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

Class assignment and referencing
by Wyatt Greenway 02 Oct '05

02 Oct '05

Hello! I want to do the following with Boost::Python: class A { public: std::string Value; }; class B { public: A Str; int Val; }; /* Boost::Code */ class_<A>("A") .def("Value", &A::Value) ; class_<B>("B") .def("Str", &B::Str) .def("Val", &B::Val) ; /*---------*/ I then wish to do this in Python: ############### MyB = B() B.Str = "Some string" print "String: %s"%B.Str # The output should be as follows: > String: Some string How do I acomplish this?

1 0

[iostreams] problem with bzip2_decompressor and incomplete files
by Tiago de Paula Peixoto 02 Oct '05

02 Oct '05

Hello. I've been experiencing a problem with the bzip2_decompressor filter when reading from a stream attached to an incomplete file. Instead of throwing an exception or reaching EOF, the program just hangs. Consider the following example code (hello.cc) taken from the documentation: ----------------------------------------------------------- #include <fstream> #include <iostream> #include <boost/iostreams/filtering_streambuf.hpp> #include <boost/iostreams/copy.hpp> #include <boost/iostreams/filter/bzip2.hpp> int main() { using namespace std; using namespace boost; using namespace boost::iostreams; ifstream file("hello.bz2", ios_base::in | ios_base::binary); filtering_streambuf<input> in; in.push(bzip2_decompressor()); in.push(file); boost::iostreams::copy(in, cout); } ----------------------------------------------------------- Suppose this is compiled as "hello". The following command will generate a simple bzip2-compressed file: $ echo -e "Hello world\n" | bzip2 > hello-complete.bz2 The next line will copy everything but the last byte from "hello-complete.bz2" to "hello.bz2": $ dd if=hello-complete.bz2 of=hello.bz2 bs=1 count=53 So now if the program is run: $ ./hello It just hangs in an infinite loop, instead of throwing an exception or reaching EOF. In the same situation, gzip_decompressor throws an exception... Is there a reason for this not happening in this case, or is this just a bug? I'm using boost 1.33.0 with GCC 4.0.1 on an i686 with GNU/Linux. Thanks for any help. -- Tiago de Paula Peixoto <tiago(a)forked.de>

2 1

Managing builds
by Aaron Griffin 02 Oct '05

02 Oct '05

I have a question, and it's something that has been bothering me for some time when dealing with boost. There are certain boost libs which require link libraries (static/dynamic). That's normal. However, if I wanted to statically link against, say, multithreaded Boost.Filesystem (gcc), I would need to add -Bstatic -lboost_filesystem-gcc-mt (or something to that effect). A majority of projects provide some sort of pkg-config files, or even their own app (gtk-config ?). Is there any functionality like this out there? Is there any way I can make this re-buildable on multiple target machines with multiple install locations in an easy manner? Ideally, something like: boost-config --static-libs filesystem would fit the standard scheme and allow for different machine to have different boost installation roots, and things of that nature. Without something like that, I am forced to either add configure flags, or force a user to modify a "config.mk" style file.

3 4

scoped_ptr help.
by John Sun 01 Oct '05

01 Oct '05

New to this topic,and need some help here. I have a class which use the scoped_ptr as a member variable. Class CTest { public: CTest(); Initialize(); ~CTest(); private: scoped_ptr<CTest2> m_spTest2; } For some reason, that I cannot initialize m_spTest2 in the member initialization list of the constructor, so I have to initialize in some other functions like in Initialize. CTest::Initialize() { int aa, bb; m_spTest2=new CTest2(aa, bb); } The compiler will complain about that, so what's the right way to do it. Thanks, Jianwei

6 8

Dynamic-only installation
by George Sakkis 01 Oct '05

01 Oct '05

Hi all, I'd like to create a single version for each boost library instead of eight, so I run: bjam -sTOOLS=gcc -sBUILD="release <runtime-link>dynamic <threading>multi" install Although it doesn't build the debug single-threaded versions, it still creates both the dynamic and the static ones. Does the static version have to be built always ? TIA, George

