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  • [C++] Question on Virtual Methods

    - by bobber205
    IF both methods are declared as virtual, shouldn't both instances of Method1() that are called be the derived class's Method1()? I am seeing BASE then DERIVED called each time. I am doing some review for an interview and I want to make sure I have this straight. xD class BaseClass { public: virtual void Method1() { cout << "Method 1 BASE" << endl; } }; class DerClass: public BaseClass { public: virtual void Method1() { cout << "Method 1 DERVIED" << endl; } }; DerClass myClass; ((BaseClass)myClass).Method1(); myClass.Method1(); Method 1 BASE Method 1 DERVIED

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  • Java how does Key Event Handling Mechanism(KeyListeners notified) work ?

    - by Carbonizer
    How does application/JVM know which classes if implemented key handling interfaces ? Does it use java Reflections or does it check all the classes for methods ? How can a application or executing JVM understanding to deliver the user event or call the specific methods on a class that implemented the keylistener interface. Does it look at all the classes if those methods are implemented or how does it know which classes implmented keylistener interface ? If you dont implement the keylistener Interface for a class but still implmentation all its methods. Do the class still process the user event occurred ?

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  • add navigation buttons with highlight to jQuery Cycle

    - by JJ Nold
    I am currently using jQuery cycle to display featured projects. I currently have the next and prev buttons setup, I also have four rounded buttons in between. I would like them to function as both a link to the corresponding slide as well as add a class to the button who's slide is currently active. I have the nav setup and the active class setup I just need the jQuery. You can see the code at http://jjnold.com/dev in the main slider at the top. I was thinking it's probably something like this to assign the class but I'm not sure how to link to the corresponding slide and have them work together. Any help is greatly appreciated. $('.featuredNavInt a').click(function() { $('.featuredNavInt a').removeClass('active'); $(this).addClass('active'); });

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  • How do you extend a Ruby module with macro-like metaprogramming methods?

    - by Ian Terrell
    Consider the following extension (the pattern popularized by several Rails plugins over the years): module Extension def self.included(recipient) recipient.extend ClassMethods recipient.class_eval { include InstanceMethods } end module ClassMethods def macro_method puts "Called macro_method within #{self.name}" end end module InstanceMethods def instance_method puts "Called instance_method within #{self.object_id}" end end end If you wished to expose this to every class, you can do the following: Object.send :include, Extension Now you can define any class and use the macro method: class FooClass macro_method end #=> Called macro_method within FooClass And instances can use the instance methods: FooClass.new.instance_method #=> Called instance_method within 2148182320 But even though Module.is_a?(Object), you cannot use the macro method in a module: module FooModule macro_method end #=> undefined local variable or method `macro_method' for FooModule:Module (NameError) This is true even if you explicitly include the original Extension into Module with Module.send(:include, Extension). How do you add macro like methods to Ruby modules?

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  • Why are Objective-C instance variables declared in an interface?

    - by Chase
    I'm just getting into Objective-C (Java is my primary OO language). Defining an object's instance variables in the interface instead of the class seems strange. I'm used to an interface being a public API definition with nothing besides method signatures (not counting constants here). Is there some reason that state is defined in an interface (even if it is private) and behaviour is defined in a class. It just seems odd that since objects are state+behavior that the definition would be split into two separate places. Is it a design benefit is some way? A pain in the rear issue that you are just forced to deal with in Objective-C? A non-issue, just different? Any background on why it's done this way? Or can you put object state in a class and I just haven't hit that part in my book yet?

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  • Programming to interfaces while mapping with Fluent NHibernate.

    - by Lucious
    Fluent Mapping I Have the following scenario public class CustomerMap : ClassMap { public CustomerMap() { Table("Customer"); Id(c = c.Id); Map(c = c.Name); HasMany(c = c.Orders); } } public class OrderMap : ClassMap<IOrder> { public OrderMap() { Table("Orders"); References(o => o.Customer).Access.; Id(o => o.Id); Map(o => o.DateCreated); } } Problems When schema exported the order table has two columns ICustomer_Id,Customer_Id. refers to an unmapped class Order exception Can you please help me out?

