May 2007 - Boost-users - lists.preview.boost.org

Yet another boost::enable_shared_from_this question
by Yaoltzin Gomez 26 May '07

26 May '07

Hello everyone Here's my problem. I have a small set of classes (I'm working on an API). Some of the classes use inheritance hierarchy. Sometimes I need to use (well lots of times) the "this" pointer and work with raw pointers inside each class. However, I would like to work with smart pointers. So I need to change the signature of my member functions to accept smart pointers, but now I need an "this" smart pointer equivalent. I derived the classes from boost::enable_shared_from_this. Basically, what I have is this: class Base : public boost::enable_shared_from_this<Base> { boost::shared_ptr<Base> GetBasePointer() { return shared_from_this(); } void Foo() { shared_ptr<Child> child( new Child ); AddChild( child, GetBasePointer() ); } }; class Derived: public Base, public boost::enable_shared_from_this<Derived> { boost::shared_ptr<Derived> GetDerivedPointer() { return shared_from_this(); } void Bar() { AnotherFunction( GetDerivedPointer() ); ... } }; Now, in the main function I have: int main(...) { boost::shared_ptr<Derived> derived( new Derived ); derived->Foo(); derived->Bar(); } Obviously, this causes a bad_weak_ptr exception, because I'm creating a Derived instance, and the shared_from_this called inside Foo throws the exception, but I need to call this functions defined in the Base class. In other words, I need access to the shared_from_this, in Base and Derived, and right now I can't do this. I would like to know if it's possible to use shared_from_this in this way, or not, and if not, what other options do I have (besides using raw pointers) This is a simplified problem, in my code, generally I have more than 2 leves of class inheritance, so things get more complicated. I hope I explained myself correctly. Thanks in advance.

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[BJam/Boost.Python] Issues Building with Boost.Build v2 using Boost 1.34.0
by Lawrence Spector 26 May '07

26 May '07

I successfully was building Boost.Python extensions using bjam version 1 in Boost 1.33.1. Since the upgrade, I converted my Jamfile to Jamfile.v2 and am getting the following errors when I try to build: bjam -sTOOLS=vc-8_0 -sBOOST_ROOT=C:\3rdparty\boost_1_34_0 -sBUILD=debug error: Could not find parent for project at '.' error: Did not find Jamfile or project-root.jam in any parent directory. Here's my Jamfile: # This is the top of our own project tree project-root ; import python ; extension MyLib # Declare a Python extension : MyLib.cpp # source # requirements and dependencies for Boost.Python extensions <template>@boost/libs/python/build/extension ## Requirements ## : <include>$(MyDir)/Include <define>_ATL_DLL <define>_AFXDLL <define>_UNICODE <define>UNICODE <runtime-link>dynamic ; -------------------------------- Here's my Jamrules: path-global BOOST_ROOT : C:/3rdparty/boost_1_34_0 ; project boost : $(BOOST_ROOT) ; -------------------------------- Any idea how to correct this? Thanks in advance, Lawrence

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bjam define=_SECURE_SCL shows no effect
by Christopher Lux 26 May '07

26 May '07

hi, after reading through this thread [1] i tried the following to build boost::program options: bjam define=_SECURE_SCL=0 define=_TESTING_SOMTHING=1 --toolset=msvc-8.0 --with-program_options variant=release to test the effect i added the folowing to the store function in program_options: #if _SECURE_SCL == 1 std::cout << "_SECURE_SCL == 1" << std::endl; #else std::cout << "_SECURE_SCL == 0" << std::endl; #endif #if _TESTING_SOMTHING == 1 std::cout << "_TESTING_SOMTHING == 1" << std::endl; #else std::cout << "_TESTING_SOMTHING == 0" << std::endl; #endif the strange thing now is, that _TESTING_SOMTHING is correctly set to 1 but _SECURE_SCL still is set to 1 and not to 0. did i miss something or is there another way to get this set properly to disable all runtime checks for release builds? [1] http://thread.gmane.org/gmane.comp.lib.boost.devel/143980/focus=144063 thx -chris -- Christopher Lux | | Bauhaus University Weimar | Faculty of Media - Virtual Reality Systems Group

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Re: [Boost-users] [date_time] UNICODE and wcout problems
by fang.wenbiao＠mail.scut.edu.cn 26 May '07

