November 2006 - Boost-users

[Filesystem]: Is an empty path relative or complete?
by Michael Partridge 20 Nov '06

20 Nov '06

Hi Boosters, I'm using the filesystem::complete function and have the following situation: bfs::path my_path(""); bfs::path current = bfs::current_path(); bfs::path p = bfs::complete(my_path, current); This results in p.string == "". Now I can see from the code that if my_path.empty() == true then a copy of my_path is returned, but I'm not certain of the rationale behind this. If I pass in an empty path and ask for it to be turned into a complete path then shouldn't I just get the base? As an additional consideration, if I go: bfs::path p = system_complete(bfs::path("")); Shouldn't I get current_path(), rather than an empty path ""? Cheers, Michael ps. sorry if this question has been answered before, I searched the archive and couldn't find any discussion.

1 0

[Serialization] NVP and xml archives
by michael mathews 19 Nov '06

19 Nov '06

Hi All, I have a class that contains a list of name value pairs . I would like the serialization to use the names for the tag names in the xml archive. Is there a way to do this or do I need to write my own custom archive? Thanks in advance Michael __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

2 7

[test] build problem/regression with RC_1_34_0
by Chris Hoeppler 18 Nov '06

18 Nov '06

Hi, With last weekend's cvs version of RC_1_34_0 is was able to use the dynamic-library version of the unit_test_framework. Since I did a cvs update yesterday I get a link error trying to do so: g++ -o build/debug/test/kern/test_macros.o -c -g -Wall -ftemplate-depth-255 -O0 -fno-inline -DBOOST_TEST_DYN_LINK -I. -I/home/hoeppler/src/boost_RC_1_34_0 test/kern/test_macros.cpp g++ -o build/debug/test/kern/test_macros -Wl,-rpath-link,. build/debug/test/kern/test_macros.o build/debug/src/kern/parser/macros.o -L/home/hoeppler/src/boost_RC_1_34_0/stage/lib -lboost_filesystem-gcc41-d -lboost_regex-gcc41-d -lboost_unit_test_framework-gcc41-d /usr/lib/gcc/i586-suse-linux/4.1.0/../../../crt1.o: In function `_start': init.c:(.text+0x18): undefined reference to `main' collect2: ld returned 1 exit status Addidtional information: This is gcc-4.1.0 on linux. The boost libs were built with the boost build system. I am setting up test_suits as follows: test_suite* init_unit_test_suite( int, char* [] ) { test_suite* test(BOOST_TEST_SUITE("Unit test macros")); // <snip> return test; } Any idea what's going wrong? Thanks Chris

3 3

[iterator] std::distance ignores random_access_traversal_tag
by Markus Werle 18 Nov '06

18 Nov '06

Hi! This was detected by profiling. I expected the code below to have a rather cheap std::distance call because my iterator was tagged as random_access. gcc-4.0.3 (cygwin) and VC8 IMHO choose the wrong std::distance algorithm, but why? The stuff compiles even when distance_to is not defined. Maybe I misunderstood the docs, especially the passage <cite url="http://boost.org/libs/iterator/doc/iterator_facade.html"> [...] where iterator-category is defined as follows: iterator-category(C,R,V) := if (C is convertible to std::input_iterator_tag || C is convertible to std::output_iterator_tag ) return C else if (C is not convertible to incrementable_traversal_tag) the program is ill-formed else return a type X satisfying the following two constraints: [..] </cite> Please explain and fix the code below. Markus #include <boost/iterator/iterator_facade.hpp> #include <boost/bind.hpp> #include <cstddef> #include <iterator> #include <iostream> template <typename ValueT, typename SizeT, typename IndexOperatorT> class signal_iter : public boost::iterator_facade <signal_iter<ValueT, SizeT, IndexOperatorT>, ValueT, // !!!!!!!!!!!!!!!!!!!!!!!!!!!!!! boost::random_access_traversal_tag, ValueT, SizeT> { public: typedef signal_iter<ValueT, SizeT, IndexOperatorT> my_own_t; inline signal_iter(IndexOperatorT IndexOperator, SizeT index) : m_IndexOperator(IndexOperator) , m_index(index) {} // quick and dirty with a dangling reference :-( inline signal_iter() : m_IndexOperator(IndexOperatorT()) , m_index(0) {} inline SizeT index() const { return m_index; } private: friend class boost::iterator_core_access; inline void increment() { ++m_index; } inline void decrement() { --m_index; } inline void advance(SizeT i) { m_index += i; } inline SizeT distance_to(signal_iter const& other) const { return other.index() - m_index; } inline bool equal(signal_iter const& other) const { return (other.index() == m_index); } inline ValueT dereference() const { return m_IndexOperator(m_index); } protected: IndexOperatorT m_IndexOperator; SizeT m_index; }; // stripped down demo class Demo { static const std::size_t mysize_ = 20; typedef std::size_t size_type; typedef double value_type; double data_[mysize_]; public: double operator[](std::size_t i) { return data_[i]; } typedef boost::_bi::bind_t <double, boost::_mfi::mf1<double, Demo, unsigned int>, boost::_bi::list2<boost::_bi::value<Demo*>, boost::arg<1> > > bind_type; typedef signal_iter<const value_type, size_type, bind_type> const_iterator; const_iterator begin() { return const_iterator (boost::bind(&Demo::operator[], this, _1), 0); } const_iterator end() { return const_iterator (boost::bind(&Demo::operator[], this, _1), mysize_); } }; int main() { Demo demo; std::cout << std::distance(demo.begin(), demo.end())<< std::endl; }

