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  • Struct like objects in Java

    - by cdv
    Is it completely against the Java way to create struct like objects? class SomeData1 { public int x; public int y; } I can see a class with accessors and mutators being more Java like. class SomeData2 { int getX(); void setX(int x); int getY(); void setY(int y); private int x; private int y; } The class from the first example is notationally convenient. // a function in a class public int f(SomeData1 d) { return (3 * d.x) / d.y; } This is not as convenient. // a function in a class public int f(SomeData2 d) { return (3 * d.getX()) / d.getY(); }

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  • How to manage member variable in C++

    - by rhapsodyn
    In brief, my question is about member variables as pointers in unmanaged C++. In java or c#, we have "advanced pointer". In fact, we can't aware the "pointer" in them. We usually initialize the member of a class like this: member = new Member(); or member = null; But in c++, it becomes more confusing. I have seen many styles: using new, or leave the member variable in stack. In my point of view, using boost::shared_ptr seems friendly, but in boost itself source code there are news everywhere. It's the matter of efficiency,isn't it? Is there a guildline like "try your best to avoid new" or something?

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  • Extend base class properties

    - by user1888033
    I need your help to extend my base class, here is the similar structure i have. public class ShowRoomA { public audi AudiModelA { get; set; } public benz benzModelA { get; set; } } public class audi { public string Name { get; set; } public string AC { get; set; } public string PowerStearing { get; set; } } public class benz { public string Name { get; set; } public string AC { get; set; } public string AirBag { get; set; } public string MusicSystem { get; set; } } //My Implementation class like this class Main() { private void UpdateDetails() { ShowRoomA ojbMahi = new ShowRoomA(); GetDetails( ojbMahi ); // this works fine } private void GetDetails(ShowRoomA objShowRoom) { objShowRoom = new objShowRoom(); objShowRoom.audi = new audi(); objShowRoom.audi.Name = "AUDIMODEL94CD698"; objShowRoom.audi.AC = "6 TON"; objShowRoom.audi.PowerStearing = "Electric"; objShowRoom.benz= new benz(); objShowRoom.audi.Name = "BENZMODEL34LCX"; objShowRoom.audi.AC = "8 TON"; objShowRoom.audi.AirBag = "Two (1+1)"; objShowRoom.audi.MusicSystem = "Poineer 3500W"; } } // Till this cool. // Now I got requirement for ShowRoomB with replacement of old audi and benz with new models and new other brand cars also added. // I don't want to modify GetDetails() method. by reusing this method additional logic i want to apply to my new extended model. // Here I struck in designing my new model of ShowRoomB (base of ShowRoomA) ... I have tried some thing like... but not sure. public class audiModelB:audi { public string JetEngine { get; set; } } public class benzModelB:benz { public string JetEngine { get; set; } } public class ShowRoomB { public audiModelB AudiModelB { get; set; } public benzModelB benzModelB { get; set; } } // My new code to Implementation class like this class Main() { private void UpdateDetails() { ShowRoomB ojbNahi = new ShowRoomB(); GetDetails( ojbNahi ); // this is NOT working! I know this object does not contain base class directly, still some what i want fill my new model with old properties. Kindly suggest here } } Can any one please give me solutions how to achieve my extending requirement for base class "ShowroomA" Really appreciated your time and suggestions. Thanks in advance,

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  • PHP class extends not working why and is this how to correctly extend a class?

    - by Matthew
    Hi so I'm trying to understand how inherteince works in PHP using object oriented programming. The main class is Computer, the class that is inheriting is Mouse. I'm extedning the Computer class with the mouse class. I use __construct in each class, when I istinate the class I use the pc type first and if it has mouse after. For some reason computer returns null? why is this? class Computer { protected $type = 'null'; public function __construct($type) { $this->type = $type; } public function computertype() { $this->type = strtoupper($this->type); return $this->type; } } class Mouse extends Computer { protected $hasmouse = 'null'; public function __construct($hasmouse){ $this->hasmouse = $hasmouse; } public function computermouse() { if($this->hasmouse == 'Y') { return 'This Computer has a mouse'; } } } $pc = new Computer('PC', 'Y'); echo $pc->computertype; echo $pc->computermouse;

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  • How to iterate over numerically named object properties

    - by Scott Schluer
    So I have a horribly designed class that I can't change that has properties like this: object.Color1 object.Color2 object.Color3 etc... How can I iterate through those with a for loop. In other words, something like this: for (int i = 0; i <= 40; i++) { string PropertyName = "Color" + i; if (object.PropertyName != "") { // do something } } Obviously this code wouldn't work but it gives you an idea of what I'm after. I have to do some processing on each property and I don't want to repeat my code 40 times. :) A loop would be perfect, I'm just not sure how to create the name of the property on the fly.

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  • Three customer addresses in one table or in separate tables?

