April 2007 - Boost-users - lists.preview.boost.org

Re: [Boost-users] [bind] binding a boost::reference_wrapper to a function template
by Barchenkov, Alexei (IT) 05 Apr '07

05 Apr '07

>The problem is that tr is ref( t ) and is interpreted by bind as a request to store a reference to t. >boost::bind( &foo< Test& >, tr ) should work, if this helps. Peter, thank you very much. Could you please clarify what you mean however, because my understanding was that on construction, boost::bind internally just stores a copy of the bound argument without regard to the signature of the function to be invoked. The conversion of the argument to the type appropriate to the function invocation occurs when the functor is actually called. Is my understanding incorrect? Thank you. -------------------------------------------------------- NOTICE: If received in error, please destroy and notify sender. Sender does not intend to waive confidentiality or privilege. Use of this email is prohibited when received in error.

2 1

bind visit_each and obtaining argument values from bind
by Braddock Gaskill 05 Apr '07

05 Apr '07

Am I correct that the bind visit_each functionality briefly mentioned in the boost::bind documentations will allow me to get at actual argument values passed to a bind statement? That would be VERY useful to me at the moment. Is there a working example? The bind_visitor.cpp example seems to be broken(?). thanks, braddock

2 3

ERROR
by Lucas de Sales Joner 05 Apr '07

05 Apr '07

C:\Arquivos de programas\Dev-Cpp\include\boost\numeric\ublas\exception.hpp exception handling disabled, use -fexceptions to enable Somebody Know what is this and how I do that de error say? _________________________________________________________________ Veja só alguns dos novos serviços online no Windows Live Ideas — são tão novos que ainda não foram disponibilizados oficialmente. http://ideas.live.com

1 0

Plot
by Lucas de Sales Joner 05 Apr '07

05 Apr '07

Somebody know how I plot a vector boost? _________________________________________________________________ Obtenha o novo Windows Live Messenger! http://get.live.com/messenger/overview

1 0

pointers to static structures
by Scott Finley 05 Apr '07

05 Apr '07

I am wondering about best practices for the use of pointers to static structures. I have a class that will essentially replace an enumeration and represent a set of options. The options will be static members of the class. I would also like to have a vector of pointers to all the static members in order to be able to query all possible values at run time. This vector would be initialized explicitly by the constructor. Is there any reason that the vector should not hold normal raw pointers? Obviously I want to use these options without copying them around all over the place, so pointers seem to be the answer, but I will never be creating an option dynamically, so I don't really have any risk of memory leaks. Is there any reason to use shared_ptr with a custom destructor that does nothing? My use case would be something like: class myOption; class myOptionSet { public: myOptionSet() { allOptions.push_back( &OPTION_1 ); allOptions.push_back( &OPTION_2 ); } vector<myOption> const &getAllOptions() { return allOptions; } static myOption const OPTION_1; // initialized in .cpp static myOption const OPTION_2; private: static vector<myOption const *> allOptions; } class OptionUsingClass { OptionUsingClass( vector<myOption> const &possibleOptions ); // This can now check that the option is a possibleOption void doSomething( myOption const &option ); // or maybe this is better... void doSomething( myOption const *option ); }; Is this a good way to do things? Should I be using some sort of pointer wrapper instead? -- /************************************** * Scott Finley * Research Software Engineer * TomoTherapy Inc. * Email: sfinley(a)tomotherapy.com * Phone: 608.824.3381 ***/

1 0

[BGL] how to build a hierarchy of graphs
by Shufei Fan 05 Apr '07

05 Apr '07

Hi, I need to build a hierarchy of graphs bottom up. Conceptually, every level(>1) of graph is a result of merging groups of nearest neighbors of its immediate lower level, according to some sort of criteria. My general question is, what is the best way of building this hierarchy using BGL?(or, BGL already has this kind of mechanism somewhere?) (I didnot read in detail concepts like subgraph, filter, etc. From the names, they seems to of help?) And Is it possible to effeciently retrieve information both within same level and across levels? Thanks in advance. Shufei

1 0

[licensing] Proper way of quoting the license
by Ruediger Berlich 05 Apr '07

05 Apr '07

Hi there, while looking for a thread-safe buffer implementation, I discovered the upcoming circular_buffer library (with a thread-safe bounded_buffer implementation on top), and William E. Kempf's tutorial implementation of a bounded buffer (boost_1_33_1/libs/thread/tutorial/bounded_buffer.cpp in the 1.33.1 boost sources). The circular_buffer library is not yet officially available as part of Boost, but fortunately the tutorial implementaion does most of what I need. That is, with the notable exception that it covers Integers only. I have thus made a few small changes, including making it a template, so I can "plug in" any type I want, and I want to use it for the time being (until circular_buffer becomes officially available). ** My question now is, what the proper way is to refer to William and honour the license terms, while still excluding any "express or implied warranty" for my changes. ** Here is my current approach: /** * Note: This class was taken (with small modifications) * from the Boost.thread tutorials * ( boost_1_33_1/libs/thread/tutorial/bounded_buffer.cpp ). * The original code contained the following text: * *************************************************************** * Copyright (C) 2001-2003 * * William E. Kempf * * * * Permission to use, copy, modify, distribute and sell this * * software and its documentation for any purpose is hereby * * granted without fee, provided that the above copyright * * notice appear in all copies and that both that copyright * * notice and this permission notice appear in supporting * * documentation. William E. Kempf makes no representations * * about the suitability of this software for any purpose. * * It is provided "as is" without express or implied warranty. * *************************************************************** * * All modifications to William E. Kempf's original code, as shown * in this file, are covered by the same license as listed above, * and are Copyright (C) 2007 Ruediger Berlich. In particular, * please note that * *************************************************************** * Ruediger Berlich makes no representations * * about the suitability of this software for any purpose. * * It is provided "as is" without express or implied warranty. * *************************************************************** * / Is this sufficient ? And [do I have to / may I / should I] include an additional copyright statement for the modifications ? Or am I just paranoid ? ;-) Thanks and have a good easter time, Ruediger

