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scoped locks
by Paul Baxter 19 Apr '06

19 Apr '06

Having looked at Boost threads and shmem 0.9 recently, I'm trying to get to grips with a 'scoped lock' ONLY design rationale having laboured under the posix threads APIs for a while. While I appreciate the reasons, I am a little confused ... All the examples I've seen show scoped locks being constructed local to a function and then destroyed automatically at the end of function scope. I would like my own lock manager object to manage a group of locks and allow me to leave one or more mutexes locked across function calls until the lock manager object goes out of scope and releases any mutexes still flagged as locked. Is this possible? e.g. a vector/array/deque of pointers to scoped_timer_locks each relating to its own mutex and constructed as unlocked. I understand that leaving mutexes locked is not a great idea! The application does think it knows what it is doing. Paul

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boost::hash
by george 19 Apr '06

19 Apr '06

hello! I wanna replace an std::map<std::string,Services*> to hash table.How I will do this? in the examples of hash library there are only examples for custom hashing.... there isn't a trivial example!:-) transactions.insert(std::pair<std::string,Services*>("Aservice",new xxxx)); transactions.insert(std::pair<std::string,Services*>("Vservice",new fffff)); transactions.insert(std::pair<std::string,Services*>("Rservice",new ttt)); ............... how I should replace this with a boost 'hashtable'? thanks for any help.

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Re: [Boost-users] [weak_ptr] thread safe?
by John Wilkinson 19 Apr '06

19 Apr '06

There is a pragma in VC6 that will activate or deactivate optimization. It can be used to wrap optimization-sensitive blocks of code. I do not remember what it is, though, and I do not have VC6 handy. I have used it, and it did alleviate an optimization-related bug. John -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Peter Dimov Sent: Wednesday, April 19, 2006 10:45 AM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] [weak_ptr] thread safe? Alain Cormier wrote: > So, can I conclude that it is a bad behavior in boost::weak_ptr? No, it is a bug in VC6. > For now, I have simply changed add_ref_lock to : > > long tmp2 = tmp + 1; > if(InterlockedCompareExchange ( &use_count_, tmp2, tmp ) == tmp2 - 1 ) > return true; > > This way, VC6 doesn't optimise the return value of > InterlockedCompareExchange and the disassembly looks ok. I don't think that there is any guarantee that this modification will reliably produce correct code, even if it happens to work in the examples we try. But if we can't think of a better way to work around the issue, this may be our best bet. _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

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using lambda as function argument.
by chun ping wang 19 Apr '06

19 Apr '06

Heres a simple question, that i want to do. Lets say you have a function call void f(double); and then you want to apply f to each argument inside vector<double> a; for_each(a.begin(), a.end(), f(_1)); // the example above isn't possible..is there a simple way to do this?

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[Xpressive] regex-like boost libraries vs re2c [was: Some timings [was: Baffled about results of search]]
by Lynn Allan 19 Apr '06

19 Apr '06

Stuart Dootson wrote: > Lynn - it might be interesting to use re2c (http://re2c.org/) to > generate regex machines and see what their performance is like - > after > all, they do clain 're2c generates warning free code that is equal > to > hand-written code in terms of size, speed and quality.' (I'm > offering > no opinion on the veracity of that statement....), so (allegedly) > they'd give a reasonable hand-code analogue.... I took a look at it, and it looks like it could possibly be quite useful if executable size was a concern .... but it is pretty obscure (at least to me) .... the only example this dummy could make any sense out of at all was to recognize a number .... and that was missing/obscuring the important illustration of how to invoke and use the generated scanner code. Were you able to get it to work to do anything even close to recognizing Days-of-the-Week (full and abbreviations)? Did you find actual compilable examples with "main" invoking the generated scanners with a test-string to crunch? <alert comment="whining"> I really wish developers would provide COMPLETE "baby steps with training wheels" examples to flatten the learning curve. Eric N. did a great job of documenting and providing examples for xpressive .... that could be a model for other projects (not just boost). I've subscribed to their sourceforge list and will swallow my pride and ask the newbie question: "This dummy doesn't expect to be able to figure out your project in 30 minutes ... how do you get it to something basic like recognize:"? ((Sunday|Sun)|(Monday|Mon)....(Saturday|Sat)) </alert>

