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[smart_ptr] enable_shared_from_this and shared_ptr to a base class
by Adam Romanek 24 Jun '13

24 Jun '13

Hi, I have a question related to using shared_from_this() and a shared_ptr to a base class. Here's a modified version of the enable_shared_from_this usage example from its documentation web page: #include <boost/enable_shared_from_this.hpp> #include <boost/shared_ptr.hpp> #include <cassert> class X { public: virtual void foo() = 0; }; class Y: public X, public boost::enable_shared_from_this<Y> { virtual void foo() { shared_from_this(); } }; int main() { X* x_ptr = new Y; boost::shared_ptr<X> sp(x_ptr); sp->foo(); } First, class Y is now derived from class X. Secondly, shared_ptr's template argument is now X and the parameter to the shared_ptr's constructor is now a pointer to X. Now, calling shared_from_this() in X and/or Y throws boost::bad_weak_ptr. Is this correct behavior? Is it documented somewhere? I know that the example is a bit unrealistic since most of the time shared_ptr is constructed directly from the pointer returned by 'new Y' or created by make_shared() but still, this is something that bothers me. WBR, Adam Romanek

3 9

Boost.Spirit how to use token in functor
by ... ... 24 Jun '13

24 Jun '13

Hi, I have a functor which is working, but its argument, which I don't know its type, I don't know what to do with it. I want to extract data out of it, I want to know is beginning and its end, I want to display the the content of the string character in my consol... but I can't retrieve this information. How could I archieve it ? What is the type of the argument relay to my function ? Is there a dOxygen like documentation (the one on the Boost site is great but a formal documentaton is also interesting). Where is the description and code source of this type ? Here is the code of my functor : struct counter{ counter() : j(0) {j = new int();} counter(const counter &model) : j(model.j) {} template <typename Token> bool operator()(Token const& t){// t is the argument I want to use ++i; ++(*j); std::ostringstream oss; oss << "global : " << i << " membre : " << *j;//typeid(t).name(); printf("%s\n", oss.str().c_str()); return true; } int* j;}; Thanks every one, cordialy,Guillaume Bersac237bis rue de Pessac33000 Bordeaux06.65.30.89.43

2 1

De Bruijn Bind (alternate bind syntax) Interest?
by David Sankel 24 Jun '13

24 Jun '13

Hello all, I've been working on an alternate bind syntax based on De Bruijn indices[1]. The syntax is very simple, yet the terms are very powerful. Here is an example of a function const that takes in an argument c and returns another function that, for all input, returns c: //λx.λy.x = λλ1 with De Bruijn indices. auto const_ = abs<1>( abs<1>( var<1,0>() ) ); More examples, further explanation, and an implementation are available here[2]. I'm thinking that this library could also be useful as a core for more syntax heavy bind variations. David [1] http://en.wikipedia.org/wiki/De_Bruijn_index [2] http://bitbucket.org/camior/de-bruijn-bind/ -- David Sankel Sankel Software www.sankelsoftware.com 585 617 4748 (Office)