1 0

[asio] init acceptor to reuse_address?
by BRIDGES Dick 01 Oct '05

01 Oct '05

I created a server something like this: handle_accept(){ do_the_right_thing(); } Class Foo { socket_acceptor acceptor_; Public: Foo(demuxer& d) : acceptor_( d, ipv4::tcp::endpoint(2525)){} Example(demuxer& d) { stream_socket* p = new stream_socket(d); acceptor_.async_accept(p, handle_accept); } } Everything works fine except when I (1) connect a client; (2) ^C the server; (3) try to restart the server - which, as expected, yields "Address already in use". Mumbling something about defaulting modern socket libraries to SO_REUSEADDR, I started trying to figure out where to call set_option(stream_socket::reuse_address(true)) - and can't work it out. I've set_option() on sockets and the acceptor but can't make the acceptor reuse the address as long as the connection that was established is still in TIME_WAIT. Do you have an example that shows how this can be done? Regards, Dick Bridges

1 0

Library's binary size
by Ugo Mendes Donelli 30 Sep '05

30 Sep '05

In the "Getting Started" section of boost web site, there should be a requirements section. When actually built and installed on Windows, the library 1.33 required more than 2GB of disk space. I was targeting VC++ 7.1. The 1.32 library used more or less 1GB of disk. The disk space requirements that I mention include the bin subdirectory created by the build process in the library's source tree, directory that I generally delete by hand shortly after. I don't think that any user will run out of disk space but it's better if the users know about this before they build the library. Ciao, Ugo

2 1

composing stream iterators?
by Robert Mathews 30 Sep '05

30 Sep '05

I have a collection of streams that I want to read from sequentially, and I want it to look like a single stream iterator to the calling code. Is there a boost template for a stream iterator that wraps a collection of other stream iterators? Thanks, Rob.

1 0

[serialization] Bug in demo.cpp?
by Paul Giaccone 30 Sep '05

30 Sep '05

Does the demo program demo.cpp <http://boost.org/libs/serialization/example/demo.cpp> have a bug in it? When I run it, it crashes at the line that does the actual serialisation: oa << s; in save_schedule(), reporting the error: Unhandled exception at 0x7c59bbf3 in SerializationDemo.exe: Microsoft C++ exception: __non_rtti_object @ 0x0012ee98 at line 260 of dbgheap.c: pvBlk = _heap_alloc_dbg(nSize, nBlockUse, szFileName, nLine); The call stack is > SerializationDemo.exe!_nh_malloc_dbg(unsigned int nSize=33, int nhFlag=1240696, int nBlockUse=5007849, const char * szFileName=0xe06d7363, int nLine=1) Line 260 + 0x15 C SerializationDemo.exe!malloc(unsigned int nSize=0) Line 139 + 0x15 C I'm compiling in Windows 2000 using Visual .NET, if this helps. Paul Giaccone PS: I modified the filename so it is correct for Windows (using backslashes) - it might be a good idea to use a boost::path here to make the code portable.

2 3

[TR1 Review] TR1 Formal Review Beginning
by Beman Dawes 30 Sep '05

30 Sep '05

The formal review of the Boost TR1 Library by John Maddock begins today, Saturday, September 24th, and runs through Wednesday, October 5th. The TR1 library provides an implementation of the C++ Technical Report on Standard Library Extensions. This library does not itself implement the TR1 components, rather it's a thin wrapper that will include your standard library's TR1 implementation (if it has one), otherwise it will include the Boost Library equivalents, and import them into namespace std::tr1. Functionality supported includes: * Reference Wrappers * Smart Pointers * Class template result_of. * Function template mem_fn. * Function Object Binders. * Polymorphic function wrappers. * Type Traits. * Random Number Generators and Distributions. * Tuples. * Tuple Interface to std::pair. * Fixed Size Array. * Hash Function Objects. * Regular Expressions. * Complex Number Algorithm Overloads. * Complex Number Additional Algorithms. Functionality in TR1 but not yet available: * Mathematical Special Functions. * Unordered Associative Set (Hash Table). * Unordered Associative Map (Hash Table). * C99 C language additions. Additional information including online documentation is available at http://freespace.virgin.net/boost.regex/tr1/index.html The complete TR1 lib source and docs can be downloaded from http://freespace.virgin.net/boost.regex/tr1/tr1-20050816.zip Please help Boost by posting your formal review of this library. Your comments may be brief or lengthy, but basically the Review Manager needs your evaluation of the library. If you identify problems along the way, please note if they are minor, serious, or showstoppers. Here are some questions you might want to answer in your review: * What is your evaluation of the design? * What is your evaluation of the implementation? * What is your evaluation of the documentation? * What is your evaluation of the potential usefulness of the library? * Did you try to use the library? With what compiler? Did you have any problems? * How much effort did you put into your evaluation? A glance? A quick reading? In-depth study? * Are you knowledgeable about the problem domain? And finally, every review should answer this question: * Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. --Beman Dawes, Review Manager

6 18