November 2009 - Boost - lists.boost.org

boost::noncopyable errors are difficult to diagnose on MSVC
by Zachary Turner 07 Nov '09

07 Nov '09

Is there anything that can be done to improve the error messages generated by the compiler when a copy fails to be made due to a boost::noncopyable? I had just finished a sprint where I had typed close to 1,000 lines of code with tons of new classes and objects before trying to compile, and one of the classes I had entered was similar to the following: class foo { public: foo(boost::asio::ip::tcp::socket& socket) : socket_(socket) { } private: boost::asio::ip::tcp::socket socket_; }; Problem here is that I forgot to add a reference to the class member, it was by value so the compiler is going to generate an error since a socket cannot be copied. The error this generated from the compiler was: 1>Q:\include\boost\1.39.0\boost/asio/basic_io_object.hpp(92) : error C2248: 'boost::noncopyable_::noncopyable::noncopyable' : cannot access private member declared in class 'boost::noncopyable_::noncopyable' 1> Q:\include\boost\1.39.0\boost/noncopyable.hpp(27) : see declaration of 'boost::noncopyable_::noncopyable::noncopyable' 1> Q:\include\boost\1.39.0\boost/noncopyable.hpp(22) : see declaration of 'boost::noncopyable_::noncopyable' 1> This diagnostic occurred in the compiler generated function 'boost::asio::basic_io_object<IoObjectService>::basic_io_object(const boost::asio::basic_io_object<IoObjectService> &)' 1> with 1> [ 1> IoObjectService=boost::asio::stream_socket_service<boost::asio::ip::tcp> 1> ] The most I can possibly figure out from this is that it's related to a socket. but this hardly helped as I had been using socket stuff all over the place. It took a long time to track this down because there was zero information about even what source file the offending code was in. I know this is sort of catering to the compiler, but is there any trickery that can be done so that at least the compiler generates an error related to the source file the object was declared in?

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ASIO
by Mohammed Rasmy 07 Nov '09

07 Nov '09

Hello, I am trying to do a POST request using Boost::Asio, of a variable x that holds an email address, and a variable y that holds the contents of a zip file. I couldn't find samples floating around and I'm unsure of how to proceed. I've come up with the following code: boost::asio::streambuf request; std::ostream request_stream(&request); wxString buffer = wxT("POST "); buffer += wxT("http://serveraddress.com"); buffer += wxT(" HTTP/1.1\r\n"); buffer += wxT("Host: serveraddress.com\r\n"); buffer += wxT("Accept: */*\r\n"); buffer += wxT("Connection: close\r\n\r\n"); buffer += wxT("email_address=test(a)test.com"); buffer += wxT("zip_file=")/*actual zip file data here?*/; request_stream << buffer.mb_str(); Note that I am using wxWidgets, wxT is nothing more than a way of defining strings there, and wxString is, well, a string. The above code compiles fine, but I am not sure how to add the zip file? Also would the above code work? I know it is working for a GET request but that's it. Please advise. Thanks for your time, Mohammed _________________________________________________________________ Keep your friends updated—even when you’re not signed in. http://www.microsoft.com/middleeast/windows/windowslive/see-it-in-action/so…

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[smart_ptr] Add make/allocate functions for boost::shared_array
by Roman Kecher 06 Nov '09

06 Nov '09

Hi, I was wondering if there's any reason not to include make_shared_array() / allocate_shared_array() in boost/make_shared.hpp (or maybe add boost/make_shared_array.hpp), along with the already existing make_shared() and allocate_shared() functions? Regards, Roman.

