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  • Who calls the Destructor of the class when operator delete is used in multiple inheritance.

    - by dicaprio-leonard
    This question may sound too silly, however , I don't find concrete answer any where else. With little knowledge on how late binding works and virtual keyword used in inheritance. As in the code sample, when in case of inheritance where a base class pointer pointing to a derived class object created on heap and delete operator is used to deallocate the memory , the destructor of the of the derived and base will be called in order only when the base destructor is declared virtual function. Now my question is : 1) When the destructor of base is not virtual, why the problem of not calling derived dtor occur only when in case of using "delete" operator , why not in the case given below: derived drvd; base *bPtr; bPtr = &drvd; //DTOR called in proper order when goes out of scope. 2) When "delete" operator is used, who is reponsible to call the destructor of the class? The operator delete will have an implementation to call the DTOR ? or complier writes some extra stuff ? If the operator has the implementation then how does it looks like , [I need sample code how this would have been implemented]. 3) If virtual keyword is used in this example, how does operator delete now know which DTOR to call? Fundamentaly i want to know who calls the dtor of the class when delete is used. Sample Code class base { public: base() { cout<<"Base CTOR called"<<endl; } virtual ~base() { cout<<"Base DTOR called"<<endl; } }; class derived:public base { public: derived() { cout<<"Derived CTOR called"<<endl; } ~derived() { cout<<"Derived DTOR called"<<endl; } }; I'm not sure if this is a duplicate, I couldn't find in search. int main() { base *bPtr = new derived(); delete bPtr;// only when you explicitly try to delete an object return 0; }

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  • Using WebSockets in a C# Web Application?

    - by sixones
    I know its possible to use WebSockets within C# using a console application running along side the web application but Im wondering if its possible to use the requests on the C# web application to create the WebSockets. I've been looking through ASP.Net and Im starting to think it wont be possible unless I use straight up C# and create my own HTTP server and then use the same socket object to generate Web Sockets (similar to the way Node.js and Socket.IO work). Any thoughts on ways to include WebSockets on a C# web application without having multiple servers / projects?

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  • Android: Creating custom class of resources

    - by Sebastian
    Hi, R class on android has it's limitations. You can't use the resources dynamically for loading audio, pictures or whatever. If you wan't for example, load a set of audio files for a choosen object you can't do something like: R.raw."string-upon-choosen-object" I'm new to android and at least I didn't find how you could do that, depending on what objects are choosen or something more dynamic than that. So, I thought about making it dynamic with a little of memory overhead. But, I'm in doubt if it's worth it or just working different with external resources. The idea is this: Modify the ant build xml to execute my own task. This task, is a java program that parses the R.java file building a set of HashMaps with it's pair (key, value). I have done this manually and It's working good. So I need some experts voice about it. This is how I will manage the whole thing: Generate a base Application class, e.g. MainApplicationResources that builds up all the require methods and attributes. Then, you can access those methods invoking getApplication() and then the desired method. Something like this: package [packageName] import android.app.Application; import java.util.HashMap; public class MainActivityResources extends Application { private HashMap<String,Integer> [resNameObj1]; private HashMap<String,Integer> [resNameObj2]; ... private HashMap<String,Integer> [resNameObjN]; public MainActivityResources() { super(); [resNameObj1] = new HashMap<String,Integer>(); [resNameObj1].put("[resNameObj1_Key1]", new Integer([resNameObj1_Value1])); [resNameObj1].put("[resNameObj1_Key2]", new Integer([resNameObj1_Value2])); [resNameObj2] = new HashMap<String,Integer>(); [resNameObj2].put("[resNameObj2_Key1]", new Integer([resNameObj2_Value1])); [resNameObj2].put("[resNameObj2_Key2]", new Integer([resNameObj2_Value2])); ... [resNameObjN] = new HashMap<String,Integer>(); [resNameObjN].put("[resNameObjN_Key1]", new Integer([resNameObjN_Value1])); [resNameObjN].put("[resNameObjN_Key2]", new Integer([resNameObjN_Value2])); } public int get[ResNameObj1](String resourceName) { return [resNameObj1].get(resourceName).intValue(); } public int get[ResNameObj2](String resourceName) { return [resNameObj2].get(resourceName).intValue(); } ... public int get[ResNameObjN](String resourceName) { return [resNameObjN].get(resourceName).intValue(); } } The question is: Will I add too much memory use of the device? Is it worth it? Regards,

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  • Python: how to inherite and override

    - by Guy
    Consider this situation: I get an object of type A which has the function f. I.e: class A: def f(): print 'in f' def h(): print 'in h' and I get an instance of this class but I want to override the f function but save the rest of the functionality of A. So what I was thinking was something of the sort: class B(A): .... def f(): print 'in B->f' and the usage would be: def main(a): b = B(a) b.f() #prints "in B->f" b.h() #print "in h" How do you do such a thing?

