May 2008 - Boost-users - lists.boost.org

[Filesystem] remove_all is not documented, is it part of the API?
by Frank Birbacher 04 May '08

04 May '08

Hi! I'm using the Filesystem library. I wrote myself a function to recursively remove a directory. Afterwards I tried to take the address of "remove" in order to use it in an STL algorithm. It didn't compile. To resolve the problem I looked into the boost source code. And there I found a "remove_all" function. I wonder what it does because I'm in need for a recursive remove function. I scanned the filesystem documentation at http://www.boost.org/doc/libs/1_35_0/libs/filesystem/doc/reference.html but it does not contain "remove_all". Is the remove_all function part of the public API of Filesystem and was just forgotten in the docs? Or must I not use "remove_all"? Regards, Frank PS: And how do I get the address of the "remove<path>" function??

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mpl mutlimap
by Hicham Mouline 04 May '08

04 May '08

hello, as i don't immediately see an MPL equivalent of multimap, here is what i am trying to achieve. I have a number of models (200 types, all of them inherit from 1 base class) and a number of contracts(400 types, also all them inherit from 1 base class), and I try to write a test suite for valid combinations. Was there a multimap in MPL, i would have stored this matrix: model1 contract1, contract17, contract156 model2 contract17 ... model200 contract23 or symetrically, indexed by contract in a multimap. Are there solutions with other MPL sequences? Rds,

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Random Distribution
by Kevin Martin 04 May '08

04 May '08

I'm looking for a random distribution which allows me to generate enums with specified probabilities. As a simple example I could have: //The enum. typedef enum {vt_car, vt_bus, vt_walk, vt_cycle} vehicle_types; //What I want to generate and the associated probabilities. boost::array<vehicle_types, 4> items = {vt_car, vt_bus, vt_walk, vt_cycle}; boost::array<double, 4> probabilities = {0.1, 0.2, 0.3, 0.4} //The random distribution. EnumGenerator eg(items, probabilities); //Generate some vehicles boost::mt19937 rng; eg(rng); eg(rng); eg(rng); I can't seem to find anything that does this. Is it there and I'm just missing it, or am I the only person who needs to do this? Thanks, Kevin Martin

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Re: [Boost-users] [ASIO] destructor called multiple times in test code
by Jose Martinez 04 May '08

04 May '08

Frank, David, Nat, Thank you very much for the info. I picked up some good tips from ur responses. I made 'int d_count' a reference counter to find out how many copies are created and it went as high as 11; why so many? It would go that high in between iterations. I tried implementing the 'int count' member as a pointer, following Frank's advice, but I keep getting segmentation faults. If my copy constructor is as follows: print (const print& p): count(p.count),t(p.t){ std::cout<<"In copy. D_count:"<<++d_count<<"\n"; }//end copy constructor I get segmentation fault in the end: In copy. D_count:3 Count=2, D_count=2 Count=2, D_count=1 Count=2, D_count=0 Segmentation fault (core dumped) If my copy constructor is as follows: jose@jmart1:~/code/boost$ ./a.out I'm in constructor: 0 In copy. D_count:2 Segmentation fault (core dumped) I would have preferred copying the value, versus the address, in the copy constructor... in case the variable was deleted while references still existed to the class object. Here is the code: =========================================== class print{ int *count; boost::asio::deadline_timer* t; static int d_count; public: print (boost::asio::io_service& io, boost::asio::deadline_timer* timer) : t(timer) { d_count++; *count = 0; std::cout<<"I'm in constructor: "<<*count<<"\n"; t->async_wait(*this); }//end print ~print(){ std::cout << "Count=" << *count << ","; std::cout << " D_count=" << --d_count << "\n"; }//end ~print print (const print& p): count(p.count), t(p.t){ std::cout<<"In copy. D_count:"<<++d_count<<"\n"; //*count = *(p.count); causes segmentation fault right away }//end copy constructor void operator ()(const boost::system::error_code& /*e*/) const{ if (*count < 2){ std::cout << *count << "\n"; ++(*count); t->expires_at(t->expires_at() + boost::posix_time::seconds(1)); t->async_wait(*this); } }//end void operator() };//end class print int print::d_count = 0; int main(){ boost::asio::io_service io; boost::asio::deadline_timer t(io, boost::posix_time::seconds(1)); print p(io, &t); io.run(); return 0; } ====================================== Here is the output: I'm in constructor: 0 In copy. D_count:2 In copy. D_count:3 In copy. D_count:4 In copy. D_count:5 In copy. D_count:6 In copy. D_count:7 In copy. D_count:8 In copy. D_count:9 Count=0, D_count=8 Count=0, D_count=7 (skipping lines to save space) In copy. D_count:11 Count=2, D_count=10 Count=2, D_count=9 Count=2, D_count=8 Count=2, D_count=7 Count=2, D_count=6 Count=2, D_count=5 Count=2, D_count=4 Count=2, D_count=3 Count=2, D_count=2 In copy. D_count:3 In copy. D_count:4 In copy. D_count:5 In copy. D_count:6 In copy. D_count:7 Count=2, D_count=6 Count=2, D_count=5 Count=2, D_count=4 Count=2, D_count=3 Count=2, D_count=2 In copy. D_count:3 Count=2, D_count=2 In copy. D_count:3 Count=2, D_count=2 Count=2, D_count=1 Count=2, D_count=0 Segmentation fault (core dumped) thanks jose "survival first, then happiness as we can manage it" ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

