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  • how a thread can signal when it's finished?

    - by Kyle
    #include <iostream> #include <boost/thread.hpp> using std::endl; using std::cout; using namespace boost; mutex running_mutex; struct dostuff { volatile bool running; dostuff() : running(true) {} void operator()(int x) { cout << "dostuff beginning " << x << endl; this_thread::sleep(posix_time::seconds(2)); cout << "dostuff is done doing stuff" << endl; mutex::scoped_lock running_lock(running_mutex); running = false; } }; bool is_running(dostuff& doer) { mutex::scoped_lock running_lock(running_mutex); return doer.running; } int main() { cout << "Begin.." << endl; dostuff doer; thread t(doer, 4); if (is_running(doer)) cout << "Cool, it's running.\n"; this_thread::sleep(posix_time::seconds(3)); if (!is_running(doer)) cout << "Cool, it's done now.\n"; else cout << "still running? why\n"; // This happens! :( return 0; } Why is the output of the above program: Begin.. Cool, it's running. dostuff beginning 4 dostuff is done doing stuff still running? why How can dostuff correctly flag when it is done? I do not want to sit around waiting for it, I just want to be notified when it's done.

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  • Any Practical Alternative to the Signals + Slots model for GUI Programming?

    - by IntermediateHacker
    The majority of GUI Toolkits nowadays use the Signals + Slots model. It was Qt and GTK+, if I am not wrong, who pioneered it. You know, the widgets or graphical objects (sometimes even ones that aren't displayed) send signals to the main-loop handler. The main-loop handler then calls the events, callbacks or slots assigned for that widget / graphical object. There are usually default (and in most cases virtual) event-handlers already provided by the toolkit for handling all pre-defined signals, therefore, unlike previous designs where the developer had to write the entire main-loop and handler for each and every message himself (think WINAPI), the developer only has to worry about the signals he needs to implement new functionality on. Now this design is being used in most modern toolkits as far as I know. There are Qt, GTK+, FLTK etc. There is Java Swing. C# even has a language feature for it ( events and delegates ), and Windows Forms has been developed on this design. In fact, over the last decade, this design for GUI programming has become a kind of an unwritten standard. Since it increases productivity and provides greater abstraction. However, my question is: Is there any alternative design, that is parallel or practical for modern GUI programming? i.e Is the Signals + Slots design, the only practical one in town? Is it feasible to do GUI Programming with any other design? Are any modern (preferably successful and popular) GUI toolkits built on an alternative design?

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  • Best boost to productivity : SSD or second screen ?

    - by jfoucher
    Within the same budget, which do you think would be the best boost to productivity for general web development : An SSD as boot drive, or a second screen ? I currently use a 16.4" laptop with full HD screen and 7200 RPM HDD Thanks EDIT: In light of the answers so far, I add that I work at home and while I have a home office with a proper desk, I'm just as often coding sitting on the sofa in the living room.

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  • 5 Easy Ways to Get High PR Links to Boost Your Site in Google

    High PR links are some of the most valuable aspects in any link-building & SEO campaign. Not only do these links make Google respect your site more, but they can also boost your site's ranking overnight. Here are 5 places to get high quality links that will do a lot of good to your site's ranking in Google.

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  • How SEO Services by a SEO Company Can Boost Your Sales

    If we look at the present scenario the importance of growing your business and expanding your online brand recognition using all the strategic SEO elements available can just not be overstated. Today to be the very best at marketing the business or even the websites has to reach to its potential customers and hiring SEO companies and SEO experts is proving best method to keep track of the latest developments in search engine optimization. In this article, know how taking help of SEO services from any SEO company can actually boost up your sales.

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  • How SEO Services by a SEO Company Can Boost Your Sales

    If we look at the present scenario the importance of growing your business and expanding your online brand recognition using all the strategic SEO elements available can just not be overstated. Today to be the very best at marketing the business or even the websites has to reach to its potential customers and hiring SEO companies and SEO experts is proving best method to keep track of the latest developments in search engine optimization. In this article, know how taking help of SEO services from any SEO company can actually boost up your sales.

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  • Advanced SEO Strategy Guaranteed to Boost Your SEO

    One of the main factors for optimising your website for page 1 on Google is to get incoming links from other web pages, and to boost the effectiveness of those links there are a few things to consider, including the relevance of the page where your link is coming from, plus the link itself needs to be relevant to the keywords that you are targeting on Google. Here's one strategy you can use for getting great incoming links to help you achieve higher Google rankings.

