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

Bizarre behaviour with Microsoft compiler
by Eric Fowler 10 Sep '06

10 Sep '06

I have a fraction of code using BGL that the MS compiler has for some reason optimized into oblivion. While this is not a boost problem per se, since it appears in a compiler I have not had problems with, I suspect all those templates are confusing the MS compiler somehow. The symptom is that when I get a property of an edge, then test on that property and branch, the test is removed from the compiled assembly. Here is the code: //header typedef property<edge_weight_t, unsigned> EdgeCountProperty; typedef adjacency_list<vecS, vecS, bidirectionalS, no_property, EdgeCountProperty> Graph; typedef graph_traits<Graph>::out_edge_iterator OutEdgeIter; ..... //code property_map<Graph, edge_weight_t>::type wgt = get(edge_weight, g); OutEdgeIter ei, ee, eMax; unsigned nTopWgt = 0; unsigned nChk = 0; for(tie(ei, ee) = out_edges(v, g), eMax = ee; ei != ee; ++ei) { nChk = wgt[*ei]; ////////This 'if' is skipped, the code acts like nChk > nTopWgt is always TRUE, even when it ain't!! if(nChk > nTopWgt); { nTopWgt = nChk; eMax = ei; } } Here is the assembly: OutEdgeIter ei, ee, eMax; 00420514 lea ecx,[ei] 00420517 call boost::detail::out_edge_iter<std::vector<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,unsigned int,boost::detail::edge_desc_impl<boost::bidirectional_tag,unsigned int>,int>::out_edge_iter<std::vector<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::e 0042051C lea ecx,[ee] 0042051F call boost::detail::out_edge_iter<std::vector<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,unsigned int,boost::detail::edge_desc_impl<boost::bidirectional_tag,unsigned int>,int>::out_edge_iter<std::vector<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::e 00420524 lea ecx,[eMax] 00420527 call boost::detail::out_edge_iter<std::vector<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,unsigned int,boost::detail::edge_desc_impl<boost::bidirectional_tag,unsigned int>,int>::out_edge_iter<std::vector<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::e unsigned nTopWgt = 0; 0042052C mov dword ptr [nTopWgt],0 unsigned nChk = 0; 00420533 mov dword ptr [nChk],0 for(tie(ei, ee) = out_edges(v, g), eMax = ee; ei != ee; ++ei) 0042053A mov eax,dword ptr [g] 0042053D push eax 0042053E mov ecx,dword ptr [v] 00420541 mov edx,dword ptr [ecx] 00420543 push edx 00420544 lea eax,[ebp-198h] 0042054A push eax 0042054B call @ILT+5420(??$out_edges@Uconfig@?$adj_list_gen@ V?$adjacency_list@UvecS@boost@@U12@UbidirectionalS@2@Uno_property@2@U ?$property@W4edge_weight_t@boost@@IUno_property@2@@2@U42@UlistS@2@@boost@@ UvecS@2@U32@UbidirectionalS@2@Uno_property@2@U?$property@ W4edge_weight_t@boost@@IUno_property@2@@2@U52@UlistS@2@@detail@boost@@ U?$bidirectional_graph_helper_with_property@Uconfig@?$adj_list_gen@ V?$adjacency_list@UvecS@boost@@U12@UbidirectionalS@2@Uno_property@2@U ?$property@W4edge_weight_t@boost@@IUno_property@2@@2@U42@UlistS@2@@boost@@ UvecS@2@U32@UbidirectionalS@2@Uno_property@2@U?$property@ W4edge_weight_t@boost@@IUno_property@2@@2@U52@UlistS@2@@detail@boost @@@4@@boost@@YA?AU?$pair@U?$out_edge_iter@Viterator@?$vector@ V?$sei_@IViterator@?$list@U?$list_edge@IU?$property@W4edge_weight_t@boost@@ IUno_property@2@@boost@@@boost@@V?$allocator@U?$list_edge@ IU?$property@W4edge_weight_t@boost@@IUno_property@2 @@boost@@@boost@@@std@@@std@@U?$property@W4edge_weight_t@boost@@ IUno_property@2@@boost@@@detail@boost@@V?$allocator@ 00420550 add esp,0Ch 00420553 push eax 00420554 lea ecx,[ee] 00420557 push ecx 00420558 lea edx,[ei] 0042055B push edx 0042055C lea eax,[ebp-1A8h] 00420562 push eax 00420563 call @ILT+4705(??$tie@U?$out_edge_iter@Viterator@?$vector@ V?$sei_@IViterator@?$list@U?$list_edge@IU?$property@W4edge_weight_t@boost@@ IUno_property@2@@boost@@@boost@@V?$allocator@U?$list_edge@ IU?$property@W4edge_weight_t@boost@@IUno_property@2 @@boost@@@boost@@@std@@@std@@U?$property@W4edge_weight_t@boost@@ IUno_property@2@@boost@@@detail@boost@@V?$allocator@V ?$sei_@IViterator@?$list@U?$list_edge@IU?$property@W4edge_weight_t@boost@@ IUno_property@2@@boost@@@boost@@V?$allocator@U?$list_edge@ IU?$property@W4edge_weight_t@boost@@IUno_property@2 @@boost@@@boost@@@std@@@std@@U?