August 2009 - Boost-users - lists.boost.org

[signals2, bind] connecting a slot with unrelated signature
by Igor R 09 Aug '09

09 Aug '09

Hello, Lets assume we've got an arbitrary signal that we don't know it's exact signature, and a function we'd like to connect as a slot. The function ignores all the signal arguments: void callback() { std::cout << "kuku" << std::endl; } int main() { signals2::signal<void(int, double, int)> sig; sig.connect(boost::bind(callback)); sig(); } The above compiles and works. Now I'd like not just to ignore signal's args, but to pass my own param: void callback(int cookie) { std::cout << cookie << std::endl; } int main() { signals2::signal<void(int, double, int)> sig; // I'd like to bind cookie=5 and to connect such a binder to the signal. // Is this possible without defining "manual" functors? sig.connect(???); sig(); }

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[Test] BOOST_TEST_NO_MAIN with pre-built BoostPro libraries
by Alexander Lamaison 08 Aug '09

08 Aug '09

Is it possible to create one's own main() implementation when using the pre-built Boost libraries from BoostPro? The difficulty seems to be that, even if I define BOOST_TEST_NO_MAIN before including unit_test.hpp, the main method still exists in the pre-built library and this causes a linker conflict. The existing code I'm wokring on specifies /FORCE to the linker to make our main override the library main but I think that's a horrible solution and would really like to try something else. Even better would be if there were a way to only invoke our code, which includes calls to framework::run(test), if a particular command-line argument were present. In all other cases it would be nice to have the default test runner behaviour. I think this may be wishful thinking though. Any advice is greatly appreciated. Alex

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Praise for boost.units
by Adrien Guillon 08 Aug '09

08 Aug '09

Just wanted to shower praise upon boost.units, which has finally filled a need I've had for a very long time. I am currently working with engineers to rebuild a simulation model, and boost.units has forced everyone to be consistent with their units... it has also forced the engineers to spend a few minutes arguing amongst themselves about the units of this variable or the other every once in a while... "is that a newton per meter squared?! No.. newton times meter... no it's... newton something else"... exactly what it should do! Good library! AJ

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Re: [Boost-users] question about multi_array use
by Alle Meije Wink 08 Aug '09

08 Aug '09

Dear Overmind and Anton, thanks for your answers. Let's see if I understand! Yes, multi_array<int, 2> and multi_array<int,3> are different types (classes?). But I wouldn't mind using a template class to wrap it if that meant I could code it once, instead of 8 times for 8 different possible dimensionalities. Would it be able to define a template class in the way I described? Overmind, I guess compared to what I had in mind (define the data container of the image [template?] class as a multi_array with a dimensionality given as a size_t parameter), the CRTP struct you are talking about specifies all of the possible types. Is that correct? If I understand it correctly then this does what I want, but does that mean that in the worst-case scenario, I have to write out the functionality for all different dimensionalities? If the parameterised template class idea is possible, that would save some typing! Best wishes, Alle Meije > From: OvermindDL1 <overminddl1(a)gmail.com> > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] question about multi_array use > Message-ID: > <3f49a9f40908071709rbd1ad80k4c5170093588f4d(a)mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > On Fri, Aug 7, 2009 at 2:04 PM, Anton Daneyko<self(a)mezhaka.com> wrote: > >> Hello, >> >> I might be wrong, but it seems the answer is "no you can't do that", because >> the dimensionality is a template parameter multi_array<int, 2> and >> multi_array<int, 3> are different types. However I would like to hear some >> else' opinion as well. >> >> Regards, >> Anton Daneyko. >> >> On Fri, Aug 7, 2009 at 3:48 PM, Alle Meije Wink <a.m.wink(a)gmail.com> wrote: >> >>> Hello, >>> >>> I would like to use the multi_array container to handle imaging data. The >>> image data can be anything up to 8-dimensional (usually up to 4) and >>> dimension information is found in records that accompany the binary data. >>> >>> Would it be possible to create an image class that takes the >>> dimensionality and extents list as parameters, so that images of all >>> dimensionalities can be treated as one class? >>> >>> For example, could the dimensionality be passed as a size_t argument? >>> >>> What I understand from the multi_array paper is that the extents list >>> would only be required whan the array is initialised. >>> > > You could always just wrap up each of the possible dimensions in a > struct that can handle the (de)serialization and everything too, > perhaps use crtp to put identical functionality in a non-virtual base > class. >

