September 2005 - Boost-users

Re: [Boost-users] static maps (was trouble with boost::assign)
by Gottlob Frege 21 Sep '05

21 Sep '05

On 9/20/05, boost-users-request(a)lists.boost.org < boost-users-request(a)lists.boost.org> wrote: > > Message: 2 > Date: Mon, 19 Sep 2005 12:35:08 -0500 > From: "Lee Crabtree" <lcrabtree(a)goisi.com> > Subject: [Boost-users] trouble with boost::assign > To: boost-users(a)lists.boost.org > Message-ID: <dgmsos$amg$1(a)sea.gmane.org> > > Hi, I'm trying initialize a static map with map_list_of. Something along > the > lines of: > > map<int,int> blarg = map_list_of(1, 2); > > However, when I go to compile, I receive the following error: ... Lee Crabtree > > > Can't help you with the error, unfortunately, but just wondering - does this map *remain* static after initialization? ie Do you do any inserts or deletes after init? I wrote a static_map<K, T> that is constructed from a static array, which I use for those cases where the map doesn't change, and I was just wondering how useful people thought it might be - ie how often do you have maps that never change after initialization from static data?

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Re: [Boost-users] algorithms and member functions
by Foster Gareth 21 Sep '05

21 Sep '05

> " > class A { > void wee(); > } > > container<A> as; > for_each(in as, a::wee()); > " > So as as not to miss the point, I think I'd better expand the pseudo code example just a tad ... " class A { int wee() { return m_wee } // returns bit flag style int int m_wee; }; container<A> as; find_if ( in as, // somehow need to say here "current->wee() & SOME_FLAG" ); " Hope that is a little more clear. Thanks again, Gaz

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algorithms and member functions
by Foster Gareth 21 Sep '05

21 Sep '05

Hello all, Take for example, a situation where, in psuedo code of course, I want to do this sort of thing ... " class A { void wee(); } container<A> as; for_each(in as, a::wee()); " I did a little google work on this and found this amazing flame war between a Java user and a Boost/C++ user: [ http://episteme.arstechnica.com/groupee/forums/a/tpc/f/6330927813/m/26500301 5731 ] It seems from this that we, as c++ users, have as options: * writing a new functor to call methods * using std::mem_fn * using the boost enhancements to the above I get the impression that boost bind and lambda are relevent here, although I've only glanced at examples. What interests me is the anonymous methods / class style syntax that Java offers. I've played with it myself, and it seems nice, and one of the proponents in the afore mentioned flame war advocates it. What is the thinking behind not introducing such syntax into C++? I am sort of working from the assumption that the template solutions (as opposed to language modification solutions) in boost at the moment, will be moved into std:: and offered as a solution rather than an update to the language. It may be that I have the wrong end of the stick there, and that the boost solutions are a temporary solution. It may also be there are good reasons to prefer the template style solution. It may also be I am talking tripe :) Anyway, I hope this doesn't make a mountain out of a mole hill. I'm just wondering about the decisions that have been / are likely to be made, in this area. I don't claim to hold any opionion on the matter, other than "I think it is an interesting matter" :) Thanks all, Gaz ********************************************** * http://www.mozilla.org/products/firefox/ * **********************************************

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BGL - edge descriptor and map
by Giulio Veronesi 21 Sep '05

21 Sep '05

I'd like to specify better my problem. I'd like to use an edge_descriptor (graph_traits<G>::edge_descriptor) as key in a map. The graph type is something like this: typedef adjacency_list<vecS, vecS, bidirectionalS, no_property, MyStuff> G; I think that I've to overload the < operator for graph_traits<G>::edge_descriptor. Is this correct? If so, given two edge_descriptors I need to access the source and the target of the edge in such a way to define a sort ordering. Thanks, Giulio

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enable_if missing from status summary
by Steven Solie 21 Sep '05

21 Sep '05

I'm finding the utility/enable_if tests are missing from the status summary for my AmigaOS port. I think the process_jam_log tool is unable to handle it for some reason because the xml output files are incorrect. I see from a Google search this has been discussed before. Has there been any resolution to this problem? --Steven

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[BGL] detecting cycles path in a graph
by Giulio Veronesi 21 Sep '05

21 Sep '05

Hi, I'd like to obtain the path of a cycle in a graph. The file dependency example in the user guide only allow to discover cycles and not the path that forms the cycle. Please, could you help me to address this problem? Thanks a lot, Giulio

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Re: [Boost-users] list of optional dependencies for building boost?
by Andrew Holden 21 Sep '05

21 Sep '05

One other I know of: the Regex library can depend on the ICU Unicode libraries (http://www-306.ibm.com/software/globalization/icu/index.jsp) Andrew Holden -----Original Message----- From: Benjamin Rutt [mailto:rutt@bmi.osu.edu] Sent: Tuesday, September 20, 2005 9:38 AM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] list of optional dependencies for building boost? OK, from what I've gathered, boost can optionally depend on python and gzip+bzip2 libraries. If anyone can think of something I have missed, let me know. Thanks, -- Benjamin Rutt _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Re: [Boost-users] Scons users?
by David Abrahams 21 Sep '05

