November 2006 - Boost-users - lists.preview.boost.org

wave - can line markers be suppressed?
by Grant, Joan 22 Nov '06

22 Nov '06

Using the wave library is there any way to suppress line markers (#line...) in a manner similar to the '-P' option of the gcc compiler's preprocessor? Thanks, Joan The information contained in or attached to this email may be subject to the Export Administration Regulations (EAR), administered by the U.S. Department of Commerce, or the International Traffic in Arms Regulations (ITAR), administered by the U.S. Department of State, and may require an export license from the Commerce or State Department prior to its export. An export can include a release or disclosure to a foreign national inside or outside the United States. Include this notice with any reproduced portion of this information.

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Another generic program that won't compile with pointee, bind, and array
by Terry G 22 Nov '06

22 Nov '06

Here's another (simplified) program I can't get to work. I'm trying to write a generic routine that finds the largest element of a sequence. It is assumed that element->size() is defined, as it is for boost::array and std::string. For some reason, the Largest template function works okay for std::strings, but not for boost::arrays. Can you tell me what is wrong? Will you please offer some improvements for error detection and debugging techniques that would have helped here? Perhaps I need a "typename" or "template" somewhere. Take it as given that I have a String class that needs to be a fixed-size array. Here's the code: #include <boost/operators.hpp> #include <boost/static_assert.hpp> #include <boost/function.hpp> #include <boost/tuple/tuple.hpp> #include <boost/iterator/iterator_traits.hpp> #include <boost/bind.hpp> #include <boost/array.hpp> #include <boost/pointee.hpp> #include <cstddef> #include <iterator> #include <algorithm> #include <functional> #include <string> #include <vector> #include <iostream> #include <iomanip> template <class InIter> InIter Largest(InIter first, InIter last) { typedef typename boost::pointee<InIter>::type ObjType; InIter largest = std::max_element(first, last, boost::bind(std::less<std::size_t>(), boost::bind(&ObjType::size, _1), boost::bind(&ObjType::size, _2)) ); return largest; } // Largest template <std::size_t N> class String: public boost::array<char, N> { public: std::string str() const { if (this->back() == '\0') return std::string(this->data()); return std::string(this->data(), this->size()); } // str String() { this->assign('\0'); } String(const std::string& str_) { if (str_.size() > this->size()) throw std::runtime_error("String::ctor: str_ too big"); int copied = str_.copy(this->c_array(), this->size()); std::fill_n(this->begin() + copied, this->size() - copied, '\0'); } // ctor operator std::string() const { return str(); } }; // String using namespace std; int main(int argc, const char* argv[]) { // typedef String<64> ArgStr; // <-- This won't compile. typedef string ArgStr; // <-- This compiles/runs ok. vector<ArgStr> args; while (--argc) args.push_back(string(*++argv)); if (args.empty()) { cout << "no args!" << endl; return EXIT_FAILURE; } cout << "args="; copy(args.begin(), args.end(), ostream_iterator<string>(cout, " ")); cout << endl; vector<ArgStr>::iterator iter = Largest(args.begin(), args.end()); cout << "Largest arg is '" << string(*iter) << "'." << endl; return EXIT_SUCCESS; } // main

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'configure' does not recognise '--without-python'
by MikeW 22 Nov '06

22 Nov '06

During Boost build, a line pops up saying "to avoid seeing this message again, use option --without-python". However, if you specify this as a "./configure" option, configure halts saying --without-python is unrecognised. I can live without it/work around it, but it should presumably be fixed ... Regards, Mike

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[BGL] how to actually search with DFS/BFS?
by martin f krafft 22 Nov '06

22 Nov '06

This may seem like a silly question, but how does one actually search with DFS or BFS? Say I want to find the first node for which a predicate returns true in a BFS traversal starting at node N... The function signatures don't have a parameter for "criteria" or "predicate", so I guess it's up for a Visitor to implement such a check. What is not clear to me is how the visitor functions can break out of the search once a condition is true. Thanks, -- martin; (greetings from the heart of the sun.) \____ echo mailto: !#^."<*>"|tr "<*> mailto:" net@madduck invalid/expired pgp subkeys? use subkeys.pgp.net as keyserver! spamtraps: madduck.bogus(a)madduck.net "information superhighway" is just an anagram for "i'm on a huge wispy rhino fart".