    - by DR
    In my application I have a Customer class and an Address class. The Customer class has three instances of the Address class: customerAddress, deliveryAddress, invoiceAddress. Whats the best way to reflect this structure in a database? The straightforward way would be a customer table and a separate address table. A more denormalized way would be just a customer table with columns for every address (Example for "street": customer_street, delivery_street, invoice_street) What are your experiences with that? Are there any advantages and disadvantages of these approaches?

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  • Objective C - creating concrete class instances from base class depending upon type

    - by indiantroy
    Just to give a real world example, say the base class is Vehicle and concrete classes are TwoWheeler and FourWheeler. Now the type of the vehicle - TwoWheeler or FourWheeler, is decided by the base class Vehicle. When I create an instance of TwoWheeler/FourWheeler using alloc-init method, it calls the super implementation like below to set the value of common properties defined in the Vehicle class and out of these properties one of them is type that actually decides if the type is TwoWheeler or FourWheeler. if (self = [super initWithDictionary:dict]){ [self setOtherAttributes:dict]; return self; } Now when I get a collection of vehicles some of them could be TwoWheeler and others will be FourWheeler. Hence I cannot directly create an instance of TwoWheeler or FourWheeler like this Vehicle *v = [[TwoWheeler alloc] initWithDictionary:dict]; Is there any way I can create an instance of base class and once I know the type, create an instance of child class depending upon type and return it. With the current implementation, it would result in infinite loop because I call super implementation from concrete class. What would be the perfect design to handle this scenario when I don't know which concrete class should be instantiated beforehand?

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  • self-destructing objects in php5?

    - by user151841
    I am working on a class in php that is basically an interface to a database row. I wanted to create a delete() method that would 1. delete the database row and 2. destroy the instance of itself so that further attempts to manipulate the row via the object would throw warnings. Doing some googling, it seems that, in php5, it's not possible for an object to unset itself. http://bugs.php.net/bug.php?id=36971 In fact they discuss the very situation I was wanting to do :( So how should I proceed? I could make boolean flag as a class property, for whether the row still exists, and have each operation check that flag and throw an error if the row has been deleted. This maintains the oo structure of code, so I would have $objDbRow->delete(); But then I have to put checks at the beginning of each method. Or, I could implement a __destruct method that deletes the row. But that would seem counter-intuitive to me; if I saw in code unset($objDbRow); All I would suspect that's happening is that the object is being discarded, not that a row is being deleted. So that to me would seem like bad practice.

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  • PHP object cannot find method

    - by Daniel Hertz
    Hello, So I have a very simple class that has a method called getThumbUrl() but when I try calling this method on an instance I get Notice: Undefined property: FlickrImage::$getFullUrl But it is clearly there. Here is the code of the function: public function getThumbUrl() { return "http://farm".$this->_farm.".static.flickr.com/".$this->_server."/".$this->_id."_".$this->_secret."_t.jpg"; } And here is where it fails: foreach($photos as $photo) { echo "<img src='$photo->getFullUrl()' />"; } Any ideas? Thanks!

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  • Javascript plugin creation

    - by Aneesh
    I want to create a plugin called 'myPlugin'. Which method should I use and what is the difference between these two methods? Please tell me the advantages too. I am from designing background and not much programming knowledge. var myPlugin = { myId:"testId", create:function(){}, destroy:function(){} } OR function myPlugin() { this.myId = "testId"; this.create = function(){}; this.destroy = function(){}; }

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  • is "Object();" a predefined function in javascript?

    - by Qlidnaque
    I come across code such as "personObj=new Object();" where a new object called personObj is being defined. What I'm trying to find out is whether Object() is a prefined function in javascript, because I understand by using the mentioned code, a instance of a class is being formed but in the example code where I'm studying from, the class Object() is not being defined anywhere, so I was wondering if Object() was a predefined function in javascript and whether I can be directed to some online resources, as all that shows up in google when I try to find Object() are articles in general javascript object oriented programming.

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  • Catch requests to non-existent classes (not autoload)

    - by Spot
    Is there a manner in which to catch requests to a class which does not exist. I'm looking for something exactly like __call() and __static(), but for classes as opposed to methods in a class. I am not talking about autoloading. I need to be able to interrupt the request and reroute it. Ideas?

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  • Creating instance of interface in C#

    - by Max
    I'm working with MS Excel interop in C# and I don't understand how this particular line of code works: var excel = new Microsoft.Office.Interop.Excel.Application(); where Microsoft.Office.Interop.Excel.Application is an INTERFACE defined as: [Guid("000208D5-0000-0000-C000-000000000046")] [CoClass(typeof(ApplicationClass))] public interface Application : _Application, AppEvents_Event { } I'm thinking that some magic happens when the interface is decorated with a CoClass attribute, but still how is it possible that we can create an instance of an interface with a new keyword? Shouldn't it generate a compile time error?

