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  • Mapping multiple keys to the same value in a Javascript hash

    - by Bears will eat you
    I use a Javascript hash object to store a set of numerical counters, set up like this [this is greatly simplified]: var myHash = { A: 0, B: 0, C: 0 }; Is there a way to make other keys, ones not explicitly in myHash, map to keys that are? For instance, I'd like [again, this is simplified]: myHash['A_prime']++; // or myHash.A_prime++; to be exactly equivalent to myHash['A']++; // or myHash.A++; e.g. incrementing the value found at the key A, not A_prime.

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  • How should I delete a child object from within a parent's slot? Possibly boost::asio specific.

    - by kaliatech
    I have written a network server class that maintains a std::set of network clients. The network clients emit a signal to the network server on disconnect (via boost::bind). When a network client disconnects, the client instance needs to be removed from the Set and eventually deleted. I would think this is a common pattern, but I am having problems that might, or might not, be specific to ASIO. I've tried to trim down to just the relevant code: /** NetworkServer.hpp **/ class NetworkServices : private boost::noncopyable { public: NetworkServices(void); ~NetworkServices(void); private: void run(); void onNetworkClientEvent(NetworkClientEvent&); private: std::set<boost::shared_ptr<const NetworkClient>> clients; }; /** NetworkClient.cpp **/ void NetworkServices::run() { running = true; boost::asio::io_service::work work(io_service); //keeps service running even if no operations // This creates just one thread for the boost::asio async network services boost::thread iot(boost::bind(&NetworkServices::run_io_service, this)); while (running) { boost::system::error_code err; try { tcp::socket* socket = new tcp::socket(io_service); acceptor->accept(*socket, err); if (!err) { NetworkClient* networkClient = new NetworkClient(io_service, boost::shared_ptr<tcp::socket>(socket)); networkClient->networkClientEventSignal.connect(boost::bind(&NetworkServices::onNetworkClientEvent, this, _1)); clients.insert(boost::shared_ptr<NetworkClient>(networkClient)); networkClient->init(); //kicks off 1st asynch_read call } } // etc... } } void NetworkServices::onNetworkClientEvent(NetworkClientEvent& evt) { switch(evt.getType()) { case NetworkClientEvent::CLIENT_ERROR : { boost::shared_ptr<const NetworkClient> clientPtr = evt.getClient().getSharedPtr(); // ------ THIS IS THE MAGIC LINE ----- // If I keep this, the io_service hangs. If I comment it out, // everything works fine (but I never delete the disconnected NetworkClient). // If actually deleted the client here I might expect problems because it is the caller // of this method via boost::signal and bind. However, The clientPtr is a shared ptr, and a // reference is being kept in the client itself while signaling, so // I would the object is not going to be deleted from the heap here. That seems to be the case. // Never-the-less, this line makes all the difference, most likely because it controls whether or not the NetworkClient ever gets deleted. clients.erase(clientPtr); //I should probably put this socket clean-up in NetworkClient destructor. Regardless by doing this, // I would expect the ASIO socket stuff to be adequately cleaned-up after this. tcp::socket& socket = clientPtr->getSocket(); try { socket.shutdown(boost::asio::socket_base::shutdown_both); socket.close(); } catch(...) { CommServerContext::error("Error while shutting down and closing socket."); } break; } default : { break; } } } /** NetworkClient.hpp **/ class NetworkClient : public boost::enable_shared_from_this<NetworkClient>, Client { NetworkClient(boost::asio::io_service& io_service, boost::shared_ptr<tcp::socket> socket); virtual ~NetworkClient(void); inline boost::shared_ptr<const NetworkClient> getSharedPtr() const { return shared_from_this(); }; boost::signal <void (NetworkClientEvent&)> networkClientEventSignal; void onAsyncReadHeader(const boost::system::error_code& error, size_t bytes_transferred); }; /** NetworkClient.cpp - onAsyncReadHeader method called from io_service.run() thread as result of an async_read operation. Error condition usually result of an unexpected client disconnect.**/ void NetworkClient::onAsyncReadHeader( const boost::system::error_code& error, size_t bytes_transferred) { if (error) { //Make sure this instance doesn't get deleted from parent/slot deferencing //Alternatively, somehow schedule for future delete? boost::shared_ptr<const NetworkClient> clientPtr = getSharedPtr(); //Signal to service that this client is disconnecting NetworkClientEvent evt(*this, NetworkClientEvent::CLIENT_ERROR); networkClientEventSignal(evt); networkClientEventSignal.disconnect_all_slots(); return; } I believe it's not safe to delete the client from within the slot handler because the function return would be ... undefined? (Interestingly, it doesn't seem to blow up on me though.) So I've used boost:shared_ptr along with shared_from_this to make sure the client doesn't get deleted until all slots have been signaled. It doesn't seem to really matter though. I believe this question is not specific to ASIO, but the problem manifests in a peculiar way when using ASIO. I have one thread executing io_service.run(). All ASIO read/write operations are performed asynchronously. Everything works fine with multiple clients connecting/disconnecting UNLESS I delete my client object from the Set per the code above. If I delete my client object, the io_service seemingly deadlocks internally and no further asynchronous operations are performed unless I start another thread. I have try/catches around the io_service.run() call and have not been able to detect any errors. Questions: Are there best practices for deleting child objects, that are also signal emitters, from within parent slots? Any ideas as to why the io_service is hanging when I delete my network client object?

