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[asio] How to reuse a socket
by george 26 Oct '06

26 Oct '06

hello, I start using asio in my project and I don't know how to reuse a socket... some code: void server(asio::io_service& io_service, short port) { tcp::acceptor a(io_service, tcp::endpoint(tcp::v4(), port)); for (;;) { tcp::socket *sock=new tcp::socket(io_service); a.accept(sock); session(sock); } } void session(tcp::socket *sock) { sock->read(...); .... sock->send("reply"); } when I send the first request everything is ok but when I try for a second one I never get a reply or an error from the server... The easy way would be to have a thread/connection model so I could block each thread waiting to a socket but I want to use a thread-pool for my server so I want to know if there is any callback parameter I could pass to my socket and when there is data availiable in the socket the asio would fire the callback function . thanks in advance, george

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Using MPL to cut array?
by Arno Schödl 26 Oct '06

26 Oct '06

Hello, __FILE__ is a macro for the path to the current source file. I would like to remove the common prefix (like "c:\dev\my_program\") from it, which is in a preprocessor macro SOLUTIONDIR. Is there a metaprogramming way to do that? So the class TSuffix should be used like this: TSuffix<x, n>::value // cuts prefix of length n off char array x It would be nice if the compiler would not even store the whole path in the executable, but only the distinguishing suffix. Any ideas how to start? TIA, Arno

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Re: [Boost-users] [boost.serialization] serialization crash
by Sohail Somani 26 Oct '06

26 Oct '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Deane Yang > Sent: Thursday, October 26, 2006 9:34 AM > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] [boost.serialization] serialization crash > > RIVASSEAU Jean Noel wrote: > > I've had the same problems. The problem is with the bool > field. Code > > restoring the archive crashes if the bool stored in the > archive is not > > equal to 0 or 1. But since you did not write a constructor > in the Obj > > class, the boolean will actually be initialized with > anything( eg, read > > 14675002 for example), and will be serialized that way in > the archive > > since it seems the serialization code does not check if the bool is > > equal to 0 or 1 (only the restoration code). > > > > So, the solution is to initialize your boolean correctly > and be very > > careful whenever you use booleans. However, I think the > Serialization > > code should be fixed (remove the check for 0 or 1, it > probably does > > more bad than good. > > > > In my (very) humble opinion, it should be at least symmetric. > So either > no check for 0 or 1 in both directions or a check for 0 or 1 in both > directions. > > But it should also be consistent with other built-in types. Since it > appears that there is no check (is one even possible?) for > uninitialized > data with other built-in types, I also vote for no check. In any case, are booleans guaranteed to be 0 or 1 even if correctly initialized?

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[boost::threads] can't compile threading at MSVC++ 8
by Ovanes Markarian 26 Oct '06

26 Oct '06

I have a problem, with the following error message. Unfortunately documentation does not state what can be the reason that threads are not included. I did not define the BOOST_DISABLE_THREADS macro. But still receive an error message: Compiling... main.cc c:\boost\include\boost-1_33_1\boost\config\requires_threads.hpp(29) : fatal error C1189: #error : "Threading support unavaliable: it has been explicitly disabled with BOOST_DISABLE_THREADS" My assumption is that I configured console project. These are my project preprocessor definitions: _CONSOLE;_SCL_SECURE_NO_WARNINGS; Can someone advise? With Kind Regards, Ovanes Markarian

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[Boost.MultiIndex] docs unclear for ey extractors
by Markus Werle 26 Oct '06

26 Oct '06

> Hi! In http://boost.org/libs/multi_index/doc/advanced_topics.html #advanced_key_extractors I do not understand how the struct name_extractor comes to use and why I have to define it. IIUC the code snippet -------------------------------- typedef multi_index_container< employee *, indexed_by< ordered_non_unique<member<employee,std::string,&employee::name> > > > employee_set; -------------------------------- takes care of all what I need even without it - or do I have to define the struct to make this work? Markus

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Re: [Boost-users] Using MPL to cut array?
by Nat Goodspeed 26 Oct '06

26 Oct '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of Arno Schödl > Sent: Thursday, October 26, 2006 2:45 AM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] Using MPL to cut array? > > __FILE__ is a macro for the path to the current source file. I would like > to remove the common prefix (like "c:\dev\my_program\") from it, which is > in a preprocessor macro SOLUTIONDIR. Is there a metaprogramming way to do > that? > > So the class TSuffix should be used like this: > > TSuffix<x, n>::value // cuts prefix of length n off char array x [Nat] ? Is MPL needed? For a classic const char[] string literal, wouldn't (__FILE__ + n) get you what you want?

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[boost.serialization] serialization crash
by Pavlo Korzhyk 26 Oct '06

26 Oct '06

The following code crashes under cygwin+boost1.33 and under mingw+boost1.33 I create text archive in a file, and then serialization crashes when restoring object from that archive. The problem seem to be with bool field, if I replace bool x; with int x; in the class Obj implementation, everything runs fine. Is this a bug in serialization code? #include <iostream> #include <sstream> #include <fstream> #include <vector> #include <map> using namespace std; #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/vector.hpp> #include <boost/serialization/map.hpp> using namespace boost; using namespace boost::serialization; class Obj { friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & x; } public: bool x; }; class Item; class Cheq : public Obj{ friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & boost::serialization::base_object<Obj>(*this); ar & v; ar & id; } public: vector<Item> v; int id; Cheq(){} }; class Item{ friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & a; ar & s; } public: int a; string s; }; class Row{ friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & m1; ar & m2; } public: map<string,string> m1,m2; }; class Data{ friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { ar & a; ar & m; ar & cheque; } public: int a; map<string,string> m; map<int,Cheq> cheque; }; BOOST_CLASS_TRACKING(Data, boost::serialization::track_never) #include "boost/serialization/export.hpp" BOOST_CLASS_EXPORT(Data); BOOST_CLASS_EXPORT(Cheq); BOOST_CLASS_EXPORT(Item); int main(int argc, char** argv) { Data d; d.cheque[0]=Cheq(); //if(argc>1 && argv[1][0]=='1') { ofstream os("datfile"); boost::archive::text_oarchive oar(os); oar << d; } //if(argc>1 && argv[1][0]=='2') { ifstream is("datfile"); boost::archive::text_iarchive iar(is); iar >> d; } cout << "without crash\n"; return 0; } -- WBR, Pavlo Korzhyk ICQ#155870780