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[bgl-python] write graphviz with position property
by David E. Konerding 19 Apr '06

19 Apr '06

Hi, From what I can tell it's not possible to correctly wirte a graphviz file that has a position property (where position is a tuple of xy) using bgl-python. The problem, as I see it, is that the wrapper for write_graphviz in bgl-python writes all the dynamic properties to the graph, but provides no ability to provide custom writer methods for those properties. So the resulting graphviz file prints references to the vertex position *object*, but not its values. Does anybody have a better suggestion? The only think I can see is to update the bgl-python wrappers to take function arguments for custom property writers Dave

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program_options question
by Santosh Joseph 19 Apr '06

19 Apr '06

If I have an option that looks like this: options_description desc("options"); desc.add_options()("server,s",value<string>(&server),""); I know this can parse the following options: --server arg -s arg but how can I also parse the following automatically: -server arg /server arg Is there a style flag to set? I looked at the documentation but I'm a little confused by all the style_t flags. or do I have to write a "additional parser"? thanks, -Santosh btw: i'm using 1.33.1 __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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is there any lib used to parse XML file in boost?
by lanser 19 Apr '06

19 Apr '06

hello, i need a simple xml prasing library, i consider there should be some in boost lib but i can't find it or document for this, help!

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Re: [Boost-users] [boost] [statechart] - BOOST_ASSERTION in state_machine::send_eventif used by multiple threads
by Oliver.Kowalke＠infineon.com 19 Apr '06

19 Apr '06

Same happens if I install a exception_translator in the enclosing state: /opt/boost/include/boost-1_33_1/boost/statechart/state_machine.hpp:833: void boost::statechart::state_machine<MostDerived, InitialState, Allocator, ExceptionTranslator>::send_event(const boost::statechart::event_base&) [with MostDerived = iris::proto::svc::sm<ogx::net::ipv4::stream>, InitialState = iris::proto::svc::proto<ogx::net::ipv4::stream>, Allocator = std::allocator<void>, ExceptionTranslator = boost::statechart::exception_translator<boost::statechart::exception_thr own>]: Assertion `get_pointer( pOutermostUnstableState_ ) == 0' failed. >Hello, >I've several threads running. Each thread has its own state_machine. >Sometime (not reproducible) I get following assertion: > >/opt/boost/include/boost-1_33_1/boost/statechart/state_machine.hpp:833: >void boost::statechart::state_machine<MostDerived, InitialState, >Allocator, ExceptionTranslator>::send_event(const >boost::statechart::event_base&) [with MostDerived = >iris::proto::svc::sm<ogx::net::ipv4::stream>, InitialState = >iris::proto::svc::proto<ogx::net::ipv4::stream>, Allocator = >std::allocator<void>, ExceptionTranslator = >boost::statechart::null_exception_translator]: Assertion `get_pointer( >pOutermostUnstableState_ ) == 0' failed.

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[statechart] - BOOST_ASSERTION in state_machine::send_event if used by multiple threads
by Oliver.Kowalke＠infineon.com 19 Apr '06

19 Apr '06

Hello, I've several threads running. Each thread has its own state_machine. Sometime (not reproducible) I get following assertion: /opt/boost/include/boost-1_33_1/boost/statechart/state_machine.hpp:833: void boost::statechart::state_machine<MostDerived, InitialState, Allocator, ExceptionTranslator>::send_event(const boost::statechart::event_base&) [with MostDerived = iris::proto::svc::sm<ogx::net::ipv4::stream>, InitialState = iris::proto::svc::proto<ogx::net::ipv4::stream>, Allocator = std::allocator<void>, ExceptionTranslator = boost::statechart::null_exception_translator]: Assertion `get_pointer( pOutermostUnstableState_ ) == 0' failed. What does get_pointer( pOutermostUnstableState_ ) != 0' indicate? Regards, Oliver

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