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  • C++ Mock/Test boost::asio::io_stream - based Asynch Handler

    - by rbellamy
    I've recently returned to C/C++ after years of C#. During those years I've found the value of Mocking and Unit testing. Finding resources for Mocks and Units tests in C# is trivial. WRT Mocking, not so much with C++. I would like some guidance on what others do to mock and test Asynch io_service handlers with boost. For instance, in C# I would use a MemoryStream to mock an IO.Stream, and am assuming this is the path I should take here. C++ Mock/Test best practices boost::asio::io_service Mock/Test best practices C++ Async Handler Mock/Test best practices I've started the process with googlemock and googletest.

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  • Google App Engine : PolyModel + SelfReferenceProperty

    - by rvandervort
    Is a PolyModel-based class able to be used as a SelfReferenceProperty ? I have the below code : class BaseClass(polymodel.PolyModel): attribute1 = db.IntegerProperty() attribute2 = db.StringProperty() class ParentClass(BaseClass): attribute3 = db.StringProperty() class ChildClass(BaseClass): parent = SelfReferenceProperty(collection_name = 'children') p = ParentClass() p.attribute1 = 1 p.attribute2 = "Parent Description" p.attribute3 = "Parent additional data" p.put() c = ChildClass() c.attribute1 = 5 c.attribute2 = "Child Description" c.parent = p.key() c.put() I execute this code and check the datastore via the development server's admin interface. The parent instance is saved to the datastore class = 'BaseClass,ParentClass', but the child is not. There is no error output to the browser (debug is turned on) and nothing in the launcher's log for my app. Is this possible to do ?

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  • What is the point/purpose of Ruby EventMachine, Python Twisted, or JavaScript Node.js?

    - by CCw
    I don't understand what problem these frameworks solve. Are they replacements for a HTTP server like Apache HTTPD, Tomcat, Mongrel, etc? Or are they more? Why might I use them... some real world examples? I've seen endless examples of chat rooms and broadcast services, but don't see how this is any different than, for instance, setting up a Java program to open sockets and dispatch a thread for each request. I think I understand the non-blocking I/O, but I don't understand how that is any different than a multi-threaded web server.

