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[Fusion] The real, real basics!
by Robert Jones 07 Sep '10

07 Sep '10

Ok, I know this is going to be laughably simple, but I think I'm making a right hash of it... For the cerebrally challenged, how do you write the specification of a function which takes any fusion vector, but only a fusion vector, as a parameter? Thx - Rob.

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[Boost.Test] TestDox output format
by Martin Moene 07 Sep '10

07 Sep '10

Dear Gennadiy and other readers, Recently I've been looking around for TestDox support for various programming languages and testing frameworks (http://en.wikipedia.org/wiki/TestDox) TestDox provides an agile way to document a project's evolving design and code by giving an overview of the suite names and test names (with test success or failure) as sentences as in: prompt>main.exe --log_level=all Running 4 test cases... example [x] Passing test reports x [ ] Failing test reports space [ ] Throwing test reports space MySuite [x] Passing test in my suite reports x *** 2 failures detected in test suite "example" To learn how this may work out under Boost.Test, I transformed the compiler_log_formatter into a simple testdox_log_formatter, see http://www.eld.leidenuniv.nl/~moene/Home/projects/testdox/. Now my question is: Would it be worthwile to add a testdox_log_formatter to the Boost.Test library itself? Best regards, Martin

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looking for some help to find some functionality
by Jeff T 07 Sep '10

07 Sep '10

Dear All, I'm new to boost, and trying to use it in an on-going development. I'm looking for some functionality but I was not able to find them in boost. I appreciate your help, comments, and suggestions. Functionality I'm looking for: 1. A way determine whether a value is not a number (eg. System.Double.IsNaN(double) in C#) 2. A way to determine if a number if infinity (eg. System.Double.IsInfinity(double) in C#) 3. Availability of Normal Density Function, Cumulative Normal Density Function, and Inverse Cumulative Normal Density. Thank you. Jeff

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thread mutex problem
by Kraus Philipp 07 Sep '10

07 Sep '10

Hi, I'm new with boost thread, I have some problems. I have got two methods, one for writing and one for reading my data and I would do this thread-safe. I have tried to do this with boost::unique_lock<boost::shared_mutex> lock(...), but I have created a deadlock. For example my methods are called within the threads and set / get data to / from a ublas matrix. void setData( const size_t row, const size_t col, const size_t data) { (1*) _matrix(row, col) = data (2*) } and getData( const size_t row, const size_t col, size_t& a, size_t& b) { a = _matrix(row, col); b = _matrix(col, row); } How can I do both methods in the correct way thread-safe? By reading the matrix data the write method need not to change the values. I have created a unique lock on (1*) and do the unlock on (2*) but this creates the deadlock. Then I have tried it with a scoped_lock on (1*) but the data in the matrix is wrong. I hope that someone can explain me the correct solution. Thanks a lot Phil

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[any] Is it possible to support polymorphism in boost::any?
by Tang Jiang Jun 07 Sep '10

07 Sep '10

Hello, It seems that boost::any does not support polymorphism in the following sample. class A {}; class B : public A {}; void foo( boost::any& _any ) { try { A* p = any_cast< A* >( _any ); <-- Only succeed when _any contain a pointer to a object that is exactly class A, but not any object that is descendant of class A, like B. do_some_thing( p ); } catch( const bad_any_cast& ) { } } void goo() { A* pa = new B; boost::any a = pa; foo( a ); } Is it possible to make it support this polymorphism usage? Because boost::any is a type-safe replacement of void*, I hope that boost::any has the same polymorphic behavior as void*. Regards, Tang Jiang Jun

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How to store on exception object ?
by Timothy Madden 07 Sep '10

07 Sep '10

Hello In a callback function I need to store and save an exception object for until the callback is finished and the control is returned to my application code. The callback is invoked by the C language code in minizip library from zlib-1.2.3 contrib directory, and I need to throw the exception when control returns to my application invoking minizip functions. This is true for any exception that might get thrown and caught in my callback, so I would like to do that for any exception type. However how can I store a thrown object for later re-throw without the actual exception type ? Is there a way to do that ? Thank you, Timothy Madden

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Re: [Boost-users] [MSM] stack overflow happens when there is a false-guard anonymous transition
by Christophe Henry 06 Sep '10

