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

[math-toolkit] algorithms for "selfmade" distributions
by Christian Henning 26 Jun '08

26 Jun '08

Hi there, I've models which return distributions as a collection of 2D values ( probability, $ value ). Does the math toolkit offer me algorithms that I could use which such distributions? I look for algorithms to convolve two distributions, resampling, etc. Thanks ahead, Christian

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[program_options] call notify() twice?
by Marty Fried 26 Jun '08

26 Jun '08

My app has a configuration file. We don't know where it will be for sure, so we are planning to make the location of the file a commandline option. So, after reading the commandline option, we will want to parse the config file. Is this a resaonable and legal thing to do? We will need to call the map's notify() function twice, if I interpret it correctly. I suppose I could try it, but I wanted to make sure I didn't use a feature that is not part of the design, and have it disabled on me in the future. -- Marty Fried public.forums(a)gmail.com Left Coast, USA.

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Re: [Boost-users] array deserialization problem
by michalurbanski 26 Jun '08

26 Jun '08

Thanks! I'll do that. As for the vector, I cannot use it cos I operate with SSE on large data structures in memory. Those are the real structures I want to serialize, so I cannot use a vector. Also none of the boost libraries fit my profile for operating on data, so i'll have to stay with the pure pointers. Anyways, thanks again :) Regards, MU. Dnia 26 czerwca 2008 12:37 Matthias Troyer <troyer(a)phys.ethz.ch> napisał(a): > > On Jun 26, 2008, at 9:03 AM, michalurbanski wrote: > > > Thanks for the reply. > > > > Is there any way to make it work if I want to allocate a block of > > memory which size depends on the other serialized elements? > > > > For example, how do I deserialize an object with attribues > > constructed like this: > > > > Test(int a, int b) { > > this->a = a; > > this->b = b; > > this->c = new float[a*b]; > > } > > There are two ways: > > 1. The easiest: you use a std::vector instead of a bare pointer for c > 2. You split serialize into save and load, and allocate the required > memory in the load function before deserializing the array > > I would recommend using a std::vector, unless the overhead in memory > consumption of two integers is a real killer for your application > > Matthias > >

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Help using graph library for bundled properties
by Abde Ali Kagalwalla 26 Jun '08

26 Jun '08

I just started using the graph library..... I want to store a class I created called bbox as vertices of a graph. So, I just used the bundled properties mentioned as mentioned in the documentation. So here is a relevant portion of the code: vector<bbox> A; boost::adjacency_list<vecS, vecS, undirectedS, bbox> G; for (int i=0; i<A.size(); i++){ for(int j=i+1; j<A.size();j++{ add_edge(A[i], A[j], G); }} But bbox is not accepted as a valid vertex_descriptor for add_edge function. So, how do I go about constructing a graph with a class that I defined as a vertex? Thanks, Abde Ali

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Re: [Boost-users] Mixing versions of boost
by dariomt＠gmail.com 26 Jun '08

26 Jun '08

> Why not to introduce an additional level of indirection ;) > Just wrap the 3d-Party lib in a DLL (or Shared Object under Linux), > than you should be find to use 2 libs with each other... Thanks for the idea. I'll give it a try, but ideally the application should be distributed as a single executable file. About versioning the boost namespace, I suppose you mean something like changing boost namespace to e.g. boost_1_35_0. Any thoughts on how much work it would take me to patch a given version of boost to do that? Is it even possible? >On Wed, Jun 25, 2008 at 6:41 PM, David Abrahams <dave(a)boostpro.com> wrote: > Vladimir Prus wrote: >> dariomt(a)gmail.com wrote: >> >>> Hi all, >>> >>> I'm using header-only boost libs in two static libraries that will >>> be linked into an executable. >>> >>> No boost components are used in the interfaces of those libs, boost >>> is only used in the implementation inside the libraries. >>> >>> Is it possible to mix versions of boost in those two static >>> libraries? Will the linker complain, or will it just get confused >>> and mess up the executable? >> >> In general, this is highly risky business. On GCC, each static >> library will contain a copy of every template function used by a static library. >> If the linker finds that the same function is used in both static >> libraries, it will put only one copy in the output executable, and if >> the definitions of those functions differ, you're in trouble. See the >> attached example, which, then run, produces: >> >> a.cpp:say >> a.cpp:say >> >> Which is clearly wrong. This *might* work with shared libraries, but >> you need to consult your toolchain documentation. > > For the past few years we've had a GCC option that allows you to > expose from dynamic libs only those names you specify, sort of like > declspec on Windows. I don't remember the name of the flag, though. >

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Re: [Boost-users] boost shared_ptr and parent child relation
by Lang Stefan 26 Jun '08

26 Jun '08

Terribly sorry, I just posted an answer to this thread without changing the subject line :-( Please check out my recent response titled 'AW: Boost-users Digest, Vol 1672, Issue 5' Sorry again for the inconvenience... Stefan

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Re: [Boost-users] Boost-users Digest, Vol 1672, Issue 5
by Lang Stefan 26 Jun '08

