June 2014 - Boost-users - lists.preview.boost.org

pure virtuals on multiple hierarchy levels
by Igor R 12 Jun '14

12 Jun '14

Hello, What's the right way to wrap the following, when exposing this hierarchy to Python: sturct base { virtual void func1() = 0; }; struct intermediate : base { virtual void func2() = 0; }; struct derived : intermediate { void func1(); void func2(); }; Thanks.

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[BGL]
by Pablo Madoery 11 Jun '14

11 Jun '14

Hello, I Have 2 graphs: graph1 and graph2, and two sets of edge descriptors. One set is associated to edges of graph1 and another set associated to edges of graph2. I don't understand why is it possible to access information about edges of graph2 by using graph1 and the edge descriptors of graph2. I realized of that because of an own mistake when using graphs. What I would like to know is why is that possible to do and if it should be an exception that can handle this situation. I send the code I was using to test this: #include <iostream> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/graphviz.hpp> #include <fstream> #include "GraphInfo.h" using namespace std; using namespace boost; typedef adjacency_list<setS, vecS, bidirectionalS, VertexInfo, EdgeInfo> Graph; void printGraph(Graph graph, string file) { ofstream ofs(file.c_str()); dynamic_properties dp; dp.property("node_id", get(vertex_index, graph)); dp.property("label", get(&EdgeInfo::weight, graph)); write_graphviz_dp(ofs, graph, dp); } int main() { Graph graph1; Graph::vertex_descriptor a1 = add_vertex(graph1); Graph::vertex_descriptor b1 = add_vertex(graph1); Graph::vertex_descriptor c1 = add_vertex(graph1); Graph::edge_descriptor e1 = (add_edge(a1, b1, graph1)).first; Graph::edge_descriptor e2 = (add_edge(b1, a1, graph1)).first; graph1[a1].id = 10; graph1[b1].id = 20; graph1[c1].id = 30; graph1[e1].weight = 1; graph1[e2].weight = 2; Graph graph2; Graph::vertex_descriptor a2 = add_vertex(graph2); Graph::vertex_descriptor b2 = add_vertex(graph2); Graph::vertex_descriptor c2 = add_vertex(graph2); Graph::vertex_descriptor d2 = add_vertex(graph2); Graph::edge_descriptor e4 = (add_edge(c2, b2, graph2)).first; Graph::edge_descriptor e5 = (add_edge(b2, c2, graph2)).first; Graph::edge_descriptor e6 = (add_edge(d2, a2, graph2)).first; Graph::edge_descriptor e7 = (add_edge(a2, d2, graph2)).first; graph2[a2].id = 10; graph2[b2].id = 20; graph2[c2].id = 30; graph2[e4].weight = 13; graph2[e5].weight = 14; graph2[e6].weight = 15; graph2[e7].weight = 16; // WHY IS THIS POSSIBLE TO DO // IT IS ASKING FOR AN EDGE OF GRAPH2 BUT USING GRAPH1 ??? double weight = graph1[e7].weight; cout<<"weight: "<<weight<<endl; printGraph(graph1, "graph1.dot"); printGraph(graph2, "graph2.dot"); cout << "end" << endl; return 0; } Thank you very much

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Fwd: Lexical cast between narrow and wide strings
by Andrew Marlow 11 Jun '14

11 Jun '14

I hope this is the right place to post my question. I expected to be able to convert between narrow and wide strings using boost lexical cast but it fails to compile. I suppose that conversion is not supplied or supported. It would be really useful to me if it was. I am developing on win32 for wince and on wince there seeem to be many places where wide strings are required, especially when using the win32 API. Is there any chance this could be added to boost? I checked using boost 1.55.0 -- Regards, Andrew Marlow http://www.andrewpetermarlow.co.uk

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Is boost asio appropriate for this use case ?
by Aaron Boxer 10 Jun '14

10 Jun '14

I am decoding an image file: the file has tagged header info mixed with 4K pixel code blocks. Platform is primarily windows, but could be osx or linux. Once I read in a code block, I can launch (asynchronously) my decode routine on this block, while continuing to read the file for header info and code blocks. Currently, I do synchronous reads using fread(...). Is is worthwhile to switch to boost asio to asynchronously read in the code blocks? The read callback could trigger my decode routine. But I wouldn't have to wait for the read before I carry on to the next code block. If so, can anyone point me to a reference/tutorial covering boost::asio asynch reads from disk?

