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[mpl] C++ Template Metaprogramming book - Question
by Kobi Cohen-Arazi 24 May '06

24 May '06

Hi, I've started reading Abrahams' and Gurtovoy's book, since I'm very interested in boost.mpl. Seems like a great book. I have a question regarding the 3rd chapter (3.1.4 section). Eventually, it says that operator* multiplies the runtime values (resulting in 6.0f) and the code uses transform to sum the meta-seq. template <class T, class D1, class D2> quantity<T, typename mpl::transform<D1,D2, plus_f>::type> operator*(quantity<T,D1> x, quantity<T,D2> y) { typedef mpl::transform<D1,D2, plus_f>::type dim; return quantity<T,dim>(x.value() * y.value()); } 1. Why passing x and y by value? why not const& 2. How did we got 6f ? 3. How and when the mpl::transform is getting into action here? I cannot spot it. Thanks -- - Kobi

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Re: [Boost-users] Exposing Class with Private ctor and dtor
by Anand, Kumar 24 May '06

24 May '06

Well marking the copy constructor as private is not required since dtor is already marked as private. You will not be able to copy construct by saying something like A *a = new A(); A a' = A(*a) //This will fail because dtor of A is private. However making the python wrapper class as boost::noncopyable works. It seems, if you do not mark the wrapper class as "noncopyable", boost python internally generates some code which requires public dtor. Kumar -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Dale McCoy Sent: Wednesday, May 17, 2006 6:24 PM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] Exposing Class with Private ctor and dtor > A class has static method to create and a static method to destroy. And the > constructors and destructor of the class is marked as private. How do I > expose such a class in Python? > <snip code> In the code you posted, the default constructor is indeed private, but the copy constructor is not. Was that intentional? If so, then it's still possible to write A otherA(A::create()); which requires public access to ~A() in order to destroy otherA. If it was not intentional, does explicitly privitizing the copy-constructor work? (Or make it clear where Boost::Python wants to copy-construct an A?) Dale _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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[regex] Static linking woes with gcc 4.0x on Fedora Core
by David Yon 24 May '06

24 May '06

I've been having great success with the regex library on Win32 and Linux, up until the time I decided to flip over to using all static linking. What used to be working code suddenly goes belly-up during static constructor initialization, but only when I statically link. When I use dynamic-linking, all appears to be well. I've tried the following permutations, each of which crashes, but each in a slightly different place: - Stock Fedora Core 4 install, with gcc 4.0.0 and boost 1.32 - Upgrade the above to gcc 4.0.2 - Upgrade boost to boost-1.33.1-6.i386.rpm (+boost-devel) - Build boost 1.33 from sources using gcc 4.0.2 When I started, it was dying when running static initializers inside the regex lib. I don't have the exact stack trace right now, but it looked like c_regex_traits<char>::init() was calling a null function pointer somewhere (similar to the top frame shown below). But now that I've come to the last step, it's dying during exit(), with the following backtrace---which isn't terribly helpful, I know: (gdb) backtrace Core was generated by `trquery'. Program terminated with signal 11, Segmentation fault. #0 0x00000000 in ?? () #1 0x08096f63 in __tcf_0 () #2 0x080fa5ee in exit () #3 0x08048d80 in DoQueryAll (ctl=@0xbfaf2a84, ttyname=0x0) at siquery.cpp:472 #4 0x08049826 in main (argc=1, argv=0xbfaf2ec4) at siquery.cpp:320 My DoQueryAll() is calling exit() directly, although I doubt that should make a difference. And again, this All Just Works(tm) when I dynamically link. Dynamic linking is not an option for us---if it came to that, then I'd be seriously looking at refactoring to replace boost.regex with either custom parsing or another regex lib. Besides, bjam *does* build a libboost_regex-XXX.a, presumably it's supposed to work. :-) Now I know that based on the above backtrace, this could be anything. I'm suspecting boost because of the first symptom where the backtrace is in c_regex_traits<char>::init(). So given the dearth of discussion on this category of problem, I'm guessing that perhaps this is a problem with gcc 4.x? Are there any known issues with boost.regex on gcc 4.0.x? Are they fixed in 4.1? Should I just fall back to Fedora Core 3 to get gcc 3.x? Thanks much! David Yon Tactical Software

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[Wave] error (2) compared to 'cpp': ill-formed directive
by Andreas Sæbjørnsen 24 May '06

24 May '06

This is a different error from the one previously reported. Using the 'samples/cpp_tokens' example preprocessor with the input file: #define __glibcpp_function_requires(...) give the following error message test.C(1): error: ill formed #define directive: __glibcpp_function_requires This error was found when preprocessing the file: #include <algorithm> where the implementation of algorithm is from gcc. The error from the custom preprocessor is: PATH_TO_GCC_STL_IMPLEMENTATION/bits/concept_check.h(52): error: ill formed #define directive: __glibcpp_function_requires It is important for us to be able to preprocess this header file since we aim for gcc compatibility. Is this standard preprocessor syntax? Could Wave support this syntax? Regards Andreas