06 Sep '10

Hi Michael, It's always nice to hear from you and have an interesting UML discussion with an expert! > I hope you are well. You know how I like to dig into this stuff... so > I'll give my thoughts. They are tainted by the the UML predecessor; > however, I think there is good logic and possibly even a specification > argument for my point of view. > > UML 2.2 Superstructure section 15.3.14 [Transition] provides the > associations for: > > trigger : Trigger[0..*] -- I am assuming that no trigger is what > you are referring to as > an anonymous transition. I don't see > that term used in current > specifications anymore. > > guard: Constraint[0..1] -- "A guard is a constraint that provides > a fine-grained control > over the firing of the transition. The > guard is evaluated > when an event occurrence is dispatched > by the state machine. > If the guard is true at that time, the > transition may be > enabled; otherwise, it is disabled. > Guards should be > pure expressions without side effects. > Guard expressions > with side effects are ill formed." > > > I would argue that the definition of the guard constraint requires that > the transition is evaluated when an event is dispatched and is only > evaluated once for that event. Because the transition is disabled if the > guard evaluates false, then the transition cannot be evaluated again > until another event is dispatched. I think your interpretation makes sense. Agreed. > I would also argue that the system is considered stable once evaluation > of an event begins. Guards are not allowed to cause side effects; > therefore, the 'state' of the system when evaluation begins should be > the same as when evaluation has completed if no transition is taken. Agreed again. > Personally, the least surprising thing (imnsho) would be that: > > 1. event is dispatched > 2. internal transitions are evaluated for current state > 3. external transitions are evaluated for current state > 4. hierarchy is followed up and 2/3 repeated > 5. if top is reached without satisfying event ... an error has > occurred and is acted upon as normal This is what is implemented for all events except for what the standard calls "Completion Events" (also called anonymous transitions in an UML book from the Booch/Rumbaugh collection). > I do not think whether a trigger is defined or not for a transition will > affect this behavior. Transitions without a trigger are simply > candidates for any event. The steps outlined above are those used for > transitions with triggers, no? I agree on the first part and disagree on the second. So, I took from the standard: "A completion transition is a transition originating from a state or an exit point but which does not have an explicit trigger, although it may have a guard defined. A completion transition is implicitly triggered by a completion event. In case of a leaf state, a completion event is generated once the entry actions and the internal activities (“do” activities) have been completed. If no actions or activities exist, the completion event is generated upon entering the state. If the state is a composite state or a submachine state, a completion event is generated if either the submachine or the contained region has reached a final state and the state’s internal activities have been completed. This event is the implicit trigger for a completion transition. The completion event is dispatched before any other events in the pool and has no associated parameters. For instance, a completion transition emanating from an orthogonal composite state will be taken automatically as soon as all the orthogonal regions have reached their final state. If multiple completion transitions are defined for a state, then they should have mutually exclusive guard conditions." So you are right and I should handle them like any other event. OTOH, the standard does not see them as a candidate for any event but as an implicit event which I have to trigger after the target state entry behavior. If a transition without an explicit trigger (event) is defined, it fires. And I should generate it only once, thus avoiding the overflow. What you suggest is a kind of an "any" take-all event, which I also find a good idea (I do not remember seeing it in the standard, but a good idea should be implemented if possible). The part of the standard which I find unpracticable is, if the guard rejects the completion event, how do we move out of this case? If I follow the standard, we would need to reenter a state, which means we would need a dummy event (not nice). This is why I suggest a process_completion() which would simply resend a completion event. Ok? Thanks for your (as usual) helpful insights, Christophe PS: reading again, I see that there is another implementation error in the current implementation, completion events have a lower priority than the event queue, I will change this on the way too.

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[asio] Close file descriptors on exec.
by Rok Breulj 06 Sep '10

06 Sep '10

Why does boost.asio not set its file descriptors to close on exec? (in 1.42, but didn't see any changelogs or tickets mentioning it).

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[MSM] stack overflow happens when there is afalse-guard anonymous transition
by Christophe Henry 06 Sep '10

06 Sep '10

>When start() got called in main(), it will enter a endless reentering between state_machine::process_event() and >state_machine::handle_eventless_transitions_helper::process_completion_event(). Finally it caused a stack overflow. > > >Could somebody please help me to fix this problem? I just committed a tentative fix into the trunk: - completion events are only tried if the previous transition was successful. This should prevent the overflow and some border cases. - calling fsm.process_completion() will retry the completion event if the guard returned false. The event is sent only once for every call of process_completion() - the completion events are, standard conforming, tried before the event queues If it works and we all agree this is the right solution, I will keep it. Thanks, Christophe

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A question about "prim_minimum_spanning_tree.hpp"
by 王伟 06 Sep '10

06 Sep '10

Hi, I'm studying MST algorithms in GPU recently.I need BGL implementation as coparison,But I have a problem in using prim_minimum_spanning_tree.hpp.The problem is:when I use large input(e.g. >1M),there's a "segmnetation error" problem.But when the input(e.g. 1K) is small,the result is noproblem. I haven't found know the reason yet.My complier is gcc 4.1.2,OS is RHEL5. Help would be appreciated. Thanks in advance. Wang wei The complete code is in the attachment.

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