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[boost] [pimpl] Boost.Pimpl review canceled
by Glen Fernandes 09 Jun '14

09 Jun '14

Hi everyone, Vladimir has elected to withdraw Boost.Pimpl submission and cancel the formal review. On behalf of Vladimir, thank you for the feedback provided in response to the pre-view announcement mail: it was especially useful to him. Best, Glen

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memory mapped file thread safety
by Aaron Boxer 09 Jun '14

09 Jun '14

Simple question: If I call get_address() on a region, can I pass this pointer to another thread and have this thread access the memory ? Thanks!

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Boost Build
by skk 09 Jun '14

09 Jun '14

I am building Boost for MSVS10.0. I have generated the bjam.exe file and run it with the command line: bjam toolset=msvc10.0 variant=debug,release threading=multi link=static Looking at the libraries built, there are no sgd libs and the linker wants: libboost_regex-vc100-mt-sgd-1_55.lib Don't know how to get the sgd libs. Thanks -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-Build-tp4663758.html Sent from the Boost - Users mailing list archive at Nabble.com.

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[Filesystem] remove and recursive_directory_iterator
by gast128 09 Jun '14

09 Jun '14

I couldn't find a description of the iterator stability of recursive_directory_iterator but it gives problems when you remove the directory which is being iterated even when that directory is empty. For example if you want to remove all empty directories, the following code will throw an exception in ++it after the 'remove' call: fs::path pthDirectory = ...; fs::recursive_directory_iterator itEnd; for (fs::recursive_directory_iterator it(pthDirectory); it != itEnd; ++it) { boost::system::error_code ec; const fs::path& rPath = it->path(); if (fs::is_directory(rPath, ec)) { if (fs::is_empty(rPath, ec)) { fs::remove(rPath, ec); } } } It seems solvable with the way one erases a map (i.e. using while (it != itEnd) and using the equivalent of map.erase(it++)). Maybe add a note to the documentation or did I overlook something?

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Writing a dynamic string into a shared memory using Boost Library
by Hany Assasa 09 Jun '14

09 Jun '14

I want to share a dynamic array of characters between two processes using Boost Shared Memory. I use the following two pieces of code to do that: *Producer Process:* char *data;unsigned int share_length;unsigned int offset; std::string data_to_share(data + offset, data + offset + share_length); boost::interprocess::managed_shared_memory managed_shm(boost::interprocess::create_only, "SomeName", 1024*1024);typedef boost::interprocess::allocator<char, boost::interprocess::managed_shared_memory::segment_manager> CharAllocator;typedef boost::interprocess::basic_string<char, std::char_traits<char>, CharAllocator> my_string; managed_shm.construct<my_string>("DataToShare")(data_to_share.c_str(), managed_shm.get_segment_manager()); *Consumer Process:* boost::interprocess::managed_shared_memory managed_shm(boost::interprocess::open_read_only, "SomeName");typedef boost::interprocess::allocator<char, boost::interprocess::managed_shared_memory::segment_manager> CharAllocator;typedef boost::interprocess::basic_string<char, std::char_traits<char>, CharAllocator> my_string; std::pair<my_string *, size_t > data = managed_shm.find<my_string>("DataToShare"); cout << "Data Size=" << data.first->length() << endl; The problem is when I try to print the length of the DataToShare in the Consumer Process it is wrong, so what is the problem in my code, is it in the Producer Part since I am doing data_to_share.c_str()which is a std::string type instead of of my_string type? *Possible Answer:* I believe the answer to my question is, converting std::string into my_string type. so can anyone tell me how to do that?

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[mpl] Cannot open include file
by Christian Henning 09 Jun '14

09 Jun '14

I have the following error when using Visual Studio 2013 on the boost master branch: 1>c:\boost\boost\mpl\vector\aux_\include_preprocessed.hpp(49): fatal error C1083: Cannot open include file: 'boost/mpl/vector/aux_/preprocessed/plain/vector10.hpp': No such file or directory I have run "b2 headers". Here is the code I'm trying to compile: // cpp_test.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <boost/mpl/vector_c.hpp> int _tmain(int argc, _TCHAR* argv[]) { return 0; } Manually I can find vector10.hpp in C:\boost\boost\mpl\vector but I don't have the folder c:/boost/mpl/vector/aux_/preprocessed/plain/ Any ideas? Thanks, Christian Regards, Christian

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