$property@W4edge_weight_t@boost@@ IUno_property@2@@boost@@@detail@boost@@@std@@@std@@ IV?$edge_desc_impl@Ubidirectional_tag@boost@@I@detail@boost@@H@detail @boost@@U123@@tuples@boost@@YA?AV?$tuple@AAU ?$out_edge_iter@Viterator@?$vector@V?$sei_@IViterator@?$list@U?$list_edge@IU ?$property@W4edge_weight_t@boost@@IUno_property@2@@boost@@@boost@@ V?$allocator@U?$list_edge@IU?$property@W4edge_weight_t@boost@@ IUno_property@2@@boost@@@boost@@@std@@@std@ 00420568 add esp,0Ch 0042056B mov ecx,eax 0042056D call @ILT+2355(??$?4U?$out_edge_iter@Viterator@?$vector@ V?$sei_@IViterator@?$list@U?$list_edge@IU?$property@W4edge_weight_t@boost@@ IUno_property@2@@boost@@@boost@@V?$allocator@U?$list_edge@ IU?$property@W4edge_weight_t@boost@@IUno_property@2 @@boost@@@boost@@@std@@@std@@U?$property@W4edge_weight_t@boost@@ IUno_property@2@@boost@@@detail@boost@@V?$allocator@V ?$sei_@IViterator@?$list@U?$list_edge@IU?$property@W4edge_weight_t@boost@@ IUno_property@2@@boost@@@boost@@V?$allocator@U?$list_edge@ IU?$property@W4edge_weight_t@boost@@IUno_property@2 @@boost@@@boost@@@std@@@std@@U?$property@W4edge_weight_t@boost@@ IUno_property@2@@boost@@@detail@boost@@@std@@@std@@ IV?$edge_desc_impl@Ubidirectional_tag@boost@@I@detail@boost@@H@detail @boost@@U012@@?$tuple@AAU?$out_edge_iter@Viterator@?$vector@ V?$sei_@IViterator@?$list@U?$list_edge@IU?$property@W4edge_weight_t@boost@@ IUno_property@2@@boost@@@boost@@V?$allocator@U?$list_edge@ IU?$property@W4edge_weight_t@boost@@IUno_property@2 @@boost@@@boost@@@std@@@std@@U?$property@W4edge_w 00420572 mov ecx,dword ptr [ee] 00420575 mov dword ptr [eMax],ecx 00420578 mov edx,dword ptr [ebp-24h] 0042057B mov dword ptr [ebp-34h],edx 0042057E jmp foo+0B8h (420588h) 00420580 lea ecx,[ei] 00420583 call boost::iterator_facade<boost::detail::out_edge_iter<std::vector<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,unsigned int,boost::detail::edge_desc_impl<boost::bidirectional_tag,unsigned int>,int>,boost::detail::edge_desc_impl<boost::bidirectional_tag,unsigned int>,boost::random_access_traversal_tag,bo 00420588 lea eax,[ee] 0042058B push eax 0042058C lea ecx,[ei] 0042058F push ecx 00420590 call boost::operator!=<boost::detail::out_edge_iter<std::vector<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,unsigned int,boost::detail::edge_desc_impl<boost::bidirectional_tag,unsigned int>,int>,boost::detail::edge_desc_impl<boost::bidirectional_tag,unsigned int>,boost::random_access_traversal_tag,boost:: 00420595 add esp,8 00420598 movzx edx,al 0042059B test edx,edx 0042059D je foo+114h (4205E4h) { nChk = wgt[*ei]; 0042059F lea eax,[ebp-180h] 004205A5 push eax 004205A6 lea ecx,[ei] 004205A9 call boost::iterator_facade<boost::detail::out_edge_iter<std::vector<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::detail::sei_<unsigned int,std::list<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> >,std::allocator<boost::list_edge<unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property> > > >::iterator,unsigned int,boost::detail::edge_desc_impl<boost::bidirectional_tag,unsigned int>,int>,boost::detail::edge_desc_impl<boost::bidirectional_tag,unsigned int>,boost::random_access_traversal_tag,bo 004205AE sub esp,0Ch 004205B1 mov ecx,esp 004205B3 mov edx,dword ptr [eax] 004205B5 mov dword ptr [ecx],edx 004205B7 mov edx,dword ptr [eax+4] 004205BA mov dword ptr [ecx+4],edx 004205BD mov eax,dword ptr [eax+8] 004205C0 mov dword ptr [ecx+8],eax 004205C3 lea ecx,[wgt] 004205C6 call boost::adj_list_edge_property_map<boost::bidirectional_tag,unsigned int,unsigned int &,unsigned int,boost::property<enum boost::edge_weight_t,unsigned int,boost::no_property>,enum boost::edge_weight_t>::operator[] (41E2E3h) ;;LOOK MA! NO 'cmp' INSTRUCTION! WHERE'D IT GO?!!? 004205CB mov ecx,dword ptr [eax] 004205CD mov dword ptr [nChk],ecx if(nChk > nTopWgt); { nTopWgt = nChk; 004205D0 mov eax,dword ptr [nChk] 004205D3 mov dword ptr [nTopWgt],eax eMax = ei; 004205D6 mov eax,dword ptr [ei] 004205D9 mov dword ptr [eMax],eax 004205DC mov ecx,dword ptr [ebp-14h] 004205DF mov dword ptr [ebp-34h],ecx } } I repeat that this is not a boost issue per se but this bug might show up more often when compiling all those templates ... Eric