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apply_wrap.hpp(48) : fatal error C1001: INTERNAL COMPILER ERROR
by Matthew Galati 26 Oct '06

26 Oct '06

MS Visual Studio 2003 - v7.1 #include <boost/graph/graph_utility.hpp> #include <boost/graph/connected_components.hpp> #include <boost/graph/kruskal_min_spanning_tree.hpp> using namespace boost; Any ideas? c:\cygwin\home\magala\DECOMP\external\boost_1_33_1\boost\mpl\aux_\preprocessed\plain\apply_wrap.hpp(48) : fatal error C1001: INTERNAL COMPILER ERROR (compiler file 'msc1.cpp', line 2701) Please choose the Technical Support command on the Visual C++ Help menu, or open the Technical Support help file for more information Thanks, Matt

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Re: [Boost-users] [Boost.Parameter] How to Use Named Parameters in a Class Hierarchy?
by Wu Yinghui, Freddie 26 Oct '06

26 Oct '06

> Wu Yinghui, Freddie wrote: >> Dear all, >> >> I'm implementing a hierarchy of classes to handle different types of >> objects. The characteristics of these objects are mostly similar (so I >> can put them into a container that knows only about the pure abstract >> base interface type), but some properties are specific to each object >> types. >> >> I plan to use Boost.Parameter for its capability of providing named >> parameter to these object types. However, I have one problem in this >> approach: Since Boost.Parameter requires that the function processing >> the ArgumentPack to be a template, I cannot make it virtual (a member >> function template cannot be virtual) in my pure abstract base >> interface. Furthermore, due to the lack of "virtual" member function, >> I cannot use >> the base class pointer to provide these named parameters to some >> subclasses. > > Depends on what you actually want to do. Perhaps you could use something > like the template pattern (pseudo-code): > > ----- > struct Parameters > : boost::parameter::parameters< ... > > {}; > > struct Base > { > BOOST_PARAMETER_MEMFUN(void, Work, 1, 4, Parameters) > { > DoWork( p[arg1], p[arg2|0], p[arg3|1] ... ); > } > > private: > virtual void DoWork(actual, args, goes, here) = 0; > }; > > class Derived : public Base > { > virtual void DoWork(actual, args, goes, here) > { > ... use args ... > } > }; > > class Derived2 : public Base > { > virtual void DoWork(actual, args, goes, here) > { > ... use args ... > } > }; > > ----- > > I've used something similar myself, hope that gives an idea on how to solve > your problem. > > // Johan Thanks for your quick reply, Johan. I actually thought of a similar solution. I guess I didn't explain my problem clear enough... Unfortunately, this solution doesn't seem to suit my need. The situation is like this: In the pseudo-code you provided, DoWork() function is declared in the Base class, and is overridden by Derived1 and Derived2, with a fixed number of arguments. My problems is that, my base class cannot predict the exact number of parameters that a derived class may have. (A derived class may have 10 parameters, while another may have none.) So it looks a little bit out-of-shape in terms of the OO programming style I'm familiar with if I'm going to provide overloads of DoWork() for all the possible parameters used by all derived classes (not to mention the undesirable dependency introduced). Thanks again for your comments! Any further thoughts? :) Cheers, Freddie -- Wu Yinghui, Freddie Research & Development Senior Software Engineer Volume Interactions Pte Ltd 1 Kim Seng Promenade, #12-01 Great World City East Tower Singapore 237994 Tel: +65 62226962 (Ext 216) Fax: +65 62226215 Email: yhwu(a)volumeinteractions.com URL: http://www.volumeinteractions.com Important: This message is intended for the recipient(s) addressed above. It contains privileged and confidential information. If you are not the intended recipient, please notify the sender immediately by replying to this message and then delete it from your system. You must not read, copy, use, or disseminate this communication in any form. Thank you.

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Re: [Boost-users] Deferred Function calls
by Nat Goodspeed 25 Oct '06

25 Oct '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of Matt Davies > Sent: Tuesday, October 24, 2006 4:33 PM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] Deferred Function calls > > I am implementing a signal & slots implementation with a twist. Normally > when a signal is fired the connected slots are called immediately. I will > need to defer the actual calls to be invoked later. Basically I need to > store the function reference (via pointer or functor) and the accompanying > parameter values to a 'composite' object. This composite object will be > stored on a buffer. Later another processor will pick this object of the > buffer and then invoke the actual function call. [Nat] Let me try to paraphrase the question to see if I understand. You aren't directly using Boost.Signals because when you call a signal it immediately passes control to each of its slots. Your slots have non-empty parameter signatures. The code that triggers the deferred call has matching argument values. If an immediate call were acceptable, you'd simply use a boost::signal and call it with those argument values. So... as Delfin Rojas suggested, you could use boost::bind to bind your boost::signal object with the argument values you later want passed to each connected slot. (I haven't tried this myself.) In the absence of bind placeholders (e.g. _1), bind will produce a nullary functor that you can store in a boost::function<void (void)>. When you later call that functor with no arguments, it should call each connected slot with the bound arguments. If this doesn't answer your question, please explain what we're missing.

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