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Re: [boost] [ANN] Phoenix-2 prerelease (Functions)
by David Abrahams 04 Nov '05

04 Nov '05

Joel de Guzman <joel(a)boost-consulting.com> writes: > Comments, feedback very welcome! > Function > > Lazy functions... > > #include <boost/spirit/phoenix/function/function.hpp> > > The function template class provides a mechanism for lazily ^^^^^^^^^^^^^^ class template > evaluating functions. Syntactically, a lazy function looks like an > ordinary C/C++ function. The function call looks familiar and feels > the same as ordinary C++ functions. Except you can't use ADL. > However, unlike ordinary > functions, the actual function execution is deferred. For example > here are sample factorial function calls: Whoa, where did factorial come from? > factorial(4) > factorial(arg1) > factorial(arg1 * 6 / factorial(ref(i))) > > These functions are automatically lazily bound Really? Even the first one? > unlike ordinary function pointers or functor objects that need to be > explicitly bound through the bind function (see Bind). > > A lazy function works in conjunction with a user defined function > object (as usual with a member operator()). I'm lost. What do you mean "in conjunction with?" > Only special forms of function objects are allowed. Even more lost! Allowed where? > This is required to enable true polymorphism I happen to have a clue as to what you mean, but most won't. Probably anyplace you mention polymorphism in this doc, you should link to the discussion of its use in this context. > (STL style monomorphic functors and function pointers can still be > used through the bind facility (see Bind)). > > > This special function object is expected to have a nested template > class apply<T0...TN> (where N is the number of arguments of its > operator()). The nested template class result should have a typedef > type that reflects the return type of its operator(). I guess you might be describing the Eval concept. It's not obvious though. This section needs to be reworked for clarity. > There is a special case Of what? > for functors that accept no arguments. Such nullary functors are > only required By what? > to define a typedef result_type that reflects the > return type of its operator(). > > > Here's an example of a simple functor that computes the factorial of > a number: I would avoid "functor" except as a parenthesized note remarking that function objects are often called functors in the C++ community. That usage of "functor" is sorta deprecated and probably never should have arisen, considering its prior use with other meanings. > struct factorial_impl > { > template <typename Arg> > struct apply > { > typedef Arg type; > }; > > template <typename Arg> > Arg operator()(Arg n) const > { > return (n <= 0) ? 1 : n * this->operator()(n-1); > } > }; > > (See factorial.cpp) Oh, here it is. Way too late. Or mentioned too early. > The functor is polymorphic. Its arguments and return type are not > fixed to a particular type. The example above can handle any Arg > type as long as it can carry out the required operations (i.e. <=, * > and - ). > > We can declare and instantiate a lazy factorial function this way: > > function<factorial_impl> factorial; Oh, this is the point of the section? Then why is it called "Function" set in normal type, instead of "function" set in code font? > Invoking a lazy function factorial does not immediately execute the function object factorial_impl. Instead, a composite object is created and returned to the caller. Example: > > factorial(arg1) Even in factorial(4) ? > does nothing more than return a composite. A second function call > will invoke the actual factorial function. Example: > > int i = 4; > cout << factorial(arg1)(i); > > will print out "24". > > Take note that in certain cases (e.g. for function objects with > state), an instance of the functor may be passed on to the > constructor. Example: > > function<factorial_impl> factorial(ftor); > > where ftor is an instance of factorial_impl (this is not necessary ^^^^ needs antecedent > in this case since factorial is a simple stateless functor). Take ^^^^ too many "this"es. Eliminate the first. > care though when using functors with state because the functors are ^^^^^^ ^ strike , > held by value. I don't think you mean that. I think you mean "Functors are often copied repeatedly, and the state may be changed in one or more copies, rather than in the original." > It is best to keep the data manipulated by a functor > outside the functor itself and keep a reference to this data inside > the functor. Also, it is best to keep functors as small as possible. > -- Dave Abrahams Boost Consulting www.boost-consulting.com

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Re: [boost] [ANN] Phoenix-2 prerelease
by David Abrahams 04 Nov '05