3 5

[Boost.Asio] Watching over a socket descriptor
by Memfis 18 Nov '06

18 Nov '06

I have an external communications library (Linux), which exposes a set of high-level APIs and a socket descriptor for me to watch over (as in select()). If there is something waiting on the socket, I am to call a function from the library that will read the data, construct some structures from it and return them. My question is if and how can I integrate this into Boost.Asio, so that I could handle connections created using Boost.Asio and the external library with the same code (to the point of actually reading some data)? -- Memfis

1 0

Newbie problems resolving header paths
by DC 18 Nov '06

18 Nov '06

I downloaded 1_33_1 and it built and installed. Actually, I'm still not sure what is meant by "install" in the docs. Does something happen than copying a bunch of files to C:\Boost ? VC71 is having trouble resolving paths to the headers. I have: In the project properties, Additional Include Directories: C:\Boost\include\boost-1_33_1; In my .cpp file, I use, for example: #include <boost/date_time/gregorian/gregorian.hpp> I still get: C:\Dev\VS2003\MyProject\Engine.h(3): fatal error C1083: Cannot open include file: 'boost/date_time/gregorian/gregorian.hpp': No such file or directory Hoping I'm overlooking something simple here. Thanks! - JC

4 5

BGL: Bundled Properties in subgraphs
by Greg Reynolds 18 Nov '06

18 Nov '06

Hi, I am trying to use the subgraph class with bundled propeties and wonder if it is still broken? I found a message on the list saying that it was broken in March 2005, but would probably be fixed shortly. I include my code below. It compiles cleanly if I don't use subgraph, i.e. just declare the adjacency_list. It also works if use the internal properties method. Thanks, Greg // ... appropriate headers using namespace std; using namespace boost; typedef unsigned long int uvid; struct VertexProperty { uvid gmr_number; vector<string> labels; }; struct EdgeProperty { std::size_t biconnected_component; vector<string> labels; }; typedef adjacency_list<setS, vecS, undirectedS, VertexProperty, EdgeProperty> GraphPlain; typedef subgraph< GraphPlain > Graph; int main(int argc, char* argv[]) { GraphPlain g1; Graph g; return 0; }

