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

serialization and ::copyFrom
by Andrei Popa 25 Mar '08

25 Mar '08

Hi there, I have a small hierarchy of classes that are serializable. I wanted to implement in base class a ::copyFrom method that can copy any data from a pointer to "this" object. The idea behind was to save the "from" pointed object to an archive and then restore the saved data in "this". Saving the input pointer was not a problem but restoring the data in "this" object was a really problem. Since loading *this will call ::load of a base class, I created an temporary shared_ptr around "this". This way the appropriate ::load of the derived class was called. But unfortunately after executing "iarchive >> p;" the px of p doesn't point anymore to "this". I don't know why? Basic code looks like: baseClass::copyFrom (const BaseClass* from) { //save *from //restore the saved data in "this" boost::shared_ptr<baseClass> p(this, baseClass::pseudo_deleter()); iarchive >> p; } pseudo_deleter dose nothing. Does anybody know way this happen? Has anybody a better idea how to implement this method? I tried also to replace the shared_pt with shared_from_this but the results are the same. An other problem that I ignored for the moment is that the used archive should be a kind of memory stream that has no file/disk operations behind. Tia, Andrei _________________________________________________________________ News, entertainment and everything you care about at Live.com. Get it now! http://www.live.com/getstarted.aspx

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Re: [Boost-users] [Mutex] behaviour??
by Sakharuk, Vlad (GMI Development) 25 Mar '08

25 Mar '08

I think u are crashing not because of mutex. The problem is here: iter.next (...) != 0 ; should be iter.next != ... end() -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Yasmina Berber Sent: Tuesday, March 11, 2008 8:05 AM To: boost-users(a)lists.boost.org Subject: [Boost-users] [Mutex] behaviour?? Hi, everybody I have a problem to understand mutex behaviour in a server client program . basically there are two threads that execute different code in two different classes but manipulate the same resource: fisrt Class is Subscriber with these members : public: ACE_Unbounded_Set<client_reference> m_set; typedef boost::recursive_mutex Mutex; typedef boost::recursive_mutex::scoped_lock Lock; Mutex mutex_set; and methods: Subscribe (client_reference) : inserts (add) a reference client to the set { ... Lock theScope( mutex_set); m_set.insert (client_reference) ... } Unsubscribe(client_reference) : removes a reference client from the set { ... Lock theScope( mutex_set); m_set.remove (client_reference) } the second class is Manager that has a shared pointer to Subscriber (SubscriberPtr) and does a specific opeartion on each client_reference inside a for loop in the method Manage() { boost::recursive_mutex::scoped_lock scoped_lock(subscriberPtr->mutex_set) for (Subscriber::Set_Iterator iter (subscriberPtr->m_set); iter.next (...) != 0 ; iter.advance ()) { specific opeartion on each client reference } } What happens is that a client can be removed (call to Unsubscribe()) by the first thread during the second one is executing manage() : the set is not well protected and this causes of course seg fault. I probably do something wrong, If you need more details please let me know. Regards. _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users -------------------------------------------------------- This message w/attachments (message) may be privileged, confidential or proprietary, and if you are not an intended recipient, please notify the sender, do not use or share it and delete it. Unless specifically indicated, this message is not an offer to sell or a solicitation of any investment products or other financial product or service, an official confirmation of any transaction, or an official statement of Merrill Lynch. Subject to applicable law, Merrill Lynch may monitor, review and retain e-communications (EC) traveling through its networks/systems. The laws of the country of each sender/recipient may impact the handling of EC, and EC may be archived, supervised and produced in countries other than the country in which you are located. This message cannot be guaranteed to be secure or error-free. This message is subject to terms available at the following link: http://www.ml.com/e-communications_terms/. By messaging with Merrill Lynch you consent to the foregoing. --------------------------------------------------------

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Re: [Boost-users] template int argument
by Sakharuk, Vlad (GMI Development) 25 Mar '08

25 Mar '08

Compiler does optimize it away. But it should compile it first to validate correctness of the code. Btw on "g++ (GCC) 3.4.6 20060404 (Red Hat 3.4.6-3)" I do not see those warnings. I also prefer to use: if(n==2) if(n==3)//without else. -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Hicham Mouline Sent: Tuesday, March 18, 2008 2:56 PM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] template int argument That's what I thought... What forbids the compiler from optimizing away the test on n value, during the template instantiation process? Thanks, -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Steven Watanabe Sent: 18 March 2008 18:47 To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] template int argument AMDG Hicham Mouline wrote: > hi, > > I have a template function <typename cT, typename tT, int n> { > .... > double array[n]; > > if (n==2) > binomial code > else if (n==3) > trinomial code (array[0] array[1] array[2]) > else > .... > > > compiler tries to compile the "trinomial code" code even when the > template > is instantiated with n=2, > and that gives warnings because of array[2] > > Is there a way to make the compiler ignore the non-binomial code ? > rds, You'll have to split it out into a separate function and use template specialization/overload resolution. template<int n> void do_n_specific_code(double (&array)[n]); template<typename cT, typename tT, int n> void f() { double array[n]; do_n_specific_code(array); } In Christ, Steven Watanabe _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users -------------------------------------------------------- This message w/attachments (message) may be privileged, confidential or proprietary, and if you are not an intended recipient, please notify the sender, do not use or share it and delete it. Unless specifically indicated, this message is not an offer to sell or a solicitation of any investment products or other financial product or service, an official confirmation of any transaction, or an official statement of Merrill Lynch. Subject to applicable law, Merrill Lynch may monitor, review and retain e-communications (EC) traveling through its networks/systems. The laws of the country of each sender/recipient may impact the handling of EC, and EC may be archived, supervised and produced in countries other than the country in which you are located. This message cannot be guaranteed to be secure or error-free. This message is subject to terms available at the following link: http://www.ml.com/e-communications_terms/. By messaging with Merrill Lynch you consent to the foregoing. --------------------------------------------------------

