode_test_dll: borland-5_8_2 cw-9.4 variable_map_test_dll: borland-5_8_2 cw-9.4 winmain_dll: cw-9.4 |python| andreas_beyer: sun-5.8 args: sun-5.8 auto_ptr: sun-5.8 back_reference: sun-5.8 bases: gcc-3_4_4_tru64 gcc-4_0_3_tru64 sun-5.8 ben_scott1: sun-5.8 bienstman1: sun-5.8 bienstman2: sun-5.8 bienstman3: sun-5.8 borrowed: sun-5.8 callbacks: sun-5.8 const_argument: sun-5.8 crossmod_exception: sun-5.8 data_members: sun-5.8 defaults: sun-5.8 dict: sun-5.8 docstring: sun-5.8 enum: sun-5.8 exception_translator: sun-5.8 exec: cw-9.4 darwin-4.0.1 gcc-3_4_4_tru64 gcc-4_0_3_tru64 msvc-8.0 qcc-3.3.5_cpp qcc-3.3.5_cpp qcc-3.3.5_gpp qcc-3.3.5_gpp sun-5.8 extract: sun-5.8 implicit: sun-5.8 indirect_traits_test: sun-5.8 injected: sun-5.8 iterator: sun-5.8 keywords: sun-5.8 list: sun-5.8 long: sun-5.8 minimal: sun-5.8 multi_arg_constructor: sun-5.8 nested: sun-5.8 numpy: sun-5.8 object: sun-5.8 object_manager: sun-5.8 opaque: sun-5.8 operators: sun-5.8 pearu1: sun-5.8 pickle1: sun-5.8 pickle2: sun-5.8 pickle3: sun-5.8 pickle4: sun-5.8 pointee: gcc-3_4_4_tru64 gcc-4_0_3_tru64 sun-5.8 pointer_type_id_test: gcc-3_4_4_tru64 gcc-4_0_3_tru64 sun-5.8 pointer_vector: sun-5.8 polymorphism: sun-5.8 polymorphism2: sun-5.8 polymorphism2_auto_ptr: sun-5.8 properties: sun-5.8 raw_ctor: sun-5.8 return_arg: sun-5.8 select_arg_to_python_test: sun-5.8 select_from_python_test: darwin-4.0.1 sun-5.8 select_holder: sun-5.8 shared_ptr: sun-5.8 slice: sun-5.8 staticmethod: sun-5.8 stl_iterator: sun-5.8 str: sun-5.8 string_literal: sun-5.8 test_pointer_adoption: sun-5.8 try: sun-5.8 tuple: sun-5.8 upcast: gcc-3_4_4_tru64 gcc-4_0_3_tru64 sun-5.8 vector_indexing_suite: sun-5.8 virtual_functions: sun-5.8 voidptr: sun-5.8 wrapper_held_type: sun-5.8 |random| random_test: intel-linux-9.0 |rational| rational_test: borland-5_6_4 vc-6_5 vc-6_5-stlport vc-7_0 |regex| regex_regress_threaded: gcc-4_0_3_tru64 |serialization| test_class_info_load_text_warchive: vc-6_5 test_non_default_ctor2_text_archive: qcc-3.3.5_cpp qcc-3.3.5_cpp qcc-3.3.5_cpp test_non_default_ctor2_text_archive_dll: qcc-3.3.5_cpp qcc-3.3.5_cpp qcc-3.3.5_cpp test_non_default_ctor2_text_warchive: qcc-3.3.5_cpp qcc-3.3.5_cpp qcc-3.3.5_cpp test_non_default_ctor2_text_warchive_dll: qcc-3.3.5_cpp qcc-3.3.5_cpp qcc-3.3.5_cpp test_reset_object_address: vc-7_0 test_reset_object_address_dll: vc-7_0 test_set_text_archive_dll: msvc-8.0 test_simple_class_binary_archive_dll: vc-6_5 test_simple_class_text_archive_dll: vc-6_5 test_simple_class_text_warchive_dll: vc-6_5 test_simple_class_xml_archive_dll: vc-6_5 test_simple_class_xml_warchive_dll: vc-6_5 test_variant_xml_archive: borland-5_8_2 test_variant_xml_archive_dll: borland-5_8_2 test_variant_xml_warchive: borland-5_8_2 test_variant_xml_warchive_dll: borland-5_8_2 |signals| dead_slot_test: gcc-3.3.6 gcc-3.3.6_linux qcc-3.3.5_cpp qcc-3.3.5_cpp qcc-3.3.5_cpp qcc-3.3.5_gpp qcc-3.3.5_gpp qcc-3.3.5_gpp trackable_test: gcc-3.3.6 gcc-3.3.6_linux qcc-3.3.5_cpp qcc-3.3.5_cpp qcc-3.3.5_cpp qcc-3.3.5_gpp qcc-3.3.5_gpp qcc-3.3.5_gpp |spirit| mix_and_match_trees: sun-5.8 |test| parameterized_test_test: vc-6_5 vc-6_5-stlport |tr1| run_random: sun-5.8 std_run_complex_overloads: sun-5.8 std_run_random: sun-5.8 std_test_bind: sun-5.8 std_test_complex: sun-5.8 std_test_function: sun-5.8 std_test_hash: sun-5.8 std_test_mem_fn: sun-5.8 std_test_random: sun-5.8 std_test_reference_wrapper: sun-5.8 std_test_reference_wrapper_tricky: gcc-3.2.3_linux gcc-3.3.6_linux gcc-3.4.5_linux gcc-3.4.5_linux_x86_64 gcc-4.0.3_linux gcc-4.1.0_linux_x86_64 intel-linux-9.0 mingw-3_4_2 msvc-7.1 msvc-8.0 qcc-3.3.5_cpp qcc-3.3.5_cpp qcc-3.3.5_gpp qcc-3.3.5_gpp vc-7_1-stlport std_test_result_of: sun-5.8 std_test_shared_ptr: sun-5.8 std_test_tuple: sun-5.8 std_test_tuple_tricky: sun-5.8 std_test_type_traits: sun-5.8 test_boost: vc-7_1-stlport test_hash: vc-7_1-stlport test_random: sun-5.8 vc-7_1-stlport test_reference_wrapper_tricky: gcc-3.2.3_linux gcc-3.3.6_linux gcc-3.4.5_linux gcc-3.4.5_linux_x86_64 gcc-4.0.3_linux gcc-4.1.0_linux_x86_64 intel-linux-9.0 mingw-3_4_2 msvc-7.1 msvc-8.0 qcc-3.3.5_cpp qcc-3.3.5_cpp qcc-3.3.5_gpp qcc-3.3.5_gpp test_regex: vc-7_1-stlport test_type_traits: sun-5.8 tr1_tky_function_type_test: sun-5.8 |typeof| function_binding_emulation: sun-5.8 function_binding_native: vc-6_5 vc-6_5-stlport vc-7_0 nested_typedef_emulation: cw-9.4 odr_no_uns: vc-6_5 vc-6_5-stlport vc-7_0 template_tpl_emulation: sun-5.8 |utility| operators_test: gcc-3.4.5_linux_x86_64 |xpressive| test7: msvc-8.0