21 Sep '05

Andy Moreton <andy.moreton(a)artimi.com> writes: > I think that the effort expended on BBv1/BBv2 would have been far better > spent on fixing the performance issues in scons. Just for the record, BBv1 predates Scons by some considerable time. When I began that project I tried to get Steven Knight to start on Scons with me and at the time he wasn't ready yet. -- Dave Abrahams Boost Consulting www.boost-consulting.com

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BGL - edge descriptor
by Giulio Veronesi 21 Sep '05

21 Sep '05

Hi, I'd like to extract the source and target vertex id from an edge_descriptor without using the graph that contains the edge. More specifically, consider the following code: typedef graph_traits<MyGraph>::edge_descriptor MyLink; void MyFunction(MyLink& link) { cout << "source vertex id: " << ??? << ", target vertex id: " << ??? << endl; } What I've to put at place of ??? to print the source and target vertex id? Is it a dirty solution to use the m_source and m_target field of the edge_descriptor structure? Thanks, Giulio

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Date_time library question
by Michal Lijowski 20 Sep '05

20 Sep '05

I just started with date_time library using boost-1.33.0-3 on FC4 and gcc 4.0.1 20050727. It is rpm version downloaded from http://download.fedora.redhat.com/pub/fedora/linux/core/development/i386/Fe…. I copied some lines of code from boost_date_time.pdf to get familiar with capabilities of this library and I encountered some problems. Here is a modified code taken from page 3 of the manual /* The following is a simple example that shows conversion of dates * to and from a std::string. ** Expected output: * 2001-Oct-09 * 2001-10-09 * Tuesday October 9, 2001 * An expected exception is next: * Exception: Month number is out of range 1..12 */ #include "boost/date_time/gregorian/gregorian.hpp" #include "boost/date_time/posix_time/posix_time.hpp" #include "boost/date_time/posix_time/posix_time_duration.hpp" #include "boost/date_time/local_time/local_time.hpp" #include <iostream> #include <string> #include <sstream> using namespace boost::gregorian; using namespace boost::local_time; using namespace boost::posix_time; using namespace std; int main() { try { //input streaming stringstream ss("2004-Jan-1"); date d; ss >> d; cout << " d " << d << endl; ptime t0; ss >> t0; cout << " t0 " << t0 << endl; date d1(1999, Jan, 1); ss >> d1; cout << " d1 " << d1 << endl; ptime t2(d1, minutes(0)); cout << " t2 " << t2 << endl; ss >> t2; cout << " t2 " << t2 << endl; date d3(2002,Feb,1); //an arbitrary date // the line below compiles with error: ‘nanosec’ was not declared in this scope // ptime t1(d3, hours(5)+nanosec(100)); //date + time of day offset ptime t1(d3, hours(5)); cout << " d3 " << d3 << endl; ptime t3 = t1 - minutes(4)+seconds(2); ptime now = second_clock::local_time(); //use the clock date today = now.date(); //Get the date part out of the time date tomorrow = today + date_duration(1); ptime tomorrow_start(tomorrow); //midnight // std::stringstream ss1("2004-Jan-1 05:21:33.20"); stringstream ss1("2004-Jan-1"); ss1 >> t2; cout << " t2 " << t2 << endl; //starting at current time iterator adds by one hour time_iterator titr(now,hours(1)); for (; titr < tomorrow_start; ++titr) { cout << (*titr) << std::endl; } } catch(std::exception& e) { std::cout << " Exception: " << e.what() << std::endl; } return 0; } And output from this program is d not-a-date-time t0 not-a-date-time d1 1999-Jan-01 t2 1999-Jan-01 00:00:00 t2 1999-Jan-01 00:00:00 d3 2002-Feb-01 t2 2004-Jan-01 00:00:00 2005-Sep-16 08:58:09 2005-Sep-16 09:58:09 2005-Sep-16 10:58:09 2005-Sep-16 11:58:09 2005-Sep-16 12:58:09 2005-Sep-16 13:58:09 2005-Sep-16 14:58:09 2005-Sep-16 15:58:09 2005-Sep-16 16:58:09 2005-Sep-16 17:58:09 2005-Sep-16 18:58:09 2005-Sep-16 19:58:09 2005-Sep-16 20:58:09 2005-Sep-16 21:58:09 2005-Sep-16 22:58:09 2005-Sep-16 23:58:09 My question is why d and t0 are not-a-date-time? Is this expected? Also the line ptime t1(d3, hours(5)+nanosec(100)); //date + time of day offset compiles with error: ‘nanosec’ was not declared in this scope Thanks, Michal

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