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  • Boost Profits on Your Website

    By now you may have already built a website but are still not raking in profits from it. Your next step is to use some SEO strategies to boost its search rankings and convince site visitors to either buy something from you or avail of an offer.

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  • Forum Sites - Boost Your Search Marketing

    Forum sites boost your search marketing. Why? Finding the right site for your business is essential to boosting your online marketing; find the right community, one that deals with your specific services. Don't waste your time in a site that has no relevance to what you're offering. Find out the hub sites for your services by using keywords related to you.

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  • How does versioning work when using Boost Serialization for Derived Classes?

    - by Venkata Adusumilli
    When a Client serializes the following data: InternationalStudent student; student.id("Client ID"); student.firstName("Client First Name"); student.country("Client Country"); the Server receives the following: ID = "Client ID" Country = "Client First Name" instead of the following: ID = "Client ID" Country = "Client Country" The only difference between the Server and Client classes is the First Name of the Student. How can we make the Server ignore First Name recieved from the Client and process the Country? Server Side Classes class Student { public: Student(){} virtual ~Student(){} public: std::string id() { return idM; } void id(std::string id) { idM = id; } protected: friend class boost::serialization::access; protected: std::string idM; protected: template<class A> void serialize(A& archive, const unsigned int /*version*/) { archive & BOOST_SERIALIZATION_NVP(idM); } }; class InternationalStudent : public Student { public: InternationalStudent() {} ~InternationalStudent() {} public: std::string country() { return countryM; } void country(std::string country) { countryM = country; } protected: friend class boost::serialization::access; protected: std::string countryM; protected: template<class A> void serialize(A& archive, const unsigned int /*version*/) { archive & BOOST_SERIALIZATION_NVP(boost::serialization::base_object<Student>(*this)); archive & BOOST_SERIALIZATION_NVP(countryM); } }; Client Side Classes class Student { public: Student(){} virtual ~Student(){} public: std::string id() { return idM; } void id(std::string id) { idM = id; } std::string firstName() { return firstNameM; } void firstName(std::string name) { firstNameM = name; } protected: friend class boost::serialization::access; protected: std::string idM; std::string firstNameM; protected: template<class A> void serialize(A& archive, const unsigned int /*version*/) { archive & BOOST_SERIALIZATION_NVP(idM); if (version >=1) { archive & BOOST_SERIALIZATION_NVP(firstNameM); } } }; BOOST_CLASS_VERSION(Student, 1) class InternationalStudent : public Student { public: InternationalStudent() {} ~InternationalStudent() {} public: std::string country() { return countryM; } void country(std::string country) { countryM = country; } protected: friend class boost::serialization::access; protected: std::string countryM; protected: template<class A> void serialize(A& archive, const unsigned int /*version*/) { archive & BOOST_SERIALIZATION_NVP(boost::serialization::base_object<Student>(*this)); archive & BOOST_SERIALIZATION_NVP(countryM); } };

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  • How can I implement a database TableView like thing in C++?