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[swap] ruminations
by Jeffrey Hellrung 06 Nov '09

06 Nov '09

1) Would it be a good idea (aside from breaking backwards compatibility) to insulate boost::swap from being found via ADL? Consider another library, tsoob, which also has a swap intended to be used in the same manner as boost::swap (i.e., it finds a free function swap via ADL, falling back to std::swap or maybe some custom swap or whatever). Now tsoob::swap and boost::swap cannot be used in the same program (ambiguous call to overloaded function swap) if the associated namespaces of the type being swapped includes both boost and tsoob (certainly possible). What I'm thinking about is the possibility of creating a namespace boost::adl which contains (what would have previously been called) boost::swap, as well as any other similar free functions. So the only way to invoke boost::adl::swap is to make it explicit; it will never be found via ADL. Plus it helps document the underlying mechanism (ADL) of boost::swap. 2) Is there some way for boost::swap and tsoob::swap to coexist peacefully while retaining backwards compatibility for both? - Jeff

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[graph] Usage (and possible removal) of LEDA and Stanford GraphBase adaptors for Boost.Graph
by Jeremiah Willcock 06 Nov '09

06 Nov '09

Are there any users of the LEDA and Stanford GraphBase adaptors for Boost.Graph? They are no longer actively maintained and there have been bug reports that the LEDA adaptor does not work with current versions of LEDA. If they are no longer used, Andrew Sutton and I will consider deprecating and/or removing them. Please reply if you would like these components kept in Boost.Graph. -- Jeremiah Willcock

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[random] Seeding again
by Steven Watanabe 06 Nov '09

06 Nov '09

AMDG The attached patch allows random number generators to be seeded with any value. Currently linear_congruential and a few other generators can assert for some seeds. (For instance minstd_rand cannot be seeded with 0). For linear_congruential I am using the algorithm described in n2960, section 26.5.3.1/4. For linear_feedback_shift I use a similar idea, adding 2^(w-k) if the seed is less than 2^(w-k). The behavior of any code that was valid before, should be unaffected by this change. The patch includes test and documentation updates. The tests pass with gcc, msvc, and como. I think it's ready to go now. Okay to commit? In Christ, Steven Watanabe

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New boost packaging suggestion for windows
by Julian Bangert 06 Nov '09

06 Nov '09

Hello, yesterday I tried to download the boostpro binaries for windows and I had to download over a gigabyte to get all configurations for VS 2008. Sadly the version also was outdated and in general not that great ( e.g. Installer quite bad to handle and you have to register to download ) . So I decided to build from source and package it for a few friends who also needed these binaries. I managed to compress boost_1_40 ( no source except headers, no python AFAIK , but everything else you get with a standard build ) from over 900MB down to 37MB by using 7z. I uploaded it here https://obliviononline.com/pub/boost/boost_1_40_0.7z . Should boost use this form of releasing binaries in the future for windows ? Alternatively, you could endorse this form, like boostpro is endorsed right now and I could host it on google code, etc . An easy to set up ( just unzip this file ) binary distribution would make compiling boost-dependent software much easier. I would be willing to distribute future releases compatible with VS 2005 and 2008 in this form. Yours, Julian Bangert __________ Information from ESET NOD32 Antivirus, version of virus signature database 4551 (20091028) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com

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Boost.Python release testing failures
by Steve M. Robbins 06 Nov '09

