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BGL: Early out search
by John Donovan 18 Mar '05

18 Mar '05

Hi, I'm using the BGL to store a quadtree*. What I want to do is search the tree, testing each vertex against some criteria. If the test fails, then I want to ignore all its children for the duration of the search, because if the parent fails; all its children will fail. If a leaf vertex passes the test, then the search should finish, otherwise continue the search. Eventually there will be a path through the tree of vertices that matched the criteria, and it's this deepest vertex (which isn't necessarily a leaf vertex) that I want. What I'm thinking is writing a custom visitor, and overriding discover_vertex() to do the test. If the test fails, colour the vertex to fool the algorithm into thinking it's searched this vertex's children. If the test succeeds, then I add the vertex to a list. When the search is over, I can play around with the list to my heart's content. 1) Should I use depth_first_visit to handle the early termination? 2) If so, how can I determine if a vertex has children before they're visited? 3) Can I colour the vertices before the algorithm does, thus fooling it into skipping the vertex's children? 4) Which colour should I use? *a quadtree is a way of dividing 2D space. Start with a rectangle, which is represented by the root node. Divide this rectangle into four equal, non-overlapping quadrants, these become the children of the root node. Repeat this process for each child until you start paraphrasing Jonathan Swift. Each node will have either exactly 0 or exactly 4 children. -John Donovan The content of this message and any attached file are confidential and/or privileged and are for the intended recipient only. If you are not the intended recipient, any unauthorised use, disclosure, copying, distribution or other dissemination is strictly prohibited. If you receive this message in error please notify the sender immediately by email, telephone or fax and then delete this email. Any attachment with this message should be checked for viruses before it is opened. Magenta Software Limited cannot be held responsible for any failure by the recipient to check for viruses before opening any attachment. Copyright in this email and attachments created by us belongs to Magenta Software Limited. Should you communicate with anyone at Magenta Software Limited by email you consent to us monitoring and reading any such correspondence.

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BGL - bundled properties
by manitou＠gmx.ch 18 Mar '05

18 Mar '05

Hello, I have encountered some problems with bundled properties in BGL. The following syntax works: property_map<CFD2CSM_graph_t, bool CFD2CSM_vertex_t::*>::type is_CSM_map = get(&CFD2CSM_vertex_t::is_CSM_node, CFD2CSM_graph); However, if I make two statements out of it I get some type-mismatch error property_map<CFD2CSM_graph_t, bool CFD2CSM_vertex_t::*>::type is_CSM_map; is_CSM_map = get(&CFD2CSM_vertex_t::is_CSM_node, CFD2CSM_graph); What is the reason for this behavior? Why is the second statement not ok? Cheers, Marc -- DSL Komplett von GMX +++ Superg�nstig und stressfrei einsteigen! AKTION "Kein Einrichtungspreis" nutzen: http://www.gmx.net/de/go/dsl

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shared_ptr changes
by Peter Dimov 18 Mar '05

18 Mar '05

I've made some pretty extensive changes to the implementation of shared_ptr. It now uses a lock-free algorithm (originally invented by Alexander Terekhov) on Windows, and the old detail/shared_count.hpp has been refactored into a number of smaller headers. A per-count pthread_mutex is still being used on non-Windows platforms, but this is also going to change soon. Now is the time to test the new implementation; please report any errors you encounter. Some of you have posted patches against the old implementation; these will need to be reexamined, too. detail/lightweight_mutex will also change "soon"; it will just map into a CRITICAL_SECTION or a pthread_mutex depending on the platform. The spin locks will disappear. shared_ptr no longer uses lightweight_mutex. If you use some of the undocumented features of shared_ptr - BOOST_SP_USE_STD_ALLOCATOR, BOOST_SP_ENABLE_DEBUG_HOOKS, sp_collector.cpp - please say so. During the refactoring I may drop some of these features in order to simplify and streamline the implementation. Thanks, -- Peter Dimov http://www.pdimov.com

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map with minimal memory footprint
by Toon Knapen 17 Mar '05

17 Mar '05

Hi all, I'm using a rather big std::map which gives good performance but the memory footprint is a bit too big. So I figured to implement an std::map as an std::vector<std::pair<T1,T2>> but thus with the interface of an std::map on top of it. I kind of recall a similar discussion and checked in the boost-sandbox but did not find anything similar. Anybody knows of implementations like these? Thanks, toon

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Re: Re: Re: how to get regex to link in windows?
by Alexis H. Rivera-Rios 17 Mar '05

17 Mar '05

John, Thanks for the info. I found the problem. It was one of the headers of an external C library that I'm including contains defines LONG as a macro function, which conflicted with Windows LONG macro, therefore causing the compiler error. (Gotta love it when the problem turns out to be such a classic error :? ). I'm really sorry I wasted your time on this. I really appreciate your help, without it I wouldn't have been able to track the problem down. Thanks again! Alexis Programming Tutorial: In Python: To do this, do this In Perl: To do this, do this or this or this or this... In C: To do this, do this, but be careful In C++: To do this, do this, but don't do this, be careful of this, watch out for this, and whatever you do, don't do this __________________________________ Do you Yahoo!? Make Yahoo! your home page http://www.yahoo.com/r/hs