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  • Android sql creating database once

    - by semajhan
    One thing i'm not understanding is how to create the database and data just once in an android application. I extend SQLiteOpenHelper and use a DataHelper class that to manipulate data. Now, I have addEvent() and updateEvent() within the DataHelper class. I create an instance of DataHelper in my Activity and addEvent() a couple of times to insert data. Well, now I don't know how to just do that once. If I restart the app, its just going to "addEvent()" again and so the data is being reset every time. Sorry for the probably really REALLY noob question. The only solution I found was not using the DataHelper class and just adding data "manually" within the onCreate() method in SQLiteOpenHelper.

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  • php query cant figure out the problem

    - by Eat
    I dont get an error but it does not return me the row values as well. How can I address the problem? <?php //DATABASE $dbConn = mysql_connect($host,$username,$password); mysql_select_db($database,$dbConn); $SQL = mysql_query("SELECT N.*, C.CatID FROM News N INNER JOIN Categories C ON N.CatID = C.CatID WHERE N.Active = 1 ORDER BY DateEntered DESC"); while ( $Result = mysql_fetch_array($SQL) or die(mysql_error())) { $CatID[] = $Result[CatID]; $NewsName[] = $Result[NewsName]; $NewsShortDesc[] = $Result[NewsShortDesc]; } // mysql_free_result($Result); ?> <div class="toparticle"> <span class="section"><?=$CatID[0] ?> </span> <span class="headline"><?=$NewsName[0] ?></span> <p><?=$NewsShortDesc[0] ?></p> </div>

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  • Is correct name enough to make it happen?

    - by Knowing me knowing you
    Guys, I've just dipped in to limits.h by MS. I tried to check what's the return type for max() fnc and to my surprise I see something like this: // TEMPLATE CLASS numeric_limits template<class _Ty> class numeric_limits : public _Num_base { // numeric limits for arbitrary type _Ty (say little or nothing) public: static _Ty (__CRTDECL min)() _THROW0() { // return minimum value return (_Ty(0)); } static _Ty (__CRTDECL max)() _THROW0() { // return maximum value return (_Ty(0));//EXACTLY THE SAME WHAT IN min<<------------------ } //... other stuff }; so how is it possiple that in both min and max return does exactly the same? So does it mean if I would write makeSanwich() return (_Ty(0)) it would make a sandwich for me? How is it possible that having this same code just fnc names different we are getting different results?

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  • ActiveRecord, has_many, polymorphic and STI

    - by leomayleomay
    I've came into a problem while working with AR and polymorphic, here's the description, class Base < ActiveRecord::Base; end class Subscription < Base set_table_name :subscriptions has_many :posts, :as => :subscriptable end class Post < ActiveRecord::Base belongs_to :subscriptable, :polymorphic => true end in the console, >> s = Subscription.create(:name => 'test') >> s.posts.create(:name => 'foo', :body => 'bar') and it created a Post like: #<Post id: 1, name: "foo", body: "bar", subscriptable_type: "Base", subscriptable_id: 1, created_at: "2010-05-10 12:30:10", updated_at: "2010-05-10 12:30:10"> the subscriptable_type is Base but Subscription, anybody can give me a hand on this?

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  • What is the definition of a Service object ?

    - by Maskime
    I've been working a lot with PHP. But recently i was sent on a work wich use Java. In PHP i used to do a lot of Singleton object but this pattern has not the same signification in Java that it has in PHP. So i wanted to go for an utility class (a class with static method) but my chief doesn't like this kind of classes and ask me to go for services object. So my guess was that a service object is just a class with a constructor that implement some public methods... Am i right ?

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  • Javascript Inheritance and Arrays

    - by Inespe
    Hi all! I am trying to define a javascript class with an array property, and its subclass. The problem is that all instances of the subclass somehow "share" the array property: // class Test function Test() { this.array = []; this.number = 0; } Test.prototype.push = function() { this.array.push('hello'); this.number = 100; } // class Test2 : Test function Test2() { } Test2.prototype = new Test(); var a = new Test2(); a.push(); // push 'hello' into a.array var b = new Test2(); alert(b.number); // b.number is 0 - that's OK alert(b.array); // but b.array is containing 'hello' instead of being empty. why? As you can see I don't have this problem with primitive data types... Any suggestions?