04 Nov '05

Joel de Guzman <joel(a)boost-consulting.com> writes: > Comments, feedback very welcome! > Values > > #include <boost/spirit/phoenix/core/value.hpp> > > Whenever we see a constant in a partially applied function, an > > actor<value<T> > > > (where T is the type of the constant) is automatically created by > default for us. > For instance: > > add(arg1, 6) > > Passing a second argument, 6, an actor<value<int> > is implicitly > created behind the scenes. This is also equivalent to: > > add(arg1, val(6)) > > val(x) generates an actor<value<T> > where T is the type of x. I think the use of "us" here is awkward. "You" would be better. "automatically by default" is confusing language. If you're not prepared to tell people what happens when the default is not taken, you probably shouldn't mention that it's a default at all. Also, I doubt that it's really _wherever_ a constant appears in a partially applied function: foo<2>() + arg1 I suggest: To represent a value of type T as an actor, we can use the value template. actor<value<T> >(x) is an actor that returns x when invoked. For instance, actor<value<int> >(6) is equivalent to val(6) an actor that, when invoked, returns the value 6. In expressions combining actors with values, the val() function is invoked implicitly, so add(arg1, 6) is equivalent to add(arg1, val(6)) an actor that adds 6 to its first argument. > In most cases, there's really no need to explicitly use val. There ^^^^^^ strike > are situations though, as we'll see later on, where this is > unavoidable. ..., but as we'll see later on, there are situations where it is unavoidable. -- Dave Abrahams Boost Consulting www.boost-consulting.com

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Boost regression notification (2005-11-04 [RC_1_33_0])
by Douglas Gregor 04 Nov '05

04 Nov '05

Boost regression test failures ------------------------------ Report time: 2005-11-04T14:47:07Z This report lists all regression test failures on release platforms. Detailed report: http://engineering.meta-comm.com/boost-regression/CVS-RC_1_33_0/developer/i… 0 failure in 0 library:

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Boost regression notification (2005-11-04 [HEAD])
by Douglas Gregor 04 Nov '05

