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[Serialization] Multiple BOOST_CLASS_EXPORT
by Sohail Somani 28 Apr '07

28 Apr '07

Hi, Is there any danger in having multiple BOOST_CLASS_EXPORTs within a shared library or executable? I have a template child class that is always serialized by base class pointer and to keep myself sane I figure I can just blindly add BOOST_CLASS_EXPORT(ChildClass<T>); at the end of the .cpp file that uses it. Thanks, Sohail

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[boost] [math toolkit] Review Ends
by Matthias Schabel 28 Apr '07

28 Apr '07

The review period for the proposed Math Toolkit by John Maddock and Paul Bristow is now over. I will be assembling responses and put together a synopsis over then next few days. Thanks to everyone who participated and submitted reviews. Matthias

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very simple shared_ptr and copy constructor question
by Robert Marion 28 Apr '07

28 Apr '07

So, I've been using std::auto_ptr for some time, and have always been careful to either create a copy constructor or make it private (same for assignment). But now that I am becoming a boost::shared_ptr convert, I think that is no longer necessary. Is that so? Thanks, Robert

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[thread] Segfault constructing a thread
by Ken Klose 28 Apr '07

28 Apr '07

I've got a singleton object that is trying to run its operator() method in a separate thread, but I'm getting a segfault when I construct the thread object: PublishedListener::PublishedListener(string directory) { _thread = new thread(*this); // segfault here } PublishedListener.h: class PublishedListener { public: static PublishedListener &getInstance(); void run(); void operator()(); boost::filesystem::path getItemDirectory(); virtual ~PublishedListener(); private: PublishedListener(std::string directory); static PublishedListener *_instance; boost::thread *_thread; boost::filesystem::path *itemDirectory; }; Thanks in advance!

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Question on Boost::statechart library orthogonal regions
by Serena Fritsch 28 Apr '07

28 Apr '07

Hi All, Apologies if there are multiple psoting of this message. I want to use the boost::statechart library. However i encountered a small problem with using the orthogonal regions. In the statechart tutorial, every class declaration is put into one file, however i would like to put each class declaration into separate files. An example ( boost specific headers are omitted for readability reasons, also .cpp files which contain only test functions): A.h #include "Machine.h" class C; class B; class A: public sc::simple_state< A, Machine, mpl::list< C, B > > {}; C.h #include "A.H" class C: public sc::simple_state<C, A::orthogonal <0> > {}; B.h #include "A.H" class B: public sc::simple_state<B, A::orthogonal <1> > {}; Machine.h class A; class B; class Machine : public sc::state_machine<Machine, A> {}; Makefile CXX = g++-3.4 CFLAG = -c -g -w -O0 OBJECTS = Main.o A.o B.o C.o Machine.o all: $(OBJECTS) $(CXX) $(OBJECTS) -o $@ Main.o: Main.cpp $(CXX) $(CFLAG) $< A.o: A.cpp A.h $(CXX) $(CFLAG) $< B.o: B.cpp B.h $(CXX) $(CFLAG) $< C.o : C.cpp C.h $(CXX) $(CFLAG) $< Machine.o: Machine.cpp Machine.h $(CXX) $(CFLAG) $< clean: rm -f *.o a.out .PHONY: clean .PHONY: all Compiling this program fails, containing the following error messages (we only list an excerpt here): /usr/include/boost/statechart/simple_state.hpp: In static member function `static void boost::statechart::simple_state<MostDerived, Context, InnerInitial, historyMode>::deep_construct_inner_impl_non_empty::deep_construct_inner_impl(const boost::intrusive_ptr<T>&, typename Context::inner_context_type::outermost_context_base_type&) [with InnerList = boost::mpl::list1<B>, MostDerived = A, Context = Machine, InnerInitial = boost::mpl::list<C, B, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na, mpl_::na>, boost::statechart::history_mode historyMode = has_no_history]': When putting all class declarations into one file, it works perfectly. So my question now is, is it possible to modularise the different state declarations into external files? Thanks very much for any insights on this Cheers Serena

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FileSystem - Test if file exists without opening the file?
by Jeff 28 Apr '07

28 Apr '07

Hello, I can see from a FileSystem example how to check for the existence of a directory. What I would like to be able to do is to check for the existence of a file but I couldn't figure out how to do it using exists(). The way that I currently check for a file's existence is by opening the file. I wonder if boost::filesystem can test for a file's existence more efficiently than having to open it like I do in the snippet below. // checking for file existence by opening the file ifstream source(fileName); if (source) ... The reason for my concern is that I am going to be reading a text document containing a list of files, and all that I need to know is if the files exist on disk or not. If there is a way to check without opening each one, that would be ideal. Thanks in Advance

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[Serialization] xml_archive + templates = :-(
by Sohail Somani 28 Apr '07

28 Apr '07

Hi, Quite sensibly, xml_archive seems to fail with archive errors when class_name contains xml characters (like <) which are quite common in templates. For example, in my tests: BOOST_EXPORT_CLASS(Something<T>); // fails when deserializing because of parse error. I fix it by doing: BOOST_EXPORT_CLASS_GUID(Something<T>,"Something_T"); // works \o/ Now, do you suppose xml_archive could be smart enough to convert < to < and similarly for other prohibited characters when serializing? Even if not, is there something I can do in 1.33.1 that would make it not so redundant? Thanks, Sohail

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[program_options] assertion failed on very logn option description
by Dmitriy Chumack 27 Apr '07

27 Apr '07

hi * Win32 VisualStudio 2005 boost_1_33_1 When I supply option description, which length exceeded value of options_description::m_default_line_length, to the options_description, then I have an assertion failure when I want to get help from my command line program: prog --help Assertion failure: file: xstring line: 173 and them comes very long assert expression. This seems to be a compiler specific issue, because the same code, compiled on Linux Slackware 11.0 with gcc 3.4.6 and the same version of boost, works nice. thanks in advance -- Best regards, Dmitriy Chumack mailto:saint.d.a@gmail.com

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[gil] top/bottom N% value
by Christian Henning 27 Apr '07

27 Apr '07

Hi guys, here is my first implementation of the bottom N% problem. The algorithm is my own invention so please let me know when there is a better way. Also, the current implementation only works for homogeneous pixel types. Any comments are more than welcome. Christian

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read_graphviz question
by Jeffrey Holle 26 Apr '07

26 Apr '07

I'm using the post 1.31.1 version of boost, which has a much nicer read_graphviz function. I'm wondering if there is a way to "ignore" unwanted properties, something akin to sending them to /dev/null. My present experience is that if an unexpected property is found, an exception is thrown. Is there a way to express that a given property is to be ignored? Better yet, is there a way to say that all unexpected properties are to be ignored?

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