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Re: [Boost-users] [statechart] Can events carry data?
by BRIDGES Dick 14 Sep '05

14 Sep '05

Sorry about the delay - got sidetracked by work. ;) Your clarifications were a great help. Many thanks for the library *AND* the help! Regards, Dick > -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > Andreas Huber > Sent: Wednesday, August 31, 2005 2:57 PM > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] [statechart] Can events carry data? > > > BRIDGES Dick wrote: > > I'm still not clear on the requirements surrounding such an > > instance. For example, the reference requires that > > <code>new E(*pCE)</code> be well-formed and make "a copy of > > pE". > > Maybe I should have described that differently. That row in the table > translates as follows: > 1. event<> subtypes must have a publicly accessible copy constructor > (compiler-generated or not) > 2. If overloaded, operator new must be publicly accessible > > Since the library only requires the quoted expressions be > well-formed, > it is up to you to define the semantics of the copying. What the > copy-ctor actually does is of no concern to the library. > > > Does the current implementation work ok with > > boost::shared_ptr? > > I assume you mean shared_ptr<> instances as members of > events? I don't > see any problems here. > > > How about auto_ptr? > > That should work if you define a copy-ctor that transfers > ownership to > the copy. > > > If a data member > > would normally require a deep copy, would I be better off > > managing it external to the event object > > I'm not sure I understand the question. I don't see how you > would manage > that data-member externally; you don't mean a global > variable, do you? > Also, are we talking about a single-threaded or an MT system? > > > - or avoiding that > > type of data altogether? How many copies are we talking > > about here? > > Events that the user allocates with new are never copied. > Stack-allocated events are copied exactly once only if they are > deferred. See Step 8 here: > > http://boost-sandbox.sourceforge.net/libs/statechart/doc/refer ence.html#process_event > Any cautions and/or advise regarding the use of data members > in events would be appreciated. The library does not introduce problems that wouldn't exist otherwise. In an ST system everything should "just work" without you spending any thought on copying, other than that a reaction might be working with the original *or* the copy of the event. In an MT system the usual precautions against race-conditions, deadlocks, etc. apply. If it is too costly to deep-copy everything in the event, you must ensure that multiple threads accessing the shared part are appropriately locking mutexes, etc. HTH, -- Andreas Huber When replying by private email, please remove the words spam and trap from the address shown in the header. _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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Re: [Boost-users] Scons users?
by Thore Karlsen 14 Sep '05

14 Sep '05

On Tue, 13 Sep 2005 18:46:08 +0500, Alex Besogonov <cyberax(a)elewise.com> wrote: > >> On the Boost.Build list we were just discussing the fact that some > >> people otherwise inclined towards Boost have chosen Scons over > >> Boost.Build. It would be useful for us to understand some of the > >> reasons why, if some of you wouldn't mind letting us know. No flames, > >> please! >Well, SCons supports distributed building and binary repositories - >that's a MAJOR selling point. And Python is much nicer than jamfiles. > >PS: there's also mxx_ru (http://eao197.narod.ru/mxx_ru/) it's a build >system based on Ruby - it has some interesting features worth attention. >Unfortunately, its documentation is only in Russian, but this should not >be a problem for Vladimir Prus :) Another Python-based build system I like a lot is A-A-P (http://www.a-a-p.org) I haven't played much with SCons, but judging from the SCons documentation, A-A-P is a lot more powerful. I've found A-A-P to be indispensable for my builds, as well as other things like web page publishing. -- Be seeing you.

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locate a vertex by the index
by Giulio Veronesi 14 Sep '05

14 Sep '05

Hi, Excuse me for the very trivial question, but I'm new with boost and I'm looking for help. How I can locate a vertex of a graph by the index of the vertex? Thanks a lot in advance, Giulio

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boost libs dlls
by ned stoyanov 14 Sep '05

14 Sep '05

I am trying to introduce boost to my current company. I was wandering whether using boost requires linking against any libraries or is it all used like the STL simply by including header files. I've used some parts of boost before, which didn't require to link against anything but I want to make sure so I can package it up properly for other ppl to use. Cheers, Ned

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Re: [Boost-users] Scons users?
by Merrill Cornish 14 Sep '05

14 Sep '05

Parveen, Thank you. That's an excellent factual reference. Merrill

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Beyond the C++ Standard Library: An Introduction to Boost
by Bjorn.Karlsson＠readsoft.com 14 Sep '05

