November 2009 - Boost-users - lists.preview.boost.org

[program_options] multiple_occurrences exception
by Sam Miller 07 Nov '09

07 Nov '09

Is there a way to determine which option triggers the multiple_occurences exception to be thrown when calling program_options::store? As an example I have a component that takes a positional --exe argument. It would be nice to know when the exception is throw if --exe had been specified earlier in the command line. Thanks, Sam

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[serialization] Serializing const* to serialized data
by Noah Roberts 07 Nov '09

07 Nov '09

Consider something like so: struct A { ...? }; struct B { std::list<A> items; }; struct C { A const* ptr_to_item_in_B_items; }; Serializing B is easy. Serialization of C ... not so much. The naive approach did not work because it wants a non-const pointer. Having read posts about the problem it seems the serialization library expects to modify the data pointed to, but I don't need or want that...I just want to recover the structure layout. Possible? Impossible?

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Slicing multi_array
by James Amundson 06 Nov '09

06 Nov '09

Hi, I want to write a function that operates on one-dimensional multi_array's and use it to modify the columns of a two-dimensional multi_array. I thought that this would be a straightforward application of slicing, i.e., views with dimensional reduction. However, my first attempt to do so does not compile. (Please see the attached source code.) When I try to pass a view to my function, I get: error: invalid initialization of non-const reference of type boost::multi_array_ref<double, 1ul>& from a temporary of type boost::detail::multi_array::multi_array_view<double, 1ul> I have now read the section on views and subarrays in the multi_array reference documentation several times, but I do not see how I can do what I want. Any suggestions? Thanks, Jim Amundson

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[ASIO]what's the meaning of CompletionCondition in boost::asio::async_read?
by zong jinliang 06 Nov '09

06 Nov '09

dears, in function: void async_read<file:///F:/boost_1_40_0/doc/html/boost_asio/reference/async_read/overload2.html> (AsyncReadStream & s,const MutableBufferSequence & buffers, CompletionCondition completion_condition,ReadHandler handler); I am puzzled for the variant: "CompletionCondition completion_condition". take follow code as example: boost::asio::async_read(socket_,boost::asio::buffer(...),boost::asio::transfer_at_least(1),boost::bind(...)); Before I think it'll return if read 1 bit, but at fact it return until receive EOF or buffer is full. So why need this variant? It can return when receive EOF or buffer is full if there is no this varant, just like: boost::asio::async_read(socket_,boost::asio::buffer(...),boost::bind(...));

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Re: [Boost-users] [date_time] obtaining the current time
by Eric J. Holtman 06 Nov '09

06 Nov '09

Sean Farrow wrote: > > Hi: > > I need to obtain the users current local time in the users current > time zone. > > How would I go about doing this. Using a window operating system and > visual studio 2008. > boost::posix_time::microsec_clock::local_time();

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Get "Native" thread id - feature request
by Ondrej Sluciak 06 Nov '09

06 Nov '09

Hello, is there a way how to get the thread id that system assigns to thread? I mean the id that is located in "thread_info->id". It would quite nice if boost could return this value, because for example if I want to set name of the thread on windows using function SetThreadName(), I need exactly that id. In my application I would have to add this "feature" directly to boost::thread.hpp, which is not very nice solution. I know that also GetThreadName(myThread->native_handle()) should work, but if I do it like this I always get a Windows error "The procedure entry point GetThreadId could not be located in the dynamic link library KERNEL32.dll". And I also guess, that this new "feature" wouldn't destroy the overall design of boost::thread architecture. To get the "real" thread id is in my opinion in general a useful thing.

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[date_time] obtaining the current time
by Sean Farrow 06 Nov '09

06 Nov '09

Hi: I need to obtain the users current local time in the users current time zone. How would I go about doing this. Using a window operating system and visual studio 2008. Cheers Sean.

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[graph] Usage (and possible removal) of LEDA and Stanford GraphBase adaptors for Boost.Graph
by Jeremiah Willcock 06 Nov '09

06 Nov '09

Are there any users of the LEDA and Stanford GraphBase adaptors for Boost.Graph? They are no longer actively maintained and there have been bug reports that the LEDA adaptor does not work with current versions of LEDA. If they are no longer used, Andrew Sutton and I will consider deprecating and/or removing them. Please reply if you would like these components kept in Boost.Graph. -- Jeremiah Willcock

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RTTI disabled in boost.graph
by Koh Hwee Miin 06 Nov '09

06 Nov '09

I'm building boost library on windows xp (32-bit) using visual c++ 2005, with RTTI enabled. Then I received a warning D9025 stating that "overriding /GR with /GR-", and after checking the jamfile I find out that RTTI was disabled for boost.graph library. I'm assuming boost library will work correctly with RTTI enabled all the while, and all my other projects are built with RTTI enabled. Will there be any undefined behavior if I try to use boost.graph in other RTTI projects? _________________________________________________________________ Windows 7: Simplify what you do everyday. Find the right PC for you. http://windows.microsoft.com/shop

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[Serialization]
by Dylan Klomparens 05 Nov '09

05 Nov '09

Hello, I have 2 questions regarding the Serialization library: ========================= I have a function that I am using to load a serialized class, called "Configuration". A particular line in the function produces a warning message. Should I be worried about this warning? The function is below, with a comment denoting the warning-producing line. void Configuration::Save(const string& Name) { ofstream Out(Name.c_str()); if(Out.fail()) throw runtime_error("Error: unable to save configuration file."); boost::archive::text_oarchive Archiver(Out); Archiver << *this; // This line produces the warning. } The warning is: C4308: negative integral constant converted to unsigned type ... error is from file: \boost\mpl\print.hpp line: 51 ========================= In a separate question, I'm wondering why this code compiles: template<class Archive> void save(Archive& ar, const boost::asio::ip::udp::endpoint& endpoint, unsigned int version) { unsigned short Port = endpoint.port(); ar << endpoint.address().to_string(); ar << Port; } But this code does not compile: template<class Archive> void save(Archive& ar, const boost::asio::ip::udp::endpoint& endpoint, unsigned int version) { ar << endpoint.address().to_string(); ar << endpoint.port(); } The only difference is endpoint.port() is stored in a seperate unsigned short. ========================= Any help is much appreciated! -- Dylan

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