- Boost-users - lists.boost.org

Re: [Boost-users] serialization::make_nvp parameters
by Hammond, John (UK New Malden) 09 Sep '09

09 Sep '09

> The space may be a problem. Boost.Serialization sticks the name directly into the XML, and <x:1 y:2></x:1 y:2> is bad. It appears that this was indeed the problem - a rookie mistake. By removing any spaces I am able to drop name.c_str() straight in to ::make_nvp() with no problems. To provide further context, the reason I want to assign the tags dynamically is because I am using the Serialization library in a simpler fashion than that for which it was designed. I only wish to provide a means of outputting the state of a window and I have no desire to export in a format that can be reliably read back in to the same system. Thanks for all your help, John ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ********************************************************************

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serialization::make_nvp parameters
by Hammond, John (UK New Malden) 09 Sep '09

09 Sep '09

Hello, I am hoping someone could answer a question I have regarding the make_nvp(..) function of the Serialization library. I am attempting to serialize a number of objects within a loop, and the name of the name-value-pair is to be assigned dynamically depending on some values taken from within the object that is to be serialized. I am currently performing the actions below: my_obj = GetMyObj(..); std::string temp = str( boost::format("x:%1% y:%2%") % _x % _y ); const char* const_temp = temp.c_str( ); ar & boost::serialization::make_nvp(const_temp, my_obj); This code compiles but will cause an exception on make_nvp. As far as I can tell, I am providing the function with the const char* that it requires, so am very confused as to why it is not performing as expected. Any help with this would be greatly appreciated. John Hammond ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ********************************************************************

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Re: [Boost-users] [shared_ptr] deleter that destroys shared_pt r -is it safe?
by Stefan Strasser 09 Sep '09

09 Sep '09

> This was fixed in 1.39, if I'm not mistaken (see revision 51643). Are you sure that it fails with the current implementation? no, "current" means 1.38 in my case.

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[BGL] delete children subgraphs
by Marti Cuquet 09 Sep '09

09 Sep '09

Hello, I have a root subgraph from which I create a lot of children subgraphs, that use too much memory. How can I delete the children subgraphs after using them? Thanks, Marti

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[shared_ptr] deleter that destroys shared_ptr - is it safe?
by Igor R 09 Sep '09

09 Sep '09

Hello, Is the following code legal and safe - a) according to the shared_ptr specs b) with the current boost::shared_ptr implementation Thanks! struct a { a() : p_(this, mem_fn(&a::delete_me)) {} void reset() { p_.reset(); } void delete_me() { delete this; } shared_ptr<a> p_; }; int main() { a* p = new a; p->reset(); }

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[statechart] Broadcasting events to orthogonal states
by Vladimír Třebický 09 Sep '09

09 Sep '09

Hi all, first of all: thanks for the great library! I just dug into the boost::statechart tutorial trying to figure out how to deal with the following simple scenario: Let's say I have a complex application server represented by a single boost::state_chart with multiple modules (eg. network, database, etc.) represented by orthogonal spaces. I have a couple of system-wide events like "system shutdown". Handling these eventa is generally non-trivial and I'd like all the modules to process it independently. As I understand, statechart tries to deliver an event across al of the orthogonal spaces discarding it once it's processed by any of them (ie. by "return transit", "return discard_event", etc.). But I'd like these events to be delivered to _all_ orthogonal spaces no matter what they do with it. I could create a state for each of the orthogonal spaces. These wrappers would accept the system-wide events, translate them to local-events, post them locally and forward the system-wide event. But that's basically like having multiple statecharts for each of the modules and dispatching system-wide events manually. Thanks, Vladimir.

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How to use boost 1.39 with eclipse
by manish4gupta 09 Sep '09

09 Sep '09

Hi , I am working on shared memory.I am using boost interprocess and regex module. I tried to install on ubuntu but it pop up errors for unrecognized function.So now i am planning to use boost interprocess and boost regex module in eclipse. How can i do that? Please help as i am in great need. Regards -- View this message in context: http://www.nabble.com/How-to-use-boost-1.39-with-eclipse-tp25356863p2535686… Sent from the Boost - Users mailing list archive at Nabble.com.

