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

python bool not C++ bool
by Nindi Singh 14 Oct '06

14 Oct '06

I would very much like to pass bools from python to C++ and have them accepted as bools. However I cannot seem to do this. My code class MyTestClass { public: MyTestClass ():theType("Empty"){} MyTestClass(bool theBool):theType("Bool"){} MyTestClass(int theInt):theType("Int"){} object GetType(){return object(theType);} std::string theType; }; void exportTestClass() { class_<MyTestClass> theClass_("TestClass"); theClass_.def(init<bool>()); theClass_.def(init<int>()); theClass_.def("GetType",&MyTestClass::GetType); } then the output in python is >>> a = TestClass(True) >>> a.GetType() 'Int' >>> a = TestClass(10) >>> a.GetType() 'Int' >>> a = TestClass(bool(True)) >>> a.GetType() 'Int' >>> I cannot see what I am doing wrong, as I understand from http://mail.python.org/pipermail/c++-sig/2005-September/009503.html that it should work. I am using boost 1.33 ___________________________________________________________ Try the all-new Yahoo! Mail. "The New Version is radically easier to use" – The Wall Street Journal http://uk.docs.yahoo.com/nowyoucan.html

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[BGL] Why does astar_search require VertexList?
by Rainer Deyke 14 Oct '06

14 Oct '06

I am in need of a path-finding function, and decided to give astar_search from BGL a try. However, I have found to my surprise that astar_search requires a VertexList graph. Looking at the source code, I see that it does indeed try to iterate over all vertices. I find this unreasonable. My graph is not infinite, but it is large, and iterating over several hundred million vertices would completely kill performance for me. (I intend to perform several of these searches per millisecond.) I know for a fact that it is possible to implement A* without iterating over all vertices. What is the rationale behind the current astar_search implementation? -- Rainer Deyke - rainerd(a)eldwood.com

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Re: [Boost-users] Is it a good style about boost::format(format-string) % arg1 % arg2 % ... % argN
by james.jones＠firstinvestors.com 14 Oct '06

14 Oct '06

I wrote: > I don't think it is or should be a primary design goal of programming in any > language to make things easy for beginners. There are all sorts of more > important goals that come first. Reading this over again I don't think I said this very well. What I mean is: It's good if the programming *language* makes things somewhat easy for beginners, or else we'll never get beginners. You can't be a master without at some point being a beginner. However, that doesn't mean that any particular library needs to be coded in such a way as to be understandable by beginners. Good libraries are often going to use powerful, advanced features of the language that beginners won't understand. ISUN, - James Jones Administrative Data Mgmt. Webmaster 375 Raritan Center Pkwy, Suite A Data Architect Edison, NJ 08837

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Question regarding ublas::identity_matrix
by YYW 14 Oct '06

14 Oct '06

Hi all, I'm a newcomer to uBlas. Please consider the following code: identity_matrix<double> matI(3); int row = matI.size1(); int col = matI.size2(); now that matI has the same number of rows and columns, why the identity_matrix template class has two "size" member functions: size1() and size2()? And has two "size" member variables: size1_ and size2_? Why not use just size() and size_?

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[function] vs2005 warning
by Michael Marcin 13 Oct '06

13 Oct '06

Hi, I'm using a few day old RC_1_34_0 from cvs. In boost\function\function_base.hpp I get a warning message that is quite annoying so I went in to remove it. The thing is I don't understand what it is complaining about. It gives this warning message: boost/function/function_base.hpp(287) : warning C4189: 'out_functor' : local variable is initialized but not referenced But the code is: functor_type* out_functor = reinterpret_cast<functor_type*>(&out_buffer.data); // Some compilers (Borland, vc6, ...) are unhappy with ~functor_type. out_functor->~Functor(); which looks a lot like it is referencing out_functor to me.. can this warning be disabled This warning shows up in several places like when compiling program options source. Although we don't have a strict 0 warning policy the simple line: boost::signal< void () > g_signal; generates a 83 line warning message for me which makes it much more difficult to glance at the output window and find helpful warnings. Thanks, Michael Marcin

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[Announce] Boost Mailing list list downtime tonight
by Doug Gregor 13 Oct '06

13 Oct '06

We will be performing a software upgrade the Open Systems Lab mail servers for the Boost mailing lists on on Friday night, Oct 13 (tonight). The Boost mailing lists hosted at lists.boost org will be offline during the following time frame: - 7:00pm-8:00pm Pacific US time (Oct 13) - 8:00pm-9:00pm Mountain US time (Oct 13) - 9:00pm-10:00pm Central US time (Oct 13) - 10:00pm-11:00pm Indiana time (Oct 13) - 10:00pm-11:00pm Eastern US time (Oct 13) - 02:00am-3:00am GMT (Oct 14) Doug

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transforming vector using map?
by Alexander Shyrokov 13 Oct '06

