November 2008 - Boost-users - lists.preview.boost.org

Hashing boost.Tokenizer and Tokenizer euqlity
by Sean Farrow 03 Nov '08

03 Nov '08

Hi: Two queries: 1. Does boost.Tokenizer support the = operator or do I need to write my own. if yes, wha is the best way of doing this, can I use std::equal? 2. I need to write a hashin function for boost.tokenizer? What is the best was of doing this? What information within Tokenizer to write a hash function. Chers Sean.

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Boost:Bind//Boost:Function -- Need some help with a constructor trying to bind to a function
by Charles Milutinovic 03 Nov '08

03 Nov '08

I am struggling to try to get bind/function working like I want. Some code first though: 1. We have a POD object. namespace POD{ class POD{};} 2. We have another class that wants to do something with a POD*. namespace Alpha{ class MethodsInHere{ void doesSomething(POD::POD* arg0){} };} 3. We have a third class, essentially a function handler, that has a boost::function reference whose signature matches the method in #2, and a constructor which wants to set the reference. namespace EventHandler{ class EventHandler{ public: EventHandler(boost::function<void (POD::POD*)>& function): assign_to_me(function){} boost::function<void (POD::POD*)>& assign_to_me; };} 4. Finally, we have an initialization class. This class wants to instantiate the EventHandler object, and to do so needs to bind the method in #2 to pass in as an argument. POD::POD* instance = new POD::POD(); Alpha::MethodsInHere mih; EventHandler eh(boost::bind(&Alpha::MethodsInHere::doesSomething, ????, _1)) -------- My question is basically if this is possible. I was having a ton of trouble getting this to work, and after digging through some docs it seems like the '?????' in line of code in #4 needs to be a reference to eh . . . which isn't constructed yet. If I'm wrong, please tell me how to construct this bind properly. If I'm right, what sort of workaround could solve this?

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Boost + STLPort + msvc8.0
by Gould, Richard Kenneth 03 Nov '08

03 Nov '08

I've read the boost build manual section on building with STLPort and a number of other posts, but nothing seems to help. I have modified user_config.jam to contain using stlport : 5.1.6 : c:\\projects\\STLPort-5.1.6\\stlport c:\\projects\\STLPort-5.1.6\\lib ; and am building with bjam --build-dir="c:\temp\build-boost" --toolset=msvc-8.0 stdlib=stlport-5.1.6 threading=multi --with-serialization -a -d2 release stage However, it fails to build libboost_serialization-vc80-mt-p-1.36.0.lib, with errors propagating from ====== BEGIN OUTPUT ====== EXIT STATUS: -1073741515 ====== END OUTPUT ====== ...failed testing.capture-output c:\projects\build-boost\boost\bin.v2\libs\config\test\all\no_std_locale_ pass.test\msvc-8.0\release\stdlib-stlport-5.1.6\threading-multi\no_std_l ocale_pass.run... I've tried various versions of Boost and STLPort in various combinations, all with the same results. Any insights much appreciated. Kind regards Richard Gould This email and any attachments are confidential and may also be privileged. If you are not the addressee, do not disclose, copy, circulate or in any other way use or rely on the information contained in this email or any attachments. If received in error, notify the sender immediately and delete this email and any attachments from your system. Emails cannot be guaranteed to be secure or error free as the message and any attachments could be intercepted, corrupted, lost, delayed, incomplete or amended. Standard Chartered PLC and its subsidiaries do not accept liability for damage caused by this email or any attachments and may monitor email traffic. Standard Chartered PLC is incorporated in England with limited liability under company number 966425 and has its registered office at 1 Aldermanbury Square, London, EC2V 7SB. Standard Chartered Bank ("SCB") is incorporated in England with limited liability by Royal Charter 1853, under reference ZC18. The Principal Office of SCB is situated in England at 1 Aldermanbury Square, London EC2V 7SB. In the United Kingdom, SCB is authorised and regulated by the Financial Services Authority under FSA register number 114276. If you are receiving this email from SCB outside the UK, please click http://www.standardchartered.com/global/email_disclaimer.html to refer to the information on other jurisdictions.