11 73

Error while linking boost. spirit
by ... ... 23 Jun '13

23 Jun '13

Hi, I just downloaded, compiled and install boost.It seems like the installation process worked fine and I successfully compiled a program using boost (boost.log for instance). But when I try to compile an example writed by the developpers of boost.spirit, it fail ! It doesn't seem like it's an inclusion resolution problems, I don't know what to do. Please help me. Here is my code (I paste it from this page) : #include <stdio.h>#include <stdlib.h> #include <boost/spirit/include/lex_lexertl.hpp>#include <boost/spirit/include/phoenix_operator.hpp>#include <boost/spirit/include/phoenix_statement.hpp>#include <boost/spirit/include/phoenix_algorithm.hpp>#include <boost/spirit/include/phoenix_core.hpp>#define BOOST_ALL_DYN_LINK//without it boost.log glitch#include <boost/log/trivial.hpp> int main(){ BOOST_LOG_TRIVIAL(trace) << "boost.log is working !"; typedef lex::lexertl::token<char const*, lex::omit, boost::mpl::false_> token_type; typedef lex::lexertl::actor_lexer<token_type> lexer_type; word_count_tokens<lexer_type> word_count_lexer; std::string str (read_from_file("mainwindow.cpp.txt")); char const* first = str.c_str(); char const* last = &first[str.size()]; lexer_type::iterator_type iter = word_count_lexer.begin(first, last); lexer_type::iterator_type end = word_count_lexer.end(); while (iter != end && token_is_valid(*iter)) ++iter; if (iter == end) { std::cout << "lines: " << word_count_lexer.l << ", words: " << word_count_lexer.w << ", characters: " << word_count_lexer.c << "\n"; } else { std::string rest(first, last); std::cout << "Lexical analysis failed\n" << "stopped at: \"" << rest << "\"\n"; } return 0; }} And here is my error log : 11:32:39 **** Incremental Build of configuration Default for project synthax_analyser ****make all g++ -O2 -g -Wall -fmessage-length=0 -c -o synthax_analyser.o synthax_analyser.cppsynthax_analyser.cpp: In function ‘int main()’:synthax_analyser.cpp:24:4: error: ‘lex’ does not name a typesynthax_analyser.cpp:27:10: error: ‘lex’ does not name a typesynthax_analyser.cpp:29:2: error: ‘word_count_tokens’ was not declared in this scopesynthax_analyser.cpp:29:20: error: ‘lexer_type’ was not declared in this scopesynthax_analyser.cpp:29:20: note: suggested alternative:In file included from /usr/local/include/boost/spirit/home/lex/meta_compiler.hpp:16:0, from /usr/local/include/boost/spirit/home/lex/reference.hpp:14, from /usr/local/include/boost/spirit/home/lex/lexer/token_def.hpp:21, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:14, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/spirit/home/lex/lexer_type.hpp:20:12: note: ‘boost::spirit::lex::lexer_type’synthax_analyser.cpp:29:32: error: ‘word_count_lexer’ was not declared in this scopesynthax_analyser.cpp:31:54: error: ‘read_from_file’ was not declared in this scopesynthax_analyser.cpp:35:2: error: ‘lexer_type’ is not a class or namespacesynthax_analyser.cpp:35:28: error: expected ‘;’ before ‘iter’synthax_analyser.cpp:36:3: error: ‘lexer_type’ is not a class or namespacesynthax_analyser.cpp:36:29: error: expected ‘;’ before ‘end’synthax_analyser.cpp:38:9: error: ‘iter’ was not declared in this scopesynthax_analyser.cpp:38:17: error: ‘end’ was not declared in this scopesynthax_analyser.cpp:38:17: note: suggested alternatives:In file included from /usr/local/include/boost/range/empty.hpp:20:0, from /usr/local/include/boost/proto/functional/range/empty.hpp:12, from /usr/local/include/boost/proto/functional/range.hpp:13, from /usr/local/include/boost/proto/functional.hpp:14, from /usr/local/include/boost/proto/proto.hpp:16, from /usr/local/include/boost/spirit/home/support/terminal.hpp:18, from /usr/local/include/boost/spirit/home/support/common_terminals.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/terminals.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:13, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/range/end.hpp:106:61: note: ‘boost::range_adl_barrier::end’In file included from /usr/local/include/boost/fusion/container/list/cons.hpp:14:0, from /usr/local/include/boost/fusion/iterator/segmented_iterator.hpp:13, from /usr/local/include/boost/fusion/sequence/intrinsic/detail/segmented_begin.hpp:11, from /usr/local/include/boost/fusion/sequence/intrinsic/begin.hpp:17, from /usr/local/include/boost/fusion/container/vector/vector10.hpp:15, from /usr/local/include/boost/fusion/container/vector.hpp:12, from /usr/local/include/boost/fusion/include/vector.hpp:10, from /usr/local/include/boost/spirit/home/phoenix/core/limits.hpp:73, from /usr/local/include/boost/spirit/home/phoenix/core.hpp:11, from /usr/local/include/boost/spirit/include/phoenix_core.hpp:14, from /usr/local/include/boost/spirit/home/support/terminal.hpp:16, from /usr/local/include/boost/spirit/home/support/common_terminals.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/terminals.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:13, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/fusion/sequence/intrinsic/end.hpp:89:5: note: ‘boost::fusion::end’In file included from /usr/local/include/boost/fusion/sequence/intrinsic/begin.hpp:13:0, from /usr/local/include/boost/fusion/container/vector/vector10.hpp:15, from /usr/local/include/boost/fusion/container/vector.hpp:12, from /usr/local/include/boost/fusion/include/vector.hpp:10, from /usr/local/include/boost/spirit/home/phoenix/core/limits.hpp:73, from /usr/local/include/boost/spirit/home/phoenix/core.hpp:11, from /usr/local/include/boost/spirit/include/phoenix_core.hpp:14, from /usr/local/include/boost/spirit/home/support/terminal.hpp:16, from /usr/local/include/boost/spirit/home/support/common_terminals.