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  • which situation abstract class i should use

    - by Bharanikumar
    Hi , Am not worked on extream level of oops in my projects , So i have little doubts , In which situation should i use abstract method or classes , Basically i know about abstract class definition and flow, I got details from this URL Doubt is which situation should i use abstract class and methods ,

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  • PHP inheriting/extending a particular instance of an Object

    - by delta9
    Is there any way to force PHP to extend an existing/particular (and for that matter, already instantiated) instance of an object? This imaginary code should explain what I am wondering: class Base { public $var; function __construct($var){ $this->var = $name; } } class Extender extends Base { function __construct($parent) { parent = $parent; } } $base = new Base('yay!'); $extender = new Extender($base); echo 'Extended base var value: '.$extender->var.'<br/>'; Output (would be): Extended base var value: yay! To be clear, I am wanting to instantiate an object that extends a PARTICULAR INSTANCE of another object, one that has already been instantiated. I am aware that I can pass a reference to an object to another object (via it's constructor function) and then add it as a property of the receiving object, I'm wondering if there is a real way to do this?

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  • Is it possible to cancel function override in parent class and use function from top level parent

    - by Anatoliy Gusarov
    class TopParent { protected function foo() { $this->bar(); } private function bar() { echo 'Bar'; } } class MidParent extends TopParent { protected function foo() { $this->midMethod(); parent::foo(); } public function midMethod() { echo 'Mid'; } public function generalMethod() { echo 'General'; } } Now the question is if I have a class, that extends MidParent because I need to call class Target extends MidParent { //How to override this method to return TopParent::foo(); ? protected function foo() { } } So I need to do this: $mid = new MidParent(); $mid->foo(); // MidBar $taget = new Target(); $target->generalMethod(); // General $target->foo(); // Bar UPDATE Top parent is ActiveRecord class, mid is my model object. I want to use model in yii ConsoleApplication. I use 'user' module in this model, and console app doesn't support this module. So I need to override method afterFind, where user module is called. So the Target class is the class that overrides some methods from model which uses some modules that console application doesn't support.

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  • Graphic editor opensource project example on c++ underlying composite pattern

    - by G-71
    Can you tell me when I can see a some opensource project (only project on C++ language), which is simple graphic editor, ?ontaining following primitive (for example): an ellipse, a rectangle, a line. And desirable, that to be able to group this primitive in one primitive (for example, Word Grouping - Group). Composite pattern use is desirable in this project. I want to see how to organize classes, but more serious for me is to see how organize grouping operation. I searched for it on codeproject.com codeproject.com, codeplex.com, but not found this. I have already some source http://pastebin.com/xe4JF5PW But in my opinion, this code is dirty and ugly. Therefore, I want to see some opensource project for example. Thanks!

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  • How can I use Object Oriented Javascript to interact with HTML Objects

    - by Steve
    I am very new to object orientated javascript, with experience writing gui's in python and java. I am trying to create html tables that I can place in locations throughout a webpage. Each html table would have two css layouts that control if it is selected or not. I can write all of the interaction if I only have one table. It gets confusing when I have multiple tables. I am wondering how to place these tables throughout a blank webpage and then access the tables individually. I think I am having trouble understanding how inheritance and hierarchy works in javascript/html. NOTE: I am not asking how to make a table. I am trying to dynamically create multiple tables and place them throughout a webpage. Then access their css independently and change it (move them to different locations or change the way the look, independently of the other tables).

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  • how to Clean up(destructor) a dynamic Array of pointers??

    - by Ahmed Sharara
    Is that Destructor is enough or do I have to iterate to delete the new nodes?? #include "stdafx.h" #include<iostream> using namespace std; struct node{ int row; int col; int value; node* next_in_row; node* next_in_col; }; class MultiLinkedListSparseArray { private: char *logfile; node** rowPtr; node** colPtr; // used in constructor node* find_node(node* out); node* ins_node(node* ins,int col); node* in_node(node* ins,node* z); node* get(node* in,int row,int col); bool exist(node* so,int row,int col); //add anything you need public: MultiLinkedListSparseArray(int rows, int cols); ~MultiLinkedListSparseArray(); void setCell(int row, int col, int value); int getCell(int row, int col); void display(); void log(char *s); void dump(); }; MultiLinkedListSparseArray::MultiLinkedListSparseArray(int rows,int cols){ rowPtr=new node* [rows+1]; colPtr=new node* [cols+1]; for(int n=0;n<=rows;n++) rowPtr[n]=NULL; for(int i=0;i<=cols;i++) colPtr[i]=NULL; } MultiLinkedListSparseArray::~MultiLinkedListSparseArray(){ // is that destructor enough?? cout<<"array is deleted"<<endl; delete [] rowPtr; delete [] colPtr; }