13 Oct '06

I have a vector of strings and I have a map that maps one string to another. How can use transform for that? This is how I do it right now: map<string, string> mapping; vector<string> strings; for(vector<string>::iterator s=strings.begin();s!=strings.end();++s) *s=mapping[*s]; I would like something like: transform(strings.begin(),strings.end(),strings.begin(),_1=mapping[_1]); Or maybe there is a predicate that already does it? I can write my own: template<T> struct mapit: public unary_function<T,T> { map<T,T> mapping; mapit(const map<T,T>& m):mapping(m){} T operator()(const T& s){return mapping[s];} } transform(strings.begin(),strings.end(),strings.begin(),mapit<string>(mapping)); Is it the proper way to do such a transformation? Thanks. -- Regards, Alexander. http://sjcomp.com

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Re: [Boost-users] [thread] bug: thread::sleep can't 'Idle'
by Darryl Green 13 Oct '06

13 Oct '06

Actually - I just tried to rtfm to find the relevant part, and it is less than obvious given the rather terse description of xtime as a time or a duration. I don't think anything in boost.threads uses xtime as a duration (any more - since about 2001)? ________________________________ From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Darryl Green Sent: Wednesday, 11 October 2006 4:48 PM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] [thread] bug: thread::sleep can't 'Idle' Hi Daniel, boost::thread:sleep takes a time, not a duration. For details, rationale etc rtfm. ________________________________ From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Daniel Winsor Sent: Wednesday, 11 October 2006 4:40 PM To: boost-users(a)lists.boost.org Subject: [Boost-users] [thread] bug: thread::sleep can't 'Idle' #include <boost/thread/thread.hpp> #include <boost/thread/xtime.hpp> #include <Windows.h>//for sleep void ExecuteThread() { for(;;) { boost::xtime time; time.nsec = 0; time.sec = 1; boost::thread::sleep(time); //Sleep(1000); } } int main() { boost::thread thread1(ExecuteThread); boost::thread thread2(ExecuteThread); thread1.join(); thread2.join(); return 0; } When this program is run with Sleep() instead of boost::thread::sleep(), and there are no other cpu intensive programs running, Task Manager shows 99% of the cpu (dual core) is idle. However, when it is run with boost::thread::sleep(), 99% of the cpu is being used by the program! This is a problem because powersaving features no longer work. When this program with boost::thread::sleep() is run with another program that is cpu intensive, Task Manager reports the other program uses 99% of the cpu, so there is no problem there. I am using an overclocked Intel Core 2 Duo 6400 if that matters. ________________________________ This e-mail is for the use of the intended recipient(s) only. If you have received this e-mail in error, please notify the sender immediately and then delete it. If you are not the intended recipient, you must not use, disclose or distribute this e-mail without the author's prior permission. We have taken precautions to minimise the risk of transmitting software viruses, but we advise you to carry out your own virus checks on any attachment to this message. We cannot accept liability for any loss or damage caused by software viruses. ________________________________ ########################################################################## This e-mail is for the use of the intended recipient(s) only. If you have received this e-mail in error, please notify the sender immediately and then delete it. If you are not the intended recipient, you must not use, disclose or distribute this e-mail without the author's prior permission. We have taken precautions to minimise the risk of transmitting software viruses, but we advise you to carry out your own virus checks on any attachment to this message. We cannot accept liability for any loss or damage caused by software viruses. ##########################################################################

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Re: [Boost-users] Is it a good style about boost::format(format-string) % arg1 % arg2 % ... % argN
by james.jones＠firstinvestors.com 13 Oct '06

13 Oct '06

From: "William Xue" <william.xue(a)gmail.com> > Yes, it's a good explanation. Thanks a lot. > > For the reason I mentioned above, I perfer to do the job like this: > ---8<--------------------------------------------->8--- > #ifdef cplusplus > class ... > { > ... > int foo(...) = 0; > ... > }; > #else > class ... > { > ... > int foo(...); > ... > }; > #endif > ---8<--------------------------------------------->8--- The problem with doing it this way is that you're repeating yourself. What happens when you need to add a method? Did you remember to add it to both sections? When a signature changes, did you change it in both sections? I don't think it is or should be a primary design goal of programming in any language to make things easy for beginners. There are all sorts of more important goals that come first. - James Jones Administrative Data Mgmt. Webmaster 375 Raritan Center Pkwy, Suite A Data Architect Edison, NJ 08837

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[BGL] adjacent_vertices strange implementation
by moritz Hilger 13 Oct '06

13 Oct '06

hi, as far as i can tell the adjacent_vertices function in adjacency list (as well as the inv_adjacent_vertices counterpart) simply wraps around the out_edge (in_edge) function. this differs from what i would expect from a function returning adjacent vertices, since in my notion a set of adjacent vertices shouldn't contain duplicate entries, which the current implementation does have when used with parallel edges. any good reason for that (or does my definition of adjacent vertices differ from everybody else's)? greetings moritz

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