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/terminals.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:13, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/fusion/sequence/intrinsic_fwd.hpp:67:16: note: ‘boost::fusion::result_of::end’In file included from /usr/local/include/boost/fusion/support/sequence_base.hpp:11:0, from /usr/local/include/boost/fusion/container/vector/vector10.hpp:11, from /usr/local/include/boost/fusion/container/vector.hpp:12, from /usr/local/include/boost/fusion/include/vector.hpp:10, from /usr/local/include/boost/spirit/home/phoenix/core/limits.hpp:73, from /usr/local/include/boost/spirit/home/phoenix/core.hpp:11, from /usr/local/include/boost/spirit/include/phoenix_core.hpp:14, from /usr/local/include/boost/spirit/home/support/terminal.hpp:16, from /usr/local/include/boost/spirit/home/support/common_terminals.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/terminals.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:13, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/mpl/begin_end_fwd.hpp:23:38: note: ‘boost::mpl::end’In file included from /usr/local/include/boost/proto/functional/range.hpp:14:0, from /usr/local/include/boost/proto/functional.hpp:14, from /usr/local/include/boost/proto/proto.hpp:16, from /usr/local/include/boost/spirit/home/support/terminal.hpp:18, from /usr/local/include/boost/spirit/home/support/common_terminals.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/terminals.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:13, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/proto/functional/range/end.hpp:19:12: note: ‘boost::proto::functional::end’In file included from /usr/local/include/boost/range/empty.hpp:20:0, from /usr/local/include/boost/proto/functional/range/empty.hpp:12, from /usr/local/include/boost/proto/functional/range.hpp:13, from /usr/local/include/boost/proto/functional.hpp:14, from /usr/local/include/boost/proto/proto.hpp:16, from /usr/local/include/boost/spirit/home/support/terminal.hpp:18, from /usr/local/include/boost/spirit/home/support/common_terminals.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/terminals.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:13, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/range/end.hpp:106:61: note: ‘boost::range_adl_barrier::end’In file included from /usr/local/include/boost/spirit/home/support/string_traits.hpp:16:0, from /usr/local/include/boost/spirit/home/support/nonterminal/expand_arg.hpp:20, from /usr/local/include/boost/spirit/home/support/context.hpp:18, from /usr/local/include/boost/spirit/home/qi/domain.hpp:18, from /usr/local/include/boost/spirit/home/qi/parser.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/token_def.hpp:17, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:14, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/spirit/home/support/container.hpp:445:5: note: ‘boost::spirit::traits::end’In file included from /usr/local/include/boost/spirit/home/support/handles_container.hpp:14:0, from /usr/local/include/boost/spirit/home/lex/lexer/token_def.hpp:16, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:14, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/spirit/home/support/attributes_fwd.hpp:43:12: note: ‘boost::spirit::result_of::end’In file included from /usr/local/include/boost/spirit/home/support/info.hpp:17:0, from /usr/local/include/boost/spirit/home/lex/lexer/token_def.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:14, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/foreach.hpp:730:1: note: ‘boost::foreach_detail_::end’synthax_analyser.cpp:38:44: error: ‘token_is_valid’ was not declared in this scopesynthax_analyser.cpp:38:44: note: suggested alternatives:In file included from /usr/local/include/boost/spirit/home/lex/lexer/lexertl/lexer.hpp:20:0, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:16, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/spirit/home/lex/lexer/lexertl/token.hpp:415:5: note: ‘boost::spirit::lex::lexertl::token_is_valid’In file included from /usr/local/include/boost/spirit/home/lex/lexer/lexertl/iterator.hpp:18:0, from /usr/local/include/boost/spirit/home/lex/lexer/lexertl/lexer.hpp:23, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:16, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/spirit/home/support/iterators/detail/split_functor_input_policy.hpp:19:21: note: ‘boost::spirit::iterator_policies::split_functor_input_is_valid_test_::token_is_valid’synthax_analyser.cpp:41:7: error: ‘iter’ was not declared in this scopesynthax_analyser.cpp:41:15: error: ‘end’ was not declared in this scopesynthax_analyser.cpp:41:15: note: suggested alternatives:In file included from /usr/local/include/boost/range/empty.hpp:20:0, from /usr/local/include/boost/proto/functional/range/empty.hpp:12, from /usr/local/include/boost/proto/functional/range.hpp:13, from /usr/local/include/boost/proto/functional.hpp:14, from /usr/local/include/boost/proto/proto.hpp:16, from /usr/local/include/boost/spirit/home/support/terminal.hpp:18, from /usr/local/include/boost/spirit/home/support/common_terminals.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/terminals.