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  • [PHP] preg_replace: replacing using %

    - by Juan
    Hi all, I'm using the function preg_replace but I cannot figure out how to make it work, the function just doesn't seem to work for me. What I'm trying to do is to convert a string into a link if any word contains the % (percentage) character. For instance if I have the string "go to %mysite", I'd like to convert the mysite word into a link. I tried the following... $data = "go to %mysite"; $result = preg_replace('/(^|[\s\.\,\:\;]+)%([A-Za-z0-9]{1,64})/e', '\\1%<a href=#>\\2</a>', $data); ...but it doesn't work. Any help on this would be much appreciated. Thanks Juan

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  • Perl, treat string as binary byte array

    - by Mike
    In Perl, is it appropriate to use a string as a byte array containing 8-bit data? All the documentation I can find on this subject focuses on 7-bit strings. For instance, if I read some data from a binary file into $data my $data; open FILE, "<", $filepath; binmode FILE; read FILE $data 1024; and I want to get the first byte out, is substr($data,1,1) appropriate? (again, assuming it is 8-bit data) I come from a mostly C background, and I am used to passing a char pointer to a read() function. My problem might be that I don't understand what the underlying representation of a string is in Perl.

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  • Why state cannot be part of Presenter in MVP?

    - by rFactor
    I read http://www.codeproject.com/KB/architecture/MVC_MVP_MVVM_design.aspx and it said: As powerful as they are, both MVC and MVP have their problems. One of them is persistence of the View’s state. For instance, if the Model, being a domain object, does not know anything about the UI, and the View does not implement any business logic, then where would we store the state of the View’s elements such as selected items? Fowler comes up with a solution in the form of a Presentation Model pattern. I wonder why Presenter can't hold View state? It already holds all View logic. As far as I understand, in MVC and MVP the state is kept in View. In PM and MVVM the state is kept in the Presentation Model. Why can't Presenter follow PM in this particular case and contain the state of the view? Here is another article which says Presenter does not hold View state, instead the view does: http://www.codeproject.com/KB/aspnet/ArchitectureComparison.aspx

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  • Multiple Servers with identical services

    - by Jerry Bailey
    I have a dozen servers in different locations all running the same web service application but each going against their own SQL Server DB. I am writing a desktop application that consumes the web services. I want to present the user with a drop down of all servers in the network that are running the same wweb service application. Do I have to add a ServiceReference for each of the servers running the web service app and thereby having as many proxies as there are servers? Or can a define a single instance of the services and dynamically build a list of endpoints to select from a drop down?

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  • Hiding the console window in a system() call

    - by Justen
    Continuing from this question With each system call, the function constructs a set of parameters and sends them off to another program that is just console-based. Is there a way I can make it so that no console window pops up for each call? I've done a search but the ones that aren't a linker issue just aren't working for me. For instance, I tried the _execl call and System::Diagnostics::Process^ myProcess = gcnew System::Diagnostics::Process; but they aren't working. The _execl will bring a console window up, scroll a bunch of stuff (from the program I called I guess), then close the my app and not even do what it was supposed to do. The System::Diagnostics::Process^ myProcess = gcnew System::Diagnostics::Process; doesn't seem to execute what I want either because the output folder that should contain files, contains nothing. So I'm open for ideas.

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  • Abstract classes in shared library

    - by JTom
    Hi, I have an ordinary abstract class that has couple of pure virtual methods. The class itself is a part of the shared library. The compilation of the shared library itself is OK. But when the library is linked to another program that has another class deriving from the abstract one in the shared library and defining the pure virtual methods, I get the following linker error: I compile like this..: g++ -I../path/to/the/library main.cpp derived.cpp -L../path/to/the/library -lsomename -o shared ...and the linker error is: libsomename.so: undefined reference to `AbstractClass::method()' It's like the abstract class cannot access its pure virtual methods but I do not try to make any instance of the abstract class anywhere in the library. What could be the problem?

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  • A controller method that calls a different method on the same controller

    - by justSteve
    I have a controller method: public ActionResult Details(int id) { Order order = OrderFacade.Instance.Load(id); return View(order); } that is used for 95% of possible invocations. For the other 5% i need to manipulate the value of id before passing to the facade. I'd like to create a separate method within this same controller that executes that manipulation and then calls this (Details) method. What would the signature of that method look like? What is the syntax to call the main Details method? public ??? ManipulatorMethod(int id) { [stuff that manipulates id] [syntax to call Details(manipulatedID)] } mny thx

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  • Rails: How to produce 404 or redirect upon undesired url exploitation?