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Re: [Boost-users] Boost:Bind//Boost:Function -- Need some help with a constructor trying to bind to a function
by Alan M. Carroll 03 Nov '08

03 Nov '08

I would think the value in the constructor should be bind(&Alpha::MethodsInHere::doesSomething, mih, _1) When you bind a non-static method, the first argument must be something with which you can call the method. That would not be eh. Of course, you have will have lifetime or copy issues with mih, but I presume you have arrangements for that and we're just seeing some simplified code. At 02:48 PM 11/2/2008, you wrote: >4. Finally, we have an initialization class. This class wants to instantiate the EventHandler object, and to do so needs to bind the method in #2 to pass in as an argument. > >POD::POD* instance = new POD::POD(); >Alpha::MethodsInHere mih; >EventHandler eh(boost::bind(&Alpha::MethodsInHere::doesSomething, ????, _1)) > >-------- > >My question is basically if this is possible. I was having a ton of trouble getting this to work, and after digging through some docs it seems like the '?????' in line of code in #4 needs to be a reference to eh . . . which isn't constructed yet.

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std-in/out communication with child process
by Michiel Helvensteijn 02 Nov '08

02 Nov '08

Hi, I'd like to open a child process within my main process and send info to its stdin and get info from its stdout/stderr. It would be handy for the unit testing suite for a compiler. It would compile some source-code to a binary, start the binary as a child process and test it. Is there a way in C++ and/or Boost to do this? Thanks! -- Michiel Helvensteijn

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Re: [Boost-users] [Graph] newbie to graph (Andrew Sutton)
by Phillip Jones 02 Nov '08

02 Nov '08

> The compilation output of the code above includes errors and can be found > here: > > http://www.cs.huji.ac.il/~lweizm45/compile_output2.txt<http://www.cs.huji.ac.il/%7Elweizm45/compile_output2.txt> I'm only slightly less of a newbie when it comes to the boost graph libraries. I ran into these same types of errors when I was trying to use kruskal's minimum spanning tree algorithm. This error from your output: error: cannot convert `boost::detail::error_property_not_found' to `long int' in assignment indicates that there is a property that is not defined in your graph, but that is needed by the kolmogorov_max_flow() function. There's two options: 1) Use the internal properties, kolmogorov_max_flow() will use them. 2) Use bundled properties, you must explicitly tell komogorov_max_flow() which property is which using bgl_named_params. You've probably already noticed that the code listing here does not work (as it appears your example is based from it): http://www.boost.org/doc/libs/1_36_0/libs/graph/doc/kolmogorov_max_flow.html For one thing, there's a typo in the #include line, but also it is incomplete and leads to all the errors you listed. The code listed here actually works: http://www.boost.org/doc/libs/1_36_0/libs/graph/example/kolmogorov-eg.cpp So you might prefer to use that as a base. Of course, it uses internal properties, and the documentation indicates that bundled properties are the preferred method now. For bundled properties, you would do something like this: struct Node { std::string name; long index; boost::default_color_type color; long distance; graph_traits<Graph>::edge_descriptor predecessor; }; struct Arc { long capacity; long residual; graph_traits<Graph>::edge_descriptor rev; }; and then call the function like so: flow = kolmogorov_max_flow(g, s, t, capacity_map(get(&Arc::capacity, g)). residual_capacity_map(get(&Arc::residual, g)). reverse_edge_map(get(&Arc::rev, g)). predecessor_map(get(&Node::predecessor, g)). color_map(get(&Node::color, g)). distance_map(get(&Node::distance, g)). vertex_index_map(get(&Node::index, g)) ); Note that each named parameter is separated by a period, not a comma. I am not able to get an error free compile using bundled properties - but by making the above changes it gets you down to about 2 errors. Maybe you can figure out the last steps (I can't). I stuck with using the internal properties because I had an example that worked, and the documentation on how to get bundled properties working with the functions is lacking.

