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

what happened to smart asserts?
by Graham Mark 07 Jun '06

07 Jun '06

A few years ago Boost included "smart asserts". It no longer does. I've lsearched the boost site and mail archives, but I can't discover why smart asserts are gone. Can anyone tell me? Thanks. G. Mark

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Boost.Signals: strange bug in example program
by Benjamin Winkler 07 Jun '06

07 Jun '06

Hi, I just downloaded the newest boost library 1.33.1 and compiled the "maximum.cpp" example from the Signals library, which goes like this: #include <algorithm> #include <iostream> #include <boost/signals/signal2.hpp> template<typename T> struct maximum { typedef T result_type; template<typename InputIterator> T operator()(InputIterator first, InputIterator last) const { if (first == last) throw std::runtime_error("Cannot compute maximum of zero elements!"); return *std::max_element(first, last); } }; int main() { boost::signal2<int, int, int, maximum<int> > sig_max; sig_max.connect(std::plus<int>()); sig_max.connect(std::multiplies<int>()); sig_max.connect(std::minus<int>()); sig_max.connect(std::divides<int>()); std::cout << sig_max(5, 3) << std::endl; // prints 15 return 0; } As stated, the correct result would be 15 but the output really is 8. However, when I print the values via std::copy(first, last, std::ostream_iterator<T>(std::cout, " ")); I get "8 15 2 1 ", which means that the values are calculated correctly. This error occurs with Microsoft Visual Studio 2005 (8.0) as well as MinGW 3.4.2. I even tried replacing std::max_element() with my own function, which expectedly didn't help. Seems like a bug to me, but I can't track it down. Could it be some issue with copying the iterator? Benjamin Winkler

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Logic Error with boost::lexical_cast
by umut tabak 07 Jun '06

07 Jun '06

Dear all, I am quite new to boost and need some help in problem that I encountered using boost. I am trying to read a .dat file to convert some of the fields to double values. The line format I am trying to read is sth like this GRID* 1086030 7.23756775373e-5.002455787667412 When I use the code it throws a logic_error, I controlled whether I am reading a valid field to convert or not and it is true. So I am using boost::lexical_cast<double>(string..) to convert that into a double value. What might be the problem to throw a logic error.(I know that it is a logic error :-) but I could not figure that out.) I would appreciate some help. Regards

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[boost.multi_array] newbie question: Best use of memory - repost
by Sebastien Fortier 07 Jun '06

07 Jun '06

Since I got no answers I'm reposting I'm currently using multi_array to represent 3D matrices of doubles, I was wondering which would be the best use since the array has to hold a very large amount of data. I' currently testing whith a multi_array of 800x800x100 to hold double or pointers to double and I have memory problems. When I declare the multi_array whith pointers to doubles I can usually go up to 775x775x100 without problems but when I try the same thing with a multi_array of doubles I get a bad alloc error. My real needs for the moment are for a multi_array of 800x600x57 but I will need bigger storage capacity in the near future, what are your sugesstions. Is the multi_array a pointer itself? How is memory management handled? How can go beyond these limits? sebastien.fortier(a)ec.gc.ca

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[future]: combining || and && futures
by Oliver.Kowalke＠qimonda.com 07 Jun '06

07 Jun '06

Hello, could the futures library add support for following construct: ft::simple_future< int > f1 = boost::bind( fac, 4); ft::simple_future< int > f2 = boost::bind( fac, 8); ft::simple_future< int > f3 = boost::bind( fac, 10); ft::future< int > f_or = f1 || f2; ft::future< fu::tuple< int, int > > f_and = f_or && f2; // doesn't compile because no match for 'operator&&' in 'f_or && f2' thx, Oliver

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program options validate function question
by Suresh T 07 Jun '06

07 Jun '06

hello boosters, I have a class ( say user_type ) that i would like to use for storing cmd line option and therefore i have a validate function for the same void validate ( boost::any& v, const std::vector<std::string>& xs, <user_type> * target, int i ) I wanted to know if it is possible to access the actual variable in which the option would be stored from within the validate function. Meaning if i the options_description is something like below: //here user_type_object is an instance of user_type ("option_name" , po::value<user_type>(&user_type_object), "some option" ) Is it possible to access the user_type_object in the validate function? If so please let me know how ? P.S: I am resending this mail as my mail sys. crashed after i sent it the first time in morningso not sure if this was sent. If any one has replied earlier request that they redo as i have lost earlier mails Thanks & Rgds, --------------------------------------------------------------------------------------------------------- Suresh.T

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program options validate function question
by Suresh T 07 Jun '06

07 Jun '06

hello boosters, I have a class ( say user_type ) that i would like to use for storing cmd line option and therefore i have a validate function for the same void validate ( boost::any& v, const std::vector<std::string>& xs, <user_type> * target, int i ) I wanted to know if it is possible to access the actual variable in which the option would be stored from within the validate function. Meaning if i the options_description is something like below: //here user_type_object is an instance of user_type ("option_name" , po::value<user_type>(&user_type_object), "some option" ) Is it possible to access the user_type_object in the validate function? If so please let me know how ? Thanks & Rgds, --------------------------------------------------------------------------------------------------------- Suresh.T