    - by Baby Diego
    I want to hide the urls for editing users and their profiles behind safer and meaningful urls. For instance, I want /user/13/edit to be /settings/account and /user/13/profile/edit to be /settings/profile. I managed to achieve that, but for that I had to load the user information from the current_user bit from the session. Like so: # users_controller def edit @user = current_user end # profiles_controller def edit @user = current_user @profile = @user.profile end But now, since I can't compare @user.id from the params with the current_user in the session, how can I stop the old urls (/user/13/edit and /user/13/profile/edit) from being exploitable? They always load the forms for the current user, so there's no harm done, but I'd be more comfortable if they just produced a 404 error or something. Thanks in advance.

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  • Best practices for using Hg with Grails?

    - by leeand00
    What should I check in/not check in? Since many of the files are sometimes auto-generated I'm not entirely sure how to handle this using version control...does it have something to do with tags? For instance in ANT, I know not to check-in my target/bin directories...but Grails adds another level of confusion to this...since some of code is generated and some of it is not. (It may become clearer as I go...but it seems to be that there needs to be some way of being able to tell what was just generated and what was modified by a developer so that it needs to be placed in version control)

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  • why does an event handler never gets called if its added within a loop on an ienumerable

    - by André Carvalho
    For instance: IEnumerable<MyType> list = someCollection.Select(i => new MyType(i)); foreach (var item in list) item.PropertyChanged += item_PropertyChanged; <-- this never gets called Bu if list is assigned like list = someCollection.Select(i => new MyType(i)).ToArray(); the event handler does get called.. Why? (i imagine it has something to do with the fact that a linq query is lazy, but the fact of looping through the result isn't enough??)

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  • What are some programming questions (or mistakes) you get wrong only as you get better?

    - by BlueRaja
    In programming, as many professions, there are mistakes you'll make now that you may not have made as a beginner. For instance, consider pointers: In C++, is there any difference between arrays and pointers? The beginner will say yes, they are two completely different concepts, and treat them as such. The intermediate programmer (having learned that arrays are pointers internally) will tell you no, they are the same thing, and may miss some crucial bugs by interchanging them all willy-nilly. The expert, however, will again say they are different things (ex. see here or here). What other questions/mistakes are like this?

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  • What is the best way to convince management that virtualization isn't always appropriate in producti

    - by uncle brad
    I work for a small company with a .NET product that was acquired by a medium sized company with "big iron" products. Recently, the medium-sized part of the company acquired another small company with a similar .NET product and management went to have a look at their technology. They make heavy use of virtualization in their production environment and it's been decided that we will too. Our product was not designed to be run in a virtual environment, but some accommodations can be made. For instance; there are times when we're resource bound due to customer initiated processes. This initiation is "bursty" by nature, but the processing can be made asynchronous and throttled. This is something that would need to be done for scalability anyway. But there is other processing that we do that isn't so easily modified because we're resource bound for extended periods of time. How do I convince management that heavy use of virtualization is probably not appropriate for us?

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  • python class attribute

    - by chnet
    Hi, i have a question about class attribute in python. class base : def __init__ (self): pass derived_val = 1 t1 = base() t2 = base () t2.derived_val +=1 t2.__class__.derived_val +=2 print t2.derived_val # its value is 2 print t2.__class__.derived_val # its value is 3 The results are different. I also use id() function to find t2.derived_val and t2.class.derived_val have different memory address. My problem is derived_val is class attribute. Why it is different in above example? Is it because the instance of class copy its own derived_val beside the class attribute?

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  • WPF webbrowser - get HTML downloaded?

    - by Mathias Lykkegaard Lorenzen
    I'm listening to the WPF webbrowser's LoadCompleted event. It has some navigation arguments which provide details regarding the navigation. However, e.Content is always null. Am I paying attention to the wrong event here? How can I fetch the HTML that was just downloaded as string? I tried some things which I would consider hacks, but they return a string of HTML, even though that was not the string downloaded. For instance, with that method when I go to a page which just sends me the string abc, I get the result <document><body>abc</body></document> or something similar. I would prefer not getting into any more hacks than nescessary to get this running.

