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

vertex descriptors
by Luis Quesada 18 Dec '06

18 Dec '06

Dear all, Sorry for the newbie question! Given the index of a vertex, how can I get its descriptor? I guess function vertex (page 225 of The Boost Graph Library) does that but the function is not defined. In fact, what I want to do is to check whether an edge belongs to a graph in a context where descriptors get invalidated after vertex removals? Suppose I have done this: // create a typedef for the Graph type typedef adjacency_list<vecS, vecS, bidirectionalS> Graph; // Make convenient labels for the vertices enum { A, B, C, D, E, N }; const int num_vertices = N; const char* name = "ABCDE"; // writing out the edges in the graph typedef std::pair<int, int> Edge; Edge edge_array[] = { Edge(A,B), Edge(A,D), Edge(C,A), Edge(D,C), Edge(C,E), Edge(B,D), Edge(D,E) }; const int num_edges = sizeof(edge_array)/sizeof(edge_array[0]); // declare a graph object Graph g(num_vertices); Then I remove some vertices. Now I want to check whether edge <A,B> is still there. Calling edge(A,B,g) would not be OK because the descriptors are no longer referring to the same vertices.... Thanks in advance for your answer, Luis

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The fibonacci heap is behaving strange
by Magnus Ekdahl 15 Dec '06

15 Dec '06

Hi, I put in 0,1,2,3,4 into a Fibonacci heap, manipulate some and get 0,2,4,1,25 back. With the relaxed heap I get 0,2,4,1,3 back, which is as expected with my code. AFAIK this is due to a bug in the Fibonacci heap? Anyway here is code adopted from the cvs (fibonacci_heap.cpp) that reproduces the result on two different machines (intel/amd), where the programs are compiled using g++ 4.0.4. Any help in clearing out this confusing result is appreciated :) #include <iostream> #include <cstdlib> #include <vector> #include <boost/pending/Fibonacci_heap.hpp> #include <boost/pending/relaxed_heap.hpp> #include <boost/graph/graph_utility.hpp> #include <boost/pending/indirect_cmp.hpp> using namespace std; using namespace boost; int main(int argc, char *argv[]) { typedef indirect_cmp<unsigned*,std::less<unsigned> > ICmp; unsigned current; const unsigned N=5; vector<unsigned> w(N); ICmp cmp(&w[0], std::less<unsigned>()); Fibonacci_heap<unsigned, ICmp> Q(N, cmp); //relaxed_heap<unsigned, ICmp> Q(N, cmp); Q.push(0); current=Q.top(); cout << current << " "; Q.pop(); w[1]=180428938; Q.push(1); w[2]=84693088; Q.push(2); w[3]=168169277; Q.push(3); w[4]=171463691; Q.push(4); current = Q.top(); cout << current << " "; Q.pop(); w[3]=164976049; Q.update(3); w[4]=59651664; Q.update(4); current = Q.top(); cout << current << " "; Q.pop(); w[1]=71988538; Q.update(1); w[3]=118964142; Q.update(3); current = Q.top(); cout << current << " "; Q.pop(); w[3]=42423833; Q.update(3); current = Q.top(); cout << current << " "; Q.pop(); return EXIT_SUCCESS; }

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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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Errors compiling Boost.Python library on Solaris
by chris botos 15 Nov '06

15 Nov '06

Hi, I'm new to this list and to Boost. I'm interested in using Boost to wrap C++ objects in Python. The environment is Solaris 10, x86. I did the following: Downloaded boost_1_33_1.tar and extracted it to /opt/boost. >setenv PYTHON_ROOT /usr/local > cd to /opt/boost/boost_1_33_1/libs/python/build > bjam I get lots of error messages, repeated throughout the compile and tend to be grouped and refer to the same line: '->' cannot appear in a constant-expression '&' cannot appear in a constant-expression template argument 1 is invalid value is not a member of '<declaration errors>' ...failed gcc-C++-action ... is also associated with the above If I "bjam" from /opt/boost/boost_1_33_1, I get the same errors when it gets to the python library. I would most appreciate any help with this! Regards, Chris Botos