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Re: [Boost-users] Is the behaviour of the binary_from_base64intended?
by F David Sacerdoti 02 Nov '08

02 Nov '08

I had the same problem and came on this thread. I'm sorry but Robert's reply is missing the point: we the users want to get the job done, and in this age base64 behavior is defined by RFC 2045 and 3548. Those documents provide the answer to the problem you describe below, and the accepted behavior we want. Boost is very good, and it is unfortunate that the lines below, while elegant and purposeful, are essentially useless. ---START--- using namespace boost::archive::iterators; typedef base64_from_binary< transform_width<string::const_iterator, 6, 8> > base64_t; typedef transform_width< binary_from_base64<string::const_iterator>, 8, 6 > binary_t; ---END--- Please consider the goal of most programmers! Python does this admirably, and generally boost as well. Thanks, Federico -------------------------- Author: Robert Ramey Date: 2007-04-13 23:51 -400 To: boost-users Subject: Re: [Boost-users] Is the behaviour of the binary_from_base64intended? Here is the problem: Suppose you have 1 byte - that's 8 bits. Now you encode that into 3 bit octet + 3 bit octet + 2 bits. The last is extended to a byte so you have a 3 byte "file". now you translate back into inary. Your "file" has 3 bytes. Each byte is translated backinto binary as 3 bits + 3 bits + 3 bits - 9 bits which turns out to be 2 bytes. So our original bitstream has been extended from 8 bits to 16. In the serialization library I record first the total number of bytes and and send that first. The iterator "stack" I use to translate is terminated by a count rather than some special "end" iterator. To me this problem is inherent in the base 64 encoding scheme as I understand it. Robert Ramey Jeffrey wrote: > Hello. > > I am seeing the same problems. base64 encoding works for some > input and not others. > > > Does anyone know if this is fixed in RC 1_34_0 or cvs head? > > Thanks, _______________________________________________ Boost-users mailing list Boost-users@??? http://lists.boost.org/mailman/listinfo.cgi/boost-users

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ASIO io_service behaviour
by Philip Gaskell 02 Nov '08

02 Nov '08

Hi all, I have got some code to test the behavior of io_service. The relevant code is as follows: void ioservice_lifotest() { boost::asio::io_service io; boost::asio::deadline_timer t(io, boost::posix_time::seconds(6)); boost::asio::io_service io2; boost::asio::deadline_timer t1(io2, boost::posix_time::seconds(1)); boost::asio::deadline_timer t2(io2, boost::posix_time::seconds(2)); boost::asio::deadline_timer t3(io2, boost::posix_time::seconds(3)); boost::asio::deadline_timer t4(io2, boost::posix_time::seconds(4)); t.async_wait(printHello); t1.async_wait(print1); t2.async_wait(print2); t3.async_wait(print3); t4.async_wait(print4); io.run(); std::cout << "bleh\n"; io2.run(); std::cout << "done\n"; } printHello(), print1(), print2(), print3() and print4() are simple functions that print different messages to the console. I was expecting printHello to be called first, then print1, then print2, then print3 and print4, because that is the order the events were added to the io_service service. However these functions were called in reverse order. It is as though the underlying queue mechanism is actually a stack. I expect I have missed some of, or misunderstood the documentation, but a few hints as to what is happening will be appreciated. -- Regards, Phil E: philip.gaskell(a)momote.com | M: +44(0)7891 199 959 | W: www.momote.com EMAIL DISCLAIMER The contents of this electronic mail message and any attachments (collectively " this message") are confidential, possibly privileged and intended only for its addressee ("the addressee"). If received in error, please delete immediately without disclosing its contents to anyone. Neither the sender nor its management or employees will in any way be responsible for any advice, opinion, conclusion or other information contained in this message or arising from its disclosure. Registered office: 8 The Parks, Haydock, Newton-Le-Willows, Merseyside. WA12 0JQ Registered in England No. 4410772.

