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Newbie trying to use multi_array ...
by Jon Pendergrass 23 Oct '02

23 Oct '02

I'm new to Boost, so please excuse my lack of knowledge. I'm trying to use the multi_array class and have hit a small snag. I'd like to have a class with a 4-D array. Initially it won't contain any data. However, Microsoft Visual C++ v6.0 complains about not finding a constructor. I want to do something like this: #include "boost/multi_array.hpp" typedef boost::multi_array<std::complex<double>, 4> t_Array4D; class foobar { t_Array4D ar; }; void foobar::SetValue() { // set extents code // set value this->ar[0][0][0][0] = 2.0; }

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Error in date_time example -- exp-time_periods.html
by David Clark 22 Oct '02

22 Oct '02

date_time/doc/exp-time_periods.html class day_period : public { should be class day_period : public time_period {

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Smart Pointers and Autocomplete
by eldritchshadows 22 Oct '02

22 Oct '02

Has anybody ever found a program which worked under Visual C++ that would list the member functions of the pointers wrapped by smart pointers. An example of what I'm talking about would be Visual Assist (except it doesn't seem to work). It would make life easier. Thanks in advance. Nathan Janken

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Error in date_time example -- exp-print_month.html
by David Clark 21 Oct '02

21 Oct '02

There are two errors in the date_time/doc/exp-print_month.html example. std::cout<<"Enter Year: "; int should be std::cout << "Enter Year: "; int year,month; and //Use the calendar to get the last day of the month int eom_day = gregorian_calendar::end_of_month_day( should be int eom_day = gregorian_calendar::end_of_month_day(year,month);

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[BGL] Why does depth_first_search not accept a source vertex parameter?
by kweeheong 21 Oct '02

21 Oct '02

Hi, I'm just learning about the BGL, and I've been sucessful in compiling and learning with examples on my VC6 Windows machine. I have a newbie question that someone with more knowledge of BGL might be able to answer : Q : Why does depth_first_search not accept a source vertex parameter, while breadth_first_search do? Is this just to be consistent with the historical definition of DFS? However, depth_first_visit and breadth_first_visit both accept a source vertex parameter. It would seem that DFS is more useful ( output is more deterministic ) if the source vertex can be specified, just like BFS. Reference : ( from the online BGL documentation ) template <class VertexListGraph, class P, class T, class R> void breadth_first_search(VertexListGraph& G, typename graph_traits<VertexListGraph>::vertex_descriptor s, const bgl_named_params<P, T, R>& params); template <class IncidenceGraph, class P, class T, class R> void breadth_first_visit(IncidenceGraph& G, typename graph_traits<IncidenceGraph>::vertex_descriptor s, const bgl_named_params<P, T, R>& params); template <class VertexListGraph, class class P, class T, class R> void depth_first_search(VertexListGraph& G, const bgl_named_params<P, T, R>& params); template <class IncidenceGraph, class DFSVisitor, class ColorMap> void depth_first_visit(IncidenceGraph& g, typename graph_traits<IncidenceGraph>::vertex_descriptor s, DFSVisitor& vis, ColorMap color);

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Error in date_time example -- exp-print_holidays.html
by David Clark 20 Oct '02

20 Oct '02

Two errors in date_time/doc/exp-print_holidays.html In function print_date std::cout << d << " [" << d. should be std::cout << d << " [" << d.day_of_week().as_short_string() << "]\n"; and year is not defined in main() std::cout << "Enter Year: "; int should be std::cout << "Enter Year: "; int year;

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A New Boost Mailing List
by Jon Kalb 18 Oct '02

18 Oct '02

As you know there are currently three Boost mailing lists: Boost - the discussion list for Boost library developers Boost-Users - the discussion list for Boost library users Boost-Announce - for library review and release announcements But we feel the need for an additional list. This list, Boost-Interest, will be an announcement list for items of interest to members of the Boost community. We see this as a low volume, moderated list on which commercial announcements are acceptable if relevant. We have written a proposed charter (below), but we invite comments and volunteers to moderate this list. Boost-Interest: Proposed Charter Boost-Interest is a moderated mailing list of announcements of interest to the Boost community. On topic messages will include announcements of books, magazine articles, papers, talks, seminars, products, tools, events, or conferences on advanced uses of C++, generic/generative/meta-programming, and, of course, the Boost libraries. Off topic will be discussions of any kind and job postings. If you are have comments on this list or its charter please send them to either or both Doug and Jon (addresses below). Also contact us if you are interested in moderating this list. Please do not ask for subscription information yet. We will announce details when we know them. -- Doug Gregor <gregod(a)cs.rpi.edu> Jon Kalb <Kalb(a)LibertySoft.com>

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^M
by Felix E. Klee 18 Oct '02

18 Oct '02

Hi, I found that at least part of the Boost code contains DOS style carriage returns. Why is that? This causes parsing errors on UNIX. Felix

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RE: [Boost-Users] Re: Error in Date_Time example - exp-days_alive.html
by Jeff Garland 18 Oct '02

18 Oct '02

David wrote: > I just checked the example code in > libs/date_time/example/gregorian/date_alive.cpp > > the correction should be > > else if (days_alive < date_duration(0)) { Thx -- I'll clean that up. Jeff

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Template class static boost::mutex initialization !?!?!
by Luc Bergeron 17 Oct '02

17 Oct '02

Hello everyone, i'm currently trying to implement a thread safe singleton using template. In the class I need to use a boost::mutex in order to protect access to the singleton pointer. The problem i'm currently encountering is that I need to initialize this static boost::mutex, but how !?!?!?! I tried using a pointer to a mutex and initialize it to null but that didn't work. I also tried to new it in the initialization but that failed too. :( Can someone help me on this one ??? Thanks in advance for any help. Luc. P.S. I'm using boost 1.29 :) P.S.S Here is my current class definition : (A link to where I got this implementation : http://www.drizzle.com/~scottb/publish/gpgems1_singleton.htm) template <typename T> class ThreadSafeSingleton { static T* d_ThreadSafeSingleton; static boost::mutex d_mutex; public: ThreadSafeSingleton() { assert(!d_ThreadSafeSingleton); int offset = (int)(T*)1 - (int)(ThreadSafeSingleton <T>*)(T*)1; d_ThreadSafeSingleton = (T*)((int)this + offset); } ~ThreadSafeSingleton() { assert(d_ThreadSafeSingleton); d_ThreadSafeSingleton = 0; } static T& GetSingleton(void) { boost::mutex::scoped_lock scoped_lock(d_mutex); assert(d_ThreadSafeSingleton); return *d_ThreadSafeSingleton; } static T* GetSingletonPtr(void) { boost::mutex::scoped_lock scoped_lock(d_mutex); return d_ThreadSafeSingleton; } }; template <typename T> T* ThreadSafeSingleton <T>::d_ThreadSafeSingleton = 0;

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