1 0

[MultiIndex] Resolving foreign keys
by Christian Henning 05 Apr '07

05 Apr '07

Hi there, beware I'm a new to Multiindex and haven't digested the whole capabilities of the library, yet. In my example I have two entities that are connected via a foreign key. In this case the key is type of an int. When retrieving the objects from a database I end up having two containers containing those objects. In the code below there are a customer_row and a order_row class. There is a one-to_many relationship between them. One customer can have several order but one order is can only one customer. So, my goal is to find an way to create order objects that are pointing to the correct row objects. So far, I don't really see how the MultiIndex lib can be of help for me. I have looked at the example six which I think came pretty close to my goal. So, taken this example, is it possible to use an key type instead of the car_manufacturer pointer? Please consider the following code: using namespace std; using namespace boost; using namespace boost::multi_index; struct primary {}; struct foreign {}; struct customer_row { int _id; string _name; customer_row( int id, const string& name ) : _id( id ), _name( name ) {} friend ostream& operator<<( ostream& os, const customer_row& c ) { os << c._id << " " << c._name << endl; return os; } }; typedef multi_index_container< customer_row, indexed_by< ordered_unique< tag< primary >, BOOST_MULTI_INDEX_MEMBER(customer_row,int,_id) > > > customer_table; struct order_row { int _id; int _customer_id; string _article; order_row( int id, int customer_id, const string& article ) : _id( id ), _customer_id( customer_id ), _article( article ) {} friend ostream& operator<<( ostream& os, const order_row& o ) { os << o._id << " " << o._customer_id << " " << o._article << endl; return os; } }; typedef multi_index_container< order_row, indexed_by< ordered_unique< tag< primary >, BOOST_MULTI_INDEX_MEMBER(order_row,int,_id) >, ordered_non_unique< tag< foreign >, BOOST_MULTI_INDEX_MEMBER(order_row,int,_customer_id) > > > order_table; struct order { const order_row* _order_row; const customer_row* _customer_row; }; int main() { customer_table ct; ct.insert( customer_row( 97, "Bon Jovi" )); ct.insert( customer_row( 98, "Billy Joel" )); ct.insert( customer_row( 99, "Morgan Freeman" )); order_table ot; ot.insert( order_row( 0, 97, "Book" )); ot.insert( order_row( 1, 97, "Car" )); ot.insert( order_row( 2, 97, "Dish Washer" )); order_table::iterator it = ot.get<primary>().begin(); order_table::iterator end = ot.get<primary>().end(); vector<order> orders; while( it != end ) { // find customer typedef customer_table::index<primary>::type customer_table_by_primary; customer_table_by_primary::iterator ic = ct.get<primary>().find( it->_customer_id ); order o; o._order_row = &( *it ); o._customer_row = &*ct.get<primary>().find( it->_customer_id ); orders.push_back( o ); ++it; } return 0; } Is there a more advanced way using the MultiIndex lib of combining two related objects so I can created my orders array? Or in different words can I structure my code more efficiently? Since this is a very simplified version it should be extensible to more entities with more than one foreign keys. Thanks ahead, Christian

2 5

[BGL] re-indexing of vertices /or edges
by Shufei Fan 05 Apr '07

05 Apr '07

Hi, Can I disable re-indexing of vertices after one of them is removed? In one of the old thread: http://thread.gmane.org/gmane.comp.lib.boost.user/10551/focus=10552 Doug said: " Vertex and edge indices are a weak point in the BGL. It seems like they should be automatically updated, but that can't be done efficiently. We have a partial solution (a graph type that is reasonably good all-around and does automatic (re-)indexing), but it's not ready for release yet." I am using release 1.33.1. Is this re-indexing released?(I assume so, from my simple trial) But, is there any way of enabling /and disabling re-indexing? Interestingly, my application needs re-indexing disabled, even though some vertices or edges are removed. Thanks, Shufei

3 5

to Jan gaspar : status of circular buffer
by Vincent Torri 05 Apr '07

05 Apr '07

Hello, I would like to know the status of the circular buffer library. The boost sandbox cvs shows regular commits, but is it close to a release (in boost 1.35, for example) ? thank you Vincent Torri

2 1