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  • Safe Cross Thread Signals/Slot C++

    - by JP
    It seem that the only implementation that provide Safe Cross-Thread Signals for both the Signal class and what's being called in the slot is QT. (Maybe I'm wrong?). But I cannot use QT in the project I'm doing. So how could I provide safe Slots call from a different thread (Using Boost::signals2 for example)? Are mutex inside the slot the only way? I think signals2 protect themself but not what's being done inside the slot. Thanks

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  • Is it possible to create a C++ factory system that can create an instance of any "registered" object

    - by chrensli
    Hello, I've spent my entire day researching this topic, so it is with some scattered knowledge on the topic that i come to you with this inquiry. Please allow me to describe what I am attempting to accomplish, and maybe you can either suggest a solution to the immediate question, or another way to tackle the problem entirely. I am trying to mimic something related to how XAML files work in WPF, where you are essentially instantiating an object tree from an XML definition. If this is incorrect, please inform. This issue is otherwise unrelated to WPF, C#, or anything managed - I solely mention it because it is a similar concept.. So, I've created an XML parser class already, and generated a node tree based on ObjectNode objects. ObjectNode objects hold a string value called type, and they have an std::vector of child ObjectNode objects. The next step is to instantiate a tree of objects based on the data in the ObjectNode tree. This intermediate ObjectNode tree is needed because the same ObjectNode tree might be instantiated multiple times or delayed as needed. The tree of objects that is being created is such that the nodes in the tree are descendants of a common base class, which for now we can refer to as MyBase. Leaf nodes can be of any type, not necessarily derived from MyBase. To make this more challenging, I will not know what types of MyBase derived objects might be involved, so I need to allow for new types to be registered with the factory. I am aware of boost's factory. Their docs have an interesting little design paragraph on this page: o We may want a factory that takes some arguments that are forwarded to the constructor, o we will probably want to use smart pointers, o we may want several member functions to create different kinds of objects, o we might not necessarily need a polymorphic base class for the objects, o as we will see, we do not need a factory base class at all, o we might want to just call the constructor - without #new# to create an object on the stack, and o finally we might want to use customized memory management. I might not be understanding this all correctly, but that seems to state that what I'm trying to do can be accomplished with boost's factory. But all the examples I've located, seem to describe factories where all objects are derived from a base type. Any guidance on this would be greatly appreciated. Thanks for your time!

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  • Methods for implementing and using graphs of nodes in C++?

    - by DistortedLojik
    I am working on a research project that deals with social networks. I have done most of the backbone of the program in C++ and am now wanting to implement a way to create the graph of nodes and the connections as well as a way to visualize the connections between people. I have looked a little into Lemon and the Boost graph library, but was wondering which one would be easier to learn and implement or if I should just code my own.

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  • Do you know of some performances test of the different ways to get thread local storage in C++?

    - by Vicente Botet Escriba
    I'm doing a library that makes extensive use of a thread local variable. Can you point to some benchmarks that test the performances of the different ways to get thread local variables in C++: C++0x thread_local variables compiler extension (Gcc __thread, ...) boost::threads_specific_ptr pthread Windows ... Does C++0x thread_local performs much better on the compilers providing it?

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  • Is there any way to limit the turbo boost speed / intensity on i7 lap?

    - by Anonymous
    I've just got a used i7 laptop, one of these overheating pavilions from HP with quad cores. And I really want to find a compromise between the temp and performance. If I use linpack, or some other heavy benchmark, the temp easily gets to 95+, and having a TJ of 100 Degrees, for a 2630QM model, it really gets me throttling, that no cooling pad or even an industrial fan could solve. I figured later that it is due to turbo boost, and if I set my power settings to use 99% of the CPU instead of 100%, and it seems to disable the turbo boost, so the temp gets better. But then again it loses quite a bit of performance. The regular clock is 2GHz, and in turbo boost it gets to 2.6Ghz, but I just wonder if I could limit it to around 2.3Ghz, that would be a real nice thing. Also there is another question I've hard time getting answer to. It seems to me that clocks are very quickly boosting up to max even when not needed, eg, it's ok if the CPU has 0% load, the clocks get to their 800MHz, but even if it gets to about 5% it quickly jumps to a max and even popping up turbo, which seems very strange to me. So I wonder if there is any way to adjust the sensitivity of the Speed Step feature. I believe it would be more logical to demand increased clock if it hits let's say 50% load. I do understand that most of these features are probably hardwired somewhere in the CPU itself or the MB, which has no tuning options just like on many laptops. But I would appreciate if you could recommend some thing, or some software. Thanks