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  • Abstract Design Pattern implementation

    - by Pathachiever11
    I started learning design patterns a while ago (only covered facade and abstract so far, but am enjoying it). I'm looking to apply the Abstract pattern to a problem I have. The problem is: Supporting various Database systems using one abstract class and a set of methods and properties, which then the underlying concrete classes (inheriting from abstract class) would be implementing. I have created a DatabaseWrapper abstract class and have create SqlClientData and MSAccessData concrete class that inherit from the DatabaseWrapper. However, I'm still a bit confused about how the pattern goes as far as implementing these classes on the Client. Would I do the following?: DatabaseWrapper sqlClient = new SqlClientData(connectionString); This is what I saw in an example, but that is not what I'm looking for because I want to encapsulate the concrete classes; I only want the Client to use the abstract class. This is so I can support for more database systems in the future with minimal changes to the Client, and creating a new concrete class for the implementations. I'm still learning, so there might be a lot of things wrong here. Please tell me how I can encapsulate all the concrete classes, and if there is anything wrong with my approach. Many Thanks! PS: I'm very excited to get into software architecture, but still am a beginner, so take it easy on me. :)

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  • How to access constant defined in child class from parent class functions?

    - by kavoir.com
    I saw this example from php.net: <?php class MyClass { const MY_CONST = "yonder"; public function __construct() { $c = get_class( $this ); echo $c::MY_CONST; } } class ChildClass extends MyClass { const MY_CONST = "bar"; } $x = new ChildClass(); // prints 'bar' $y = new MyClass(); // prints 'yonder' ?> But $c::MY_CONST is only recognized in version 5.3.0 or later. The class I'm writing may be distributed a lot. Basically, I have defined a constant in ChildClass and one of the functions in MyClass (father class) needs to use the constant. Any idea?

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  • javascript : make a new safe class constructor

    - by guilin ??
    sometimes we loss the new keyword when define new object, obj = new Clazz(); //correct obj = Clazz(); //wrong, but no syntax error, hard to debug. I want to write a function to help me create Class and make it new safe. var Class = function(constructor){ //when constructor // if not call by new return new constructor(); // else constructor(); } var MyClazz = Class(function(name){ this.name = name }, SuperClazz1, SuperClass2 ) MyClazz.extend({ show: function(){console.log(this.name)} }) obj1 = new MyClazz(); obj2 = MyClazz(); // obj1 should same as obj2 Is it possible, any exists module?

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  • Can a problem have a relation of aggregation and composition both between two classes at same point

    - by learner
    Can a problem have a relation of aggregation and composition both between two classes at same point of time? Like any real time scenario where there can be aggregation corresponding to one method and composition related to other method. I m unable to figure out any scenario where both composition and aggregation occurs simultaneously between two classes. Any help will be appreciable.

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  • Is it possible for an abstract class to force it's children to have a constructor in PHP?

    - by Logan Serman
    I would like to do something like this: abstract class Foo { public function __construct() { echo 'This is the parent constructor'; } abstract function __construct(); } class Bar extends Foo { // constructor is required as this class extends Foo public function __construct() { //call parent::__construct() if necessary echo 'This is the child constructor'; } } But I get a fatal error when doing this: Fatal error: Cannot redeclare Foo::__construct() in Foo.php on line 8 Is there another way to ensure child classes have a constructor?

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  • C#: Specify that a function arg must inhert from one class, and implement an interface?

    - by Rosarch
    I'm making a game where each Actor is represented by a GameObjectController. Game Objects that can partake in combat implement ICombatant. How can I specify that arguments to a combat function must inherit from GameObjectController and implement ICombatant? Or does this indicate that my code is structured poorly? public void ComputeAttackUpdate(ICombatant attacker, AttackType attackType, ICombatant victim) In the above code, I want attacker and victim to inherit from GameObjectController and implement ICombatant. Is this syntactically possible?

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  • A self-creator: What pattern is this? php

    - by user151841
    I have several classes that are basically interfaces to database rows. Since the class assumes that a row already exists ( __construct expects a field value ), there is a public static function that allows creation of the row and returns an instance of the class. Here's a pseudo-code example : class fruit { public $id; public function __construct( $id ) { $this->id = $id; $sql = "SELECT * FROM Fruits WHERE id = $id"; ... $this->arrFieldValues[$field] = $row[$value]; } public function __get( $var ) { return $this->arrFieldValues[$var]; } public function __set( $var, $val ) { $sql = "UPDATE fruits SET $var = $val WHERE id = $this->id"; } public static function create( $id ) { $sql = "INSERT INTO Fruits ( fruit_name ) VALUE ( '$fruit' )"; $id = mysql_insert_id(); $fruit = & new fruit($id); return $fruit; } } $obj1 = fruit::create( "apple" ); $obj2 = & new fruit( 12 ); What is this pattern called? Edit: I changed the example to one that has more database-interface functionality. For most of the time, this kind of class would be instantiated normally, through __construct(). But sometimes when you need to create a new row first, you would call create().

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