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  • Javascript Instance Variable Syntax (AJAX page refresh)

    - by Rosarch
    I'm having difficulty with Javascript instance variables. I'm trying to make an easy way to refresh the chat page, looking for new messages. The AJAX call supplies a mid, or the lowest message id to be returned. This allows the call to only ask for the most recent messages, instead of all of them. MessageRefresher.prototype._latest_mid; function MessageRefresher(latest_mid) { this._latest_mid = latest_mid; // it thinks `this` refers to the MessageRefresher object } MessageRefresher.prototype.refresh = function () { refreshMessages(this._latest_mid); // it thinks `this` refers to the window this._latest_mid++; } function refreshMessages(latest_mid) { $.getJSON('API/read_messages', { room_id: $.getUrlVar('key'), mid: latest_mid }, function (messages) { for (var i = 0; i < messages[0].length; i++) { var newChild = sprintf("<li>%s: %s</li>", messages[1][i], messages[0][i]); $("#messages").append(newChild); } }); var messageRefresher = new MessageRefresher(0); setInterval(messageRefresher.refresh, 1000); This results in all the messages being printed out, over and over again. I know it has other bugs, but the main issue I'm trying to work out right now is the use of the instance variable. Or is there another way I should be going about doing this?

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  • Is it true that in most Object Oriented Programming Languages, an "i" in an instance method always r

    - by Jian Lin
    In the following code: <script type="text/javascript"> var i = 10; function Circle(radius) { this.r = radius; this.i = radius; } Circle.i = 123; Circle.prototype.area = function() { alert(i); } var c = new Circle(1); var a = c.area(); </script> What is being alerted? The answer is at the end of this question. I found that the i in the alert call either refers to any local (if any), or the global variable. There is no way that it can be the instance variable or the class variable even when there is no local and no global defined. To refer to the instance variable i, we need this.i, and to the class variable i, we need Circle.i. Is this actually true for almost all Object oriented programming languages? Any exception? Are there cases that when there is no local and no global, it will look up the instance variable and then the class variable scope? (or in this case, are those called scope?) the answer is: 10 is being alerted.

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  • Output of the following code

    - by terrific
    String s1 = "Amit"; //true String s2 = "Amit"; //true String s3 = new String("abcd"); //true String s4 = new String("abcd"); //false System.out.println(s1.equals(s2)); //true System.out.println((s1==s2)); //true System.out.println(s3.equals(s4)); //false System.out.println((s3==s4)); //false Assume it to be in main why the output of the above code is true true true false and not true true false false???

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  • Why does PHP 5.2 disallow abstract static class methods?

    - by Artem Russakovskii
    After enabling strict warnings in PHP 5.2, I saw a load of strict standards warnings from a project that was originally written without strict warnings: Strict Standards: Static function Program::getSelectSQL() should not be abstract in Program.class.inc The function in question belongs to an abstract parent class Program and is declared abstract static because it should be implemented in its child classes, such as TVProgram. I did find references to this change here: Dropped abstract static class functions. Due to an oversight, PHP 5.0.x and 5.1.x allowed abstract static functions in classes. As of PHP 5.2.x, only interfaces can have them. My question is: can someone explain in a clear way why there shouldn't be an abstract static function in PHP?

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  • Set The Progress Bar Over 100% C#

    - by PhaDaPhunk
    its my first time using a ProgressBar in c#. The idea is to use the ProgressBar as an health bar in a simple game. The thing is I think the bar's maximum value is 100% but i would like to give it a higher value like let's say 1000% or, not sure if it's possible, give the bar an integer value instead of a percentage. progressBar1.Increment(100); This is where I initialize the health to 100points. Even if I use this syntax: progressBar1.Increment(1000); And I subtract : progressBar1.Increment(-25); The player is loosing 1/4 of is life as if he only had 100 Health Points. Any idea how I could change the maximum Bar value? Thanks in advance.

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  • "Abstract static" method - how?

