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

[multi_array] Slices, views and sub_arrays
by Robert Jones 10 Oct '08

10 Oct '08

Hi All I'm still plugging away at trying to make use of multi_array, but I seem to be having a few problems! I suspect my understanding of the basic paradigm is flawed. I'm bit confused about views and slices. If I start with a rectangular, 2 dimensional grid, take a view of the whole grid, and then use a single subscript to index into that view, then I expected the result to be a view of one less dimension then the original view. However, it seems to be a "sub_array". #include "boost/multi_array.hpp" struct Cell { int i; }; int main( ) { typedef boost :: multi_array_types :: index_range range; boost :: multi_array< Cell, 2 > grid( boost :: extents[ 9 ][ 9 ] ); boost :: multi_array< Cell, 2 > :: const_array_view< 2 > :: type const_grid_view = grid[ boost :: indices[ range( ) ][ range( ) ] ]; boost :: multi_array< Cell, 2 > :: const_array_view< 1 > :: type const_row_view = const_grid_view[ 5 ]; return 0; } The error message from the last assignment is this sample.cpp: In function `int main()': sample.cpp:13: error: conversion from `boost::detail::multi_array::const_sub_array<Cell, 1u, const Cell*>' to non-scalar type `boost::detail::multi_array::const_multi_array_view<Cell, 1u, const Cell*>' requested which seems to confirm I've got all my consts and dimensions correct. So, why is this wrong? Also, does the return type of sub_array, rather than array_view, mean that the contents of the relevant cells have been copied? Thanks - Rob.

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program option::force to suppy only short name
by Lloyd 10 Oct '08

10 Oct '08

Hi, I am using boost program options library Can I supply only "short names" eg. options_desctiprion desc("sample"); desc.add_options() ("help,h","display help") (",c","compress") ; in the case of option "c" we don't want to allow the user to supply a long name. Howe can we do this? Thanks, Lloyd ______________________________________ Scanned and protected by Email scanner

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Re: [Boost-users] mpl programming task
by peter_foelsche＠agilent.com 09 Oct '08

09 Oct '08

I think the following code would be easier: #include <map> #include <vector> typedef std::map<size_t, size_t> CInt2IntMap; typedef std::vector<size_t> CIntVector; static CInt2IntMap convert(const CIntVector &_r) { CInt2IntMap s; for (size_t i = 0; i < _r.size(); i++) s.insert(std::make_pair(_r[i], s.size())); return s; }

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mpl programming task
by peter_foelsche＠agilent.com 09 Oct '08

09 Oct '08

Anybody able to tell me how to convert the following code into it's mpl equivalent? #include <map> #include <vector> typedef std::map<size_t, size_t> CInt2IntMap; typedef std::vector<bool> CBooleanVector; static CInt2IntMap convert(const CBooleanVector &_r) { CInt2IntMap s; for (size_t i = 0; i < _r.size(); i++) if (_r[i]) s.insert(std::make_pair(i, s.size())); return s; }

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boost::variant construction,assignment
by Hicham Mouline 09 Oct '08

09 Oct '08

hello, class parameters { public: parameters(); ~parameters(); const R& getR() const; void setR(const R& rhs); const V& getV() const; void setV(const V& rhs); private: const R* r_; const V* v_; }; R and V are typedefs of variant<>. I have chosen to make the private members r_ and v_ as pointers to allow for r_=0 and v_=0 (is this a "never do this" thing?). R setter is implemented like this: void parameters::setR(const R& rhs) { if (!r_) r_ = new R( rhs ); else *r_ = rhs; } then ~parameters() { if (r_) delete r_; } There is no operator= for variant<> it seems? regards,

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Re: [Boost-users] [Graph] Subgraphs with bundled properties
by Cooprider, Nathan (US NonSSA) 09 Oct '08