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  • Java how to load modules

    - by gerardorn
    heres my problem: im building a server that loads modules. each module is a .jar file. inside the jar theres all the classes that the module need. the server needs to read the jar, find the main class (it doesnt have the main method on it is just the class that makes the module work but not as a different program), build an object of that class and store it in a vector of modules so that it can acces to a specific module depending on the job to be done. how can i do that? as far as the server, it is listening and reciving request, but thes no modules to delegate the job to, since my vector of modules is empty

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  • Question on Virtual Methods

    - by bobber205
    IF both methods are declared as virtual, shouldn't both instances of Method1() that are called be the derived class's Method1()? I am seeing BASE then DERIVED called each time. I am doing some review for an interview and I want to make sure I have this straight. xD class BaseClass { public: virtual void Method1() { cout << "Method 1 BASE" << endl; } }; class DerClass: public BaseClass { public: virtual void Method1() { cout << "Method 1 DERVIED" << endl; } }; DerClass myClass; ((BaseClass)myClass).Method1(); myClass.Method1(); Method 1 BASE Method 1 DERVIED

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  • Force result for empty() test on an object

    - by hsz
    Hello ! Simple class for example: class Foo { protected $_bar; public function setBar( $value ) { $this->_bar = $value; } } And here is the question: $obj = new Foo(); var_dump( empty( $obj ) ); // true $obj->setBar( 'foobar' ); var_dump( empty( $obj ) ); // false Is it possible to change class's behaviour with testing it with empty() function so it will returns true when object is not filled with data ? I know about magic function __isset( $name ) but it is called only when we test specific field like: empty( $obj->someField ); but not when test whole object.

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  • Passing User Data with SetTimer

    - by GJ
    I am calling SetTimer in a function of a Class. SetTimer(NULL, 0, 10000, (TIMERPROC) TimerCallBack); Where TimerCallBack is: static VOID CALLBACK TimerCallBack(HWND, UINT, UINT, DWORD) Now my need is to call one of the method of class which initiated timer, since TimerCallBack is static it has no access to the class object anymore. I cant find any way to pass object pointer along with the SetTimer so that I can receive it back on Callback function. Is there any other way to achieve this, if its not supported using SetTimer then which other way I can implement this.

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  • Sharing base object with inheritance

    - by max
    I have class Base. I'd like to extend its functionality in a class Derived. I was planning to write: class Derived(Base): def __init__(self, base_arg1, base_arg2, derived_arg1, derived_arg2): super().__init__(base_arg1, base_arg2) # ... def derived_method1(self): # ... Sometimes I already have a Base instance, and I want to create a Derived instance based on it, i.e., a Derived instance that shares the Base object (doesn't re-create it from scratch). I thought I could write a static method to do that: b = Base(arg1, arg2) # very large object, expensive to create or copy d = Derived.from_base(b, derived_arg1, derived_arg2) # reuses existing b object but it seems impossible. Either I'm missing a way to make this work, or (more likely) I'm missing a very big reason why it can't be allowed to work. Can someone explain which one it is? [Of course, if I used composition rather than inheritance, this would all be easy to do. But I was hoping to avoid the delegation of all the Base methods to Derived through __getattr__.]

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  • 'Caching' a large table in ASP.NET

    - by TheNewGuy
    I understand that each page refresh, especially in 'AjaxLand', causes my back-end/code-behind class to be called from scratch... This is a problem because my class (which is a member object in System.Web.UI.Page) contains A LOT of data that it sources from a database. So now every page refresh in AjaxLand is causing me to making large backend DB calls, rather than just to reuse a class object from memory. Any fix for this? Is this where session variables come into play? Are session variables the only option I have to retain an object in memory that is linked to a single-user and a single-session instance?