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[Boost.Test] Controlling Windows debug trace output
by Alexander Lamaison 08 Aug '09

08 Aug '09

I've recently noticed the Boost.Test outputs anything output using the Windows debug trace functions such as ATLTRACE. Thanks for this! This makes these trace functions so much more useful. However, I was wondering if there was some way to control this output. Ideally, I don't want my automoated test runs to output all these tracelines. Is there a flag to the test runnner that will turn them of? Many thanks. Alex Lamaison

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Boost::asio, set tcp_nodelay, bad file descriptor?
by Alex Black 08 Aug '09

08 Aug '09

I'm experimenting with turning off the Nagle algorithm to possibly improve the performance of my socket server, I'm processing lots of small requests and I'd like as little latency as possible. Here is a code snippet: void CBaseWebServer::StartAccept() { try { shared_ptr<tcp::socket> pSocket(new tcp::socket(m_IoService)); boost::asio::ip::tcp::no_delay option(true); pSocket->set_option(option); m_pAcceptor->async_accept(*pSocket, bind(&CBaseWebServer::HandleAccept, this, pSocket, boost::asio::placeholders::error)); } catch ( ... ) { cout << "Unexpected exception caught in " << BOOST_CURRENT_FUNCTION << endl << boost::current_exception_diagnostic_information(); } } I'm getting an exception on the set_option line: Unexpected exception caught in void CBaseWebServer::StartAccept() Throw in function (unknown) Dynamic exception type: N5boost16exception_detail10clone_implINS0_19error_info_injectorINS_6syst em12system_errorEEEEE std::exception::what: Bad file descriptor What am I doing wrong here? Thanks! - Alex

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[BGL] Bug - Can't correctly copy bundled data
by Caligula 07 Aug '09

07 Aug '09

Hi, I've been working on this bug for a few weeks now. Its sort of a show stopper for me. I'm not able to copy a simple string datum from one element in a bundled property struct to another such element. Just go to http://pastebin.org/7125 And see pastebin references. I have found an ugly workaround for now, but I would really like it to work properly. Hope someone can/will help me with this. I'm also having trouble with copy_graph. I think people should be able to store and retrieve high level elements such as graphs, subgraphs, vertices, adges and their data. BGL seems to be deficient in this regard. Thanks Caligula

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[Singals]problem about add a new connection in slot callback
by mos 07 Aug '09

07 Aug '09

Hi! I'm afraid i can't discribe the problem very well, so please see the code: #include <boost/signal.hpp> #include <iostream> using namespace std; typedef boost::signal<void ()> signal_t; typedef boost::signals::connection connection_t; signal_t g_signal; void test_b() { cout << "b" << endl; } void test_a() { cout << "a" << endl; g_signal.connect(test_b); } int _tmain(int argc, _TCHAR* argv[]) { connection_t t = g_signal.connect(test_a); g_signal(); t.disconnect(); g_signal(); return 0; } int the function test_a , I perfer call test_b next signal that mean output is "a b" but test_b is called immediately and the output is "a b b" how can I solve the problem? mos.

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question about multi_array use
by Alle Meije Wink 07 Aug '09

07 Aug '09

Hello, I would like to use the multi_array container to handle imaging data. The image data can be anything up to 8-dimensional (usually up to 4) and dimension information is found in records that accompany the binary data. Would it be possible to create an image class that takes the dimensionality and extents list as parameters, so that images of all dimensionalities can be treated as one class? For example, could the dimensionality be passed as a size_t argument? What I understand from the multi_array paper is that the extents list would only be required whan the array is initialised. Best wishes Alle Meije

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[BGL] Bug - Can't correctly copy bundled data.
by Caligula 07 Aug '09

07 Aug '09

Hi all, Been working on this bug for a few weeks now. Its sort of a show stopper for me. Not able to copy a simple string datum from one element in a bundled property struct to another such element. See attachment. Hope someone can/will help me with this. Thanks -Caligula

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