February 2005 - Boost-users

Problem with autotools + options
by Uzytkownik 11 Feb '05

11 Feb '05

1. How check does and where boost is by Autotools(autoconf+automake)? I try to check by AC_CHECK_HEADERS(boost/filesystem/path.hpp,,exit), but it don't work. 2. How in program_options use the options from list? For example --method=[http,ftp] Thanks. -- Linux user: #376500 (patrz http://counter.li.org/)

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problem with push_relabel_max_flow
by Matthias Linkenheil 11 Feb '05

11 Feb '05

Hi, I used the edmunds_karp_max_flow algorithm in my project and it worked fine. Then I changed it to the push_relabel_max_flow algorithm but it doesn't work. I get an access violation at line 562 in the push_relabel_max_flow.hpp . Line 560: ai = out_edges(u, g).first; -> u is the node, that is directly connected with the source, when access violation occurs. Have anyone a suggestion where the problem could be? Thanks, Matthias

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Concatenation of many std::string
by Chateauneu Remi 11 Feb '05

11 Feb '05

I'm working on an application with many std::string concatenations, everywhere. This is consuming a lot of CPU resources, due to temporary strings, memory allocation, etc... Due to the size of the existing code, it is not possible to make big changes. I tried first to transform these kind of expressions: std::string a = b + c + d + e ; ... into ... std::string a(b); a += c ; a += d ; a += e ; ... and it is definitively faster, but not enough. I've then worked on a method, just by adding a special object after the '=' sign, which transforms these concatenations into a two pass operation, the first to calculate the total length and allocate the destination string, and the second pass to actually copy the source strings into the destination. One just need to re-write the concatenations this way : std::string a = my_special_object() + b + c + d + e ; But maybe I am reinventing the wheel. Is there in Boost, a way to speed up this kind of operation ? Thanks in advance. -- DSL Komplett von GMX +++ Superg�nstig und stressfrei einsteigen! AKTION "Kein Einrichtungspreis" nutzen: http://www.gmx.net/de/go/dsl

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building boost::regex lib with mingw from gnu/linux
by atoral＠dlsi.ua.es 11 Feb '05

11 Feb '05

Hi, I would like to use the boost regex lib in a c++ program. This is being developed under gnu/linux (Debian-Sarge Kernel 2.4.27) with gcc 3.3.5. Also, we are creating binaries for Win32 by cross compiling with MinGW (i586-mingw32msvc-g++ (GCC) 3.4.2 (mingw-special)). Thus, i have to build the boost::regex library for both gnu/linux and win32. There was no problem to get the linux version (it is included in Debian, and anyway the source succeded to compile), but i'm having trouble to compile the win version. I compile from <boost_root_dir>/boost_1_31_0/libs/regex/build by using generic.mak (make -f generic.mak). in this file i've just added these lines: CXX=i586-mingw32msvc-g++ LINKER=i586-mingw32msvc-ar This is the output i obtain: xxxxx@xxxxx:~/boost/boost_1_31_0/libs/regex/build$ make -f generic.mak i586-mingw32msvc-g++ -o generic/boost_regex/c_regex_traits.o -c -O2 -I../../../ ../src/c_regex_traits.cpp ../src/c_regex_traits.cpp: In static member function `static size_t boost::c_regex_traits<boost::regex_wchar_type>::strnarrow(char*, size_t, const boost::regex_wchar_type*)': ../src/c_regex_traits.cpp:1052: error: `wcstombs' is not a member of `std' make: *** [generic/boost_regex/c_regex_traits.o] Error 1 any clues about what i'm doing wrong? thanks

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Re;proposed modif for boost::signals::connection
by frantz.maerten＠igeoss.com 10 Feb '05

10 Feb '05

Here is now in attachement (tgz) the 2 patches (and not in the email)

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BGL + Subgraph + Propertymap issue...
by Gordon Smith 09 Feb '05

09 Feb '05

The following example produces the following (unexpected results): name: graph name: subgraph 1 name sg2: subgraph 2 name sg: subgraph 2 Do subgraphs share the same property_map? Gordon. // SubGraphPropertyTest.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include <string> #include <iostream> #include <boost/cstdlib.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/subgraph.hpp> int main() { using namespace boost; using std::string; typedef adjacency_list<vecS, vecS, directedS,no_property, property<edge_index_t, int>, property<graph_name_t, string> > graph_t; graph_t g; get_property(g, graph_name) = "graph"; std::cout << "name: " << get_property(g, graph_name) << std::endl; typedef subgraph<graph_t> subgraph_t; subgraph_t sg; get_property(sg, graph_name) = "subgraph 1"; std::cout << "name: " << get_property(sg, graph_name) << std::endl; subgraph_t sg2 = sg.create_subgraph(); get_property(sg2, graph_name) = "subgraph 2"; std::cout << "name sg2: " << get_property(sg2, graph_name) << std::endl; std::cout << "name sg: " << get_property(sg, graph_name) << std::endl; return exit_success; }

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Re: Another boost bind question
by Surya Kiran Gullapalli 09 Feb '05

09 Feb '05

Well Daniel, You were right, i was mixing up both the namespaces and that screwed up the code. Now i'm qualifiying the bind function, with the appropriate namespace. That solved the problem. Thanks, Surya

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Another boost bind question
by Surya Kiran Gullapalli 09 Feb '05

09 Feb '05

Hi, Please find the attached file. Whats wrong with bind, I'm getting compilation errors . =================== temp_bind.cpp: In constructor `temp::temp()': temp_bind.cpp:30: error: no matching function for call to `if_then(const boost::lambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::action<3, boost::lambda::function_action<3, boost::lambda::detail::unspecified> >, boost::tuples::tuple<bool (temp::*const)(int) const, temp* const, const boost::lambda::lambda_functor<boost::lambda::placeholder<1> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > >, std::basic_ostream<char, std::char_traits<char> >&)' ================== Surya Kiran Gullapalli Sr. Development Engineer Fluent India Pvt. Ltd., Pune

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RE: [Boost-users] boost::signals block/unblock
by Nat Goodspeed 09 Feb '05

09 Feb '05

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of frantz.maerten(a)igeoss.com > Sent: Tuesday, February 08, 2005 11:44 AM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] boost::signals block/unblock > > I wonder there's a way to connect a slot to signal (which gives a > connection), > temporarily disconnect this connection, and reconnect it later (like a > block > function) > > My problem is that I need to emit a signal to the connected slots given a > condition. If a connection satisfies the precondition, it will be > notified, > otherwise it is temporarily disconnected. [Nat] Might it be simpler to test the condition in your custom combiner class? Leave all the slots connected, but for a given invocation, skip any that fail the condition.

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BOOST_STRONG_TYPEDEF
by gast128 08 Feb '05

08 Feb '05

Dear all, I was playing with the serialization library, and ran into the BOOST_STRONG_TYPEDEF. In our own development environment we have a similar feature based on the article 'True typedefs' from Matthew Wilson (CUJ march 2003): BOOST_STRONG_TYPEDEF(long, HBLA); BOOST_STRONG_TYPEDEF(long, HBLUB); HBLABLA hBla(1); HBLUB hBlub(3); bool bOk = false; bOk = (hBlub == hBla); //rejected if base types are different bOk = (hBlub != hBla); //does not compile on VC 7.1 bOk = (hBlub < hBla); //rejected if base types are different hBlub = hBla; //accepted by boost_strong_typedef, this is a deliberate choice So I guess one can discuss about some behavior. But perhaps if it supports '==', it should also support '!='? Wkr, me

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