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Matching wildcards
by Dilts, Daniel D. 25 Mar '08

25 Mar '08

Using Boost.Filesystem, is there a way to get a list of all of the files that match a wildcard pattern, such as image*.* ? This e-mail transmission contains information that is confidential and may be privileged. It is intended only for the addressee(s) named above. If you receive this e-mail in error, please do not read, copy or disseminate it in any manner. If you are not the intended recipient, any disclosure, copying, distribution or use of the contents of this information is prohibited. Please reply to the message immediately by informing the sender that the message was misdirected. After replying, please erase it from your computer system. Your assistance in correcting this error is appreciated.

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[enable_if] Type choices
by Robert Dailey 25 Mar '08

25 Mar '08

Hi, I have a simple template function that takes one argument. For example: template< typename t_type > void foo( t_type param ) { } I want to restrict the type of t_type to a certain subset of types, such as 'char' or 'wchar_t'. If the user passes in any type other than those two types, the compiler should not be able to find an overload for foo() that matches the argument types. Note that I would also be using boost::enable_if to test this condition, however I do not see anything in type_traits or anywhere else to perform such a test. I thought of using mpl::vector to create a list of types the function would take and using enable_if to check if the type is in the container, but this seems like a lot of work. I want to see if there is a simpler, more compact solution. Thanks.

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[python] Extending: Understanding ownership of pointers
by Robert Dailey 25 Mar '08

25 Mar '08

Hi, I had a bit of trouble deciding which mailing list to post this question (Python or boost). I decided to post it here since the way I'm extending is boost-specific, however the fundamental question is in regards to how Python internally handles ownership. I do not feel there is a perfect location for this question, so I hope you'll forgive the semi-off topicness of the question. Right now I'm exposing a function to Python that returns a pointer to a custom object owned by a third party library. In most cases I can manage to use boost::shared_ptr when I'm returning pointers, however since this is a third party library I cannot do this. Since the pointer I'm returning is owned and managed by another object, I gave my def() the following return policy: return_value_policy<reference_existing_object>() I simply assumed this was correct. How does Python handle the pointer to this object? Is there some documents in either boost or the python documentation that I can read to understand a little more about how Python handles object ownership when the Python objects really represent C++ pointers? Perhaps someone could give me a brief rundown on the concept. Thanks in advance.

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[python] Py_Finalize(): To call, or not to call?
by Robert Dailey 25 Mar '08

25 Mar '08

Hi, I remember reading in the boost documentation a while back that Py_Finalize() should not be called when using Boost.Python to embed or extend python. I cannot find that documentation again, unfortunately. Is this a true statement or is it safe to call Py_Finalize()? If not, why can this not be called? How does Boost.Python handle finalizing the interpreter? Thanks.

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serialization & registration questions
by Jerry 25 Mar '08

25 Mar '08

Is there a direct way to check if a class is registered correctly? And why would this differ when using binary/XML mediums? My binary serialization problem persists (sorry!) when using fast_binary_archive though the same works when using the XML serializer. Also I thought I'd try and see what happens when using an archive implemented from scratch according to the boost docs. Is the implementation section of the archive class reference up to date with 1.34.1 ? I was getting hard to decipher template error messages using VC++ 7.1 SP1. Thanks.

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BGL: Copy constructor for Boost graphs
by Ethan Kim 25 Mar '08

25 Mar '08

Hi, I have a question on the copy constructor for boost graphs. When I make a copy G of a graph D as follows: Graph G(D); It makes a deep copy of D, correct? If so, is there a way to maintain a map from vertices in G to vertices in D, and vice versa? Or is this something I have to do manually with std::map? It seems that the copy constructor (as above) is quite time-consuming.. Thanks for any help in advance! -- Ethan DH Kim

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tokenizing with xpressive
by Dilts, Daniel D. 24 Mar '08

24 Mar '08

I'm trying to tokenize lines of a file using the included static regex. I only care about the tokens indicated by s* = ... When I use the sregex_token_iterator to parse the lines, I only get the last match for s2 and s3. How should I change things so that I can get every match for s2 and s3 rather than just the last match? sregex whitespace_regex = *_s; sregex line_regex = whitespace_regex >> (s1 = +_d) >> whitespace_regex >> ( +( '\"' >> (s2 = *~as_xpr('\"')) >> '\"' >> whitespace_regex >> ':' >> whitespace_regex >> '\"' >> (s3 = *~as_xpr('\"')) >> '\"' >> whitespace_regex ) | +( '\"' >> (s2 = *~as_xpr('\"')) >> '\"' >> whitespace_regex ) ); This e-mail transmission contains information that is confidential and may be privileged. It is intended only for the addressee(s) named above. If you receive this e-mail in error, please do not read, copy or disseminate it in any manner. If you are not the intended recipient, any disclosure, copying, distribution or use of the contents of this information is prohibited. Please reply to the message immediately by informing the sender that the message was misdirected. After replying, please erase it from your computer system. Your assistance in correcting this error is appreciated.

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