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Bidirectionnal filtered multigraph
by Robert weldon 03 Aug '04

03 Aug '04

I've created a bidirectional filtered multigraph from an adjacency_list with vectorS and listS as containers for the vertices and egdes respectively. It seems the function edge(u,v,g) does not work properly for this kind of graph. I can detect the existence of an edge (u,v) if I iterate explicitly through the out_edges of the filtered graph but not if I use edge() directly on the filtered graph. Also, I get an exception when I remove an edge that was invisible to the edge(u,v,g) function while the bidirectionnal version of remove_edge for adjacency_list is erasing the edge ID form the in_edge list of the graph. Any idea why edge() does not work in this case? Patrick --------------------------------- Do you Yahoo!? New and Improved Yahoo! Mail - Send 10MB messages!

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Print all routes in a graph
by Daniele Carlucci 03 Aug '04

03 Aug '04

Hi all, I have seen the mail with dijikstra algorithm, there is a way to print all the routes in a graph from a node A and a node B? Thanks Daniele Carlucci

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Function Adaptor that takes an Address
by Ewan Mellor 03 Aug '04

03 Aug '04

I have a function T & foo() and I wish to use a function adaptor to turn this into T * foo2() In other words, I want a function adaptor that takes the address of its given function's result. Does such a thing exist in boost? TIA, Ewan Mellor.

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[BGL] Importing adjacency list from a txt file
by Rui Carvalho 03 Aug '04

03 Aug '04

Hi, I've got a file with the adjacency list of a graph, where each line contains the node index followed by the index of nodes that are adjacent to it (comma-separated). One of the lines of this file could read like: 1,3,4 This would mean that node '1' is adjacent to nodes '3' and '4' (undirected & unweighted graph). I'm declaring it as: typedef adjacency_list < vecS, vecS, undirectedS, no_property, no_property > Graph; Graph g; My question is: is there a simple way of reading the adjacency list into the graph from my txt file? I found Kevin_Bacon, but was looking for something more powerful. Then I found adjacency_list_io.cpp (is it documented?), but it wouldn't compile on MSVC. Am I missing something obvious? Thanks, Rui

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bind and weak pointers
by Jeff Williams 02 Aug '04

02 Aug '04

What is the prefered method of creating a boost::function<void()>, via boost bind, that is calling a member function of a class, and that class instance is held inside the bind object as a weak ptr. Thus, when the function is called, it will try to lock the shared_ptr, if successful it calls the bound function, otherwise it does nothing. Is there an standard way of doing this? Or do I have to write my own custom intermediate function? (which is how I do it now). Jeff

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execution order of slots (signals)
by oliver.kowalke＠t-online.de 02 Aug '04

02 Aug '04

Hello, if I create a signal sig with n slots (slots are ordered by group). What happens if : - I call sig(); and the first called slot removes the slot which is its successor - I call sig(); and the first slot connects a new slot to signal which has a higher priority (group -> higher values are executed at first) with best regards, Oliver -- "Der Spezialist ist ein Barbar, dessen Unwissenheit nicht allumfassend ist." Master's Voice, S.LEM

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RE: [Boost-users] Window API
by Ben Hutchings 02 Aug '04

02 Aug '04

Dr Jekyll <drjekyll(a)empirics.net> wrote: > Hi, > I use a library, which itself use Boost. This library define > > #define Handle boost::shared_ptr Ugh. > But because I intende to use WINAPI , this definition results > in a conflict > > c:\Program Files\Microsoft Visual Studio .NET > 2003\Vc7\PlatformSDK\Include\WinUser.h(3282): error C2751: > 'boost::shared_ptr' : the name of a function parameter cannot > be qualified <snip> > What should I do, if I have to keep the #define line in my library... Don't use that library. Its code quality is so low that you will probably waste more time working around its bugs then you can save by using it. If you disagree with this assessment, perhaps you could write and use a wrapper header that does something like: #ifndef LIBRARY_WRAPPER_H #define LIBRARY_WRAPPER_H #include "library.h" #undef Handle // undefine any other unwanted macros #endif // !defined(LIBRARY_WRAPPER_H)

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lambda and shared_ptr
by Vladimir Krasovsky 02 Aug '04

02 Aug '04

Hello boost-users(a)lists.boost.org, It seems to me that currently lambda's bind does not support shared_ptr as a second argument to bind, when first argument is a pointer-to-member. But boost::bind handles it perfectly. It would be nice for me to be able to write something like this: using namespace boost::lambda; struct SomeClass { int member1; }; boost::shared_ptr<SomeClass> ptr(new SomeClass); (bind(&SomeClass::member1, ptr) = _1)(5); Is it possible with current implementation of lambda? Or I have missed something important? -- Best regards, Vladimir mailto:vkrasovsky@yandex.ru

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[Help on implementation of boost regex]
by hackervalley 02 Aug '04

02 Aug '04

Hello, I try to use boost regex . I don't have a lot of experience of using boost regex . Boost regex examples aren't so explicit for me. So I need some help to parse this example file. Point(1) = {0,0,0,0.1}; Point(2) = {1,0,0,0.1}; Point(3) = {0,1,0,0.1}; Point(4) = {1,1,0,0.1}; Line(1) = {1,2}; Line(2) = {2,4}; Line(3) = {4,3}; Line(4) = {3,1}; Line Loop(5) = {2,3,4,1}; Plane Surface(6) = {5}; I can't read each informations to use it after. I can't match for use IdentificationNumber of Point(IdentificationNumber). Actually my code look so : /* g++ -Wall -O2 -o ifstream ifstream.cc */ #include <iostream> #include <fstream> #include <string> /* boost regex header */ #include <boost/regex.hpp> using namespace std; using namespace boost; int main (int argc, char argv[]) { char buffer[256]; string filename; string inputstring; cout << "Input filename "; cin >> filename; ifstream readfile (filename.c_str (), ios::in); if (!readfile.is_open ()) { cout << "Error opening file" << endl; return 0; } regex exPoint ("Point"); regex exLine ("Line"); regex IdentificationNumber ("[:digit:]"); while (!readfile.eof ()) { readfile.getline (buffer, 200); inputstring = buffer; if (regex_search (inputstring, exPoint)) { cout << "Point" << endl; smatch result; if (regex_search (inputstring, result, IdentificationNumber)) { cout << "Identification Number " << result << endl; } else cout << "Error regex_match" << endl; } if (regex_search (inputstring, exLine)) { cout << "Line" << endl; } cout << buffer << endl; } readfile.close (); return (0); } Thank you for help. Best regards hackervalley http://hackervalley.free.fr

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Accessing Internal Properties
by Jeffrey Holle 02 Aug '04

02 Aug '04

I'm using BGL checked out of CVS on Tue Jun 29 05:25:17 EDT 2004. Also using gcc 3.4.1 on a linux machine. I've a question of how to access internal properties. It appears that there are basically two templated function families for this: get - returns a value get_property_iter_range - returns iterator range get_property - returns a reference Are there more? I'm interested in the later. I've seen in the examples get_property being used to access properties global to a graph, but not edge or vertex properties. What I'd like to see is a varient of get_property (or equivalent) that takes an edge descriptor, so it provides access to a particular edge's named property. Does what I'm looking for exist?

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