26 Jun '08

Have you seen my previous post on this matter? I suggested extracting the services that your children need to refer to a superclass. You can solve your observer pattern in the same way, and much more elegantly besides. Here's an example: class Notification; // forward declaration - add any details your 'children' want to talk about Template <class Observable> class Observer { public: void register(const Observable* observable); // might call notify() below void unregister(const Observable* observable); // might call notify() below virtual void notify(const Notification* notification) = 0; protected: void stopNotification(); // call to prevent forwarding notifications // ... }; class MyChild; // forward decl. // MyParent definition. // note that for readability purposes I added the method definitions inline, // although they need to be defined after the MyChild definition. Move these // to the implementation file if needed! class MyParent : public Observer<MyChild> { public: MyParent() : m_child(new MyChild(this)) {} ~MyParent() { stopNotification(); delete m_child; } virtual void notify(const Notification* notification); // react to notifications here! // ... Private: MyChild* m_child; }; class MyChild { public: MyChild(Observer* myParent) : m_parent(myParent) { m_parent.register(this); } ~MyChild() { m_parent.unregister(this); } private: Observer* m_parent; }; The Observer base object of the parent will still be valid at least to the point where the MyParent destructor code ends. This means the MyChild object is free to call Observer::unregister(). MyParent's call to stopNotification() makes sure Observer::unregister() does not call MyParent::notify() which may not be valid at this point. Unless I'm missing something important this should work perfectly: Moreover, your Observer pattern implementation is independent from your actual Parent or Child classes and can be reused. Basically, whenever you have a structure where a 'child' needs to acces a specific service from a 'parent', consider whether this service can be extracted into an independent super class or interface like I did above. Hope this helps, Stefan -----Ursprüngliche Nachricht----- Dealing out a weak_ptr to a child, convert it to a shared_ptr when needed does not prevent the parent getting deleted in a next sequence of calls, leading to have a pointer to a child, without an exisitng parent. Other posts where about the need for calling the parent during destruction. Well there is one major case: if a parent is the observer of its child, the destructor of the child is the ideal candidate for unregistering. But in above case it leads to crashes. Although in this case the parent gets destroyed (in which the unregistering at the parent may be superfluous) there may be other observers for the child. All in all if I think about it, it can be solved (through a global register for instance), but not with above described proposal, which was attractive due to local character of the solution (child know only parents, maybe one class more). Then again it seems that c# and a gc wouldn't help in this case either. They break a cyclcic dependency, but it is forbidden to call object references in finalizers. Then again to get at that stage all observing objcts to the child had already give up their referneces, e.g soemthing like (in c++): Parent::~Parent() { std::for_each(m_vChilds.begin(), m_vChilds.begin(), boost::bind(&Parent::Notify, this, _1, eDelete); //type std::vector< boost::shared_ptr<Child> > m_vChilds.clear(); } etc. I know this sounds a little bit over the top, but we develop a pretty large application in our company, where you can not track all pointer of lifetime of object. Ideally a framework would solve lifetiem problems. Boost smart_ptr's help (and do a great job), but not completely. ------------------------------ _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users End of Boost-users Digest, Vol 1672, Issue 5 ********************************************

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Boost.Units and Ublas and Math
by Pat Hawley 26 Jun '08

26 Jun '08

Hi, I have been trying to use ublas with a user-defined numeric type and have been having problems with that--problems with resolving sqrt etc since the sqrt in ublas invokes std::sqrt. I wanted to use the policy and exception handling in the Math library with the ublas class, but I haven't been able to figure out the helper functions that would allow the use of my numeric types. Can this be done? Any suggestions would be appreciated. My next step would be to add units to the numeric values--assuming this can be done in the context of ublas. Is it possible to use Boost.Units and Boost.Ublas together? For example create a ublas vector of positions? What's the best approach for arithmetic operations, units, vectors, matrices, and user-defined exceptions using Boost? Thanks for your help, Pat

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Re: [Boost-users] How can i use boost in mingw in windows XP
by filerz-boost＠yahoo.com 25 Jun '08

25 Jun '08

Hi, ----- Original Message ---- > From: Daniel Krügler <dsp(a)bdal.de> > To: boost-users(a)lists.boost.org > Sent: Wednesday, 25 June, 2008 2:46:28 PM > Subject: Re: [Boost-users] How can i use boost in mingw in windows XP > > wang wenhua wrote: > > Bremen, > > It's easier for all of us, if you just call me Daniel ;-) > > > Thank you very much. > > > > I know how to compiled boost. > > > > But while i am trying "using namespace boost;", there is always > > error. > > Could it be the OP is trying to call 'using namespace boost;" before including any boost header file. I am just trying to fill in the gap till the OP sends the code :-) -dky Unlimited freedom, unlimited storage. Get it now, on http://help.yahoo.com/l/in/yahoo/mail/yahoomail/tools/tools-08.html/

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Possible library submissions: fuzzy logic library, new container
by Alex Shafir 25 Jun '08

25 Jun '08

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