26 May '07

atoi(beg->c_str()); ------------------------ From: Kirit S忙lensminde <kirit.saelensminde(a)gmail.com> To: boost-users(a)lists.boost.org Sent: 2007-05-26 11:35 Subject: Re: [Boost-users] [date_time] UNICODE and wcout problems >Filip Konvi膷ka wrote: >> Hi, >> >> in MSVC 8.0 _UNICODE build, after I send a ptime to wcout, I can no >> longer print "international" characters. When I use a temporary >> wostringstream for printing the ptime, everything is OK. Minimal repro >> see below (the "2" at the end is never printed). With some characters >> like the "拧" in the example, the output is totally cut off; with others, >> like "谩", the codepage is changed, so the characters are displayed >> incorrectly. >> >> Any suggestions? > >This is a problem in the MSVC libraries. If you print a character above >code 255 then the stream crashes and is good for nothing afterwards. >Only std::wstringstream doesn't have this problem. > >I think if you buy the Dinkumware libraries this works. The _cputws >function does work as you would expect, but it can't be piped. The >behaviour also changes if you run the program from a command shell with >Unicode turned on ( cmd.exe /u). > >I did talk to PJ Plauger about it on clc. This is what he explained: > >"When you write to a wofstream, the wchar_t sequence you write gets >converted to a byte sequence written to the file. How that conversion >occurs depends on the codecvt facet you choose. Choose none any you get >some default. In the case of VC++ the default is pretty stupid -- the >first 256 codes get written as single bytes and all other wide-character >codes fail to write. " > >http://groups.google.com/group/comp.lang.c++/browse_thread/thread/3c2032537… > > >Kirit > > > >_______________________________________________ >Boost-users mailing list >Boost-users(a)lists.boost.org >http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Using the block iterator version of the dynamic_bitset constructor?
by Graham Reitz 26 May '07

26 May '07

How do you use the BlockInputIterator version of the dynamic_bitset? template <typename BlockInputIterator> dynamic_bitset(BlockInputIterator first, BlockInputIterator last, const Allocator& alloc = Allocator()) What kind of iterator should I use? Thanks in advance for any help, Graham

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Moving from Loki::Functor to Boost
by Scott Ribe 25 May '07

25 May '07

I have an application that depends pretty heavily on Loki::Functor, including some extensions/fixes I've made. That works great. But I want to use smart pointers more extensively (in particular I have a need for weak references), and so before I go further with advanced template use, I'd like to switch to Boost, since it's being actively developed. Can anybody point me to a reference comparing Loki's Functor's to Boost's function wrappers? I'm ready to dive into "Beyond the C++ Standard Library", but first I'd like to know if there's anything like a guide for moving my current code. (I only use other parts of Loki very lightly, BTW.) In addition to figuring out the straight substitution of one library for the other, I have to cope with the modifications I've made to Functor: - they can be "null" in the sense of not being bound to a function call and throwing an exception if called (so that they can be embedded in a class and assigned a value later) - there are initialization forms, and corresponding macros, that record the file & line where a functor is created, and log invocations - they can wrap method calls to Objective-C objects Heh, the last one reveals a bit about the platform I'm developing for ;-) -- Scott Ribe scott_ribe(a)killerbytes.com http://www.killerbytes.com/ (303) 722-0567 voice

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Question about Boost string tokenizer
by Meryl Silverburgh 25 May '07

25 May '07

Hi, I have the following loop to tokenize a string. But how can I pass the sub-string to ato()? for(boost::tokenizer<>::iterator beg=tok.begin(); beg!=tok.end();++beg){ int value = atoi(*beg); cout << value << "\n"; i++; } I get this error, in my code: : error: cannot convert 'const std::basic_string<char, std::char_traits<char>, std::allocator<char> >' to 'const char*' for argument '1' to 'int atoi(const char*)'

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mkdir -p and cp -r
by Patrick Lacasse 25 May '07

25 May '07

What is the boost::filesystem way to do a system( "mkdir -p somedir" ); or a system( "cp -r somedir_orig somedir_dest" ); ? Should I write a recursive function for that ?

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[Serialization] Thread-unsafe singleton
by Sohail Somani 25 May '07

25 May '07

Robert, I've seen this thread here: http://thread.gmane.org/gmane.comp.lib.boost.user/21885 And I believe I am coming across the same issue (static *serializer instances) manifesting itself as an assertion failure: Assertion failed: lookup(eti) == m_self->m_map.end(), file vendor/boost/libs/serialization/src/extended_type_info.cpp, line 77 That assertion means that a type_info key is being registered twice. I've verified this via cout (\o/ for debugging). Now I am also of the opinion that there is no way to do this initialization without bringing a threading library into Boost.Serialization. From reading the comments in the code, it appears that the only reason the library is using these singletons is because of VC6. Is it possible to have some thread-safe way (perhaps via ifdefs?) to do these singletons? Or do you think there is another reason I am having this issue? Thanks, Sohail PS: I'm using 1.33.1. If the issue is fixed in 1.34, I'd be very glad!

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boost::filesystem::path throws exception: invalid name
by Vivek Nallur 24 May '07

24 May '07

My code looks something like this: try{ fs::path full_path (fs::initial_path()); full_path = fs::system_complete(fs::path(filePath, fs::native)); fs::create_directories(full_path); INFO << "Directory successfully created: " << full_path.native_directory_string() << std::endl; retval = true; }catch(std::exception& ex){ WARN << "Could not create directory: " << filePath << " " << ex.what() << std::endl; } return retval; ========== When filePath is "c:\a\b\", boost throws an exception saying invalid path name c:\a\b\ in path "c:\a\b\" when filePath is "c:\\a\\b\\", boost throws exactly the same exception when filePath is "c:/a/b/", the exception string changes saying invalid path name "c:" in path "c:/a/b/" What am I doing wrong? -Vivek

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