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Boost regex does't work
by Yoshiyuki Watanabe 02 Nov '08

02 Nov '08

Hi, I'm a new user of boost. I have a trouble to use boost. I downloaded boost_1_36_0 and put it on directory where I prefer. To use with eclipse, I set the path. Property->c/c++build->settings->GCC C++ compiler->directories Some functions like boost/tokenizer or boost/lexical_cast is working well, but only the function boost/regex doesn't work. Compile is finished safely, but once I tried to run, an error is appear ,and the process stops. Undefined symbols: "boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::do_assign(char const*, char const*, unsigned int)", referenced from: boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign(char const*, char const*, unsigned int)in main.o ld: symbol(s) not found collect2: ld returned 1 exit status Would someone have ideas to use boost/regex on eclipse? My plattform is Mac OSX Leopard. Thanks,

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Re: [Boost-users] [Graph] newbie to graph (Andrew Sutton)
by Lior Weizman 02 Nov '08

02 Nov '08

Hello, Thank you for your reply. I implemented your suggestions but the problem persists. Below is the current version of my code: --------------------------------------------------------------CODE---------------------------------------------------------------------- #include <boost/config.hpp> #include <iostream> #include <string> #include <boost/graph/kolmogorov_max_flow.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/write_dimacs.hpp> #include <boost/graph/read_dimacs.hpp> using namespace boost; struct Arc; struct Node; typedef adjacency_list<vecS,vecS,directedS,Node,Arc> Graph; struct Arc { long capacity; long residual_capacity; Graph::edge_descriptor reverse; }; struct Node { std::string name; }; int main() { typedef Graph::vertex_descriptor vertex_descriptor; typedef Graph::edge_descriptor edge_descriptor; typedef std::pair<edge_descriptor, bool> EdgePair; typedef std::pair<int,int> Pair; Graph g; property_map<Graph, long Arc::*>::type capacity = get(&Arc::capacity, g); property_map<Graph, Graph::edge_descriptor Arc::*>::type rev = get(&Arc::reverse,g); long flow; vertex_descriptor s, t; Pair edge_array[6] = { Pair(0,1), Pair(0,2), Pair(0,3), Pair(2,4), Pair(1,3), Pair(4,3), }; EdgePair edge_desc_obj; EdgePair edge_from_first=add_edge(edge_array[0].first,edge_array[0].second,g); g[edge_from_first.first].capacity=1; for (int i = 1; i < 5; ++i){ edge_desc_obj=add_edge(edge_array[i].first, edge_array[i].second,g); g[edge_desc_obj.first].capacity=i+1; } EdgePair edge_to_last=add_edge(edge_array[5].first,edge_array[5].second,g); g[edge_to_last.first].capacity=4; char str[2]; int i=0; vertex_descriptor v1=*vertices(g).first,v2=*vertices(g).second; while (v1!=v2) { sprintf(str,"%d",i); g[v1].name=str; std::cout << str; v1++; i++; } edge_descriptor from_s,to_t; from_s=edge_from_first.first; to_t=edge_to_last.first; s=source(from_s,g); t=target(to_t,g); flow = kolmogorov_max_flow(g, s, t); return 0; } -------------------------------------------------------------------END OF CODE------------------------------------------------------------------ The compilation output of the code above includes errors and can be found here: http://www.cs.huji.ac.il/~lweizm45/compile_output2.txt<http://www.cs.huji.ac.il/%7Elweizm45/compile_output2.txt> Again, if I remove the call to kolmogorv_max_flow, everyting is fine. If I replace the call to kolmogorov_max_flow with the line: write_dimacs_max_flow(g, capacity, identity_property_map(),s, t, std::cout); The output is: -------------------------------------- OUTPUT ------------------------------------------------------ c DIMACS max-flow file generated from boost::write_dimacs_max_flow p max 5 6 n 1 s n 4 t a 1 2 1 a 1 3 2 a 1 4 3 a 2 4 5 a 3 5 4 a 5 4 4 ---------------------------------------- END OF OUTPUT -------------------------------------------------- Which means that the graph was created correctly. Any suggestions? Thanks, Lior

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