    - by Industrial-antidepressant
    How can I implement a TableView like thing in C++? I want to emulating a tiny relation database like thing in C++. I have data tables, and I want to transform it somehow, so I need a TableView like class. I want filtering, sorting, freely add and remove items and transforming (ex. view as UPPERCASE and so on). The whole thing is inside a GUI application, so datatables and views are attached to a GUI (or HTML or something). So how can I identify an item in the view? How can I signal it when the table is changed? Is there some design pattern for this? Here is a simple table, and a simple data item: #include <string> #include <boost/multi_index_container.hpp> #include <boost/multi_index/member.hpp> #include <boost/multi_index/ordered_index.hpp> #include <boost/multi_index/random_access_index.hpp> using boost::multi_index_container; using namespace boost::multi_index; struct Data { Data() {} int id; std::string name; }; struct row{}; struct id{}; struct name{}; typedef boost::multi_index_container< Data, indexed_by< random_access<tag<row> >, ordered_unique<tag<id>, member<Data, int, &Data::id> >, ordered_unique<tag<name>, member<Data, std::string, &Data::name> > > > TDataTable; class DataTable { public: typedef Data item_type; typedef TDataTable::value_type value_type; typedef TDataTable::const_reference const_reference; typedef TDataTable::index<row>::type TRowIndex; typedef TDataTable::index<id>::type TIdIndex; typedef TDataTable::index<name>::type TNameIndex; typedef TRowIndex::iterator iterator; DataTable() : row_index(rule_table.get<row>()), id_index(rule_table.get<id>()), name_index(rule_table.get<name>()), row_index_writeable(rule_table.get<row>()) { } TDataTable::const_reference operator[](TDataTable::size_type n) const { return rule_table[n]; } std::pair<iterator,bool> push_back(const value_type& x) { return row_index_writeable.push_back(x); } iterator erase(iterator position) { return row_index_writeable.erase(position); } bool replace(iterator position,const value_type& x) { return row_index_writeable.replace(position, x); } template<typename InputIterator> void rearrange(InputIterator first) { return row_index_writeable.rearrange(first); } void print_table() const; unsigned size() const { return row_index.size(); } TDataTable rule_table; const TRowIndex& row_index; const TIdIndex& id_index; const TNameIndex& name_index; private: TRowIndex& row_index_writeable; }; class DataTableView { DataTableView(const DataTable& source_table) {} // How can I implement this? // I want filtering, sorting, signaling upper GUI layer, and sorting, and ... }; int main() { Data data1; data1.id = 1; data1.name = "name1"; Data data2; data2.id = 2; data2.name = "name2"; DataTable table; table.push_back(data1); DataTable::iterator it1 = table.row_index.iterator_to(table[0]); table.erase(it1); table.push_back(data1); Data new_data(table[0]); new_data.name = "new_name"; table.replace(table.row_index.iterator_to(table[0]), new_data); for (unsigned i = 0; i < table.size(); ++i) std::cout << table[i].name << std::endl; #if 0 // using scenarios: DataTableView table_view(table); table_view.fill_from_source(); // synchronization with source table_view.remove(data_item1); // remove item from view table_view.add(data_item2); // add item from source table table_view.filter(filterfunc); // filtering table_view.sort(sortfunc); // sorting // modifying from source_able, hot to signal the table_view? // FYI: Table view is atteched to a GUI item table.erase(data); table.replace(data); #endif return 0; }

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  • Twisted pair cable twists and unwanted signals issue

    - by ziaharipur
    I am confused about one point I have read the following paragraph from the networking book. “the twists in the twisted pair cable are used to avoid the unwanted signals. For example one twist, one wire is closer to the noise source and the other is farther; in the next twist the reverse is true. Twisting makes its probable that both wires are equally affected by the unwanted signal. This means that the receiver which calculate the difference between the two receives no unwanted signal.” Now ok I understood the purpose of twists but I am confused about how receiver will calculate the difference when it will receive the signal?. How unwanted signal will be eliminated ? Another thing that I want to make clear is , I am beginner please provide such an answer that can be understood.

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  • Asus V1S, no video signals but boots ok

    - by user52441
    Hey folks! I got a mayor problem with my 3 year old my Asus V1S notebook. After installing VMWare Player an rebooting the screen remained black and there was no POST screen. Also the other video outputs - VGA and HDMI - send no signals. However the maschine boots into Windows 7 properly (sounds waren played) and I can log in by blindly typing my pw. Testend WIN-P and functiom keys but no luck with that. Google is no help here, thats why I basketball you superusers! Please give me hints if you have any idea or if you experienced a similar problem. Thank you so much!

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  • Using in the same time Boost in release and debug mode

    - by Oodini
    Hello, The title is just for teasing. :-) I know it isn't possible, but here is my problem. My app (a DLL, actually) uses Boost. It also uses an external API, which also uses Boost. The external API is of course provided in a release binary, anlong the needed release Boost binaries. When I compile/link my DLL in release mode, I have no problem. I precise I link my app to Boost in a dynamic way (BOOST_ALL_DYN_LINK). In debug mode, I can't load my DLL. I am not sure it is because of Boost, but I suspect Windows doesn't like working with two Boost (the release one called by the external lib, and the debug one called by my code). Will it work better if I link my code statically with the release Boost ? I don't think it is related to CRT, because I have nothing in the Events Viewer. I use Visual Studio 2005 SP1. Thanks.

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  • Equvalent c++0x program withought using boost threads..

    - by Eternal Learner
    I have the below simple program using boost threads, what would be the changes needed to do the same in c++0X #include<iostream> #include<boost/thread/thread.hpp> boost::mutex mutex; struct count { count(int i): id(i){} void operator()() { boost::mutex::scoped_lock lk(mutex); for(int i = 0 ; i < 10000 ; i++) { std::cout<<"Thread "<<id<<"has been called "<<i<<" Times"<<std::endl; } } private: int id; }; int main() { boost::thread thr1(count(1)); boost::thread thr2(count(2)); boost::thread thr3(count(3)); thr1.join(); thr2.join(); thr3.join(); return 0; }

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  • C++ Multithreaded server help

    - by kisplit
    Hello all, I'm working on a multithreaded server in c++ using boost-asio. Currently a design problem I'm running into deals with erasing a connection. I have a single server instance which holds a vector of connection objects. These connections receive commands which I parse. One command in particular deals with sending data to ALL connections in my vector. Now when a connection disconnects I'm currently erasing this connection from the vector and calling the destructor. It seems like I'm going to run into problems when someone 'SendAll' at the same time someone 'Disconnect'. Could anyone recommend a better design or just point me in the right direction? Any help greatly appreciated. Thanks

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  • What's correct way to remove a boost::shared_ptr from a list?

