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

Re: [Boost-users] [uBLAS] iterator for matrix?
by Lang Stefan 11 Mar '08

11 Mar '08

You may be looking for the matrix storage container which you can access via matrix<...>::data() like this: #include <boost/numeric/ublas/matrix.hpp> using namespace std; using namespace boost::numeric::ublas; matrix<double> m (3, 3); copy ( m.data().begin(), m.data().end(), ostream_iterator<double>(cout, " ") ); Of course, if you have a sparse matrix, the number of elements referenced by matrix::data() may be lower than the number of elements your matrix normally should have. Also you have no control over the order of elements: they may be stored by row, by column, or in yet another way! Cheers, Stefan > Date: Tue, 11 Mar 2008 14:25:58 +0800 > From: "Chung-Lin Wen" <jonathan.clwen(a)gmail.com> > Subject: [Boost-users] [uBLAS] iterator for matrix? > To: boost-users(a)lists.boost.org > Message-ID: > <eb7d82f30803102325w448b5a81w352bfa71a48b7258(a)mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > Hi, > > It seems the ublas::matrix don't have begin() and end() that > the ordinary > STL container would have. > It do have begin1(), begin2(), end1(), end2(), but it only > traverse a row or > a column. > So, how could I use the iterators rather than hand-crafted for-loop to > traverse the whole matrix? > > e.g., > copy( matrix.begin(), matrix.end(), > ostream_iterator<element_type>(cout, " ") ) ; // ERROR: won't > compile: matrix don't have begin & end > > (I know matrix have overloaded the operator<<, it's only an example )

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Boost forceinline?
by Robert Dailey 11 Mar '08

11 Mar '08

Hi, I read a thread a while back posted on the boost mailing list concerning a need for a portable forced inline option from the boost library. Instead of giving the OP a direct answer, conversation lead on to discussion involving use cases for forced inline and whether or not it was appropriate to use it, which wasn't very helpful. I'm posting here to see if the boost library has such a feature. I did some searching but I was not able to find anything helpful. Help is appreciated. Thanks in advance.

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[uBLAS] iterator for matrix?
by Chung-Lin Wen 11 Mar '08

11 Mar '08

Hi, It seems the ublas::matrix don't have begin() and end() that the ordinary STL container would have. It do have begin1(), begin2(), end1(), end2(), but it only traverse a row or a column. So, how could I use the iterators rather than hand-crafted for-loop to traverse the whole matrix? e.g., copy( matrix.begin(), matrix.end(), ostream_iterator<element_type>(cout, " ") ) ; // ERROR: won't compile: matrix don't have begin & end (I know matrix have overloaded the operator<<, it's only an example )

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REG_PERLEX
by Phil Hystad 10 Mar '08

10 Mar '08

Does anyone know the definition of REG_PERLEX? I am using the regex/regcomp traditional unix/posix API supported by Boost Regular Expression library. On a Windows 32 bit platform we are forced to use REG_PERLEX on the regcomp flags argument whereas for the same application we get by using a zero flag value on regcomp on platforms: Mac OS X and Linux. Thanks, phil phystad(a)mac.com

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[thread] Priority?
by Ovanes Markarian 10 Mar '08

10 Mar '08

Hello, I used boost thread library a lot and like it very much. Currently, I was reading the C++ Standerd proposal and saw that a thread (as well as boost::thread) does not have a priority. Which reason was it not to implement the thread priority in boost, and why is it not considered in the upcoming standard? I understand this feature is rarely required, but if someone suddenly needs to start a real-time priority thread he/she will be forced to use a third party lib again. Or is there smth. what I miss? Many thanks, Ovanes

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[statechart] Getting state information into the machine
by Commander Pirx 10 Mar '08

10 Mar '08

I'm using the Statechart Library in conjunction with the really exciting Asio Library to set up a communication server. There is a very helpful documentation of the Statechart Library too. But one topic is puzzling me: How to to get data into the state machine? Here is an simple example: Each session object of the server has two states: signed-off and authorized. Receiving a login event leads to a transition to the authorized state. Thats pretty easy. But the login data (stored in the login event) got lost. I can hold this data in the state machine itself (outermost_context()). Or I can use a pseudo event to forward this data to the authorized state. But I'm looking for a nifty way to avoid this overhead. I like this concept of state-local storage very much. But I'm not shure about how to use it.

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Query state on an asynchronous_state_machine
by Jarl Friis 10 Mar '08

10 Mar '08

Hi. Can anyone tell me how to query a state on an asynchronous_state_machine? The obvious answer would be to say use the state_downcast method (which is inherited from state_machine. But in practise it seems harder than so. But opposed to state_machine, when using asynchronous_state_machine the instance is not created explicitely, it is created implicitely by the scheduler, like this: myMachine = myEventHandler.create_processor<AsyncMachine>(); , hence there is no handle to the state machine itself. All I have is a handle to the processor (sc::fifo_scheduler<>::processor_handle ). So is there a way to come from sc::fifo_scheduler<>::processor_handle to AsyncMachine (which inherits sc:asynchronous_state_machine)? Jarl

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[Boost.Iterators] iterator_facade + a class design issue
by Ashkan Aliabadi 10 Mar '08

10 Mar '08

Dear all, I've decided to write an ABC named BasicIterator, from which all derived iterators are to be descended. The reason being that I have to refer to iterators inside an interface and I need a general base type as a place holder to which I can refer. Besides, I don't want to use CRTP in the interface, but I don't care if I'm forced to use it inside BasicIterator. As discussed in the interoperability section of iterator_facade (here<http://www.boost.org/libs/iterator/doc/iterator_facade.html#interoperability>), the euqal() function must be templatized. The problem is that I have to make equal() a pure virtual member function in order to force derived types override it, but templated virtual functions on the other hand, are not valid. So I was wondering what the best approach is. How can I achieve both of these goals? Please advise. Any ideas/suggestions are welcome. Thanks in advance

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[signals] callback for synchronization, how to do?
by Rainer Thaden 10 Mar '08

10 Mar '08

Hi all, maybe a simple question, but I just can't figure it out: I have a class which triggers an action on a remote device. A different thread polls for the response and sends a signal that the response has arrived. What I simply want is a blocking call like this: // connect to the signal which reports the response otherClass.sigResponse().connect( some sort of lamda magic?) SendCommand(cmd); // Wait somehow until the response has arrived WaitForSigResponse(); return; Any help appreciated. Thanks, Rainer

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remove_copy_if adapted as copy_if
by PJ Durai 09 Mar '08

09 Mar '08

Can anyone with advanced template-fu show me to an adaptation of remove_copy_if to be copy_if ? I do realize you just have to negate the predicate parameter of remove_copy_if. I would prefer to use a function that does that automatically, since the code would be easier for my co-workers to follow. thanks pj

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