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  • C++ templated factory constructor/de-serialization

    - by KRao
    Hi, I was looking at the boost serialization library, and the intrusive way to provide support for serialization is to define a member function with signature (simplifying): class ToBeSerialized { public: //Define this to support serialization //Notice not virtual function! template<class Archive> void serialize(Archive & ar) {.....} }; Moreover, one way to support serilization of derived class trough base pointers is to use a macro of the type: //No mention to the base class(es) from which Derived_class inherits BOOST_CLASS_EXPORT_GUID(Derived_class, "derived_class") where Derived_class is some class which is inheriting from a base class, say Base_class. Thanks to this macro, it is possible to serialize classes of type Derived_class through pointers to Base_class correctly. The question is: I am used in C++ to write abstract factories implemented through a map from std::string to (pointer to) functions which return objects of the desired type (and eveything is fine thanks to covariant types). Hover I fail to see how I could use the above non-virtual serialize template member function to properly de-serialize (i.e. construct) an object without knowing its type (but assuming that the type information has been stored by the serializer, say in a string). What I would like to do (keeping the same nomenclature as above) is something like the following: XmlArchive xmlArchive; //A type or archive xmlArchive.open("C:/ser.txt"); //Contains type information for the serialized class Base_class* basePtr = Factory<Base_class>::create("derived_class",xmlArchive); with the function on the righ-hand side creating an object on the heap of type Derived_class (via default constructor, this is the part I know how to solve) and calling the serialize function of xmlArchive (here I am stuck!), i.e. do something like: Base_class* Factory<Base_class>::create("derived_class",xmlArchive) { Base_class* basePtr = new Base_class; //OK, doable, usual map string to pointer to function static_cast<Derived_class*>( basePtr )->serialize( xmlArchive ); //De-serialization, how????? return basePtr; } I am sure this can be done (boost serialize does it but its code is impenetrable! :P), but I fail to figure out how. The key problem is that the serialize function is a template function. So I cannot have a pointer to a generic templated function. As the point in writing the templated serialize function is to make the code generic (i.e. not having to re-write the serialize function for different Archivers), it does not make sense then to have to register all the derived classes for all possible archive types, like: MY_CLASS_REGISTER(Derived_class, XmlArchive); MY_CLASS_REGISTER(Derived_class, TxtArchive); ... In fact in my code I relies on overloading to get the correct behaviour: void serialize( XmlArchive& archive, Derived_class& derived ); void serialize( TxtArchive& archive, Derived_class& derived ); ... The key point to keep in mind is that the archive type is always known, i.e. I am never using runtime polymorphism for the archive class...(again I am using overloading on the archive type). Any suggestion to help me out? Thank you very much in advance! Cheers

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  • To what extent do code-signing certificates boost sales of your software?

    - by Dan W
    In the experiences of everyone here, have you found a certificate to boost sales of your (downloadable) program? I produce .NET software and upon clicking the installation file, Windows 7 pops up a message saying the software is from an "unknown publisher" and to proceed with caution. For Windows 8, this appears to be even more prominent, and may adversely affect the number of downloads, and therefore the number of sales. A certificate will help soften this 'warning' by (for example) changing the warning's colour from orange to blue, and give the publisher's name instead of 'unknown'. But I'd like more tangible evidence since many people are obviously used to that message, and may not care and download anyway. So has anyone noticed a jump in sales after the switch?

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  • using BOOST_FOREACH with std::map

    - by kmote
    I'd like to iterate over a std::map using BOOST_FOREACH and edit the values. I can't quite get it. typedef std::pair<int, int> IdSizePair_t; std::map<int,int> mmap; mmap[1] = 1; mmap[2] = 2; mmap[3] = 3; BOOST_FOREACH( IdSizePair_t i, mmap ) i.second++; // mmap should contain {2,3,4} here Of course this doesn't change anything because I'm not iterating by reference. So I substitute this line instead (as per the example in the Boost docs): BOOST_FOREACH( IdSizePair_t &i, mmap ) and I get the compiler error: error C2440: 'initializing' : cannot convert from 'std::pair<_Ty1,_Ty2>' to 'IdSizePair_t &' with [ _Ty1=const int, _Ty2=int ] Any suggestions?