3 3

[Python] Wrapping a base class' method
by bernhard.maeder＠zkb.ch 17 Nov '06

17 Nov '06

Hi Boosters I'm trying to export some base class' methods with the derived class directly. See the following code: // ----------------------------------------------------- #include <boost/python.hpp> struct my_base_class { int const & get_base_i() const { return i_; } int i_; }; struct my_class : my_base_class { int const & get_i() const { return i_; } int i_; }; using namespace boost::python; BOOST_PYTHON_MODULE(_test) { class_<my_class>("MyClass") .add_property("i", make_function(&my_class::get_i, return_value_policy<copy_const_reference>())) .add_property("basei", make_function(&my_class::get_base_i, return_value_policy<copy_const_reference>())) ; } // ----------------------------------------------------- Now python throws the following at me: h[ 1] >>> from _test import * h[ 1] >>> MyClass().basei Traceback (most recent call last): File "<stdin>", line 1, in ? Boost.Python.ArgumentError: Python argument types in None.None(MyClass) did not match C++ signature: None(my_base_class {lvalue}) So, my question is: Am I not supposed to do this at all? The same seems to work flawlessly when returning by value instead of by reference.... Thanks for your input Bernhard ___________________________________________________________________ Disclaimer: Diese Mitteilung ist nur fuer die Empfaengerin / den Empfaenger bestimmt. Fuer den Fall, dass sie von nichtberechtigten Personen empfangen wird, bitten wir diese hoeflich, die Mitteilung an die ZKB zurueckzusenden und anschliessend die Mitteilung mit allen Anhaengen sowie allfaellige Kopien zu vernichten bzw. zu loeschen. Der Gebrauch der Information ist verboten. This message is intended only for the named recipient and may contain confidential or privileged information. If you have received it in error, please advise the sender by return e-mail and delete this message and any attachments. Any unauthorised use or dissemination of this information is strictly prohibited.

2 1

[ptr_container] linker error
by Mark Snelling 17 Nov '06

17 Nov '06

Hi, I'm having trouble using the boost::ptr_container library. I seem to get this linker error with the code below under MSVC8. error LNK2001: unresolved external symbol "public: __thiscall boost::ptr_container_detail::static_move_ptr<struct Test,struct boost::ptr_container_detail::clone_deleter<struct boost::ptr_container_detail::reversible_ptr_container<struct boost::ptr_container_detail::sequence_config<struct Test,class std::list<void *,class std::allocator<void *> > >,struct boost::heap_clone_allocator>::null_clone_allocator<0> > >::static_move_ptr<struct Test,struct boost::ptr_container_detail::clone_deleter<struct boost::ptr_container_detail::reversible_ptr_container<struct boost::ptr_container_detail::sequence_config<struct Test,class std::list<void *,class std::allocator<void *> > >,struct boost::heap_clone_allocator>::null_clone_allocator<0> > >(class boost::ptr_container_detail::static_move_ptr<struct Test,struct boost::ptr_container_detail::clone_deleter<struct boost::ptr_container_detail::reversible_ptr_container<struct boost::ptr_container_detail::sequence_config<struct Test,class std::list<void *,class std::allocator<void *> > >,struct boost::heap_clone_allocator>::null_clone_allocator<0> > > &)" (??0?$static_move_ptr@UTest@@U?$clone_deleter@U ?$null_clone_allocator@$0A@@?$reversible_ptr_container@ U?$sequence_config@UTest@@V?$list@PAXV?$allocator@PAX@std@@@std@@@ ptr_container_detail@boost@@Uheap_clone_allocator@3@@ ptr_container_detail@boost@@@ptr_container_detail@boost@@@ ptr_container_detail@boost@@QAE@AAV012@@Z) ----- SAMPLE CODE BEGIN ----- #include <boost/ptr_container/ptr_list.hpp> struct Test { int a; int b; }; typedef boost::ptr_list< Test > MyList; typedef MyList::auto_type TestPtr; struct MyClass { MyList theList; void push( TestPtr& t ) { theList.push_back( t.release() ); } TestPtr pop() { TestPtr t = theList.pop_front(); return t; } }; int main( int argc, char* argv[] ) { TestPtr t( new Test ); MyClass c; c.push( t ); t = c.pop(); return 0; } ----- SAMPLE CODE END ----- I'm not aware of the ptr_container library having an import library and am at a loss at why this error is occurring, although it seems to be with the MyClass::pop() method. Is it because it's returning the auto_type by value? If so what are the alternatives? Any help would be greatly appreciated. Thanks Mark.

2 1

[asio] error_code and categories
by Dean Kassmann 17 Nov '06

17 Nov '06

With the new changes to asio error handling; I'm updating some code and running into a problem on windows with vc8 The old syntax: void my_handler(const asio::error& error) { if (!error) { // woot sucess } else { // failure } } The new syntax: void handler(const boost::system::error_code& error) { if (error == boost::asio::error::success) { // doesn't work because error_code::category() differs } else { // failure } } doesn't seem to work because the error_code categories differ. Am I doing somthing wrong/stupid? Cheers, Dean

2 1