July 2008 - Boost-users - lists.preview.boost.org

a little imperfection in options_description.cpp example (program options)
by Guido Ziliotti 10 Jul '08

10 Jul '08

// A helper function to simplify the main part. template<class T> ostream& operator<<(ostream& os, const vector<T>& v) { copy(v.begin(), v.end(), ostream_iterator<T>(cout, " ")); /* this is line 21 */ return os; } SHOULD BE REPLACED WITH // A helper function to simplify the main part. template<class T> ostream& operator<<(ostream& os, const vector<T>& v) { copy(v.begin(), v.end(), ostream_iterator<T>(os, " ")); /* this is line 21: "os" replaces "cout" */ return os; }

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get/fetch" regex output - currently to console, into a field in order to continue it's processing
by M 10 Jul '08

10 Jul '08

hello boost group i tested this program from "boost.regex" to find url's inside .htm file: /* * * Copyright (c) 2003 * John Maddock * * Use, modification and distribution are subject to the * Boost Software License, Version 1.0. (See accompanying file * LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) * */ /* * LOCATION: see http://www.boost.org for most recent version. * FILE regex_token_iterator_example_2.cpp * VERSION see <boost/version.hpp> * DESCRIPTION: regex_token_iterator example: spit out linked URL's. */ #include "stdafx.h" #include <fstream> #include <iostream> #include <iterator> #include <boost/regex.hpp> boost::regex e("<\\s*A\\s+[^>]*href\\s*=\\s*\"([^\"]*)\"", boost::regex::normal | boost::regbase::icase); void load_file(std::string& s, std::istream& is) { s.erase(); if(is.bad()) return; // // attempt to grow string buffer to match file size, // this doesn't always work... s.reserve(is.rdbuf()->in_avail()); char c; while(is.get(c)) { // use logarithmic growth stategy, in case // in_avail (above) returned zero: if(s.capacity() == s.size()) s.reserve(s.capacity() * 3); s.append(1, c); } } int main(int argc, char** argv) { std::string s; int i; // argc = 2; // argv[1] = "C:/schmidt23_cpp/example/debug/bookmark.htm"; for(i = 1; i < argc; ++i) { std::cout << "Findings URL's in " << argv[i] << ":" << std::endl; s.erase(); std::ifstream is(argv[i]); load_file(s, is); is.close(); boost::sregex_token_iterator i(s.begin(), s.end(), e, 1); boost::sregex_token_iterator j; while(i != j) { std::cout << *i++ << std::endl; } } return 0; } i need to know how to "get/fetch" the output - currently to console, into a field in order to continue it's processing? thanks meir

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Bessel functions for complex arguments
by Alessandro A. Bellina 10 Jul '08

10 Jul '08

Hello Boost users, I am in need of computing Bessel functions of complex arguments. These are not implemented yet in the Boost library, correct? I try sending std::complex arguments to cyl_bessel or sph_bessel and they give me errors. Thanks, Alessandro -- Alessandro A. Bellina Graduate Student Bioacoustics Research Laboratory Electrical and Computer Engineering University of Illinois at Urbana-Champaign

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mpl sequence -> tuple
by Cory Nelson 10 Jul '08

10 Jul '08

Is there anything in boost that creates a tuple of the types in a MPL sequence? -- Cory Nelson

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Boost File System on Cygwin and native paths
by Andrej van der Zee 09 Jul '08

09 Jul '08

Hi, I am having some troubles with Boost File System on Cygwin. It seems to use Posix file paths as native, but I need Windows paths since I am using Cygwin to develop an application for Windows. I compiled my own projects and the boost libraries on Cygwin using msvc-8.0. Do I need to pass some special compiler flag to tell the file system library that native is Windows, and not Cygwin/Posix? Cheers, Andrej __________________________________________________________ Not happy with your email address?. Get the one you really want - millions of new email addresses available now at Yahoo! http://uk.docs.yahoo.com/ymail/new.html

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[assert] Control Flow Warnings with BOOST_ASSERT(false)
by Michiel Helvensteijn 09 Jul '08