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  • Device driver with generic communication media layer

    - by Tom
    Greetings all, I'm trying to implement driver for an embedded device with generic communication media layer. Not sure what is the best way to do it so I'm seeking an advice from more experienced stackoverflow users:). Basically we've got devices around the country communicating with our head office. Usual form of communication is over TCP/IP, but could be also using usb, RF dongle, IR, etc. The plan is to have object corresponding with each of these devices, handling the proprietary protocol on one side and requests/responses from other internal systems on the other. The thing is how create something generic in between the media and the handling objects. I had a play around with the TCP dispatcher using boost.asio but trying to create something generic seems like a nightmare :). Anybody tried to do something like that? What is the best way how to do it? Cheers, Tom

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  • Explain Python extensions multithreading

    - by Checkers
    Python interpreter has a Global Interpreter Lock, and it is my understanding that extensions must acquire it in a multi-threaded environment. But Boost.Python HOWTO page says the extension function must release the GIL and reacquire it on exit. I want to resist temptation to guess here, so I would like to know what should be GIL locking patterns in the following scenarios: Extension is called from python (presumably running in a python thread). And extension's background thread calls back into Py_* functions. And a final question is, why the linked document says the GIL should be released and re-acquired?

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  • How to make Visual Studio Pause after executing a console app in debug mode?

    - by Jason Dagit
    I have a collection of boost unit tests I want to run as a console application. When I'm working on the project and I run the tests I would like to be able to debug the tests and I would like to have the console stay open after the tests run. I see that if I run in release mode the console window stays up after the program exits, but in debug mode this is not the case. I do not want to add 'system("pause");' or any other hacks like reading a character to my program. I just want to make Visual Studio pause after running the tests with debugging like it would if I were running in release mode. I would also like it if the output of tests were captured in one of Visual Studio's output windows but that also seems to be harder than it should be. How can I do this? Thanks!

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  • Functional data structures in C++

    - by drg
    Does anyone know of a C++ data structure library providing functional (a.k.a. immutable, or "persistent" in the FP sense) equivalents of the familiar STL structures? By "functional" I mean that the objects themselves are immutable, while modifications to those objects return new objects sharing the same internals as the parent object where appropriate. Ideally, such a library would resemble STL, and would work well with Boost.Phoenix (caveat- I haven't actually used Phoenix, but as far as I can tell it provides many algorithms but no data structures, unless a lazily-computed change to an existing data structure counts - does it?)

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  • bjam wih visual studio 2010

    - by ra170
    ok, so I ran into problems with Boost under visual studio 2010, so I decided to rebuild it with bjam: such as: bjam --toolset=msvc-10.0 --build-type=complete After running bjam (successfully?) it created a new directory under boost_1_42_0 called: bin.v2 Inside bin.v2 is directory called: libs. Two issues: 1. there's lot less libs under that new directory (about 13), the old directory libs has 88. Is it supposed to be like that or did something fail? 2. the structure is somewhat different too. What do I do with this exactly? Meaning, do I copy it over to the original libs, delete the old libs, try rebulding it with different flags?

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  • Tuples of unknown size/parameter types

    - by myahya
    I need to create a map, from integers to sets of tuples, the tuples in a single set have the same size. The problem is that the size of a tuple and its parameter types can be determined at runtime, not compile time. I am imagining something like: std::map<int, std::set<boost::tuple> > but not exctly sure how to exactly do this, bossibly using pointers. The purpose of this is to create temporary relations (tables), each with a unique identifier (key), maybe you have another approach.

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  • How to add event listners / signals to a simple superman class?

    - by Kabumbus
    I can and would love to use boost or std for this. Sorry - I am new to C++. So I created a really simple program like: #include <iostream> #include <string> using namespace std; class superman { public: string punch(){return cout << "superman: I hit the bad guy!" << endl;}; }; int main() { superman clark; clark.punch(); cin.get(); } I want to add an event listner that would tell me when clark punched and cout something like "superman punched!". How to add such event listner and event function to my class?

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  • No network packets sent immediately after quick physical disconnect and reconnect.

    - by Hans
    I am using Boost's ASIO libraries to establish a UDP connection to a remote server. To make sure the connection is active, every second a keep-alive message is sent to the server. I have noticed that if I unplug the network cable and reinsert it quickly, the first 2 or 3 keep-alive messages after the reinsert are never sent. I tested this by running wire-shark on the server. I have seen it take up to 5 seconds before the client starts sending out network traffic again. The client is running under Linux (2.6.2), if that helps.