09 Oct '08

I would like to use a set to store my nodes inside a graph that uses subgraphs, but that does not seem to work. The code below does not compile if I switch vecS to setS and adjust the vertex properties to have an index (replace Node, with the commented portion after it). However, not using a subgraph and having the adjacency list be the graph directly fixes the issue. Any insights as to what I should do Nathan #include <string> #include <boost/graph/adjacency_list.hpp> #include <boost/config.hpp> #include <boost/graph/subgraph.hpp> using namespace boost; struct Node { std::string name; float weight; }; // want vecS to be setS for fast lookups typedef adjacency_list < listS, setS, directedS, Node, // property<vertex_index_t, int, Node >, property<edge_index_t, int> > PlainGraph; typedef subgraph<PlainGraph> Graph; int main () { Graph g; Graph::vertex_descriptor tmp = add_vertex(g); struct Node x; put(get(vertex_bundle,g), tmp, x); }

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[Python] rule python-extension unknown
by Robert MacHardy 09 Oct '08

09 Oct '08

Boost Users, I am trying to build the Hello World python example. When I execute bjam I get the "rule python-extension unknown" error. I believe this to be because my user-config.jam file is never being used. The tutorial states to configure the rules in the user-config.jam file in my home directory. My home directory is "C:\Documents and Settings\robert.machardy". I did not find the file there, and this does not appear to be the place for jam files. I found the file user-config.jam in "C:\Program Files\boost\boost_1_36_0\tools\build\v2", I edited it and copied to my home directory. I configured it for the following: # Configure specific msvc version (searched for in standard locations and PATH). using msvc : 7.1 ; using python : 2.6 : C:\Program Files\Python26; Please help. Thank you, Robert MacHardy

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Re: [Boost-users] boost::variant construction,assignment
by Hicham Mouline 09 Oct '08

09 Oct '08

Thank you. I apologize, one often fails to grasp the obvious, regards, > ----- Original Message ----- > From: "Steven Watanabe" <watanabesj(a)gmail.com> > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] boost::variant construction,assignment > Date: Thu, 09 Oct 2008 10:06:05 -0700 > > > AMDG > > Hicham Mouline wrote: > > const R* r_; > > > > > > *r_ = rhs; > > > > > > There is no operator= for variant<> it seems? > > > > Sure there is, but only works for non-const variant<>s. > > In Christ, > Steven Watanabe

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boost::program_options
by Duy Nguyen 09 Oct '08

09 Oct '08

When I try to use the boost::program_options library to read a property file, I got the error when I run "make" on Cygwin (I installed Cygwin on WIndows XP). > make g++.exe -I /cygdrive/c/MyTest/Test1/include/boost-1_34_1/ -c TestInit.cpp Test.cpp TestDriver.cpp g++.exe -I /cygdrive/c/MyTest/Test1/include/boost-1_34_1/ -c TestInit.cpp Test.cpp TestDriver.cpp g++.exe -I /cygdrive/c/MyTest/Test1/include/boost-1_34_1/ -c TestInit.cpp Test.cpp TestDriver.cpp g++.exe TestInit.o Test.o TestDriver.o -o "TestDriver" -L/cygdrive/c/MyTest/Test1/lib -lboost_program_options-gcc34-mt-d-1_34_1 -lg2c Info: resolving vtable for boost::program_options::variables_mapby linking to __imp___ZTVN5boost15program_options13variables_mapE (auto-import) Then when I run my program, it does not work. If I comment out the "try ... catch" block which uses the boost::propram_options library then it compiles and works fine. Please show me how to fix it. Thank you.

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shared_ptr and std::set::erase
by Javier Jerónimo 09 Oct '08

09 Oct '08

Hello, I have: std::set< boost::shared_ptr< A > > m_set; and when I try to do: m_set.erase( somesharedptr ); the shared_ptr is not removed from the set. There is already a shared_ptr object pointing to the same A object inside the set. I think it's because the definition of "shared_ptr<>::operator<" and its use in std::set<>::erase. What's the correct way of using a shared_ptr inside a set? Thanks.

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