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[BGL] Constantness bug in kruskal_minimum_spanning_tree
by Fernando Cacciola 22 Nov '06

22 Nov '06

Hi I have a graph-like data structure which supports both const and non-const vertex and edge iterators and handles, and I want to interface it to the BGL. FWIW. the iterators and handles are class types, and the const versions are different classes than the non-const ones, so removing const qualification is not the way to bind a const type to its non-const version. AFAICT, the proper way to address both types of iterator/handles is by specializing both graph_traits<MyGraph> and graph_traits<MyGraph const>. It all works fine with my own BGL-like algorithms, but now I want to call kruskal_minimum_spanning_tree and I can't. The problem is that the kruskal function takes a "const Graph&" argument but it declares the internal types like this: typedef typename graph_traits<Graph>::edge_descriptor Edge ; (and so for the vertex_descriptor, etc) but then, lines like this: tie(vb,ve) = vertices(G) or this source(e, G) fails to compile with my graph because it attempts to bind a const iterator/handle to a non-const iterator/handle, which my data structure intentionally forbids. Unless I am missing something obvious (and I hope I am), this is a bug in the kruskal function: it should declare the working types like this: typedef typename graph_traits<Graph const>::edge_descriptor Edge ; Am I right? If yes, what can I do?? Is there any "constant correct" BGL algorithm? I'm calling kruskal just as an example showing how the data structure can be interfaced to the BGL. TIA Fernando Cacciola

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Re: [Boost-users] Boost configure options for crosscompilation ?
by Hughes, James 22 Nov '06

22 Nov '06

This is the command line I used to build boost using Bjam for an arm platform, not sure if that helps with what you need, but here it is anyway!! bjam "-sGCC_ROOT_DIRECTORY=/opt/montavista/mobilinux/devkit/arm/iwmmxt_le" "-sGCC=iwmmxt_le-gcc" "-sGXX=iwmmxt_le-g++" stage Stage is the folder in which all the libs are placed, other parameters should be self explanatory. James > -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of MikeW > Sent: 20 November 2006 15:59 > To: boost-users(a)lists.boost.org > Subject: [Boost-users] Boost configure options for crosscompilation ? > > I would like to crosscompile Boost under Buildroot. > > I created what appeared to be a successful package file, but > found that the native compiler and tools were used rather > that Buildroot's crosscompiler toolchain. > > However, I could not see any other 'configure' options to > switch to using a crosscompiler (EPREFIX looked promising at > first but seems to be a path prefix, rather than a tool > prefix such as "arm-linux-"). > > I note an earlier post (unable to post a 'follow-up' to it) > seemed to successfully do a cross build. > > Could you tell me how Boost is 'configure'd to use the > crosstools rather than the native tools ? > > Thanks, > Mike > > _______________________________________________ > Boost-users mailing list > Boost-users(a)lists.boost.org > http://lists.boost.org/mailman/listinfo.cgi/boost-users > This message (including any attachments) contains confidential and/or proprietary information intended only for the addressee. Any unauthorized disclosure, copying, distribution or reliance on the contents of this information is strictly prohibited and may constitute a violation of law. If you are not the intended recipient, please notify the sender immediately by responding to this e-mail, and delete the message from your system. If you have any questions about this e-mail please notify the sender immediately.

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[regex] Conditional Replacement?
by Scott Meyers 22 Nov '06

22 Nov '06

If I want to replace all the regex matches in a string, no problem, regex_replace is just what I'm looking for. But suppose I want to replace each match only if some predicate is satisfied, e.g., to implement something like a string replacement in a text editor where the user is allowed to approve or reject each proposed replacement. Is there any direct support for something like this? The only way I can think of to do this is to iterate over the string to be searched, finding each match and then consulting the predicate to see if the replacement should be performed for that match. If so, I can call regex_replace on the found substring, but then I'll get back a new string, and I'll have to manually handle the process of knitting together the final revised string from the original string and the results of each substitution. This is essentially what regex_replace already does, except it unconditionally does a substitution for each match. What it seems I want is something like regex_replace_if. Is there such a thing in Boost or TR1? If not, is it because there is little demand for such functionality? That would surprise me, because pretty much every text editor allows one to iteratively search for a match and query the user to see if a replacement should be performed at that point. Thanks, Scott

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thread: not joinable?
by Robert Marion 21 Nov '06