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[BGL] graph & reverse_graph type conversion
by Jean-Charles Campagne 24 May '06

24 May '06

Given a type of graph G such as : typedef adjacency_list < listS, listS, bidirectionalS > G; and its reverse graph type : typedef reverse_graph<G> RG How can I convert a graph RG to a graph G simply ? For instance, I would like to apply a function like : void foo(G x); to graphs of type G as well as type RG. I looked in the documentation, unsuccesfully. I tried to change the type of the function to : void foo(RG x); It worked for some functions, but not for others like : void bar(RG x) { // ... add_vertex(x); //... } The compiler complains about : 'Config::vertex_descriptor boost::add_vertex( const Config::vertex_property_type &, boost::adj_list_impl<Derived,Config,Base> &)' : expects 2 arguments - 1 provided Apparently there seems to be no default type conversion ... ? PS : I am currently using VC++ 7.1.

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[Wave] error: ill-formed directive
by Andreas Sæbjørnsen 24 May '06

24 May '06

Using the 'samples/cpp_tokens' example preprocessor with the following code: #define true 1 #define false 0 gives the following error: test.C(1): error: ill formed preprocessor directive: #define Preprocessing the same file with 'cpp' give no error. If any of the two lines in the file is removed the other line will cause an error. I guess the error occurs because 'true' is not an T_IDENTIFIER, but a T_TRUE. Could you imagine a clean fix to this issue? Regards. Andreas

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[regex] "EXC_BAD_ACCESS" when iterating over smatch captures
by Christopher Hart 24 May '06

24 May '06

All: I'm trying to run the captures example included in the Boost.Regex documentation. When running the captures example verbatim, I get: "Program received signal: "EXC_BAD_ACCESS"." This is happening on Mac OS X 10.4.6 (Intel) with Boost 1.33.1. This problem seems to be related to the definition of BOOST_REGEX_MATCH_EXTRA - if I don't use captures and leave the macro undefined, other regex functions work fine. >From gdb: (gdb) backtrace #0 0x00003ad4 in boost::sub_match<__gnu_cxx::__normal_iterator<char const*, std::string> >::str () #1 0x00003b3a in boost::operator<< <char, std::char_traits<char>, __gnu_cxx::__normal_iterator<char const*, std::string> > () #2 0x00001ff1 in print_captures () #3 0x000021e6 in main () The instruction that caused the error: 0x00003ad4 <+0068> movsbl (%eax),%eax I'm way out of my depth on this one. Does anyone have any thoughts on what to try? Has anyone been able to use captures on an Intel Mac system, or could this be a platform specific issue? Thanks, Chris

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[BGL] how does automatic vertex_index creation work?
by Sebastian Weber 23 May '06

23 May '06

Hi folks! I defined a customary graph type which always uses integers in a bound range to adress the vertices. It is therefore as if one would use an adjacency_list with vecS as vertex storage set. Since I want to run an algorithm requiring a vertex_index property to be present on my custom graph, I was looking at the code of the adjacency_list graph. The docs say, that somewhere in the code the vertex_index map does get created automatically if the vertex set is vecS, but where and how is it done? The code is just too big or too advanced for me to find the appropiate lines. Could someone please enlighten me? Thanks in advance, Sebastian Weber

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IBM iSeries support
by MARobertson＠dstsystems.com 23 May '06

23 May '06

I was just wondering if anyone out there has tried using any of the Boost libraies on IBM's iSeries platforms. Its one of the platforms that I have to support. I'd like to use a few of the Boost libraries, but am not sure how to proceed. My main concern is the libraries that require a binary( like Boost.Regex ). The header only libraries that I'm interested in, I've been able to use( so far at least ). Marc Robertson Principal Architect AWD Development DST Technologies, Inc. ----------------------------------------- This e-mail and any attachments are intended only for the individual or company to which it is addressed and may contain information which is privileged, confidential and prohibited from disclosure or unauthorized use under applicable law. If you are not the intended recipient of this e-mail, you are hereby notified that any use, dissemination, or copying of this e-mail or the information contained in this e-mail is strictly prohibited by the sender. If you have received this transmission in error, please return the material received to the sender and delete all copies from your system.

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poll of tool usage and machine spec
by Jan Stetka 23 May '06

23 May '06

Would anyone else be interested in a poll, implemented on a website, of what tools e.g. gcc, visual c++ and machine spec: RAM, operating system, CPU boost users have?

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