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[serialization] binary_iarchive performance degradation with Intel 9.0 compiler
by Bill Lear 06 Jun '06

06 Jun '06

It could be that I'm being foolish, or that there is something very strange going on in how the Boost serialization library interacts with the Intel C++ compiler that I don't understand. I'll post a short question first, eliding underlying motivations, to see if this warrants further discussion. I am running on 64-bit Linux, using the Intel C++ compiler, version 9.0, and gcc 3.4.5. I have a large, complex data structure that I am serializing. All serialize methods use the BOOST_SERIALIZATION_NVP macro. The data structure serializes and deserializes accurately for each of text, xml, and binary archives. The size on disk is about 250 megabytes, using the binary archives. The load method I use is roughly this: #include <boost/archive/binary_oarchive.hpp> #include <boost/archive/binary_iarchive.hpp> //#include <boost/archive/text_oarchive.hpp> //#include <boost/archive/text_iarchive.hpp> //#include <boost/archive/xml_oarchive.hpp> //#include <boost/archive/xml_iarchive.hpp> #include "Foo.hh" Foo* load(const string& filename) { istream ifs(filename.c_str(), ios::binary); Foo* foo = 0; boost::archive::binary_iarchive ia(ifs); ia >> BOOST_SERIALIZATION_NVP(foo); return foo; } Above this method, note the commented-out text and xml archive headers. Here is the strange part: When using the Intel compiler, and run with the text and xml archive headers commented out, the load method takes about 9.6 seconds. When I uncomment the text and xml headers, the load time almost doubles, to 18.8 seconds or so. I do not see this with gcc. So the question is: have I done something foolish here, or is this wacky? I am using the following command to compile the code: % icpc -O2 -Ob2 -ip <...> Any help appreciated. Bill

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Re: [Boost-users] [multi_index].[composite_key] Index creation atrun-time.
by JOAQUIN LOPEZ MU?Z 06 Jun '06

06 Jun '06

----- Mensaje original ----- De: Prashant Thakre <prashant.thakre(a)gmail.com> Fecha: Martes, Junio 6, 2006 9:06 pm Asunto: Re: [Boost-users] [multi_index].[composite_key] Index creation atrun-time. > Hi, > Thanks for the reply. You're welcome. I'm afraid I'll have to ask for some more info before I can try to answer your original question, though :( > This is what I am trying to achieve: > a) Each entry in the container will have tuple containing n-elements > tuple < t0, t1 ..., tn >, where n is known at run-time. This entry > will also have other elements. But, how are you planning to actually implement this? Certainly you can't do the following: class element { public: boost::tuple<t0,t1,...tn> tp; ... }; because you don't know n at compile time. This question is important, since how you actually implement the run-time knowledge of n will surely determine the way you can plug a composite_key into the scheme. If you can provide some actual code, no matter how sketchy, showing how you implement your element type, so much the better. Looking fwd to your feedback, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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Re: [Boost-users] [multi_index].[composite_key] Index creation at run-time.
by Prashant Thakre 06 Jun '06

06 Jun '06

Hi, Thanks for the reply. This is what I am trying to achieve: a) Each entry in the container will have tuple containing n-elements tuple < t0, t1 ..., tn >, where n is known at run-time. This entry will also have other elements. b) Multi_index container will have a composite_key, consisting of each tuple element. As per 2) it should be possible to just have std::vector<T> as a tuple and define the composite key in terms of each element of the tuple i.e. [ tuple.at(0), ..., tuple.at(n-1) ]. Please correct me if am wrong. Thanks once again. -- regards, Prashant Thakre > Date: Tue, 06 Jun 2006 13:00:09 +0200 > From: Joaqu?n M? L?pez Mu?oz <joaquin(a)tid.es> > Subject: Re: [Boost-users] [multi_index].[composite_key] Index > creation at run-time. > To: boost-users(a)lists.boost.org > Message-ID: <44856039.19A00631(a)tid.es> > Content-Type: text/plain; charset=iso-8859-1 > > Prashant Thakre ha escrito: > > > Hi, > > I would like to know if it's possible to define a multi_index using > > composite_key,where the number of keys which are part of the > > composite_key are only known at run-time. > > Thanks again. > > -- > > regards, > > Prashant Thakre > > Hello, > > The short answer is no, you must know the number of keys a > composite_key is made of at compile time. The long answer is, > depending on your usage scenario, maybe you can have something > close to what you're after: > > 1. If the maxium number of keys of the composite_key is bounded > then you can use that maximum and later on, at run-time, take > advantage of only the first N key slots. > 2. You can have std::vector<> as the key, the comparison semantics > of this container in some ways resembles that of an infinite-length > composite key. > > If you can describe what you are pursuing with a little more detail > maybe I can provide more focused help. > > Thanks for using B.MI, best regards, > > Joaqu?n M L?pez Mu?oz > Telef?nica, Investigaci?n y Desarrollo

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