21 Nov '06

Hi, I've written my first boost::thread application, and I get this assertion: /boost_1_33_1/libs/thread/src/thread.cpp:223: void boost::thread::join(): Assertion 'm_joinable' failed. I call the thread as: void _pollMode( Controller& ctrl ) { // do polling ... for my testing, left blank } void SomeClass::startPolling() { m_pCtrl = new Controller; boost::function<void (Controller&)> funcPoll; funcPoll = &_pollMode; m_thr = new boost:thread(boost::bind( funcPoll, *m_pCtrl)); // never get past this line (unless copy ctor modified) } The Controller class has a copy constructor defined, which gets called several times (by the thread class?) Controller( const Controller& ctrl ) { boost::mutex::scoped_lock lock( m_mutex ); m_thr = ctrl.m_thr; // bad ?? BUT ... if I do m_thr = NULL; then everything is ok. Why??? What's going on here??? } Any help/explanation would be appreciated. Rob ____________________________________________________________________________________ Sponsored Link Mortgage rates near 39yr lows. $420k for $1,399/mo. Calculate new payment! www.LowerMyBills.com/lre

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Statechart tutorial problem and possible solution
by Michael 21 Nov '06

21 Nov '06

I am going through the tutorial for Statechart. Going through the section "adding reactions", while debug build links fine, in a release mode linker issues following complaints: 1>FSM.obj : error LNK2001: unresolved external symbol "public: void __thiscall boost::statechart::detail::no_context::no_function<struct EvReset>(struct EvReset const &)" (??$no_function@UEvReset@@@no_context@detail@statechart@boost@@QAEXABUEvReset@@@Z) 1>FSM.obj : error LNK2001: unresolved external symbol "public: void __thiscall boost::statechart::detail::no_context::no_function<struct EvStartStop>(struct EvStartStop const &)" (??$no_function@UEvStartStop@@@no_context@detail@statechart@boost@@QAEXABUEvStartStop@@@Z) I ended up adding following line to my cpp file: template< class Event > void sc::detail::no_context::no_function( const Event & ) {}; and it cured the linker complaint. Michael

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Problem with sub_range
by abir basak 21 Nov '06

21 Nov '06

Hi, I am not sure if it is the proper newsgroup to get answers related to boost usage. I am facing a problem with boost::sub_range for a const container which is not allowing me to access the indexed operator. Below a short program to demonstrate the problem. Necessary headers are included. Boost version 1.33.1 typedef vector<int> VI; VI v(10); int data[] = {0,1,2,3,4,5,6,7,8,9}; copy(data,data+10,v.begin());///inserted a few int to std::vector<int> ///prints 0 1 2 3 4 5 6 7 8 9 copy(v.begin(),v.end(),ostream_iterator<int>(cout," ")); cout<<endl; const VI& cv = v; /// a const reference to the container. VI::iterator it = v.begin(); ///got an random access iterator it[1] = 100; /// index operator allows to change it copy(v.begin(),v.end(),ostream_iterator<int>(cout," ")); cout<<endl; ///prints 0 100 2 3 4 ... VI::const_iterator it1 = v.begin(); ///got a const_iterator cout<<it1[1]<<endl; /// returns const_reference, assignment is not allowed, access is allowed. prints 100 boost::sub_range<VI> r(v.begin()+2,v.begin()+8); ///got a sub_range ///prints 2 3 4 5 6 7 copy(r.begin(),r.end(),ostream_iterator<int>(cout," ")); cout<<endl; r[2] = 400; cout<<r[2]<<endl;/// prints 400 ///prints 2 3 400 5 6 7 copy(r.begin(),r.end(),ostream_iterator<int>(cout," ")); ///so far everything is fine. Here problem starts /// a const sub_range ? boost::sub_range<const VI> r1(cv.begin()+2,cv.begin()+8); ///prints 2 3 400 5 6 7 copy(r1.begin(),r1.end(),ostream_iterator<int>(cout," "));cout<<endl; ///next statement is don't compile cout<<r1[2]<<endl; ///=> not allowed gives error under Visual Studio 7.1 cannot convert from 'const std::allocator<_Ty>::value_type' to 'boost::iterator_range<IteratorT>::value_type &' Why it tried to convert it to value_type& instead of const value_type& ? cout<<typeid(r1.begin()).name()<<endl; says r1.begin() is a const_iteartor. So the statement cout<<r1[2]<<endl; should return a const_reference. Am I mis interpreting the const version of sub_range ? If so, what is a const counterpart of sub_range, which behaves just like a pair of const_iterator ? Any help is appreciated. Thanks abir

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