06 Nov '09

Hi, I'm running Boost nightly regression tests on a 64-bit Debian linux platform for quite some time. I've recently added gcc 4.4 and Boost.Python is failing miserably; c.f. http://tinyurl.com/yl7yjkv If I click on a test result URL, such as for "andreas_beyer" [http://tinyurl.com/yft8k3o] I'm redirected ("See boost/bin.v2/libs/python/build/gcc-4.4/debug") which shows that the compile succeeded, but nothing more [http://tinyurl.com/yft8k3o] Digging into the bjam.log file, it turns out these tests are skipped because the Boost.Python library failed to build. It would be nice to improve the error reporting to make this clear. The compilation error is: "g++-4.4" -ftemplate-depth-128 -std=c++0x -O0 -fno-inline -w -g -fPIC -DBOOST_ALL_NO_LIB=1 -DBOOST_PYTHON_SOURCE -I".." -I"/usr/include/python2.5" -c -o "/home/steve/Packages/boost/upstream/testing/release/results/boost/bin.v2/libs/python/build/gcc-4.4/debug/object/function_doc_signature.o" "../libs/python/src/object/function_doc_signature.cpp" ../libs/python/src/object/function_doc_signature.cpp: In static member function 'static boost::python::str boost::python::objects::function_doc_signature_generator::pretty_signature(const boost::python::objects::function*, size_t, bool)': ../libs/python/src/object/function_doc_signature.cpp:238: error: no match for 'operator%' in '"%s %s(%s%s%s%s)" % std::make_tuple(_Elements&& ...) [with _Elements = boost::python::str&, const boost::python::api::object&, boost::python::str, boost::python::str, boost::python::str, std::string](((const boost::python::api::object&)(& f->boost::python::objects::function::m_name)), ((boost::python::str&&)(& boost::python::str::join(const T&) const [with T = boost::python::api::object_slice](((const boost::python::api::object_slice&)((const boost::python::api::object_slice*)(& boost::python::api::object_operators::slice(const T&, const V&) [with T = int, V = size_t, U = boost::python::api::object](((const int&)((const int*)(&0))), ((const size_t&)((const size_t*)(&(((size_t)arity) - n_overloads))))))))))), ((boost::python::str&&)(&((n_overloads != 0u) ? ((((size_t)arity) != n_overloads) ? boost::python::str(((const char*)" [,")) : boost::python::str(((const char*)"[ "))) : boost::python::str()))), ((boost::python::str&&)(& boost::python::str::join(const T&) const [with T = boost::python::api::object_slice](((const boost::python::api::object_slice&)((const boost::python::api::object_slice*)(& boost::python::api::object_operators::slice(const T&, const V&) [with T = size_t, V = unsigned int, U = boost::python::api::object](((const size_t&)((const size_t*)(&(((size_t)arity) - n_overloads)))), ((const unsigned int&)((const unsigned int*)(& arity)))))))))), ((std::string&&)(& std::basic_string<char, std::char_traits<char>, std::allocator<char> >(n_overloads, 93, ((const std::allocator<char>&)((const std::allocator<char>*)(& std::allocator<char>())))))))' ../boost/python/object_operators.hpp:104: note: candidates are: boost::python::api::object boost::python::api::operator%(const boost::python::api::object&, const boost::python::api::object&) ../libs/python/src/object/function_doc_signature.cpp:249: error: no match for 'operator%' in '"%s(%s%s%s%s) -> %s" % std::make_tuple(_Elements&& ...) [with _Elements = const boost::python::api::object&, boost::python::str, boost::python::str, boost::python::str, std::string, boost::python::str&](((boost::python::str&&)(& boost::python::str::join(const T&) const [with T = boost::python::api::object_slice](((const boost::python::api::object_slice&)((const boost::python::api::object_slice*)(& boost::python::api::object_operators::slice(const