04 Nov '05

Boost regression test failures ------------------------------ Report time: 2005-11-04T06:00:10Z This report lists all regression test failures on release platforms. WARNING: The following libraries have failing regression tests but do not have a maintainer on file. Once a maintainer is found, add an entry to libs/maintainers.txt to eliminate this message. io Detailed report: http://engineering.meta-comm.com/boost-regression/CVS-HEAD/developer/issues… 294 failures in 13 libraries: bind (7) concept_check (12) graph (2) io (1) mpl (1) serialization (30) spirit (8) thread (4) tr1 (147) tuple (1) type_traits (58) typeof (18) xpressive (5) |bind| bind_dm3_test: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 vc-7_1 |concept_check| stl_concept_covering: cw-9_4 gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin intel-win32-9_0 intel-win32-9_0 mingw-3_4_2 vc-7_1 |graph| graphviz_test: vc-7_1 layout_test: intel-win32-9_0 |io| ios_state_unit_test: intel-win32-9_0 |mpl| size_t: gcc-4_0-darwin |serialization| test_class_info_load_binary_archive: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_binary_archive_dll: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_text_archive: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_text_archive_dll: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_text_warchive: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_text_warchive_dll: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_xml_archive: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_xml_archive_dll: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_xml_warchive: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin test_class_info_load_xml_warchive_dll: gcc-3_3-darwin gcc-3_4_3-sunos gcc-4_0-darwin |spirit| action_tests_debug: gcc-3_4_3-sunos distinct_tests_debug: gcc-3_4_3-sunos escape_char_parser_tests_debug: gcc-3_4_3-sunos grammar_def_test_debug: gcc-3_4_3-sunos switch_problem_debug: gcc-3_4_3-sunos switch_tests_single_debug: gcc-3_4_3-sunos traverse_tests: intel-win32-9_0 traverse_tests_debug: intel-win32-9_0 |thread| test_condition: gcc-3_4_3-sunos test_mutex: gcc-3_4_3-sunos test_tss: gcc-3_4_3-sunos gcc-3_4_3-sunos |tr1| run_complex_overloads: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.4.4-linux run_random: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.4.4-linux std_test_array: gcc-2.95.3-linux std_test_array_tricky: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 vc-7_1 std_test_bind: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 std_test_bind_tricky: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 vc-7_1 std_test_boost: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux std_test_complex: gcc-2.95.3-linux std_test_function: gcc-2.95.3-linux std_test_function_tricky: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 vc-7_1 std_test_hash: gcc-2.95.3-linux std_test_mem_fn: gcc-2.95.3-linux std_test_mem_fn_tricky: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 vc-7_1 std_test_random: gcc-2.95.3-linux std_test_reference_wrapper: gcc-2.95.3-linux std_test_reference_wrapper_tricky: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 vc-7_1 std_test_regex: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.4.4-linux std_test_result_of: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux std_test_shared_ptr: gcc-2.95.3-linux std_test_tr1_include: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux std_test_tuple: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux std_test_tuple_tricky: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 vc-7_1 std_test_type_traits: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3_3-darwin test_algorithm: gcc-2.95.3-stlport-4.6.2-linux test_array_tricky: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 vc-7_1 test_bind: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 test_bind_tricky: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 vc-7_1 test_complex: gcc-2.95.3-linux test_exception: gcc-2.95.3-stlport-4.6.2-linux test_function_tricky: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 vc-7_1 test_functional: gcc-2.95.3-linux test_hash: gcc-2.95.3-linux test_mem_fn_tricky: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 vc-7_1 test_memory: gcc-2.95.3-linux test_new: gcc-2.95.3-stlport-4.6.2-linux test_reference_wrapper_tricky: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 vc-7_1 test_regex: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.4.4-linux test_result_of: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux test_tr1_include: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux test_tuple: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux test_tuple_tricky: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3.4.4-linux gcc-3_3-darwin intel-win32-9_0 vc-7_1 test_type_traits: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3_3-darwin test_utility: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux |tuple| tuple_test_bench: gcc-3_4_3-sunos |type_traits| tr1_add_const_test: gcc-2.95.3-linux tr1_add_cv_test: gcc-2.95.3-linux tr1_add_pointer_test: gcc-2.95.3-linux tr1_add_reference_test: gcc-2.95.3-linux tr1_add_volatile_test: gcc-2.95.3-linux tr1_aligned_storage_test: gcc-2.95.3-linux tr1_alignment_of_test: gcc-2.95.3-linux tr1_extent_test: gcc-2.95.3-linux tr1_has_nothrow_assign_test: gcc-2.95.3-linux tr1_has_nothrow_constr_test: gcc-2.95.3-linux tr1_has_nothrow_copy_test: gcc-2.95.3-linux tr1_has_trivial_assign_test: gcc-2.95.3-linux tr1_has_trivial_constr_test: gcc-2.95.3-linux tr1_has_trivial_copy_test: gcc-2.95.3-linux tr1_has_trivial_destructor_test: gcc-2.95.3-linux tr1_has_virtual_destructor_test: gcc-2.95.3-linux tr1_is_abstract_test: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux gcc-3.3.6-linux gcc-3_3-darwin tr1_is_arithmetic_test: gcc-2.95.3-linux tr1_is_array_test: gcc-2.95.3-linux tr1_is_base_of_test: gcc-2.95.3-linux tr1_is_class_test: gcc-2.95.3-linux tr1_is_compound_test: gcc-2.95.3-linux tr1_is_const_test: gcc-2.95.3-linux tr1_is_convertible_test: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux tr1_is_empty_test: gcc-2.95.3-linux tr1_is_enum_test: gcc-2.95.3-linux tr1_is_floating_point_test: gcc-2.95.3-linux tr1_is_function_test: gcc-2.95.3-linux tr1_is_fundamental_test: gcc-2.95.3-linux tr1_is_integral_test: gcc-2.95.3-linux tr1_is_member_func_test: gcc-2.95.3-linux tr1_is_member_obj_test: gcc-2.95.3-linux tr1_is_member_pointer_test: gcc-2.95.3-linux tr1_is_object_test: gcc-2.95.3-linux tr1_is_pod_test: gcc-2.95.3-linux tr1_is_pointer_test: gcc-2.95.3-linux tr1_is_polymorphic_test: gcc-2.95.3-linux gcc-2.95.3-stlport-4.6.2-linux tr1_is_reference_test: gcc-2.95.3-linux tr1_is_same_test: gcc-2.95.3-linux tr1_is_scalar_test: gcc-2.95.3-linux tr1_is_signed_test: gcc-2.95.3-linux tr1_is_union_test: gcc-2.95.3-linux tr1_is_unsigned_test: gcc-2.95.3-linux tr1_is_void_test: gcc-2.95.3-linux tr1_is_volatile_test: gcc-2.95.3-linux tr1_rank_test: gcc-2.95.3-linux tr1_remove_all_extents_test: gcc-2.95.3-linux tr1_remove_const_test: gcc-2.95.3-linux tr1_remove_cv_test: gcc-2.95.3-linux tr1_remove_extent_test: gcc-2.95.3-linux tr1_remove_pointer_test: gcc-2.95.3-linux tr1_remove_reference_test: gcc-2.95.3-linux tr1_remove_volatile_test: gcc-2.95.3-linux |typeof| data_member_native: cw-9_4 function_native: cw-9_4 function_ptr_native: cw-9_4 function_ref_native: cw-9_4 lvalue_native: cw-9_4 member_function_native: cw-9_4 modifiers_emulation: cw-9_4 modifiers_native: cw-9_4 noncopyable_native: cw-9_4 std_emulation: cw-9_4 std_native: cw-9_4 template_dependent_native: cw-9_4 template_enum_native: cw-9_4 template_int_native: cw-9_4 template_multiword_native: cw-9_4 template_tpl_native: cw-9_4 template_type_native: cw-9_4 type_native: cw-9_4 |xpressive| test3u: gcc-3_3-darwin test4u: gcc-3_3-darwin test5u: gcc-3_3-darwin test6u: gcc-3_3-darwin test9u: gcc-3_3-darwin