    - by polyglot
    There are already several SO questions on why there is not abstract static method/field as such, but I'm wondering about how one would go about implementing the following psuedo-code: class Animal { abstract static int getNumberOfLegs(); // not possible } class Chicken inherits Animal { static int getNumberOfLegs() { return 2; } class Dog inherits Animal { static int getNumberOfLegs() { return 4; } Here is the problem: Assuming that I want make sure that every class that inherits Animal to contain getNumberOfLegs() method (i.e. almost like an interface, except I do want the abstract class to implement several methods that are common to all child classes, hence pure interface does not work here). getNumberOfLegs() obviously should be a static method (assuming that in a perfect world we dont' have crippled chicken and dogs so getNumberOfLegs is not instance-dependent). Without an "abstract static" method/field, one can either leave the method out from Animal class, then there is the risk that some child class do not have that method. Or one can make getNumberOfLegs an instance method, but then one would have to instantiate a class to find out how many legs that animal has - even though it is not necessary. How do one usually go about implementing this situation?

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  • Can I have two names for the same variable?

    - by Roman
    The short version of the question: I do: x = y. Then I change x, and y is unchanged. What I want is to "bind" x and y in such a way that I change y whenever I change x. The extended version (with some details): I wrote a class ("first" class) which generates objects of another class ("second" class). In more details, every object of the second class has a name as a unique identifier. I call a static method of the first class with a name of the object from the second class. The first class checks if such an object was already generated (if it is present in the static HashMap of the first class). If it is already there, it is returned. If it is not yet there, it is created, added to the HashMap and returned. And then I have the following problem. At some stage of my program, I take an object with a specific name from the HashMap of the first class. I do something with this object (for example change values of some fields). But the object in the HashMap does not see these changes! So, in fact, I do not "take" an object from the HashMap, I "create a copy" of this object and this is what I would like to avoid.

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  • Dilemma with two types and operator +

    - by user35443
    I have small problem with operators. I have this code: public class A { public string Name { get; set; } public A() { } public A(string Name) { this.Name = Name; } public static implicit operator B(A a) { return new B(a.Name); } public static A operator+(A a, A b) { return new A(a.Name + " " + b.Name); } } public class B { public string Name { get; set; } public B() { } public B(string Name) { this.Name = Name; } public static implicit operator A(B b) { return new A(b.Name); } public static B operator +(B b, B a) { return new B(b.Name + " " + a.Name); } } Now I want to know, which's conversion operator will be called and which's addition operator will be called in this operation: new A("a") + new B("b"); Will it be operator of A, or of B? (Or both?) Thanks....

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  • Checking method visibility in PHP

    - by phobia
    Is there any way of checking if a class method has been declared as private or public? I'm working on a controller where the url is mapped to methods in the class, and I only want to trigger the methods if they are defined as public.

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  • Implimenting Zend MVC for my existing site-first step?

    - by Joel
    Hi guys, OK-newbie question here. I'll try not to bombard SO with lots of questions-and hopefully this first one will show me the method I'll need to follow for subsequent conversions. I have a web-based calendar system that I developed, but it was coded for me procedurally (using PHP). I'm now working on learning OO and wanting to integrate this site into my localhost Zend Framework and slowly start converting parts to OO and the Zend Framework MVC process in particular. As I've said before, I understand that this will be a slow process, and when I'm done, I still probably won't have anything as OO friendly as if I had rewritten it from scratch, but I'd like to use this as a learning experience. So, I have dropped the whole site into my localhose/zend/Public folder, and everything is showing up great and linking to the database, etc. My question is-what would be the easiest first component to switch over to the MVC model? This site has a bit of everything-forms, login, authentication, some jQuery, etc. Can anyone point to a tutorial that would address what I'm trying to do? If indeed, a form would be one of the simpler things to switch, can someone walk me through those changes? Another idea is changing over all the header info, etc? Thanks for any pointers on where to start! EDIT: Also, I understand that SO is mainly for specific coding questions-I'm happy to share specific code, once I have an idea about which section to tackle first...

