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Bug in boost::regex_match 1.33.0 Win64/cl1400 and Linux/gcc323
by rlop＠gmx.de 11 Oct '05

11 Oct '05

Hello, After upgrading from boost 1.32 to boost 1.33.0, we get an exception in boost::regex_match. The exception is std::runtime_error: Regular expression too big , and only under Win64/cl1400 and RHEL/gcc323 Changing the regex slightly sometimes avoids the exception... Attached a small example, which can be used to reproduce the exception. #include <boost/regex.hpp> int main(void) { boost::regex validValue = boost::regex("([x]{0,64})?"); boost::regex_match("T",validValue); return 0; } best regards Robert Lopuszanski -- 5 GB Mailbox, 50 FreeSMS http://www.gmx.net/de/go/promail +++ GMX - die erste Adresse f�r Mail, Message, More +++

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Arrays in Boost::Python
by Wyatt Greenway 11 Oct '05

11 Oct '05

How do I acomplish this: class A { public: int *Buffer; vector<string> Array; A() { this->Buffer = new int[10]; /* Set items in Buffer */} } /* Boost code */ class_<A>("A") .def("Buffer", &A::Buffer) .def("Array", &A::Array) ; /*-----*/ And in python it would look like so: > MyA = A() > print MyA.Buffer[0] > MyA.Array.append("Hello world!") > print MyA.Array[0] ??????? Thanks in advance for any help

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boost::any Question
by Piyush Kapadia 10 Oct '05

10 Oct '05

I am new user of Boost, I tried to use boost::variant first, but in comparison to boost::any performance of boost::variant appears to be around 4 times slower, so settled for boost::any. Also boost::any has cleaner interface but I don't know how to query current type information for boost::any ? My code looks like following map<unsigned int, boost::any> result_table; result_table[1] = 543.434; vector<int> vec; .. Some vec population code; result_table[2] = vec; Now I need to develop a stringify function for result_table; I can fetch the results back as boost::any value = result_table[2]; But I need to know the type of value, so that I can treat it accordingly to stringify; I know there exists type_traits, but very limited examples of type_traits is provided on Boost documentation and particularly, I am clueless about how to use type_traits in above context to find out what is the current type returned by result_table[int] Also I want to know if Boost has any Hash map implementation that can be superior in performance compare to regular std::map ?? Thanks, Piyush

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[BGL] Simple question about accessing vertex property
by Giulio Veronesi 10 Oct '05

10 Oct '05

Hi, How do I access the vertex_index property of a vertex? Is it necessary to use the get function? More precisaly, let us consider the following: typedef adjacency_list<vecS, vecS, bidirectionalS, no_property, property<edge_weight_t, int> > TGraph; typedef graph_traits<TGraph>::vertex_descriptor TNode; Suppose that 'vertex' is a TNode. Is it correct to do int idx = vertex; to get in idx the vertex_index of vertex? Thanks in adavnce, Giulio

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Boost Serialization Question.
by Piyush Kapadia 10 Oct '05

10 Oct '05

I am able to use Boost XML and TEXT serialization but Binary Serialization fails to read file, though it can write binary file. Is Binary Serialization fully Supported and if so does it work with STD container classes ?

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Re: [Boost-users] __stdcall bind-s with boost::bind andboost::lambda
by Bulygin, Sergey 10 Oct '05

10 Oct '05

boost::lambda::bind<RetType>(..) works like a charm. :) Thanks a lot, Peter! Sergey Peter Dimov wrote: > To bind to __stdcall calling convention function with boost::bind, > there is a macro to define: BOOST_BIND_ENABLE_STDCALL. How can I do > the same (bind to __stdcall-type function) with boost::lambda::bind? You may want to try specifying the return type explicitly as in bind<void>(my_stdcall_function, _1, 0) and see if it helps.

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__stdcall bind-s with boost::bind and boost::lambda
by Bulygin, Sergey 10 Oct '05

10 Oct '05

To bind to __stdcall calling convention function with boost::bind, there is a macro to define: BOOST_BIND_ENABLE_STDCALL. How can I do the same (bind to __stdcall-type function) with boost::lambda::bind? Thank you, Sergey

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Type List Iteration?
by Duane Murphy 10 Oct '05

10 Oct '05

How do I iterate over a type list and call a function? MPL? I have a base class BASE that has several subclasses A, B, C that have special capabilities, but no way to identify those capabilities aside from the type. I would like to determine if an object of type BASE is also of one of the special subclasses: ie void f( BASE* base) { if ( dynamic_cast< A* >( base ) != NULL ) { some_function( dynamic_cast< A* >( base ) ); } else if ( dynamic_cast< B* >( base ) != NULL ) { some_function( dynamic_cast< B* >( base ) ); } else if ( dynamic_cast< C* >( base ) != NULL ) { some_function( dynamic_cast< C* >( base ) ); } } I think you can see why I'd like a type list iterator solution to this. I have arranged for the some_function to be a template as well to make things easier. What I am looking for is the equivalent of find_if() but for types and done at run time. I looked over MPL, but MPL seems to apply at compile time without a door to the run time world. :-) Thanks for your helpful tips! ...Duane

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[mpl] nested lambdas?
by Geoffrey Romer 10 Oct '05

10 Oct '05

Suppose I'm tying to build a nested lambda expression, like so (typename...::type omitted for simplicity): lambda<higher_order_func<lambda<foo<_1> >, _2> > - Is this legal? - Does the _1 refer to the first argument of the inner lambda, or of the outer lambda? - Can the above be overridden? I.e. what if I want to refer to the arguments of both lambdas within the inner lambda?

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[iostreams] Closing a filtering_ostream
by Paul Giaccone 10 Oct '05

10 Oct '05

How do you close a filtering_ostream object once you have finished writing to it? In my program below, I would expect the file "hello.bz2" to have been written once the close() function has been called, but it is not the case. The contents are not actually written until I exit the scope in which the filtering_ostream object is defined (at which point the destructor presumably does the job). (The file "some_text.txt" contains just the text "hello world!" so I would expect it not to be written until the file is closed.) I would like to be able to do this explicitly and not have to rely on the destruction of the object - could you explain how can this be done? Another question: what should the second parameter to close() be? I've used BOOST_IOS::trunc here, but is there some other more appropriate value? Thanks, Paul Giaccone #include <fstream> #include <iostream> #include <boost/iostreams/copy.hpp> #include <boost/iostreams/filter/bzip2.hpp> #include <boost/iostreams/device/file.hpp> #include <boost/iostreams/filtering_stream.hpp> int main(void) { { boost::iostreams::filtering_ostream out; out.push(boost::iostreams::bzip2_compressor()); out.push(boost::iostreams::file_sink("hello.bz2", BOOST_IOS::trunc)); std::ifstream input_stream("some_text.txt"); boost::iostreams::copy(input_stream, out); input_stream.close(); if (!boost::iostreams::flush(out)) { std::cerr << "failed to write file" << std::endl; } boost::iostreams::close(out, BOOST_IOS::_Dummy_enum_val); } //exiting scope closes the stream; close() seems not to boost::iostreams::filtering_istream in; in.push(boost::iostreams::bzip2_decompressor()); in.push(boost::iostreams::file_source("hello.bz2")); boost::iostreams::copy(in, std::cout); std::cout.flush(); return 0; }

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