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:13, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/range/end.hpp:106:61: note: ‘boost::range_adl_barrier::end’In file included from /usr/local/include/boost/fusion/container/list/cons.hpp:14:0, from /usr/local/include/boost/fusion/iterator/segmented_iterator.hpp:13, from /usr/local/include/boost/fusion/sequence/intrinsic/detail/segmented_begin.hpp:11, from /usr/local/include/boost/fusion/sequence/intrinsic/begin.hpp:17, from /usr/local/include/boost/fusion/container/vector/vector10.hpp:15, from /usr/local/include/boost/fusion/container/vector.hpp:12, from /usr/local/include/boost/fusion/include/vector.hpp:10, from /usr/local/include/boost/spirit/home/phoenix/core/limits.hpp:73, from /usr/local/include/boost/spirit/home/phoenix/core.hpp:11, from /usr/local/include/boost/spirit/include/phoenix_core.hpp:14, from /usr/local/include/boost/spirit/home/support/terminal.hpp:16, from /usr/local/include/boost/spirit/home/support/common_terminals.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/terminals.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:13, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/fusion/sequence/intrinsic/end.hpp:89:5: note: ‘boost::fusion::end’In file included from /usr/local/include/boost/fusion/sequence/intrinsic/begin.hpp:13:0, from /usr/local/include/boost/fusion/container/vector/vector10.hpp:15, from /usr/local/include/boost/fusion/container/vector.hpp:12, from /usr/local/include/boost/fusion/include/vector.hpp:10, from /usr/local/include/boost/spirit/home/phoenix/core/limits.hpp:73, from /usr/local/include/boost/spirit/home/phoenix/core.hpp:11, from /usr/local/include/boost/spirit/include/phoenix_core.hpp:14, from /usr/local/include/boost/spirit/home/support/terminal.hpp:16, from /usr/local/include/boost/spirit/home/support/common_terminals.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/terminals.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:13, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/fusion/sequence/intrinsic_fwd.hpp:67:16: note: ‘boost::fusion::result_of::end’In file included from /usr/local/include/boost/fusion/support/sequence_base.hpp:11:0, from /usr/local/include/boost/fusion/container/vector/vector10.hpp:11, from /usr/local/include/boost/fusion/container/vector.hpp:12, from /usr/local/include/boost/fusion/include/vector.hpp:10, from /usr/local/include/boost/spirit/home/phoenix/core/limits.hpp:73, from /usr/local/include/boost/spirit/home/phoenix/core.hpp:11, from /usr/local/include/boost/spirit/include/phoenix_core.hpp:14, from /usr/local/include/boost/spirit/home/support/terminal.hpp:16, from /usr/local/include/boost/spirit/home/support/common_terminals.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/terminals.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:13, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/mpl/begin_end_fwd.hpp:23:38: note: ‘boost::mpl::end’In file included from /usr/local/include/boost/proto/functional/range.hpp:14:0, from /usr/local/include/boost/proto/functional.hpp:14, from /usr/local/include/boost/proto/proto.hpp:16, from /usr/local/include/boost/spirit/home/support/terminal.hpp:18, from /usr/local/include/boost/spirit/home/support/common_terminals.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/terminals.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:13, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/proto/functional/range/end.hpp:19:12: note: ‘boost::proto::functional::end’In file included from /usr/local/include/boost/range/empty.hpp:20:0, from /usr/local/include/boost/proto/functional/range/empty.hpp:12, from /usr/local/include/boost/proto/functional/range.hpp:13, from /usr/local/include/boost/proto/functional.hpp:14, from /usr/local/include/boost/proto/proto.hpp:16, from /usr/local/include/boost/spirit/home/support/terminal.hpp:18, from /usr/local/include/boost/spirit/home/support/common_terminals.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/terminals.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:13, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/range/end.hpp:106:61: note: ‘boost::range_adl_barrier::end’In file included from /usr/local/include/boost/spirit/home/support/string_traits.hpp:16:0, from /usr/local/include/boost/spirit/home/support/nonterminal/expand_arg.hpp:20, from /usr/local/include/boost/spirit/home/support/context.hpp:18, from /usr/local/include/boost/spirit/home/qi/domain.hpp:18, from /usr/local/include/boost/spirit/home/qi/parser.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer/token_def.hpp:17, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:14, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/spirit/home/support/container.hpp:445:5: note: ‘boost::spirit::traits::end’In file included from /usr/local/include/boost/spirit/home/support/handles_container.hpp:14:0, from /usr/local/include/boost/spirit/home/lex/lexer/token_def.hpp:16, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:14, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/spirit/home/support/attributes_fwd.hpp:43:12: note: ‘boost::spirit::result_of::end’In file included from /usr/local/include/boost/spirit/home/support/info.hpp:17:0, from /usr/local/include/boost/spirit/home/lex/lexer/token_def.hpp:15, from /usr/local/include/boost/spirit/home/lex/lexer.hpp:14, from /usr/local/include/boost/spirit/home/lex.hpp:13, from /usr/local/include/boost/spirit/home/lex/lexer_lexertl.hpp:15, from /usr/local/include/boost/spirit/include/lex_lexertl.hpp:16, from synthax_analyser.cpp:12:/usr/local/include/boost/foreach.hpp:730:1: note: ‘boost::foreach_detail_::end’synthax_analyser.cpp: At global scope:synthax_analyser.cpp:54:1: error: expected declaration before ‘}’ tokenmake: *** [synthax_analyser.o] Error 1 Cordialy,Guillaume Bersac237bis rue de Pessac33000 Bordeaux06.65.30.89.43