    - by Catskul
    I have a std::list of boost::shared_ptr<T> and I want to remove an item from it but I only have a pointer of type T* which matches one of the items in the list. However I cant use myList.remove( tPtr ) I'm guessing because shared_ptr does not implement == for its template argument type. My immediate thought was to try myList.remove( shared_ptr<T>(tPtr) ) which is syntactically correct but it will crash from a double delete since the temporary shared_ptr has a separate use_count. std::list< boost::shared_ptr<T> > myList; T* tThisPtr = new T(); // This is wrong; only done for example code. // stand-in for actual code in T using // T's actual "this" pointer from within T { boost::shared_ptr<T> toAdd( tThisPtr ); // typically would be new T() myList.push_back( toAdd ); } { //T has pointer to myList so that upon a certain action, // it will remove itself romt the list //myList.remove( tThisPtr); //doesn't compile myList.remove( boost::shared_ptr<T>(tThisPtr) ); // compiles, but causes // double delete } The only options I see remaining are to use std::find with a custom compare, or to loop through the list brute force and find it myself, but it seems there should be a better way. Am I missing something obvious, or is this just too non-standard a use to be doing a remove the clean/normal way?

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  • Is it possible to use boost::bind to effectively concatenate functions?

    - by Catskul
    Assume that I have a boost::function of with an arbitrary signature called type CallbackType. Is it possible to use boost::bind to compose a function that takes the same arguments as the CallbackType but calls the two functors in succession? Hypothetical example using a magic template: Template<typename CallbackType> class MyClass { public: CallbackType doBoth; MyClass( CallbackType callback ) { doBoth = bind( magic<CallbackType>, protect( bind(&MyClass::alert, this) ), protect( callback ) ); } void alert() { cout << "It has been called\n"; } }; void doIt( int a, int b, int c) { cout << "Doing it!" << a << b << c << "\n"; } int main() { typedef boost::function<void (int, int, int)> CallbackType; MyClass<CallbackType> object( boost::bind(doIt) ); object.doBoth(); return 0; }

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  • boost::unordered_map is... ordered?

    - by Thanatos
    I have a boost::unordered_map, but it appears to be in order, giving me an overwhelming feeling of "You're Doing It Wrong". Why is the output to this in order? I would've expected the underlying hashing algorithm to have randomized this order: #include <iostream> #include <boost/unordered_map.hpp> int main() { boost::unordered_map<int, int> im; for(int i = 0; i < 50; ++i) { im.insert(std::make_pair(i, i)); } boost::unordered_map<int, int>::const_iterator i; for(i = im.begin(); i != im.end(); ++i) { std::cout << i->first << ", " << i->second << std::endl; } return 0; } ...gives me... 0, 0 1, 1 2, 2 ... 47, 47 48, 48 49, 49

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  • Using Qt signals/slots instead of a worker thread

    - by Rob
    I am using Qt and wish to write a class that will perform some network-type operations, similar to FTP/HTTP. The class needs to connect to lots of machines, one after the other but I need the applications UI to stay (relatively) responsive during this process, so the user can cancel the operation, exit the application, etc. My first thought was to use a separate thread for network stuff but the built-in Qt FTP/HTTP (and other) classes apparently avoid using threads and instead rely on signals and slots. So, I'd like to do something similar and was hoping I could do something like this: class Foo : public QObject { Q_OBJECT public: void start(); signals: void next(); private slots: void nextJob(); }; void Foo::start() { ... connect(this, SIGNAL(next()), this, SLOT(nextJob())); emit next(); } void Foo::nextJob() { // Process next 'chunk' if (workLeftToDo) { emit next(); } } void Bar::StartOperation() { Foo* foo = new Foo; foo->start(); } However, this doesn't work and UI freezes until all operations have completed. I was hoping that emitting signals wouldn't actually call the slots immediately but would somehow be queued up by Qt, allowing the main UI to still operate. So what do I need to do in order to make this work? How does Qt achieve this with the multitude of built-in classes that appear to perform lengthy tasks on a single thread?

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