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[ASIO] destructor called multiple times in test code
by Jose Martinez 04 May '08

04 May '08

OK I think I figured out the problem. I think I did something stupid. I can't just take an undefined pointer and assign a number to the address it is pointing to. class print{ int* count; boost::asio::deadline_timer* t; static int d_count; public: print (boost::asio::io_service& io, boost::asio::deadline_timer* timer) : t(timer) { d_count++; std::cout<<"I'm in constructor: "<<*count<<" Addr of count:"<<count<<"\n"; *count = 0; // DO NOT DO THIS I should have passed the value for count as an argument then assign its address to the member variable *count. Like this: class print{ int* count; boost::asio::deadline_timer* t; static int d_count; public: print (boost::asio::io_service& io, boost::asio::deadline_timer* timer, int *c) : t(timer), count(c) { d_count++; std::cout<<"I'm in constructor: "<<*count<<" Addr of count:"<<count<<"\n"; The copy constructor would then look like this. print (const print& p): t(p.t), count(p.count){++d_count;} This matches with what Frank was saying about managing the state of operator()() outside of the object. thanks! jose "survival first, then happiness as we can manage it" ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

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Queries of a Boost newbie
by ajay gopalakrishnan 03 May '08

03 May '08

Hi all, I have worked on C++ for a long time in the past, but then I stopped using C++ and moved to other languages like Java sheerly because I was facing portability and repeatability issues with my programs. However, with the advent of Boost, I am very excited to go back to C++ again. Boost looks like a pretty big package to easily go through and seems daunting at first to get used to using it. I have been trying to read the documentation and packages available, but it is proving to be a bit difficult to get started quickly. I work mainly in Machine Learning & Data Mining and this job mainly requires me to write very efficient and fast code for numerical processing programs as well as do a lot of data, especially text preprocessing. It would be great if you cant point to me some good packages in Boost for the following tasks. Packages that are very good and don't have a very steep learning curve. - Text Parsing. package that lets me do something like what Sed and Awk can do. - Linear Algebra - Eigen analysis, matrix operations, Matrix decomposition etc. - Optimization routines - Linear programming , Quadratic Programming etc. - HTML, XML parsing etc. Please do let me know if I am posting in the wrong forum. Thanks & Regards, Ajay Gopalakrishnan.

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[concept check] Documentation is out of sync
by Kimon Hoffmann 03 May '08

03 May '08

Hi all, I've just observed that a small part of the concept check documentation is out of sync with the current implementation. The page "Implementation" still uses the deprecated way of defining and checking concepts: http://www.boost.org/doc/libs/1_35_0/libs/concept_check/implementation.htm The rest of the pages seem to be up to date. Another small thing I noticed is that the page "Using Concept Checks" has the "Prev" and "Next" links at the bottom of the page switched compared to the other pages. http://www.boost.org/doc/libs/1_35_0/libs/concept_check/using_concept_check… Best regards, Kimon

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boost.graph topological_sort help
by James Sutherland 02 May '08