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Global object initialization [was: Phoenix-2 prerelease]
by David Abrahams 04 Nov '05

04 Nov '05

Joel de Guzman <joel(a)boost-consulting.com> writes: > Comments, feedback very welcome! Here are some sample preset definitions of arg1..argN actor<argument<0> > const arg1 = argument<0>(); actor<argument<1> > const arg2 = argument<1>(); actor<argument<2> > const arg3 = argument<2>(); and its BLL_1.._N style counterparts: You shouldn't use the BLL abbrev., especially not without introducing it first. I suggest "Boost.Lambda" actor<argument<0> > const _1 = argument<0>(); actor<argument<1> > const _2 = argument<1>(); actor<argument<2> > const _3 = argument<2>(); Have you considered the ODR/initialization order implications of this? Eric and I have been discussing this in another context, and it seems to us that you have a choice: 1. The placeholders are statically initialized const POD objects in an unnamed namespace and you have likely ODR violation when used by templates in multiple translation units. 2. The placeholders are dynamically initialized references in an unnamed namespace and you risk undefined behavior when they are used without initialization due to initialization order issues 3. The placeholders are dynamically initialized objects in an unnamed namespace, and you have likely ODR violation *and* initialization order issues Seems from the doc like you have #3, which is the worst of both worlds. No? -- Dave Abrahams Boost Consulting www.boost-consulting.com

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Re: [boost] [ANN] Phoenix-2 prerelease
by David Abrahams 04 Nov '05