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Re: Re: how to get regex to link in windows? (John Maddock)
by Alexis H. Rivera-Rios 17 Mar '05

17 Mar '05

John, I took out the hardcoded library and let the code figure it out by itself. I also removed the BOOST_REGEX_NO_W32 as you suggested but then I get compiler errors in the windows code (This was the reason I put BOOST_REGEX_NO_W32) Here are the errors; Linking to lib file: libboost_filesystem-vc71-mt-gd-1_32.lib Linking to lib file: libboost_regex-vc71-mt-gd-1_32.lib c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\WinNT.h(8390) : error C2143: syntax error : missing ')' before '->' c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\WinNT.h(8390) : error C2143: syntax error : missing ';' before '->' c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\WinNT.h(8390) : error C2165: 'left-side modifier' : cannot modify pointers to data c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\WinNT.h(8390) : error C2059: syntax error : ')' c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\WinBase.h(2382) : error C2143: syntax error : missing ')' before '->' c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\WinBase.h(2382) : error C2143: syntax error : missing ';' before '->' c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\WinBase.h(2382) : error C2165: 'left-side modifier' : cannot modify pointers to data c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\PlatformSDK\Include\WinBase.h(2382) : error C2059: syntax error : ')' Programming Tutorial: In Python: To do this, do this In Perl: To do this, do this or this or this or this... In C: To do this, do this, but be careful In C++: To do this, do this, but don't do this, be careful of this, watch out for this, and whatever you do, don't do this __________________________________ Do you Yahoo!? Yahoo! Small Business - Try our new resources site! http://smallbusiness.yahoo.com/resources/

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composition and arguement binding: what to use: boost::bind vsboost::mpl vs boost::lambda
by Robert Mathews 17 Mar '05

17 Mar '05

I've become rather confused about the exact relationship between these libraries. In particular, boost::mpl seems to contain placeholders and lambda templates just like boost::bind and boost::lambda. That leds me to wonder if there would be any point to using boost::bind or boost::lambda if you are using boost::mpl? In fact, if boost::mpl is a functional superset of the other two libraries, why not drop those libraries from boost altogether and eliminate the confusion? Rob.

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[regex] Unresolved external symbols under VC7.1 w/ dynamic linking
by Klaus Nowikow 17 Mar '05

17 Mar '05

Hello, when I define the symbol BOOST_DYN_LINK (in my project settings) I get the following linker errors in MSVC 7.1: FilterDlg.obj : error LNK2001: unresolved external symbol "wchar_t * boost::re_detail::wide_lower_case_map" (?wide_lower_case_map@re_detail@boost@@3PA_WA) FilterDlg.obj : error LNK2001: unresolved external symbol "private: static unsigned short * boost::w32_regex_traits<wchar_t>::wide_unicode_classes" (?wide_unicode_classes@?$w32_regex_traits@_W@boost@@0PAGA) When linking Boost.Regex statically, everything is ok. I am using /Zc:wchar_t ("Treat wchar_t as Built-in type") in my project settings. Any ideas what's going wrong? Regards, Klaus

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Boost.Build -- how to get started?
by Arkadiy Vertleyb 17 Mar '05

17 Mar '05

Hi all, I am trying to use Boost.Build to build my own project. However I found out that the documentation, while doing a good job in explaining details, is petty difficult to use if all one wants to know is how to use bjam to build a "Hello world" project in a couple of toolsets. I already downloaded bjam.exe, and I have no problem in creating the jamfile. However, AFAIU, I need more files to be installed, such as jamrools, files that describe toolsets, etc. Can anybody to just list which files are needed, where to get, and where to put them? Or point me to where it's described if I missed something... Unless, of course, this is kind of Illuminati path, and one only deserves to use this tool if able to figure out how? :-) Thanks a lot in advance. Regards, Arkadiy

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what should be used if shared_polymorphic_cast is deprecated?
by Bernard Chen 16 Mar '05

16 Mar '05

Hello, I was looking at the casting functions and the one that had the behavior I wanted most was the shared_polymorphic_cast. I do not want an empty shared_ptr<T> to be created if the cast cannot be performed. I would prefer to have an exception thrown in debug mode and release mode. The problem is that while going through the shared_ptr.hpp, I found a comment on line number 388 just above all the cast conversion functions "// shared_*_cast names are deprecated. Use *_pointer_cast instead." I have not found a *_pointer_cast function that does what I want. The dynamic_pointer_cast does not throw an exception. Is there a good alternative? Should I enforce a standard on my team of using dynamic_pointer_cast along with a run-time check of seeing if an empty shared_ptr<T> was created? Thanks, Bernard

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