November 2009 - Boost-users

Boost::Pool - Singleton_pool
by Ondrej Sluciak 02 Nov '09

02 Nov '09

Hi, Is there a way on how to derive a class from pool::singleton_pool class? Something like: template<typename T> genericsingleton : boost::singleton_pool<boost::pool_allocator_tag, sizeof(T)> If I want to do this I always get this error: Error 1 error C2248: 'boost::singleton_pool<Tag,RequestedSize>::singleton_pool' : cannot access private member declared in class 'boost::singleton_pool<Tag,RequestedSize>' c:\mycode\boosttest\boosttest\genericsingleton.h 23 Thank you for answer.

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boost::thread on Windows CE?
by Frank Black 02 Nov '09

02 Nov '09

Hi, So I've finally succeded in building some libs I need for Windows CE, using STLPort. One of those libs is thread. It builds fine, but when I try to use it from a simple sample I get some link errors (see below). What I wonder is if threads is even possible to use under WinCE? Looking at the code, theres only a folder for pthreads and one for win32, but inside the win32 files there's some UNDER_CE switches. Anyone had success using it under wince? The link errors I get is: Error 1 error LNK2019: unresolved external symbol tss_cleanup_implemented referenced in function "void __cdecl boost::`anonymous namespace'::create_current_thread_tls_key(void)" (?create_current_thread_tls_key@?A0x78389a16@boost@@YAXXZ) libboost_thread-vc80-mt-sgdp-1_40.lib Error 2 error LNK2019: unresolved external symbol gmtime referenced in function "public: static struct tm * __cdecl boost::date_time::c_time::gmtime(unsigned long const *,struct tm *)" (?gmtime@c_time@date_time@boost@@SAPAUtm@@PBKPAU4@@Z) libboost_thread-vc80-mt-sgdp-1_40.lib Thanks!

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[serialiization] Database archive
by Pascal Kesseli 02 Nov '09

02 Nov '09

Hi everyone Currently, I am planning to apply the boost serialization library to my entity objects for allowing me to serialize them to XML for transmission over SOAP. I would also very much appreciate the possibility to store these entities in a relational database, if possible without any additional effort. Thinking of this, the possibility of creating an sqlite implementation of the archive class came to my mind. Is the archive interface suitable for such a task, thinking of issues like primary key management and so on? Or does such an implementation already exist? Thank you for any recommendations and best regards Pascal

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[thread] About the virtual in virtual operator()
by Richard Vock 02 Nov '09

02 Nov '09

I don't really know wether this is a Boost.Thread related question or a general c++ related, but since I couldn't decide I will disturb you first ;) Maybe you have the patience to look at this minimalistic framework (I stripped almost all functionality): http://pastebin.com/m7dcc833f This compiles well and running it gives me the expected: # starting # This is A # This is B # shutting down The problem is, that I want to run the kernels as threads. Have (again) a look at the highlighted lines (27-29): If I replace 27 by 28+29 I (expectedly) get a compile error since Kernel is abstract. However if I make it non-abstract by implementing the operator() in it, it is this function (namely Kernel::operator()) which get's called instead of TestKernel::operator(). Note that Program will not be able to know about the concrete child classes of Kernel so it cannot dynamic_cast<ConcretKernel*> the pointers and I don't want to use maschine-specific ways like __decltype. I imagine this is merely the old non-static member function pointer problem, however I tried dozens of ways to get around this and the only thing that worked was to add a ConcreteKernel::run() { thread t(*this); t.join(); } to *each* single child class of Kernel which gets rather un- managable with 50 and more descendants. I hope that made sense and that I didn't fail that hard, Richard Vock

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[Spirit] xml parse tree printing double leaf node
by HT4N - 02 Nov '09

02 Nov '09

When I generating parse tree and dump it using the built-in tree-to-xml function, even from a simple grammar, I wonder why it prints out the leaf node twice. For instance: Parameter = ParameterName >> ParameterValue; The tree it prints it looks more or less like the following (note the repetition of ParameterName and ParameterValue nodes): <Parameter> <ParameterName> <ParameterName> <value>Foo</value> </ParameterName> </ParameterName> </ParameterValue> <ParameterValue> <value>Bar</value> </ParameterValue> </ParameterValue> </Parameter> I would be expecting more something like: <Parameter> <ParameterName> <value>Foo</value> </ParameterName> </ParameterValue> <value>Bar</value> </ParameterValue> </Parameter> Is there any directive or secret that I don't know ? Thanks HT _________________________________________________________________ Windows 7: I wanted more reliable, now it's more reliable. Wow! http://microsoft.com/windows/windows-7/default-ga.aspx?h=myidea?ocid=PID247…

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Boost Functionality question: Explicit dynamic library loading
by Sarbak, Joseph 01 Nov '09