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  • template specilization using member enums

    - by Altan
    struct Bar { enum { Special = 4 }; }; template<class T, int K> struct Foo {}; template<class T> struct Foo<T::Special> {}; Usage: Foo<Bar> aa; fails to compile using gcc 4.1.2 It complains about the usage of T::Special for partial specilization of Foo. If Special was a class the solution would be to a typename in front of it. Is there something equivalent to it for enums (or integers)? Thanks, Altan

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  • Extension methods on a static object

    - by Max Malygin
    I know (or so I hear) that writing extension methods for a single stand alone .net class (not an implementation of IEnumerable) is potential code smell. However, for the sake of making the life easier I need to attach a method to the ConfigurationManager class in asp.net. It's a static object so this won't work: public static List<string> GetSupportedDomains(this ConfigurationManager manager) { //the manager needs to be static. } So the question is - is it possible to write an extension method for a static class in .net?

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  • OnClientClick event for keeping track of prints?

    - by Ram
    Hello, I am trying to keep track of prints that are made for a page. The page has Print this page link. And the code for it is like below: This is written in .cs file as there are many conditions for displaying this. And i am appending here using String Builder. sbOutput.AppendFormat("<td align=\"right\" valign=\"bottom\"><div style =\"float:right;text-align:right; valign:bottom;width:200px\"class=\"print_button notPrinted\"><a class=\"notPrinted\" href=\"#\" onclick=\"window.print();\">PRINT THIS COUPON </a><img src=\"images/print-icon-34x34.gif\" class=\"notPrinted\" align=\"absmiddle\" /></div> </td></tr></table>", couponid, Userid, locationid); Do i have to use onclientclick or something else?? Thanks so much in advance.

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  • New records added to DataGridView aren't displayed

    - by Ross
    I have a custom Order class, groups of which are stored in List<Order> and a DataGridView. I think the problem is in my implementation so here's how I'm using it: In the form enclosing DataGridView (as OrdersDataGrid): public partial class MainForm : Form { public static List<Order> Orders; public MainForm() { // code to populate Orders with values, otherwise sets Orders to new List<Order>(); OrdersDataGrid.DataSource = Orders; } Then in another form that adds an Order: // Save event public void Save(object sender, EventArgs e) { Order order = BuildOrder(); // method that constructs an order object from form data MainForm.Orders.Add(order); } From what I can tell from the console this is added successfully. I thought the DataGrid would be updated automatically after this since Orders has changed - is there something I'm missing? The DataGrid accepts the class since it generates columns from the members.

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  • Remove a DIV using a link

    - by GSTAR
    HTML: <div class="row"> <!-- content --> <a href="#" class="remove">remove</a> </div> JS: $('.remove').click(function(){ $(this).parent().remove(); return false; }); If there is only one DIV it works OK but when there are multiple DIVS (class="row") it won't do anything. No errors are returned either. EDIT: I should add that by default there is only one div - additional divs get dynamically created using a jQuery clone function - perhaps this is why it won't recognise the new link/div?

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  • C++ enforce conditions on inherited classes

    - by user231536
    I would like to define an abstract base class X and enforce the following: a) every concrete class Y that inherits from X define a constructor Y(int x) b) it should be possible to test whether two Y objects are equal. For a, one not very good solution is to put a pure virtual fromInt method in X which concrete class will have to define. But I cannot enforce construction. For b), I cannot seem to use a pure virtual method in X bool operator == (const X& other) const =0; because in overridden classes this remains undefined. It is not enough to define bool operator == (const Y& other) const { //stuff} because the types don't match. How do I solve these problems?

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  • Global Import/using Aliasing in .NET

    - by Josh Stodola
    Using import aliasing in a single class, we can reference class library namespaces by assigning our own custom alias like this: ' VB Imports Db = Company.Lib.Data.Objects // C# using Db = Company.Lib.Data.Objects; And then we are able to reference the classes inside of Company.Lib.Data.Objects by using the Db alias that we assigned. Is it possible to do this at the global level so that the alias is applied to the entire solution instead of the given file? Currently, we are working with web applications, so I was hoping we could add something to web.config, but I am also interested in whether or not this is possible with windows forms, console apps, and/or class libraries.

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