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Re: [boost] Numerical integration library?
by Sohail Somani 02 Aug '06

02 Aug '06

> -----Original Message----- > From: boost-bounces(a)lists.boost.org > [mailto:boost-bounces@lists.boost.org] On Behalf Of John Maddock > Sent: Wednesday, August 02, 2006 4:51 AM > To: boost(a)lists.boost.org > Subject: Re: [boost] Numerical integration library? > > Sohail Somani wrote: > > If I can only suggest: Decouple evaluation of the objective function > > from its derivatives. Or have another concept that is not callable. > > > > I have an example of how one can specify a family of functions and > > their derivatives: > > > > http://sohail.taggedtype.net/software/newton_raphson.cxx > > > > You can blame the idle hands for this one. > > :-) > > I see what you're doing, but I deliberately wanted the > derivatives to be > calculated at the same time as f(x): the functions I was interested in > (incomplete beta and gamma's) have terms that are common to both the > derivative and the objective function, and I wanted the option of > calculating both the derivatives and the objective function > at the same > time. I'll be interested to see the evolution of your library. Will definitely try it out at some point. Thanks for the link! Sohail

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[serialization] facets for non-finite numbers
by Johan Råde 02 Aug '06

02 Aug '06

At the suggestion of Robert Ramey's, I have put together facets for reading and writing non-finite numbers, such as infinity and not-a-number, to text streams, in a consistent and portable way. The code, with documentation and tests, is available in the Boost Vault, serialization/non_finite_num_facets.zip. If there is enough interest in the code, I will submit it for a mini-review, in order to have it added to the serialization lib. --------------------------------------------- What does the code do? The following test fails on VC++ 7.1: stringstream s; double x = numeric_limits<double>::infinity(); double y; ss << x; ss >> y; assert(x == y); The situation gets even worse when text files are required to be portable between different platforms. But the following test succeeds: stringstream s; locale old_locale; locale tmp_locale(old_locale, new extended_num_put<char>); locale new_locale(tmp_locale, new extended_num_get<char>); s.imbue(new_locale); double x = numeric_limits<double>::infinity(); double y; ss << x; ss >> y; assert(x == y); For more info, read the documentation. ------------------------------------------------------------ --Johan Råde

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