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  • Retrieve entities with children per one sql call. ADO.NET Entity framework

    - by Andrew Florko
    Hello everybody, I have two tables: A & B B { B1: Field1, B2: Field2, ... } A { Children: List of B, A1: Field1, A2: Field2, } I want to retrieve "A" entities with related "B" entities like this: DataContext.A.Select( a = new MySubset( A1 = a.A1, Children = a.Children.Select(b = b.B1).ToList()); But EF can't translate ToList into SQL, so i have to call ToList() per each instance in query producing additional network call. How can I avoid this? Thank you in advance.

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  • Domain Model and Contracts

    - by devoured elysium
    I am modelling a DVD Rental Store: A Client gives its clientNumber to the System. The System checks whenever the given clientNumber is valid. The Client gives the name of the DVD he wants to rent. ... n. ...I will later have to form an association between a new instance of "RentDVD" class concept to the current Client c. My Domain Model is something like: I've made the Contract for the first and second operations as: Preconditions: none Postconditions: there exists a Client c such that c.clientNumber = clientNumber. Now, I don't know if I should form an association between this Client c and the DVDStore(that I intend to use as front-end). If I don't make the association, how will I later be able to "reference" this same Client? Should I be making an association between Client and a different concept? Thanks

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  • Mod_Rewrite: Testing URL got indexed in Google - How do I create a proper 301 redirect?

    - by Jonathan Wold
    I worked on a website for which I had a "development URL" that looked something like this: www.domainname.com.php5-9.dfw1-2.websitetestlink.com/ Now, several weeks after the website launch, there is at least one page of content indexed on Google with that URL. Question: How do I redirect all requests from that test URL to reroute to the actual domain? So, for instance, I would want: www.domainname.com.php5-9.dfw1-2.websitetestlink.com/page-name To go to: www.domainname.com/page-name The website is powered by WordPress and hosted on a PHP server. I've experimented with .htaccess without much success.

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  • Sqlalchemy layout with WSGI application

    - by TheDude
    I'm working on writing a small WSGI application using Bottle and SqlAlchemy and am confused on how the "layout" of my application should be in terms of SqlAlchemy. My confusion is with creating engines and sessions. My understanding is that I should only create one engine with the 'create_engine' method. Should I be creating an engine instance in the global namespace in some sort of singleton pattern and creating sessions based off of it? How have you done this in your projects? Any insight would be appreciated. The examples in the documentation dont seem to make this entirely clear (unless I'm missing something obvious). Any thoughts?

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  • Single database with multiple instances of Django

    - by jwesonga
    I have a Django project where the company will have a main site like www.ourcompany.org and a bunch of sub-domains like project.ourcompany.org. Content appearing in the sub-domains like case studies should also appear in the main site. I've decided to use multiple instances of Django BUT one database for each sub-domain so that I can have some flexibility and take advantage of the Sites framework. What I'm not sure of is how to access the models across the multiple instances. If I have a model: class CaseStudy(models.Model): title=models.CharField(max_length=100) site=models.ManyToMany(Site) Do I need to create this model in every instance so that I can have access to the object?

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  • Retrieving datatypes from underlying database

    - by H4mm3rHead
    Hi, Im making an application that displays information about an underlying database. The database can be anything, but is typically either Oracle, MSSQL or MySQL. I am trying to extract the datatype but cannot seem to get this right. I have a DbConnection because i dont know whether I need a OleDbConnection or an OdbcConnection. On this connection I make a GetSchema("Columns", "mytablename") query and gets the result back. It seems though that there are some inconsistencies with my datatypes or the query returns different datatypes for the different databases. For instance, in my MSSQL database I query and get an integer back (which seems to be the OleDbType) which I map to a datatype. My varchars is now of type char - no length - and this confuses me a bit. I guess my main question is something like: Is there any way of making a uniform way of extracting datatypes across providers and having an "accurate" representation of the datatype?

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