2 1

How to get a graph with edges sorted by weight (or some other property) ?
by Eric Fowler 09 Sep '06

09 Sep '06

Title says it all, I have a graph with weighted edges, and want to iterate through them in order of weights. To make it more interesting the edges are defined with setS and must be - actually, I could work around - but it would be more convenient to keep setS. A brief example would help. Thanks. Eric

2 1

[regex] Perl regex special characters
by Andriy Tylychko (mail.ru) 08 Sep '06

08 Sep '06

Hi <http://www.boost.org/libs/regex/doc/syntax_perl.html> http://www.boost.org/libs/regex/doc/syntax_perl.html says: Perl Regular Expression Syntax In Perl regular expressions, all characters match themselves except for the following special characters: .[{()\*+?|^$ Q: what about "]}" symbols? Best regards, Andriy Tylychko, telia(a)vichnavich.com www.vichnavich.com <http://www.vichnavich.com/>

3 3

How to get a graph that does not accept parallel edges?
by Eric Fowler 08 Sep '06

08 Sep '06

How do I declare a graph that does not allow parallel edges? I have come up with this but IMO it is sort of, well, kludgey: typedef adjacency_list<setS, vecS, bidirectionalS> Graph; This works because std::set does not like multiple entries. But what if for performance reasons (say) I want a listS or vecS instead of setS? In adjacency_list.hpp I find: template <> struct parallel_edge_traits<setS> { typedef disallow_parallel_edge_tag type; }; Which suggest the existence of a more elegant mechanism. Anybody know what that is? Eric

3 2

Re: [Boost-users] How to use bind/lambda in a conditional
by Baranowski, Daniel 08 Sep '06