02 May '08

Can one use topological_sort with the following: typedef adjacency_list<listS, listS, directedS> Graph; typedef graph_traits<Graph>::vertex_descriptor Vertex; Graph g; // ... populate graph ... typedef vector<Vertex> SortVerts; SortVerts verts; topological_sort( g, std::back_inserter(verts) ); I currently have this working with a adjacency_list<vecS, vecS, directedS> graph but I need to use lists so that I don't run into trouble when I am removing vertices... Thanks for any advice, James

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[ASIO] destructor called multiple times in test code
by Jose Martinez 02 May '08

02 May '08

I was messing around with the ASIO timer examples, the examples that test out the asynch-timers. I was trying to remove the Bind calls from those examples. I stumbled on the following behavior. I created a class function object and overloaded the () operator and would call t->async_wait(*this); in the constructor. And t->expires_at(t->expires_at() + boost::posix_time::seconds(1)); t->async_wait(*this); in the operator() overload function. Anyways to make a long story short the destructor that should have only been called once, gets called multiple times, but the constructor gets called once. To make things even funnier, the destructor has no affect when changing the value on member objects. ================================== Here is the code: class print{ int count; boost::asio::deadline_timer* t; int d_count; public: print (boost::asio::io_service& io, boost::asio::deadline_timer* timer) :count(0), t(timer), d_count(0){ std::cout<<"I'm in constructor: "<<count<<"\n"; t->async_wait(*this); }//end print ~print(){ std::cout << "Count=" << count << ","; std::cout << " D_count=" << ++d_count << "\n"; }//end ~print void operator ()(const boost::system::error_code& /*e*/){ if (count < 2){ std::cout << count << "\n"; ++(count); t->expires_at(t->expires_at() + boost::posix_time::seconds(1)); t->async_wait(*this); } }//end void operator() };//end class print int main(){ boost::asio::io_service io; boost::asio::deadline_timer t(io, boost::posix_time::seconds(1)); print p(io, &t); io.run(); return 0; } ============================== Here is the output: jose@jmart1:~/code/boost$ ./a.out I'm in constructor: 0 Count=0, D_count=1 Count=0, D_count=1 Count=0, D_count=1 Count=0, D_count=1 Count=0, D_count=1 Count=0, D_count=1 Count=0, D_count=1 Count=0, D_count=1 Count=0, D_count=1 Count=0, D_count=1 Count=0, D_count=1 Count=0, D_count=1 Count=0, D_count=1 0 Count=1, D_count=1 Count=1, D_count=1 Count=1, D_count=1 Count=1, D_count=1 Count=1, D_count=1 Count=1, D_count=1 Count=1, D_count=1 Count=1, D_count=1 Count=0, D_count=1 Count=1, D_count=1 Count=1, D_count=1 Count=1, D_count=1 Count=1, D_count=1 Count=1, D_count=1 Count=1, D_count=1 1 Count=2, D_count=1 Count=2, D_count=1 Count=2, D_count=1 Count=2, D_count=1 Count=2, D_count=1 Count=2, D_count=1 Count=2, D_count=1 Count=2, D_count=1 Count=1, D_count=1 Count=2, D_count=1 Count=2, D_count=1 Count=2, D_count=1 Count=2, D_count=1 Count=2, D_count=1 Count=2, D_count=1 Count=2, D_count=1 Count=2, D_count=1 Count=0, D_count=1 Any ideas what the heck is going on? Thanks a lot! jose "survival first, then happiness as we can manage it" ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

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added two Eclipse plug-ins for BJam support to Boost Subversion
by Frank Birbacher 02 May '08

02 May '08

Hi! I've created two small plug-ins for Eclipse: the first adds syntax highlighting to jamfiles, the second scans jamfiles for main targets and provides them in a tree view for easy building, like the MakeTargets view. Currently, they are in Boost svn at: http://svn.boost.org/svn/boost/sandbox-branches/birbacher/eclipse_contrib/ but they might as well move somewhere else soon. The svn contains a complete eclipse 3.3 project from which the "export -> Deployable plug-ins and fragments" command creates a ready-to-use Eclipse plug-in. The plug-ins depend on CDT. Both aren't perfect of course. I've hacked them in a couple of hours. I'd appreciate patches which fix bugs or improve features. Regards, Frank

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