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  • Struggling with ASP.NET MVC auto-scaffolder template

    - by DanM
    I'm trying to write an auto-scaffolder template for Index views. I'd like to be able to pass in a collection of models or view-models (e.g., IQueryable<MyViewModel>) and get back an HTML table that uses the DisplayName attribute for the headings (th elements) and Html.Display(propertyName) for the cells (td elements). Each row should correspond to one item in the collection. Here's what I have so far: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl" %> <% var items = (IQueryable<TestProj.ViewModels.TestViewModel>)Model; // How do I make this generic? var properties = items.First().GetMetadata().Properties .Where(pm => pm.ShowForDisplay && !ViewData.TemplateInfo.Visited(pm)); %> <table> <tr> <% foreach(var property in properties) { %> <th> <%= property.DisplayName %> </th> <% } %> </tr> <% foreach(var item in items) { HtmlHelper itemHtml = ????; // What should I put in place of "????"? %> <tr> <% foreach(var property in properties) { %> <td> <%= itemHtml.Display(property.DisplayName) %> </td> <% } %> </tr> <% } %> </table> Two problems with this: I'd like it to be generic. So, I'd like to replace var items = (IQueryable<TestProj.ViewModels.TestViewModel>)Model; with var items = (IQueryable<T>)Model; or something to that effect. A property Html is automatically created for me when the view is created, but this HtmlHelper applies to the whole collection. I need to somehow create an itemHtml object that applies just to the current item in the foreach loop. I'm not sure how to do this, however, because the constructors for HtmlHelper don't take a Model object. How do I solve these two problems?

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  • What is the recommended way to pass data back and forth between two threads using C#

    - by kenalex
    I am trying to make an app that will pass data between two servers Connection1 and Conenction2 using sockets.What i would like to do is receive data from Connection1 and pass it to Connection2 and vice-versa.Connection1 and Conenction2 are on different threads. What is the best way to call methods on different threads in order to pass data back and forth between them.Both threads will use the same message object type to communicate in both directions between them. Thanks

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  • iPhone Human Interface Guidelines question

    - by Kyle
    iPhone Human Interface Guidelines -- Do they apply for OpenGL games? GL games typically have custom buttons, custom lists, etc. Take the Quake player list for example, if ported, it wouldnt be a typical UI list object. Does this mean the reviewer in question would reject anything that wasn't using standard UI? Or, is there an exception for games.

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  • LINQ-to-SQL - C# - OnValidate()

    - by Mark Comix
    Hello, I have a system with 3 layers and I am using LINQ-to-SQL to persist. I want to validate if the description field of my object is empty. I am using partial classes and the method OnValidate(). If the field is empty, it throws an exception. Is this correct? What do I do after the exception to not close the form, letting the user continue working? Thank you very much Sorry for my poor english

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  • XNA Level config file in C#

    - by Midday
    I'm working on as small game for class and was wondering what is a easy way to handel level configuration files. Like object placements , names, etc. I'm new to C# but fluent in Java, Ruby. so XML? YML? text, serialized objects?

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  • Poll C# app's memory usage at runtime?

    - by maxfridbe
    I have an app that, while running, needs to poll its own memory usage. It would be ideal if it could list out the memory usage for each object instantiated. I know this can be achieved by WMI, but I was hoping for something that doesn't rely on WMI.

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  • setTimeout not working in windows script (jscript)

    - by Sibo Lin
    When I try to run the following code in my program setTimeout("alert('moo')", 1000); I get the following error Error: Object expected Code: 800A138F Source: Microsoft JScript runtime error Why? Am I calling the wrong function? What I want to do is delay the execution of the subsequent function.

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  • CoGetClassObject gives many First-chance exceptions in ATL project. Should I worry?