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concurrent garbage collector
by Taylor Holliday 23 Jun '13

23 Jun '13

Hey Boost, After struggling with breaking shared_ptr cycles in my app, I wrote a little concurrent garbage collector which uses boost::lockfree::queue. Its actually fairly general purpose, and I've released the code here: https://gist.github.com/wtholliday/5793270 Inspired by my question on stack overflow: http://stackoverflow.com/questions/17116189/concurrent-garbage-collection-f… I'm also working on releasing my unit test... its just quite dependent on other code. For the interface: the basic idea is you have a RootPtr<T> used to manage the collector's root set (please forgive my propensity for CamelCase). You have to explicitly manage references between collectable objects (via AddEdge and RemoveEdge functions), but I think that could be made safe using another smart pointer type which knows the collectable object which owns it. At this point I'm not too concerned about performance, as my object graphs aren't that big. I bet a GC guru could implement this without using a queue of events. Anyway, this is the kind of thing I'd love to see in boost someday, so it would be great to read your opinions of it :-) cheers - Taylor W. Taylor Holliday, Owner/Founder Subatomic Software, San Francisco

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Re: [boost] [Multiprecision] Does MP use references internally?
by Daryle Walker 21 Jun '13

21 Jun '13

Nearly all operators, besides assigning and dereferencing ones, are supposed to return by value. Changing that, even with the “innocuous” (unary)+, is surprising. Daryle W. Sent from Windows Mail From: John Maddock Sent: ‎Thursday‎, ‎June‎ ‎20‎, ‎2013 ‎4‎:‎13‎ ‎AM To: boost(a)lists.boost.org > Is Boost.MP giving users references-to-types instead of class types when > requesting a numeric type? Pointers may be objects in and of themselves, > but references aren't; they're just aliases; trying to intentionally use > them as first-class objects is arguably broken. I don't see why this is a problem, but the first error is coming from: auto const aa = +a, bb = +b; Now, in Boost.Multiprecision the unary operator+ is a noop that returns a reference to self, could that be a cause of the issue?