T&, const V&) [with T = int, V = size_t, U = boost::python::api::object](((const int&)((const int*)(&0))), ((const size_t&)((const size_t*)(&(((size_t)arity) - n_overloads))))))))))), ((boost::python::str&&)(&((n_overloads != 0u) ? ((((size_t)arity) != n_overloads) ? boost::python::str(((const char*)" [,")) : boost::python::str(((const char*)"[ "))) : boost::python::str()))), ((boost::python::str&&)(& boost::python::str::join(const T&) const [with T = boost::python::api::object_slice](((const boost::python::api::object_slice&)((const boost::python::api::object_slice*)(& boost::python::api::object_operators::slice(const T&, const V&) [with T = size_t, V = unsigned int, U = boost::python::api::object](((const size_t&)((const size_t*)(&(((size_t)arity) - n_overloads)))), ((const unsigned int&)((const unsigned int*)(& arity)))))))))), ((std::string&&)(& std::basic_string<char, std::char_traits<char>, std::allocator<char> >(n_overloads, 93, ((const std::allocator<char>&)((const std::allocator<char>*)(& std::allocator<char>())))))), ((boost::python::str&)(& ret_type)))' ../boost/python/object_operators.hpp:104: note: candidates are: boost::python::api::object boost::python::api::operator%(const boost::python::api::object&, const boost::python::api::object&) ../libs/python/src/object/function_doc_signature.cpp:262: error: no match for 'operator%' in '"%s %s(%s%s%s%s) %s" % std::make_tuple(_Elements&& ...) [with _Elements = boost::python::str, const boost::python::api::object&, boost::python::str, boost::python::str, boost::python::str, std::string, boost::python::str](((const boost::python::api::object&)(& f->boost::python::objects::function::m_name)), ((boost::python::str&&)(& boost::python::str::join(const T&) const [with T = boost::python::api::object_slice](((const boost::python::api::object_slice&)((const boost::python::api::object_slice*)(& boost::python::api::object_operators::slice(const T&, const V&) [with T = int, V = size_t, U = boost::python::api::object](((const int&)((const int*)(&0))), ((const size_t&)((const size_t*)(&(((size_t)arity) - n_overloads))))))))))), ((boost::python::str&&)(&((n_overloads != 0u) ? ((((size_t)arity) != n_overloads) ? boost::python::str(((const char*)" [,")) : boost::python::str(((const char*)"[ "))) : boost::python::str()))), ((boost::python::str&&)(& boost::python::str::join(const T&) const [with T = boost::python::api::object_slice](((const boost::python::api::object_slice&)((const boost::python::api::object_slice*)(& boost::python::api::object_operators::slice(const T&, const V&) [with T = size_t, V = unsigned int, U = boost::python::api::object](((const size_t&)((const size_t*)(&(((size_t)arity) - n_overloads)))), ((const unsigned int&)((const unsigned int*)(& arity)))))))))), ((std::string&&)(& std::basic_string<char, std::char_traits<char>, std::allocator<char> >(n_overloads, 93, ((const std::allocator<char>&)((const std::allocator<char>*)(& std::allocator<char>())))))), ((boost::python::str&&)(&(cpp_types ? boost::python::str(((const char*)"")) : boost::python::str(((const boost::python::str&)((const boost::python::str*)(& ret_type))))))))' ../boost/python/object_operators.hpp:104: note: candidates are: boost::python::api::object boost::python::api::operator%(const boost::python::api::object&, const boost::python::api::object&) ...failed gcc.compile.c++ /home/steve/Packages/boost/upstream/testing/release/results/boost/bin.v2/libs/python/build/gcc-4.4/debug/object/function_doc_signature.o... I hope this helps the Boost.Python maintainers to fix it. Let me know if you need more info. Thanks, -Steve