    - by Andrew
    Hello, I have written a COM object that in turn uses a thrid party ActiveX control. In my FinalConstruct() for my COM object, I instantiate the ActiveX control with the follow code: HRESULT hRes; LPCLASSFACTORY2 pClassFactory; hRes = CoInitializeEx(NULL,COINIT_APARTMENTTHREADED); bool bTest = SUCCEEDED(hRes); if (!bTest) return E_FAIL; if (SUCCEEDED(CoGetClassObject(__uuidof(SerialPortSniffer), CLSCTX_INPROC_SERVER, NULL, IID_IClassFactory2, (LPVOID *)(&pClassFactory)))) { ... more set up code When I step over the line if (SUCCEEDED(CoGetClassObject(__uuidof(SerialPortSniffer), ..., I get 20+ lines in the Output window stating: First-chance exception at 0x0523f82e in SillyComDriver.exe: 0xC0000005: Access violation writing location 0x00000000. I also get the lines: First-chance exception at 0x051e3f3d in SillyComDriver.exe: 0xC0000096: Privileged instruction. First-chance exception at 0x100ab9e6 in SillyComDriver.exe: 0xC000001D: Illegal Instruction. Notice these are first-chance exceptions. The program runs as expected I can access the third party methods/properties. Still, I'm left wondering why they are occurring. Perhaps my way of instantiating the ActiveX control (for which I want use of it's methods/properties and not it's GUI stuff) is incorrect? Besides the code I'm showing, I also put the line import "spsax.dll" no_namespace in the stdafx.h That's all the code necessary for my simple demo project. I noticed this problem because I had (inadvertently) set the "break on exceptions" options in my "real" project and it was breaking on this line. Once I removed it, it also works. If you're read this far thank you, and perhaps I can ask one other minor question. In my demo project, if I right click on SerialPortSniffer and "go to definition", it takes me to the file C:....\AppData\Local\Temp\spsax.tlh. Can someone explain that? Finally, in my "real" project, right clicking on SerialPortSniffer and going to difinition leads to "The symbol 'SerialPortSniffer' is not defined". It doesn't seem to affect the program though. Is there some setting I've messed up? By the way, all my code is written w/ VS2008. Thanks, Dave

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  • Does this data structure have a name? Sort of a "linked matrix"?

    - by Bob
    Let's say I wanted similar functionality to a doubly linked list but needed a matrix instead so that each node was structured like this: public class Node { Node Up, Down, Left, Right; object Value; } Is there a name for such a structure? I've looked through this Wikipedia listing of data structures but didn't see anything similar. Unless I just missed it.

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  • Referencing CDI producer method result in h:selectOneMenu