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  • How to properly dispose of an object

    - by VoodooChild
    Hi Guys, I am experiencing something weird and have a workaround already, but I don't think I understood it well. If I call the Method below numerous times within a class: public void Method() { Foo a = new Foo(); a.Delegate1Handler = ViewSomething(); } So I am reinitializing "a" every time but for some reason a.Delegate1Handler is still around from the previous initialization, and therefore ViewSomething() is called again and again and again.... I feel like I am forgetting something critical here? Foo's guts look like: public delegate void Delegate1(T t); public Delegate1 Delegate1Handler { get; set; }

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  • How would I associate a "Note" class to 4+ classes without creating lookup table for each associatio

    - by Gthompson83
    Im creating a project tasklist application. I have project, section, task, issue classes, and would like to use one class to be able to add simple notes to any object instance of those classes. The task, issue tables both use a standard identity field as a primary key. The section table has a two field primary key. The project table has a single int primary key defined by the user. Is there a way to associate the note class with each of these without using a seperate lookup table for each class? I'm not so sure my original idea is a decent way to implement this. I considered the following (each variable mapping to a field n the notes table. Private _NoteId As Integer Private _ProjectId As Integer Private _SectionId As Integer Private _SectionId2 As Integer Private _TaskId As Integer Private _IssueId As Integer Private _Note As String Private _UserId As Guid Then I would be able to write seperate methods (getProjectNotes, getTaskNotes) to get notes attached to each class. I started writing this a few weeks ago but got pulled away before i could finish. When revisiting this code today my first thought "this is retarded". Thoughts on drawbacks to this design?

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  • How to avoid "incomplete implementation" warning in partial base class

    - by garph0
    I have created a protocol that my classes need to implement, and then factored out some common functionality into a base class, so I did this: @protocol MyProtocol - (void) foo; - (void) bar; @end @interface Base <MyProtocol> @end @interface Derived_1 : Base @end @interface Derived_2 : Base @end @implementation Base - (void) foo{ //something foo } @end @implementation Derived_1 - (void) bar{ //something bar 1 } @end @implementation Derived_2 - (void) bar{ //something bar 2 } @end In this way in my code I use a generic id<MyProtocol>. The code works (as long as Base is not used directly) but the compiler chokes at the end of the implementation of Base with a warning: Incomplete implementation of class Base Is there a way to avoid this warning or, even better, a more proper way to obtain this partially implemented abstract base class behavior in Objc?

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  • Can a function/class know the context from where it is being invoked or instantiated?

    - by vrode
    Let's take this class as example and assume that get_context() returns the source of the call: class A { public function __construct( ) { if( get_class( get_context( ) ) == B ) { return true; } else { return false; } } } class B { function __construct( ) { $a = new A( ); } } $a = new B( ); // returns true, as B is the invoking class of A $a = new A( ); // returns false, as B is invoked outside of any class So, my questions are: 1) can a function know the context that calls it? 2) can a object know context from where it has been instantiated? Or am I dreaming up new features not implementable in PHP?

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  • Is this the correct why of speaking to a "Content Manager" Class?

    - by DeanMc
    I am creating a silverlight site. I am currently breaking out my ideas into pieces of functionality. One of the idea's I have is the concept of a content manager. This is essentially a UI control with 4 regions. Top, Bottom, Right & Left. I also have a collection of objects that are considered "Menu Items". These are controls that function as a way to navigate around, similar to links. The idea I have is to implement an IMenuItem interface. Among the standard pieces of information (Text, PageReference, etc) I was also going to hold a reference to the content manager. My idea behind this thinking is that I can pass the PageReference to a property on the ContentManager and then call a method which knows how to update the content manager accordingly. Is this the best way of implementing this or is their some sort of pattern for it?

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  • Javascript: Access the right scope "under" apply(...)

    - by Chau
    This is a very old problem, but I cannot seem to get my head around the other solutions presented here. I have an object function ObjA() { var a = 1; this.methodA = function() { alert(a); } } which is instantiated like var myObjA = new ObjA(); Later on, I assign my methodA as a handler function in an external Javascript Framework, which invokes it using the apply(...) method. When the external framework executes my methodA, this belongs to the framework function invoking my method. Since I cannot change how my method is called, how do I regain access to the private variable a? My research tells me, that closures might be what I'm looking for.

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  • Multiple Inheritance Debates II: according to Stroutroup

    - by asksuperuser
    I know very well about the traditional arguments about why Interface Inheritance is prefered to multiple inheritance, there has been already a post here : http://stackoverflow.com/questions/191691/should-c-include-multiple-inheritance But according to Stroutroup the real reason why Microsoft and Sun decided to get rid off multiple inheritance is that they have vested interest to do so: instead of putting features in the languages, they put in frameworks so that people then become tied to their platform instead of people having the same capability at a language standard level. What do you think ?

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