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  • Daylight saving time of current tz

    - by spam2
    Hi, in my c++ software I've used Boost in some parts and also for the local time. OK, now my problem is to make a check if in my machine is active or not the DST. With the follow part of code I can know only the difference from the UTC time. In my case the difference is 2 hours because is active the DST ptime tLoc = second_clock::local_time(); ptime tUTC = second_clock::universal_time(); time_duration tDiff = tUTC - tLoc; local_time_zone = tDiff.hours(); I think that the boolean funcion has_dst() can help, right? My system is Debian GNU/Linux. Thanks

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  • .NET Regular expressions on bytes instead of chars

    - by brickner
    Hi, I'm trying to do some parsing that will be easier using regular expressions. The input is an array (or enumeration) of bytes. I don't want to convert the bytes to chars for the following reasons: Computation efficiency Memory consumption efficiency Some non-printable bytes might be complex to convert to chars. Not all the bytes are printable. So I can't use Regex. The only solution I know, is using Boost.Regex (which works on bytes - C chars), but this is a C++ library that wrapping using C++/CLI will take considerable work. How can I use regular expressions on bytes in .NET directly, without working with .NET strings and chars? Thank you.

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  • Referring to this pointer in a static assert?

    - by Tyson Jacobs
    Is it possible to write a static assert referring to the 'this' pointer? I do not have c++11 available, and BOOST_STATIC_ASSERT doesn't work. struct blah { void func() {BOOST_STATIC_ASSERT(sizeof(*this));} }; Produces: error C2355: 'this' : can only be referenced inside non-static member functions error C2027: use of undefined type 'boost::STATIC_ASSERTION_FAILURE' In MSVC 2008. Motivation: #define CLASS_USES_SMALL_POOL() \ void __small_pool_check() {BOOST_STATIC_ASSERT(sizeof(*this) < SMALL_MALLOC_SIZE;} \ void* operator new(size_t) {return SmallMalloc();} \ void operator delete(void* p) {SmallFree(p);}

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  • Detect aborted connection during ASIO request

    - by Tim Sylvester
    Is there an established way to determine whether the other end of a TCP connection is closed in the asio framework without sending any data? Using Boost.asio for a server process, if the client times out or otherwise disconnects before the server has responded to a request, the server doesn't find this out until it has finished the request and generated a response to send, when the send immediately generates a connection-aborted error. For some long-running requests, this can lead to clients canceling and retrying over and over, piling up many instances of the same request running in parallel, making them take even longer and "snowballing" into an avalanche that makes the server unusable. Essentially hitting F5 over and over is a denial-of-service attack. Unfortunately I can't start sending a response until the request is complete, so "streaming" the result out is not an option, I need to be able to check at key points during the request processing and stop that processing if the client has given up.

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  • When to use the Flyweight Pattern

    - by elmt
    So I've just gotten on the boost train and was checking out the flyweight pattern and was interested in implementing it in my project. Obviously, it doesn't make sense to use it on any class that has only has one instance of it. However, say I have 5 instances of an class. Should I be using the flyweight pattern or should it be only used for a class that has at least N instances. I realize that many factors will influence this answer (how many fields there are, the size of the fields, etc.).

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  • Hidden Features and Dark Corners of STL?

    - by Andrei
    C++ developers, all know the basics of C++: Declarations, conditionals, loops, operators, etc. Some of us even mastered the stuff like templates, object model, complex I/O, etc. But what are the most hidden features or tricks or dark corners of C++/STL that even C++ fans, addicts, and experts barely know? I am talking about a seasoned C++ programmer (be she/he a developer, student, fan, all three, etc), who thinks (s)he knows something 99% of us never heard or dreamed about. Something that not only makes his/her work easier, but also cool and hackish. After all, C++ is one of the most used programming languages in the world, thus it should have intricacies that only a few privileged know about and want to share with us. Boost is welcome too! One per post with an example please P.S Examples are important for other developers to copy and paste!

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  • Returning references while using shared_ptrs

    - by Goose Bumper
    Suppose I have a rather large class Matrix, and I've overloaded operator== to check for equality like so: bool operator==(Matrix &a, Matrix &b); Of course I'm passing the Matrix objects by reference because they are so large. Now i have a method Matrix::inverse() that returns a new Matrix object. Now I want to use the inverse directly in a comparison, like so: if (a.inverse()==b) { ... }` The problem is, this means the inverse method needs to return a reference to a Matrix object. Two questions: Since I'm just using that reference in this once comparison, is this a memory leak? What happens if the object-to-be-returned in the inverse() method belongs to a boost::shared_ptr? As soon as the method exits, the shared_ptr is destroyed and the object is no longer valid. Is there a way to return a reference to an object that belongs to a shared_ptr?

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