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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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• How to override part of an overload function in JavaScript

  - by Guan Yuxin

  I create a class with a function like this var Obj=function(){this.children=[];this.parent=null;}//a base class Obj.prototype.index=function(child){ // the index of current obj if(arguments.length==0){ return this.parent?this.parent.index(this):0; } // the index of a child matchs specific obj [to be override] return -1; } basically it is just an overload function composed of index() and index(child). Then I create a sub class,SubObj or whatever, inherits from Obj SubObj.prototype.prototype=Obj; Now, it's time to override the index(child) function,however, index() is also in the function an I don't want to overwrite it too. One solution is to write like this var Obj=function(){this.children=[];this.parent=null;}//a base class Obj.prototype.index=function(child){ // the index of current obj if(arguments.length==0){ return this.parent?this.parent.index(this):0; } // the index of a child matchs specific obj [to be override] return this._index(this); } Obj.prototype._index=function(this){ return -1; } SubObj.prototype._index=function(this){/* overwriteing */} But this will easily mislead other coders as _index(child) should be both private(should not be used except index() function) and public(is an overload function of index(),which is public) you guys have better idea?

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• Class works without declaring variables?

  - by Maxim Droy

  I'm learned php as functional and procedure language. Right now try to start learn objective-oriented and got an important question. I have code: class car { function set_car($model) { $this->model = $model; } function check_model() { if($this->model == "Mercedes") echo "Good car"; } } $mycar = new car; $mycar->set_car("Mercedes"); echo $mycar->check_model(); Why it does work without declaration of $model? var $model; in the begin? Because in php works "auto-declaration" for any variables? I'm stuck

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• What is faster: write PHP code using "functions" or writing it as pure script?

  - by Ole Jak

  What is faster: writing PHP code using functions or writing it as pure script? So, as I see it Apache or any other server will create from PHP code using functions a pure script... I mean we had: function foo($a, $b){ return ($a + $b); echo foo(4, 5)} and Apache will turn it into something like: echo (5 + 4) Or will it?

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• How to "wrap" implementation in C#

  - by igor

  Hello, I have these classes in C# (.NET Framework 3.5) described below: public class Base { public int State {get; set;} public virtual int Method1(){} public virtual string Method2(){} ... public virtual void Method10(){} } public class B: Base { // some implementation } public class Proxy: Base { private B _b; public class Proxy(B b) { _b = b; } public override int Method1() { if (State == Running) return _b.Method1(); else return base.Method1(); } public override string Method2() { if (State == Running) return _b.Method2(); else return base.Method2(); } public override void Method10() { if (State == Running) _b.Method10(); else base.Method10(); } } I want to get something this: public Base GetStateDependentImplementation() { if (State == Running) // may be some other rule return _b; else return base; // compile error } and my Proxy's implementation will be: public class Proxy: Base { ... public override int Method1() { return GetStateDependentImplementation().Method1(); } public override string Method2() { return GetStateDependentImplementation().Method2(); } ... } Of course, I can do this (aggregation of base implementation): public RepeaterOfBase: Base // no any overrides, just inheritance { } public class Proxy: Base { private B _b; private RepeaterOfBase _Base; public class Proxy(B b, RepeaterOfBase aBase) { _b = b; _base = aBase; } } ... public Base GetStateDependentImplementation() { if (State == Running) return _b; else return _Base; } ... But instance of Base class is very huge and I have to avoid to have other additional copy in memory. So I have to simplify my code have to "wrap" implementation have to avoid a code duplication have to avoid aggregation of any additional instance of Base class (duplication) Is it possible to reach these goals?

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• What's the benefits of SOA over OO?

  - by ghedas

  I want to know the differences between SOA and OO, and why SOA is going to popular?

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• When do you use metaclasses?

  - by johannix

  Just started looking into metaclasses and while they seem powerful, I can think of other ways to accomplish the same type of thing. I was wondering when metaclasses have been found to be the right answer and why.

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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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• iterate only through existing objects properties, not them from parent class?