    - by user953217
    I have a named session scoped bean CustomerRegistration which has a named producer method getNewCustomer which returns a Customer object. There is also CustomerListProducer class which produces all customers as list from the database. On the selectCustomer.xhtml page the user is then able to select one of the customers and submit the selection to the application which then simply prints out the last name of the selected customer. Now this only works when I reference the selected customer on the facelets page via #{customerRegistration.newCustomer}. When I simply use #{newCustomer} then the output for the last name is null whenever I submit the form. What's going on here? Is this the expected behavior as according to chapter 7.1 Restriction upon bean instantion of JSR-299 spec? It says: ... However, if the application directly instantiates a bean class, instead of letting the container perform instantiation, the resulting instance is not managed by the container and is not a contextual instance as defined by Section 6.5.2, “Contextual instance of a bean”. Furthermore, the capabilities listed in Section 2.1, “Functionality provided by the container to the bean” will not be available to that particular instance. In a deployed application, it is the container that is responsible for instantiating beans and initializing their dependencies. ... Here's the code: Customer.java: @javax.persistence.Entity @Veto public class Customer implements Serializable, Entity { private static final long serialVersionUID = 122193054725297662L; @Column(name = "first_name") private String firstName; @Column(name = "last_name") private String lastName; @Id @GeneratedValue() private Long id; public String getFirstName() { return firstName; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getLastName() { return lastName; } public void setLastName(String lastName) { this.lastName = lastName; } @Override public String toString() { return firstName + ", " + lastName; } @Override public Long getId() { return this.id; } } CustomerListProducer.java: @SessionScoped public class CustomerListProducer implements Serializable { @Inject private EntityManager em; private List<Customer> customers; @Inject @Category("helloworld_as7") Logger log; // @Named provides access the return value via the EL variable name // "members" in the UI (e.g., // Facelets or JSP view) @Produces @Named public List<Customer> getCustomers() { return customers; } public void onCustomerListChanged( @Observes(notifyObserver = Reception.IF_EXISTS) final Customer customer) { // retrieveAllCustomersOrderedByName(); log.info(customer.toString()); } @PostConstruct public void retrieveAllCustomersOrderedByName() { CriteriaBuilder cb = em.getCriteriaBuilder(); CriteriaQuery<Customer> criteria = cb.createQuery(Customer.class); Root<Customer> customer = criteria.from(Customer.class); // Swap criteria statements if you would like to try out type-safe // criteria queries, a new // feature in JPA 2.0 // criteria.select(member).orderBy(cb.asc(member.get(Member_.name))); criteria.select(customer).orderBy(cb.asc(customer.get("lastName"))); customers = em.createQuery(criteria).getResultList(); } } CustomerRegistration.java: @Named @SessionScoped public class CustomerRegistration implements Serializable { @Inject @Category("helloworld_as7") private Logger log; private Customer newCustomer; @Produces @Named public Customer getNewCustomer() { return newCustomer; } public void selected() { log.info("Customer " + newCustomer.getLastName() + " ausgewählt."); } @PostConstruct public void initNewCustomer() { newCustomer = new Customer(); } public void setNewCustomer(Customer newCustomer) { this.newCustomer = newCustomer; } } not working selectCustomer.xhtml: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:f="http://java.sun.com/jsf/core" xmlns:h="http://java.sun.com/jsf/html" xmlns:ui="http://java.sun.com/jsf/facelets"> <h:head> <title>Auswahl</title> </h:head> <h:body> <h:form> <h:selectOneMenu value="#{newCustomer}" converter="customerConverter"> <f:selectItems value="#{customers}" var="current" itemLabel="#{current.firstName}, #{current.lastName}" /> </h:selectOneMenu> <h:panelGroup id="auswahl"> <h:outputText value="#{newCustomer.lastName}" /> </h:panelGroup> <h:commandButton value="Klick" action="#{customerRegistration.selected}" /> </h:form> </h:body> </html> working selectCustomer.xhtml: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:f="http://java.sun.com/jsf/core" xmlns:h="http://java.sun.com/jsf/html" xmlns:ui="http://java.sun.com/jsf/facelets"> <h:head> <title>Auswahl</title> </h:head> <h:body> <h:form> <h:selectOneMenu value="#{customerRegistration.newCustomer}" converter="customerConverter"> <f:selectItems value="#{customers}" var="current" itemLabel="#{current.firstName}, #{current.lastName}" /> </h:selectOneMenu> <h:panelGroup id="auswahl"> <h:outputText value="#{newCustomer.lastName}" /> </h:panelGroup> <h:commandButton value="Klick" action="#{customerRegistration.selected}" /> </h:form> </h:body> </html> CustomerConverter.java: @SessionScoped @FacesConverter("customerConverter") public class CustomerConverter implements Converter, Serializable { private static final long serialVersionUID = -6093400626095413322L; @Inject EntityManager entityManager; @Override public Object getAsObject(FacesContext context, UIComponent component, String value) { Long id = Long.valueOf(value); return entityManager.find(Customer.class, id); } @Override public String getAsString(FacesContext context, UIComponent component, Object value) { return ((Customer) value).getId().toString(); } }

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  • Refactoring many nested ifs or chained if statements

    - by Icarus
    Hi, I have an object with large number of similar fields (like more than 10 of them) and I have to assign them values from an array of variable length. The solution would be either a huge nested bunch of ifs based on checking length of array each time and assigning each field OR a chain of ifs checking on whether the length is out of bounds and assigning each time after that check. Both seem to be repetitive. Is there a better solution ?

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  • How does .NET compiler compare two strings?

    - by Pankaj
    string a="I am comparing 2 string"; string b="I am comparing 2 string"; if(a==b) return true; else return false; How does a .NET compiler compare two strings? Does a string work like a struct(int)? string is class so a=b means we are comparing 2 object, but i want to compare 2 values.

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  • It's possible to create variable to hold fields of class dynamically???

    - by yossharel
    hi all, In my 'Person' class, I have some fields like 'firstname','lastname','nickname' and so on. I want to write code to search dynamically, sometimes by 'firstname' and sometimes by 'nickname' field. The code I want to write, should be like this: Object someVariable = "firstname"; Person result = ListOfPerson.Where(p => p.someVariable = "exp").FirstOrDefault(); Can anyone Know if it's possible?

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  • JMF. Create new custom streamdatasource

    - by Afro Genius
    Hi there. I am looking to create a means of building a DataSource object (and hence a Processor) that gets data from a stream instead of a file, RTP, and so on. I am writing a module for a much larger application that is meant to transparently transcode audio data. Going through the JMF docs only specify how to create a source from file however I need to be able to create a source from a stream within my application. Any idea where I can start looking?

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