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Sequence of Types, What For?
by Terry G 14 Nov '06

14 Nov '06

I've just finished reading C++ Template Metaprogramming again. I just don't get it. Why would someone use a type container? I have used enable_if, along with some of the logic functions for managing an overload set. Otherwise, I'm clueless. I'd really like a reference to an MPL primer or some case studies. Too much pain with very little gain. Time to ask for help. Rereading this, it sounds negative. Really, I think the MPL is really cool! terry

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Boost:ASIO mailing list/group
by Stas 10 Nov '06

10 Nov '06

What is a right group/ mailing list ot ask ASIO related questions? Regards Stas

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progress_display+CProgressBar MFC
by Gennady Khokhorin 07 Nov '06

07 Nov '06

I'm wonder what could be a schema to connect boost::progress_timer to MFC CProgressBar (msvc) gui? Thanks in advance. gok

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[mpl::map] generating map for 150 types
by Ovanes Markarian 06 Nov '06

06 Nov '06

Hi! I need to define a map with int_<1...150>->Type1...150 pairs. Im source file I define: #define BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS #define BOOST_MPL_LIMIT_MAP_SIZE 150 #include <boost/mpl/map.hpp> When compiling I get an error in the file: ...\boost\include\boost-1_33_1\boost\mpl\map.hpp on line: 36 fatal error C1083: Cannot open include file: 'boost/mpl/map/map150.hpp': No such file or directory Development environment is Visual C++ 8 Express Edition The help states: BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS is an boolean configuration macro regulating library's internal use of preprocessed headers. When defined, it instructs the MPL to discard the pre-generated headers found in boost/mpl/aux_/preprocessed directory and use preprocessor metaprogramming techniques to generate the necessary versions of the library components on the fly. In this implementation of the library, the macro is not defined by default. To change the default configuration, define BOOST_MPL_CFG_NO_PREPROCESSED_HEADERS before including any library header. I did what is written here and get this compiler error. Can someone suggest smth? With Kind Regards, Ovanes Markarian

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Any interest in a separate Boost.TR1 release/download?
by John Maddock 05 Nov '06

05 Nov '06

I wonder if people would find a separate download for the Boost TR1 components useful ? At present this is vapourware: I'm not sure how easy it will be to sort out documentation and build issues when extracting the TR1 subset, but I'm prepared to put together a preliminary (alpha) release of such a beast if there's demand, and from there we can at least see how viable releasing such a Boost subset would be. Thought? Thanks, John.

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[Boost.Parameter] How to Use Named Parameters in a Class Hierarchy?
by Wu Yinghui, Freddie 02 Nov '06

02 Nov '06

Dear all, I'm implementing a hierarchy of classes to handle different types of objects. The characteristics of these objects are mostly similar (so I can put them into a container that knows only about the pure abstract base interface type), but some properties are specific to each object types. I plan to use Boost.Parameter for its capability of providing named parameter to these object types. However, I have one problem in this approach: Since Boost.Parameter requires that the function processing the ArgumentPack to be a template, I cannot make it virtual (a member function template cannot be virtual) in my pure abstract base interface. Furthermore, due to the lack of "virtual" member function, I cannot use the base class pointer to provide these named parameters to some subclasses. So my question is: Is there a way to tackle this problem? (Use Boost.Parameter with virtual member functions? Or avoid using Boost.Parameter, but provide a way to access subclass properties that are not know directly via the base class?) Any suggestion is welcomed! Cheers, Freddie -- Wu Yinghui, Freddie Research & Development Senior Software Engineer Volume Interactions Pte Ltd 1 Kim Seng Promenade, #12-01 Great World City East Tower Singapore 237994 Tel: +65 62226962 (Ext 216) Fax: +65 62226215 Email: yhwu(a)volumeinteractions.com URL: http://www.volumeinteractions.com Important: This message is intended for the recipient(s) addressed above. It contains privileged and confidential information. If you are not the intended recipient, please notify the sender immediately by replying to this message and then delete it from your system. You must not read, copy, use, or disseminate this communication in any form. Thank you.

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