  - by ajsie

  i have a class that extends another. when i iterate the current object i get all properties, even those from the superclass. i only want to iterate through the current object. how could i do that? foreach($this as $key => $value) { echo $key . ': ' . $value; }

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• Why C# doen't support multiple inheritance [closed]

  - by Jibu P C_Adoor

  Possible Duplicate: Should C# include multiple inheritance? One of my friend asked me the question i.e.Why C# doen't support multiple inheritance

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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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• How should I organize my C# classes? [closed]

  - by oscar.fimbres

  I'm creating an email generator system. I'm creating some clases and I'm trying to make things right. By the time, I have created 5 classes. Look at the class diagram: I'm going to explain you each one. Person. It's not a big deal. Just have two constructors: Person(fname, lname1, lname2) and Person(token, fname, lname1, lname2). Note that email property stays without value. StringGenerator. This is a static class and it has only a public function: Generate. The function receives a Person class and it will return a list of patterns for the email. MySql. It contains all the necessary to connect to a database. Database. This class inherits from MySql class. It has particular functions for the database. This gets all the registries from a table (function GetPeople) and return a List. Each person from the list contains all data except Email. Also it can add records (List but this must contains an available email). An available email is when an email doesn't have another person. For that reason, I have a method named ExistsEmail. Container. This is the class which is causing me some problems. It's like a temporary container. It supposed to have a people list from GetPeople (in Database class) and for each person it adds, it must generate a list of possible names (StringGenerator.Generate), then it selects one of the list and it must check out if exists in the database or in the same container. As I told above this is temporal, it may none of the possible emails is available. So the user can modify or enter a custom email available and update the list in this container. When all the email's people are available, it sends a list to add in the database, It must have a Flush method, to insert all the people in the database. I'm trying to design correct class. I need a little help to improve or edite the classes, because I want to separate the logic and visual, and learn of you. I hope you've been able to understand me. Any question or doubt, please let me know. Anyway, I attached the solution here to better understand it: http://www.megaupload.com/?d=D94FH8GZ

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• Can I refer to an object in its constructor?

  - by Roman

  Can I do the following? public Manager(String userName) { game = new Game(userName); game.addManager(this); } The problem is that I refer to an object (this) in its constructor (before it was actually created).

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• mysqli insert into database

  - by Simon

  Hello all i have this script and i will not insert into the database and i get no errors :S, do you know what it is? function createUser($username, $password) { $mysql = connect(); if($stmt = $mysql->prepare('INSERT INTO users (username, password, alder, hood, fornavn, efternavn, city, ip, level, email) VALUES (?,?,?,?,?,?,?,?,?,?)')) { $stmt->bind_param('ssssssssss',$username,$password, $alder, $hood, $fornavn, $efternavn, $city, $ip, $level, $email); $stmt->execute(); $stmt->close(); } else { echo 'error: ' . $mysql->error; }

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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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• 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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• How value objects are saving and loading?

  - by yeraycaballero

  Since there isn't respositories for value objects. How can I load all value objects? Suppose we are modeling a blog application and we have this classes: Post (Entity) Comment (Value object) Tag (Value object) PostsRespository (Respository) I Know that when I save a new post, its tags are saving with it in the same table. But how could I load all tags of all posts. Has PostsRespository got a method to load all tags? I usually do it, but I want to know others opinions

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• Java debug error

  - by ivor

  Hello, I wonder if anyone can help - I have this error showing recently when debugging in eclipse - what doe it mean by resource, an imported package or the location of some java files ? Can't find resource for bundle sun.awt.resources.awt, key AWT.EventQueueClass MissingResourceException (id =45) Thanks

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• how to implement a callback in runnable to update other swing class

  - by wizztjh

  I have a thread like this public class SMS { class Read implements Runnable { Read(){ Thread th = new Thread(this); th.start(); } @Override public void run() { // TODO Auto-generated method stub while (true){ Variant SMSAPIReturnValue = SMSAPIJava.invoke("ReadSMS"); if (SMSAPIReturnValue.getBoolean()){ String InNumber = SMSAPIJava.getPropertyAsString("MN"); String InMessage = SMSAPIJava.getPropertyAsString("MSG"); } } } } } How do I update the message to another GUI class in the same package(I understand how to put nested class to another package ....). Should I implement a callback function in SMS class? But how? Or should I pass in the Jlabel into the class?