09 Jul '08

I've been using the BOOST_ASSERT macro. I like it because it can throw an exception rather than use the abort signal. And I can catch exceptions in automated unit-tests. However, I sometimes use assert(false) in locations that should be unreachable. And the compiler (well, GCC at least) understands this, because assert() calls abort() if the expression equals (evaluates to) false. If I use BOOST_ASSERT in this way, the compiler shows me various warnings about the flow of control. It does not know that my implementation of assertion_failed() throws an exception. To get rid of those warnings, I've changed BOOST_ASSERT for my personal use: #define BOOST_ASSERT(expr) { \ if (!(expr)) { \ ::boost::assertion_failed(#expr, BOOST_CURRENT_FUNCTION, \ __FILE__, __LINE__); \ abort(); \ } \ } It may not be the best way. For example, there may have been a reason to push everything into the ternary operator that I am not aware of. But it seems to work. I believe this functionality should be part of the library. Probably optional by defining another constant (BOOST_ENABLE_ASSERT_ABORT or somesuch). Are the developers aware of this problem? Do you think it will be solved in the library? Thanks in advance for your reply, -- Michiel Helvensteijn

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[BGL] problems with depth_first_search
by M. Siebeneicher 09 Jul '08

09 Jul '08

Hello list members, I tries to use 'depth_first_search' in a very simple manner but I get an weird compilation error. Here's a snippet of my code: typedef adjacency_list<listS, listS, bidirectionalS, Vertex> BGL_Graph; // Vertex is a bundled property BGL_Graph g(...) . . . typedef boost::property_map<BGL_Graph, boost::vertex_index_t>::type VertexIndexMap; VertexIndexMap vertex_id = boost::get(boost::vertex_index, g); vector<default_color_type> colormap(num_vertices(g)); depth_first_search( g , visitor(default_dfs_visitor()) , make_iterator_property_map(colormap.begin(), vertex_id) ); I use a graph with listS for the VertexList. Then I try to specify my own color map (created like the default color map) and want to set a dfs visitor (here the default one). But the compiler can't find 'initialize_vertx' and 'start_vertex'. I atteched the compiler output but it's a german version. greetz Manuel -- GMX startet ShortView.de. Hier findest Du Leute mit Deinen Interessen! Jetzt dabei sein: http://www.shortview.de/wasistshortview.php?mc=sv_ext_mf@gmx

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Problem with destructor being declared protected.
by Tony May 09 Jul '08

09 Jul '08

I am trying to build a helloworld program using bjam so that it can be imported into a python script. I get an error message that mentions a problem with the destructor being declared protected. Has anyone noticed this problem when building with Boost and Delta3D? C:\Program Files\boost\boost_1_35_0\boost/python/object/value_holder.hpp(67) : warning C4624: 'boost::python::objects::value_holder<Value>' : destructor could not be generated because a base class destructor is inaccessible I didn't get this error when building with the ide.

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[Boost] Is their any conflicts between boost::thread (and bind...) with inherited methods ?
by Germain BARRET 09 Jul '08

09 Jul '08

Is their any probleme with boost::thread and inherited functions ? Here is an example of what doesn't work to me : Class A { public: makeWork() { runThat(); } ; protected: virtual runThat(void); } //A Class B : public A { public : init() { boost::thread(makeWork); }; //v1 init() { boost::thread(boost::bind(B::makeWork)); }; //v2 private : runThat(void) { printf("foo"); }; } No way, once makeWork never run, or with boost::bind, boost::ref, boost::function... I have still errors (do I need to post the errors... ?) That why befor posting any error log, I ask if there are known problems with inheritage and boost::thread ? Of course I know how to use boost::thread and boost::bind, for example if I had this to B, it works Class B : public A { ... public : init2() { boost::thread(foo); }; private : foo(void) { printf("foo"); }; ... } So what ??? In fact, in the real case, B inherit from another class one of my own invention : Singleton<CLASS> no need to explain what it does... maybe the "1 object only" is a problem for boost ? PS : the docs have very few complete examples, do you preview to extend it ? (usage of thread, bind, function, ref in the same example please) monolithic examples are OK to understand the principle, but not to understand complex usages...

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bjam command line syntax
by Johan Råde 09 Jul '08

09 Jul '08

What is the bjam command line syntax for disabling "Secure SCL" when I build boost with MSVC 9.0? Is it bjam --toolset=msvc-9.0 --cxxflags="-D_SECURE_SCL=0" --Johan

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