01 Nov '09

Hello, I'm curious to know whether boost has support for explicitly loading shared libraries in a cross-platform fashion. I have done my own search of the 1.40.0 boost code base and could not find any abstraction around dlopen,dlsym,dlclose and their equivalents on windows. While it would be easy for me to write wrappers around this functionality, I would prefer to use something in boost if already available. Thank you and regards, Joe Sarbak ________________________________________ This E-Mail (including any attachments) may contain privileged or confidential information. It is intended only for the addressee(s) indicated above. The sender does not waive any of its rights, privileges or other protections respecting this information. Any distribution, copying or other use of this E-Mail or the information it contains, by other than an intended recipient, is not sanctioned and is prohibited. If you received this E-Mail in error, please delete it and advise the sender (by return E-Mail or otherwise) immediately. This E-Mail (including any attachments) has been scanned for viruses. It is believed to be free of any virus or other defect that might affect any computer system into which it is received and opened. However, it is the responsibility of the recipient to ensure that it is virus free. The sender accepts no responsibility for any loss or damage arising in any way from its use. E-Mail received by or sent from RBC Capital Markets is subject to review by Supervisory personnel. Such communications are retained and may be produced to regulatory authorities or others with legal rights to the information. IRS CIRCULAR 230 NOTICE: TO COMPLY WITH U.S. TREASURY REGULATIONS, WE ADVISE YOU THAT ANY U.S. FEDERAL TAX ADVISE INCLUDED IN THIS COMMUNICATION IS NOT INTENDED OR WRITTEN TO BE USED, AND CANNOT BE USED, TO AVOID ANY U.S. FEDERAL TAX PENALTIES OR TO PROMOTE, MARKET, OR RECOMMEND TO ANOTHER PARTY ANY TRANSACTION OR MATTER.

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Re: [Boost-users] Debugging memory corruption? (C++)
by Marshall Clow 01 Nov '09

01 Nov '09

On Nov 1, 2009, at 10:33 AM, Jean-Denis Muys wrote: > >> Followup on my memory corruption bug: >> >> I got a few suggestions (thanks everybody): >> >> - a memory watch point: I may be able to use that idea, but so far, I >> could not clearly identify a fixed location that's corrupted. >> - Guard Malloc: I have a machine that I started about 12 hours ago >> with Guard Malloc enabled. The host app hasn't finished launching >> yet. >> - Valgrind: I still have 10.5 running on a Mac mini, so I started the >> host app under Valgrind. It's veryyyy slow. Still running. >> - static analyzer: it doesn't detect anything wrong (but of course, >> my >> code is C++). >> >> I also wanted to report that I made some significant progress on how >> to call malloc heap checking facility at will. > > I managed to "fix" the memory corruption bug I had. Actually, I > still don't understand why it used to crash and not anymore. This is > a rather peculiar situation, that you might find interesting. > > The following idiom corrupted memory: > > long bad() > { > [...] > > sql::ResultSet *results = preparedStmt->executeQuery(); > > [...] > > delete results; > zoneCheck(); > > return result; > } > > While this one runs fine and nice: > > long good() > { > [...] > > std::auto_ptr<sql::ResultSet>results(preparedStmt->executeQuery()); > > [...] > > zoneCheck(); > > return result; > } > > > Since all std::auto_ptr does is to call delete on its internal > pointer when it goes out of scope (even in case of an exception), I > am still totally puzzled by this behaviour. > > As an aside, the library behind all this is mySQL's C++/Connector. > > I'd be interested by a possible explanation: my C++ is not sharp (no > pun, really) enough to grasp all the subtleties. Well, in the first case delete is called *before* zoneCheck, and in the second, it is called *after*. To me, that suggests that looking at the destructor for sql::ResultSet. -- Marshall

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[regex] Using Boost.Regex rather than std::regex with VC++
by Ahmed Charles 01 Nov '09

01 Nov '09

I'm using VC2010, which provides an implementation of std::regex/std::tr1::regex and boost gladly uses this implementation rather than it's own. I'd like to turn this off, so that I get the boost version when including: #include <boost/regex.hpp> Thanks in advance.

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bad_any_cast being thrown but no idea why
by John Yamokoski 01 Nov '09

01 Nov '09

I have been pulling my hair out over this bug for a day or two now. Here's the synopsis. I have a boost::any object which is storing a std::string. Any test I do to check if indeed the any object is holding onto a std::string object verifies what I already know. For instance, the following function always returns true for my boost::any object: bool is_string(const boost::any& operand) { return ( operand.type() == typeid(std::string) ); } Also if I just print out the typeinfo information for the boost::any object is also shows that its holding onto a std::string: std::stringstream ss; ss << "any object: " << obj.type().name() << ", a string: " << typeid(std::string).name(); yields, any object: Ss, a string: Ss However, whenever I try and actually cast my object to a string (boost::any_cast<std::string>(...)), I always get "boost::bad_any_cast: failed conversion using boost::any_cast". Could this possibly be a compiler issue? I saw one other thread where "-fvisibility=hidden" was causing some problems for boost::program_options and std::string. In my situation, I have a library which is responsible for creating those boost::any objects. Then its in a separately compiled library where I am getting the problems.

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[Random] uniform_01
by Robert Patterson 01 Nov '09

01 Nov '09

Hi, I was looking at the docs for the uniform_01 distribution: http://www.boost.org/doc/libs/1_39_0/libs/random/random-distributions.html#… I read the following note "Note: The current implementation is buggy, because it may not fill all of the mantissa with random bits." I do not understand the problem. I looked at the code, which does what I expect. Why is it a problem if some of the mantissa bits are not 'random'? As I understand the requirement is the real numbers are uniformly distributed; the bit patterns should not matter provided they represent numbers with the right mathematical properties. Thanks Robert Patterson http://como.cheng.cam.ac.uk/index.php?Page=People&Section=riap2

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