14 Sep '05

Dear All, A long time ago, I came here--to the Boost developers and Boost users mailing lists--asking for help with reviewing a book about the Boost libraries. Your response was fantastic. Back then, I concluded my email with saying thanks to all Boosters; for the libraries, the ideas, the research, the discussions, and the enthusiasm. Today, when the book is finally shipping, I'd like to extend that thank you to the Boosters who helped make "Beyond the C++ Standard Library" reality. Beman Dawes, Rob Stewart, David Abrahams, Aleksey Gurtovoy, David Brownell, Douglas Gregor, Duane Murphy, Eric Friedman, Eric Niebler, Fernando Cacciola, Frank Griswold, Jaakko Järvi, James Curran, Jeremy Siek, John Maddock, Kevlin Henney, Michiel Salters, Paul Grenyer, Peter Dimov, Phil Boyd, Ronald Garcia, Thorsten Ottosen, Tommy Svensson, and Vladimir Prus; thank you all so much! I sincerely hope that I am giving something back to the amazing Boost community through this book. Best regards, Björn Karlsson

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Re: [Boost-users] Scons users?
by Sohail Somani 13 Sep '05

13 Sep '05

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > Foster Gareth > Sent: Tuesday, September 13, 2005 10:47 AM > To: boost-users(a)lists.boost.org > Subject: Re: [Boost-users] Scons users? > > > I suppose in terms of scons and boost, then next question is > how easy is it > to build rpm/deb packages etc when using these build systems? > Its very easy > with autotooled projects. I think this is an area where scons is lacking. Its great in building, but not so good at deployment.

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Putting together boost::any, mpl::vector, iterator::filter_iterator
by Stephen Gross 13 Sep '05

13 Sep '05

I've put together a class called 'AnyVector' for doing type-based iteration on a vector. The basic idea is that AnyVector wraps a std::vector<boost::any>. The AnyVector lets you iterate across a subset of the underlying vector by using filter_iterators. The filter iterators, in turn, dereference to the requested type for ease of use. For instance, you can do the following: === CODE === AnyVector<> a; a.push_back(1); a.push_back(std::string("hello")); a.push_back(2); a.push_back(std::string("goodbye")); for(AnyVector<>::Iterator<int> i = a.begin<int>(); i != a.end<int>(); ++i) std::cout << (*i + 5); for(AnyVector<>::Iterator<std::string> i = a.begin<std::string>(); i != a.end<std::string>(); ++i) std::cout << i->length(); ============ Furthermore, you can restrict (at compile-time) which objects are allowed to be inserted into the AnyVector. This is done by listing those types when you create your AnyVector: === CODE ==== AnyVector<int, std::string> a; // Only allows int's and string's a.push_back(3.5); // Fails at compile time - double's not allowed! ============= Would this be a useful addition to boost, or does it already exist somewhere in boost and I just missed it? --Steve Stephen Gross Case Western School of Medicine Cleveland, OH "By Grabthar's hammer, by the sons of Worvan, you shall be avenged." - Dr. Lazarus

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Filter_iterator and boost::any follow-up
by Stephen Gross 13 Sep '05

13 Sep '05

>I think you'll need to use something like: >for(filter_itr f(i.begin(), i.end()); f != filter_itr(i.end()); ++f) Ok, cool, I've got it working on a vector of ints. My next question is this: I've got a vector of boost::any's, and I want to iterate across only the boost::any's representing int's. For example: === CODE === template<typename T> struct isT { bool operator() (const boost::any & a) const { return a.type() == typeid(T); } }; int main() { std::vector<boost::any> av; av.push_back(1); av.push_back(std::string("hello")); av.push_back(2); typedef boost::filter_iterator<isT<int>, std::vector<boost::any>::iterator > int_itr; for(int_itr itr(av.begin()); itr != int_itr(av.end()); ++itr) ; } ========= Unfortunately, the above code seg faults when executed. I imagine I've probably constructed my filter_iterator incorrectly somehow. Any ideas? Thanks, --Steve Stephen Gross Case Western School of Medicine Cleveland, OH "By Grabthar's hammer, by the sons of Worvan, you shall be avenged." - Dr. Lazarus

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Newbie question on filter_iterators
by Stephen Gross 13 Sep '05

13 Sep '05

Ok, I'm trying to learn the basics of filter_iterators. I've got a vector of ints. I want to iterate across the vector and print out every positive value in the vector. Currently, my code doesn't work because g++ doesn't like me assigning a vector::iterator to a filtered_iterator. Obviously, I've missed some crucial point on how the filtered_iterator is supposed to work. The example code in the boost library doesn't really address this specific use. Can someone show me how to make the code below work as intended? Thanks in advance, --Steve ==== CODE FOLLOWS ==== struct is_positive { bool operator() (int i) { return i >= 0; } }; int main() { std::vector<int> i; i.push_back(-5); i.push_back( 5); i.push_back(-4); i.push_back( 4); i.push_back(-3); i.push_back( 3); i.push_back(-2); i.push_back( 1); typedef boost::filter_iterator<is_positive, std::vector<int>::iterator> filter_itr; for(filter_itr f = i.begin(); f != i.end(); ++f) { std::cout << *f << std::endl; } return 0; }

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