08 Sep '06

> From: "Andriy Tylychko > > Baranowski, Daniel > > std::for_each(myVector.begin(), myVector.end(), > boost::lambda::if_then(boost::lambda::_1 == 3, [...])); > > Best regards, > Andriy Tylychko Thanks Andriy! That definitely got me on the correct track! It still took me awhile, but I got it! It looks so simple now. Anyhow, since I'm sure I'm not the only person that will ever have this problem when learning to use bind and lambda, here is a sample program that I wrote in vc8 to figure out the solution: #include <vector> #include <iostream> #include <conio.h> #include <boost/lambda/lambda.hpp> #include <boost/lambda/if.hpp> #include <boost/lambda/bind.hpp> #include <algorithm> using namespace std; using namespace boost; using boost::lambda::_1; using boost::lambda::if_then; struct MyObjectClass { MyObjectClass(int Data) : MyData(Data) { }; int GetData() const { return MyData; }; int MyData; }; class TestClass { typedef vector<MyObjectClass> t_ObjVector; t_ObjVector myVector; void PrintObj(const MyObjectClass & MyObj) { cout << MyObj.GetData() << endl; } void PrintInt(int MyInt) { cout << MyInt << endl; } public: TestClass() { myVector.push_back( MyObjectClass(1) ); myVector.push_back( MyObjectClass(2) ); myVector.push_back( MyObjectClass(2) ); myVector.push_back( MyObjectClass(3) ); myVector.push_back( MyObjectClass(3) ); myVector.push_back( MyObjectClass(4) ); } void RunTest() { // regular for loop t_ObjVector::iterator end = myVector.end(); t_ObjVector::iterator itr = myVector.begin(); for(itr; itr != end; ++itr) { if((*itr).GetData() == 3) PrintObj(*itr); } // for_each using lambda concepts for_each(myVector.begin(), myVector.end(), if_then(bind(&MyObjectClass::GetData, _1) == 3, bind(&TestClass::PrintObj, this, _1) ) ); } }; int main (int argc, char **argv) { TestClass Test; // Run the test Test.RunTest(); getch(); return 0; } Thanks again for the help! Daniel ********************************************************************************************** Disclaimer - This email and any files transmitted with it are proprietary and may contain privileged or copyright information. You must not present this message to another party without gaining permission from the sender. If you are not the intended recipient you must not copy, distribute or use this email or the information contained in it for any purpose other than to notify us. If you have received this message in error, please notify the sender immediately, and delete this email from your system. We do not guarantee that this material is free from viruses or any other defects although due care has been taken to minimize the risk. eSafe scanned this email for viruses, vandals and malicious contentAny views expressed in this message are those of the individual sender, except where the sender specifically states them to be the views of LSI. **********************************************************************************************

1 0

Re: [Boost-users] [string_algo] wildcard support?
by james.jones＠firstinvestors.com 08 Sep '06

08 Sep '06

From: "Richard Dingwall" <rdingwall(a)gmail.com> > Cheers. I was rather hoping not to have to use regular expressions; > they're kinda beyond the intended users of my program (it's for a > user-defined filter function, and I don't expect them to be familiar > with regex syntax). > > I cheaped out and used an old C wildcmp(wild.c_str(), text.c_str()) > method instead. Just because YOU use regex internally doesn't mean to have to expose full regex capabilities to the users. You could, for example, use a */? wildcard arrangement like DOS or bash shell uses, use a regex to verify that the wildcard pattern was valid, and then translate this into a real regex for the internal search. Use Boost!! Don't cheap-out. :) - James Jones Administrative Data Mgmt. Webmaster 375 Raritan Center Pkwy, Suite A Data Architect Edison, NJ 08837

1 0

[serialization] different behaviour between xml_wiarchive and binary_wiarchive
by Oliver Mutz 08 Sep '06

08 Sep '06

In my application I'm trying to serialize data alternatively to xml_wiarchive or binary_wiarchive. Writing and reading XML works without any problems. Binary writing seems to work too, but reading the file throws an exception with exception_code 'unregistered_class'. What I do is reading the XML data, writing binary and reading binary back in. I thought there should be no difference which kind of archive I use. Am I missing a point? I would be thankful for any hint. I know that it is hard to guess where the problem might be without seeing any code, but I by now I was not able to create some simple example which shows the same behaviour. I'm using Windows XP (SP2) with MSVC 8.0. Thanks. Oliver

2 4

How to use bind/lambda in a conditional for_each?
by Baranowski, Daniel 08 Sep '06