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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 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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• 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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• how to make objects globally accessible?

  - by fayer

  i have this code: class IC_Core { /** * Database * @var IC_Database */ public static $db = NULL; /** * Core * @var IC_Core */ protected static $_instance = NULL; private function __construct() { } public static function getInstance() { if ( ! is_object(self::$_instance)) { self::$_instance = new self(); self::initialize(self::$_instance); } return self::$_instance; } private static function initialize(IC_Core $IC_Core) { self::$db = new IC_Database($IC_Core); } } but when i wanna access IC_Database with: $IC = IC_Core::getInstance(); $IC->db->add() // it says that its not an object. i think the problem lies in self::$db = new IC_Database($IC_Core); but i dont know how to make it work. could someone give me a hand=) thanks!

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• Is this a problem typically solved with IOC?

  - by Dirk

  My current application allows users to define custom web forms through a set of admin screens. it's essentially an EAV type application. As such, I can't hard code HTML or ASP.NET markup to render a given page. Instead, the UI requests an instance of a Form object from the service layer, which in turn constructs one using a several RDMBS tables. Form contains the kind of classes you would expect to see in such a context: Form= IEnumerable<FormSections>=IEnumerable<FormFields> Here's what the service layer looks like: public class MyFormService: IFormService{ public Form OpenForm(int formId){ //construct and return a concrete implementation of Form } } Everything works splendidly (for a while). The UI is none the wiser about what sections/fields exist in a given form: It happily renders the Form object it receives into a functional ASP.NET page. A few weeks later, I get a new requirement from the business: When viewing a non-editable (i.e. read-only) versions of a form, certain field values should be merged together and other contrived/calculated fields should are added. No problem I say. Simply amend my service class so that its methods are more explicit: public class MyFormService: IFormService{ public Form OpenFormForEditing(int formId){ //construct and return a concrete implementation of Form } public Form OpenFormForViewing(int formId){ //construct and a concrete implementation of Form //apply additional transformations to the form } } Again everything works great and balance has been restored to the force. The UI continues to be agnostic as to what is in the Form, and our separation of concerns is achieved. Only a few short weeks later, however, the business puts out a new requirement: in certain scenarios, we should apply only some of the form transformations I referenced above. At this point, it feels like the "explicit method" approach has reached a dead end, unless I want to end up with an explosion of methods (OpenFormViewingScenario1, OpenFormViewingScenario2, etc). Instead, I introduce another level of indirection: public interface IFormViewCreator{ void CreateView(Form form); } public class MyFormService: IFormService{ public Form OpenFormForEditing(int formId){ //construct and return a concrete implementation of Form } public Form OpenFormForViewing(int formId, IFormViewCreator formViewCreator){ //construct a concrete implementation of Form //apply transformations to the dynamic field list return formViewCreator.CreateView(form); } } On the surface, this seems like acceptable approach and yet there is a certain smell. Namely, the UI, which had been living in ignorant bliss about the implementation details of OpenFormForViewing, must possess knowledge of and create an instance of IFormViewCreator. My questions are twofold: Is there a better way to achieve the composability I'm after? (perhaps by using an IoC container or a home rolled factory to create the concrete IFormViewCreator)? Did I fundamentally screw up the abstraction here?

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• Exposing members or make them private in Python?

  - by deamon

  Is there a general convention about exposing members in Python classes? I know that this is a case of "it depends", but maybe there is a rule of thumb. Private member: class Node: def __init__(self): self.__childs = [] def add_childs(self, *args): self.__childs += args node = Node() node.add_childs("one", "two") Public member: class Node2: def __init__(self): self.childs = [] node2 = Node2() node2.childs += "one", "two"

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