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[rdb] 0.2.00 - bind parameter and result + dynamic sql
by Jean-Louis Leroy 05 Nov '09

05 Nov '09

I have uploaded version 0.2.01 to the vault. It contains two new major features. The first is the ability to bind parameters to variables allocated outside the prepared statement, e.g.: // in the following examples the database contains: // id first_name name age // 1 Homer Simpson 37 // 2 Marge Simpson 34 BOOST_FIXTURE_TEST_CASE(prepared_select_bind_integer_param, springfield_fixture) { person p; BOOST_AUTO(st, db.prepare(select(p.first_name).from(p).where(p.id == _))); integer id_param; st.bind_parameters(id_param); id_param = 1; BOOST_RDB_CHECK_SELECT_RESULTS(st.execute(), "((Homer))"); id_param = 2; BOOST_RDB_CHECK_SELECT_RESULTS(st.execute(), "((Marge))"); } The possibility of passing parameters to execute() remains but this is more efficient, as execute(params) binds the parameters each time it is called. Likewise, it is now possible to bind results, e.g.: BOOST_FIXTURE_TEST_CASE(prepared_select_bind_results, springfield_fixture) { person p; BOOST_AUTO(st, db.prepare(select(p.id, p.first_name).from(p))); integer id; varchar<30> first_name; st.bind_results(id, first_name); BOOST_AUTO(results, st.execute()); results.fetch(); BOOST_CHECK(!id.is_null()); BOOST_CHECK_EQUAL(id.value(), 1); BOOST_CHECK(!first_name.is_null()); BOOST_CHECK_EQUAL(string(first_name), "Homer"); results.fetch(); BOOST_CHECK(!id.is_null()); BOOST_CHECK_EQUAL(id.value(), 2); BOOST_CHECK(!first_name.is_null()); BOOST_CHECK_EQUAL(string(first_name), "Marge"); } The second feature is dynamic creation of statements. A fully static system doesn't make it possible e.g. to create a search form, where you enter (optional) values and the program returns a list of matching values. Dynamic statement parts (lists of expressions, columns, tables) are created via the make_dynamic() function. It returns a "stable" type, which does not incorporate the full type information for the encapsulated sql code. This makes it possible to create dynamic collections of sql constructs and pass them to a statement. Static and dynamic parts can be miexed freely. For example: BOOST_FIXTURE_TEST_CASE(prepared_select_bind_dynamic_integer_param, springfield_fixture) { person p; dynamic_boolean predicate = make_dynamic(p.id == _); BOOST_AUTO(st, db.prepare(select(p.first_name).from(p).where(predicate))); integer id_param; dynamic_values params; params.push_back(make_dynamic(id_param)); st.bind_parameters(params); id_param = 1; BOOST_RDB_CHECK_SELECT_RESULTS(st.execute(), "((Homer))"); id_param = 2; BOOST_RDB_CHECK_SELECT_RESULTS(st.execute(), "((Marge))"); } Here a dynamic boolean expression is used in the where clause. It contains a parameter so it is necessary to pass a collection of dynamic values when executing the statement. Here is a more complex example: BOOST_FIXTURE_TEST_CASE(prepared_select_dynamic_tables, springfield_fixture) { person p("husband"); person spouse("wife"); partner::qualified link; dynamic_expressions exprs; exprs.push_back(make_dynamic(spouse.first_name)); dynamic_tables tables; tables.push_back(make_dynamic(spouse)); tables.push_back(make_dynamic(link)); dynamic_boolean predicate = make_dynamic(p.id == link.husband && link.wife == spouse.id); BOOST_AUTO(st, db.prepare(select(p.first_name, exprs).from(p, tables).where(predicate))); varchar<30> him; dynamic_values results; varchar<30> her; results.push_back(make_dynamic(her)); st.bind_results(him, results); BOOST_AUTO(cursor, st.execute()); cursor.fetch(); BOOST_CHECK(!him.is_null()); BOOST_CHECK_EQUAL(string(him), "Homer"); BOOST_CHECK(!her.is_null()); BOOST_CHECK_EQUAL(string(her), "Marge"); } Here the projection is partly dynamic, and so is the table list and the where clause. Static entities are checked at compile-time as usual, and dynamic entities at run-time - and thus may fail with an exception. However, the system is designed to (attempt to) minimize the risk of type mismatch in the dynamic parts - no casts are required in client code (nor in the implementation ftm). The test suite contains several other examples of dynamic statements (see test_odbc_dynamic.cpp). At this point I feel that all the major features in the scope of this project have been addressed. Okay a lot is still missing - e.g. more types (currently only integer and varchar are supported), constraints, count() and such functions, group/order by... - but all these should be easy to implement in the existing framework. And the thing needs cleaning up and documentation, plus testing on Unix. J-L

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[filesystem][system] Usage guideline request
by Andrey Semashev 05 Nov '09

05 Nov '09

Hi, I'm updating our software from Boost 1.33 to 1.40 and one of the major issues I encountered is using exceptions from Boost.Filesystem. The exception basic_filesystem_error has changed its interface in a breaking way, as it now relies on Boost.System error codes. I'm not aware of whether this change has been announced properly and the API deprecation period has been offered. And that is actually not what bothers me mostly. The 1.33 version of Boost.Filesystem offered a number of unified error codes that our code used to react accordingly. For example, there were error codes out_of_space_error, already_exists_error, which were used on any platform supported by Boost.Filesystem. Now, with Boost.System in place, there are at least three sets of errors: system::errc, system::windows_error and system::linux_error, although, I assume, the latter is an addition to system::errc. In order to check for the older out_of_space_error I now have to write something like this: catch (basic_filesystem_error& e) { if ( e.code() == system::errc::make_error_code( system::errc::no_space_on_device) #if defined(WIN32) || e.code() == system::windows_error::make_error_code( system::windows_error::disk_full) #endif ) { // out_of_space_error } } Is this the right way to do this? Is there a portable way to do it? I tried to find a better way in the Boost.System documentation, but was highly disappointed as there is virtually no documentation at all. Also, no examples available for this library. I wonder how this library passed the review in the first place.

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