08 Sep '06

Hey all! I've really enjoyed using boost::bind for calling member functions and such. I wish I had found this earlier! Anyhow, I'm trying to write for_each statement that only passes the object to a function if certain conditions are met. Unfortunately, I'm not well versed enough in boost::bind (and I've never used the lambda library) so I'm not sure how to do this! Can someone lend me a hand? I couldn't find anything in the mail archives. If I were writing a regular for-loop, this is how it would look: vector<MyObjClass> myVector; myVector.push_back(MyObjClass(2)); myVector.push_back(MyObjClass(3)); myVector.push_back(MyObjClass(3)); myVector.push_back(MyObjClass(5)); myVector.push_back(MyObjClass(6)); vector<MyObjClass>::iterator end = myVector.end(); vector<MyObjClass>::iterator itr; for(itr = myVector.begin(); itr != end; ++itr) { if((*itr).GetValue() == 3) ProcessingFunction(*itr); } And here's the for_each that just passes every object into the processing function: // From inside a function in a class called ThisClass vector<MyObjClass> myVector; myVector.push_back(MyObjClass(2)); myVector.push_back(MyObjClass(3)); myVector.push_back(MyObjClass(3)); myVector.push_back(MyObjClass(5)); myVector.push_back(MyObjClass(6)); vector<MyObjClass>::iterator begin = myVector.begin(); vector<MyObjClass>::iterator end = myVector.end(); for_each(begin, end, boost::bind(&ThisClass::ProcessingFunction, this, _1)); So I guess the question is, how do I add the condition into the for_each? I know there's got to be a way! Thanks for any help! Daniel ********************************************************************************************** Disclaimer - This email and any files transmitted with it are proprietary and may contain privileged or copyright information. You must not present this message to another party without gaining permission from the sender. If you are not the intended recipient you must not copy, distribute or use this email or the information contained in it for any purpose other than to notify us. If you have received this message in error, please notify the sender immediately, and delete this email from your system. We do not guarantee that this material is free from viruses or any other defects although due care has been taken to minimize the risk. eSafe scanned this email for viruses, vandals and malicious contentAny views expressed in this message are those of the individual sender, except where the sender specifically states them to be the views of LSI. **********************************************************************************************

3 2

[Signals] Relationships to other libraries and terms
by Scott Meyers 08 Sep '06

08 Sep '06

I've been trying to make sense of Boost.Signals, especially in terms of some other libraries I'm familiar with. Part of the problem is terminology, I think, e.g., callbacks, slots, and delegates (as in .NET, but also as used by some for bound member function pointers (e.g.,http://www.codeproject.com/cpp/FastDelegate.asp)) I'm hoping people will take a look at what follows, correct any errors they see, and maybe lend additional insight so that my understanding will be improved. We start with "callable entities" -- things that can be called, e.g., function pointers, function objects, bound member functions, etc. As I understand it: - A callback (function or object) is a callable entity - A slot in Boost.Signals is a callable entity - boost::bind and boost::lambda create callable entities. - A boost::function object stores a callable entity. We also have collections of callable entities: - A .NET delegate is a collection of 0 or more callable entities with a given signature. - A signal in Boost.Signals is a collection of 0 or more callable entities with signatures compatible with a given signature. Objects of these collection types are also callable entities: - When a Boost.Signals signal or a .NET delegate is called, it invokes the callable entities it contains. Is that correct? Also, does anybody know where the name "slot" comes from in this context? I've found this term to be a stumbling block for trying to understand this stuff. Thanks, Scott

5 6

[asio] tcp::socket state query?
by Rod Morison 08 Sep '06

08 Sep '06

Is there way to query the local status of a socket in asio? Or, is there another technique for state & error management? For example, something lick the TcpSocket state in Qt v4. I.e., AbstractSocket::UnconnectedState 0 The socket is not connected. QAbstractSocket::HostLookupState 1 The socket is performing a host name lookup. QAbstractSocket::ConnectingState 2 The socket has started establishing a connection. QAbstractSocket::ConnectedState 3 A connection is established. QAbstractSocket::BoundState 4 The socket is bound to an address and port (for servers). QAbstractSocket::ClosingState 6 The socket is about to close (data may still be waiting to be written). QAbstractSocket::ListeningState 5 For internal use only. (from http://doc.trolltech.com/4.2/qabstractsocket.html#SocketState-enum) Here's why I'm asking: I'm looking at the chat_client.cpp example.The socket is connected via async_connect in the chat_client constructor. If the first resolved endpoint fails to connect the handler tries an async_connect with the next endpoint. First question: Are the async requests initiated under an io_servce (and executed by the run() method) queued in the order they are called via async_xxx calls? (I'm assuming/hoping that's a yes.) So the issue I have with the chat_client design is as follows: because iterating the endpoint list (to connect the socket) is in a handler, what if another socket operation slipped in ahead of that handler, say a write (assuming the first endpoint failed)? I'd want the do_write() function to be able to check the socket state. I can do the state control myself via the handlers and a class state variable, but is there a better way? (Similarly, this app can happily go writing to an unconnected socket--I realize it's a sample, not production code, but I'm thinking through my _real_ app here.) Hope this makes sense, Rod

1 0