04 Nov '05

Joel de Guzman <joel(a)boost-consulting.com> writes: > Comments, feedback very welcome! template <typename Eval> struct actor : Eval { return_type operator()() const; template <typename T0> return_type operator()(T0& _0) const; template <typename T0, typename T1> return_type operator()(T0& _0, T1& _1) const; //... }; Is that really what the declaration of actor looks like? I have a hard time believing that there's an identifier called return_type involved. IMO this is just confusing. Are you sure you want to show any code here at all? Oh! and you're using _0, _1, et. al. as parameter names! Wow, really confusing! -- Dave Abrahams Boost Consulting www.boost-consulting.com

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[MPL.Math] semantics of integral_part and fractional_part metafunctions
by Cromwell Enage 04 Nov '05

04 Nov '05

--- Manfred Doubar wrote: > BUT I would expect that both integer and fractional > _parts *included* the sign - and I tend to think > anything else would inevitably lead to confusion. I set up the current semantics of is_negative, integral_part, and fractional_part to match the semantics of the corresponding typedefs in mixed_number_impl. BTW, integral_part used to be called whole_part because it returned whole numbers, which were were nonnegative. > I have a good hint of why you might have gone down > this path, Now you know exactly why. > but I can only think that its going to be cause for > error. No, the difference between our definitions of integral_part and fractional_part will be the cause for error. It turns out that Mathematica <http://mathworld.wolfram.com/> agrees with you, so I'll go ahead and change the metafunction semantics. Cromwell D. Enage __________________________________ Yahoo! Mail - PC Magazine Editors' Choice 2005 http://mail.yahoo.com

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Re: [boost] [ANN] Phoenix-2 prerelease
by David Abrahams 04 Nov '05

04 Nov '05

zvrba(a)globalnet.hr writes: > On Thu, Nov 03, 2005 at 04:55:59PM -0500, David Abrahams wrote: >> >> Rewrite that paragraph: >> > Totally off-topic, but while you're at it.. > > 1. Where did you learn these elements of style? Any online > references? http://www.amazon.com/exec/obidos/tg/detail/-/020530902X/103-0796082-472383… > 2. As for asne.org. Can you please give some navigation on the site > where to find editorial tips (how did you find e.g. > http://www.asne.org/index.cfm?ID=4364 ?) Google. > Is there an index of such tips?o I dunno. > I'm asking because I've found out for myself how hard it is to write a > good, clear and concise text... Strunk & White is the bible. -- Dave Abrahams Boost Consulting www.boost-consulting.com

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Website spelling error (still there)
by Jeffrey Williams 04 Nov '05

04 Nov '05

A while back I reported a web site spelling error to this list. It is still there. Which means either I am reporting it to the wrong place, or noone cares or perhaps I am wrong about the spelling error. I'll report it again: On the boost home page, under the latest news in the Serialization library section is says this: Improved seialization of shared pointers Shouldn't this be: Improved serialization of shared pointers Or in the field of serialization does "seialization" actually have a specific meaning? Jeff

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[network] Boost.Network proposal v0.4
by Pedro Lamarão 04 Nov '05

04 Nov '05

Fellow Boosters, this is an update on my proposal for (the beggining of?) a Boost.Network library, located in the "Input - Output" folder of the Sandbox. I consider it feature complete for a 1.0 milestone; the features being: * IOStreams through boost::iostreams (providing a "talker" type model of Device over sockets). * A listener class. * A wrapper for the name resolution services of the system library. * Types to store network addresses with formatted output operators. There's still some more documentation to write, though. Please give one last shot at this proposal. Last time people objected to it as a "Boost.Network" library for not being sufficiently generic (in which it doesn't support "multiplexing" or "asynchronicity"), so perhaps I should move it deeper inside, like, Boost.IOStreams.Network. What do you think? The four components provided could be considered independently: the listener class is as simple as it gets, with a private "accept" method for RAII initialization of whatever socket wrapper type; the model of Device is also as simple as it gets; maybe there is some other interesting stuff to improve the getaddrinfo wrapper and the address types. Possible areas of improvement for the future are: * selector/poller (which is sitting around here waiting) * full formatted input and output for address types * asynchronous resolver (based on Boost.Threads). * Wrapper for sendfile/TransmitFile. -- Pedro Lamarão

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