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[asio] compile error on Solaris 10
by Wang, Paul 08 Sep '09

08 Sep '09

I'm including <boost/asio.hpp> and I'm getting the following compile error on Solaris 10 using gcc 3.4.3 with both Boost 1.39 and 1.40. In file included from /opt/boost_1_39_0/boost/asio/detail/socket_types.hpp:111, from /opt/boost_1_39_0/boost/asio/detail/win_iocp_io_service_fwd.hpp:24, from /opt/boost_1_39_0/boost/asio/io_service.hpp:37, from /opt/boost_1_39_0/boost/asio/basic_io_object.hpp:20, from /opt/boost_1_39_0/boost/asio/basic_socket.hpp:24, from /opt/boost_1_39_0/boost/asio/basic_datagram_socket.hpp:25, from /opt/boost_1_39_0/boost/asio.hpp:20, ... /usr/include/net/if.h:99: error: template argument required for `struct map' Does anyone know of a work around for this? Thanks, Paul

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Can we pass variable argument list to boost format?
by ajil koshy 08 Sep '09

08 Sep '09

Hi, I'd like to know if there is a way by which we can pass the variable argument list to boost format. I have a function which creates formatted output strings for logging purpose. Currently, I'm using _vsnwprintf_s function internally to handle variable argument lists which the caller may be pass to this function. Can this be done using boost format? Thanks Ajil

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Re: [Boost-users] shared_ptr and weak_ptr concurrency
by Jerry Jeremiah 08 Sep '09

08 Sep '09

Just to make sure I understand, am I right that this assumes x86/x64 CPUs and only those built in types up to register size (no 64 bit integers) and may not include single bytes in all circumstances? If you wrote code that depended on this assumption how could you be sure it wouldn't be ported to a box with a different CPU (I move stuff all the time between x86 and AIX, HPUX and sometimes a VAX). Can I make the same assumptions or not? And how can I be sure? Thanks, Jerry Message: 1 Date: Fri, 4 Sep 2009 11:58:46 -0400 From: John Dlugosz <JDlugosz(a)TradeStation.com> To: "boost-users(a)lists.boost.org" <boost-users(a)lists.boost.org> Subject: Re: [Boost-users] shared_ptr and weak_ptr concurrency Message-ID: <89030B4A18ECCD45978A3A6B639D1F240266A3F2C7(a)FL01EXMB01.trad.tradestation .com> Content-Type: text/plain; charset="utf-8" I know that on x86 and x64 architectures, assigning to or reading from any location up to the native general-purpose register size is atomic if the item in question is properly aligned for its size. That is, { a=b; in parallel with b=c; } will not read a partially-changed b, if b is declared in the normal manner. Reading oddly-aligned things out of a packed stream, or using pragmas to change the alignment options, may upset this. Furthermore, the cache is coherent among multiple CPUs or cores, even on a NUMA server. What you have to watch out for is when the compile actually issues the read or write, since it can us a register and save it back to memory much later, or re-arrange the requests. Furthermore, the chip queues requests to memory with reads having priority, so a write followed by a read needs special consideration. Assigning to a (non-volatile) char might do something ?interesting?. For example, if two separate char variables are declared, the compiler might keep them in registers and save them both out at the end with a single 16-bit write. The x86/x64 instruction set is conducive to that, but not to other cases. But in general an architecture might indeed merge separate variables to single larger register. The compiler might then re-save something that didn?t change, thus clobbering a change made on another thread. The current C++ standard does not address threads, so there is indeed no portable way to guarantee that. You have to encapsulate and implement for each architecture, and use compiler-specific extensions. It would be interesting to see a list of architectures noting whether or not primitive type reads and writes are atomic, at least verifying that they are even if there is nothing listed that doesn?t. I?m sure they would all have footnotes to that, as I described above for the one I?m familiar with. --John From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Kevin Kassil Sent: Friday, September 04, 2009 9:32 AM To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] shared_ptr and weak_ptr concurrency Stefan, On Thu, Sep 3, 2009 at 2:30 AM, Stefan Strasser <strasser(a)uni-bremen.de<mailto:strasser@uni-bremen.de>> wrote: ... why would you even need a lock here? the shared_ptr doc says that you can expect the same thread safety from shared_ptr as you can from built-in types. you can use multiple-readers-single-writer without any locks on built-in types. You can? Is assigning to a char or a double guaranteed to be atomic? How can the compiler guarantee that? -- What if there is some architecture for which it's not a single instruction assignment? Kevi

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