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ptr_map_adapter::insert non const key argument
by Gaetano Mendola 21 Jun '13

21 Jun '13

Hi, it seems that the method: std::pair<iterator,bool> ptr_map_adapter::insert( key_type& key, mapped_type x ) has the key argument non const? Is there a valid reason for it or it's just a mistake? Regards Gaetano Mendola

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How do I specify no padding bytes within a struct/class?
by Daryle Walker 20 Jun '13

20 Jun '13

I've never done this before, so I'm asking first: how do I specify that a struct/class should have no padding at all, at the start, end, or middle? My classes have internal arrays, and specifying no padding lets users use an array of classX<T> as an array of T (just like C++11 std::complex). Complier-specific answers are OK, as long as I can use preprocessor flags to isolate them. I have a preprocessor flag that's currently set to 0 to indicate that there's no packing. I'll change it to 1 whenever I get a compiler's packing support. Daryle W.

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[Multiprecision] Does MP use references internally?
by Daryle Walker 20 Jun '13

20 Jun '13

This may be an artifact of the compiler's error reporting mechanism, but the errors' expansion of the MultiPrecision type I'm using has reference types in it. Types from Boost.MP seem to be a shell class template that wraps an engine and several options. Some of the errors that pop up when using Boost.MP when using Boost.Test with my custom complex-number class: - Boost.MPL calls within Boost.Test complain that it's trying to get a pointer to a reference. - My own code uses arrays everywhere, and I get errors about making arrays to references. I'm not doing anything (too) advanced. Is Boost.MP giving users references-to-types instead of class types when requesting a numeric type? Pointers may be objects in and of themselves, but references aren't; they're just aliases; trying to intentionally use them as first-class objects is arguably broken. Daryle W.

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Re: [boost] [c++11]
by Niall Douglas 19 Jun '13

19 Jun '13

> I wasn't suggesting making the library strictly C++03-compatible. My main > point was that the library has to be compatible with _todays_ and even better > - _yesterdays_ compilers to be actually useful. My choice of "reasonable" time > frame is 3-5 years, as I mentioned. That includes VS 2008 and VS 2010, which > already had some C++11 features, including rvalue references. Making VS 2013 > absolute minimum is a no-go, IMHO. I don't think anyone is making VS2013 an absolute minimum - rather they're making variadic templates an absolute minimum. Something which any other compiler than VS has had for years, and something which unlike many, if not most other C++11 language features is something which lets you write a ton of stuff you simply can't write without them. Now, nothing in proposed Boost.AFIO uses variadic templates in a way not replaceable with preprocessor programming. However it very /nearly/ did: I had this neato bit of evil variadic instantiation which let you convert an unknown set of trailing args into a std::tuple<> for storage, then /unpack/ said std::tuple<> back into an unknown set of trailing args, all with perfect forwarding. Effectively it was a compile-time std::function<> implementation. As proposed Boost.AFIO is also a closure execution engine where that closure can take arbitrary args and return arbitrary returns, that evil variadic template machinery was really useful because it lets you skip using std::function<> with its implied virtual function call. As proposed Boost.AFIO currently nests, in the worst case scenario, a fully bound std::function<> calling a partially bound std::function<> calling a partially bound std::function<>, that's three nested virtual indirect function calls. Recent Intel CPUs can prefetch and branch predict two nesting levels, but they can't cope with three, so performance takes a real nose dive and hence one of the reasons we currently see a peak 80k IOPS. That evil variadic template machinery gets rid of that problem. And its only replacement is std::function<> - you *cannot* implement that functionality (pure compile time std::function<>) without variadic templates because you can't properly unpack them without. None of this matters for proposed Boost.AFIO. But it certainly matters for the forthcoming C++11 only libraries coming soon to Boost, because they make /very/ heavy usage of functionality only possible with variadic templates. That means that they will require, as an absolute minimum for VS, VS2013 or Nov 2012 CTP. Other C++11 features one can make do without without too much cost, but losing variadic templates means a ton of extra source code complexity, much longer compile times and chopping out a lot of what C++11 enables which simply can't be done in C++03. I suspect that those libraries are probably going to force a new "variadic template support is mandatory" category of Boost libraries, probably sooner rather than later. I agree it's going to be frustrating for those stuck with older compilers: I pity those whose employers force MSVC6 on them to this very day. Niall --- Opinions expressed here are my own and do not necessarily represent those of BlackBerry Inc.

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