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  • Formal name of Magento’s Class Override Design Pattern?

    - by Alan Storm
    Magento is a newish (past 5 years) PHP based Ecommerce system with an architecture that's similar to the Java Spring framework (or so I've been told) One of the features of the Framework is certain classes are not directly instantiated. Rather than do something like $model = new Mage_Foo_Model_Name(); you pass an identifier into a static method on a global application object $model = Mage::getModel('foo/name'); and this instantiates the class for you. One of the wins with this approach is getModel checks a global configuration system for the foo/name identifier, and instantiates the class name it finds in the configuration system. This allows you to change the behavior of a Model system wide with a single configuration change. Is there a formal, Gang of Four or otherwise, name that describes this system/design pattern? The instantiation itself looks like a classic Factory pattern, but I'm specifically interested in the whole "override a class in the system via configuration" aspect. Is there a name/concept that covers this, or is it contained within the worldview of a Factory?

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  • Updating the Jpanel of a class

    - by ivor
    Hi, After some advice on using jpanel - I'm new to java and playing around with the GUI elements. Bascially what I'm curious about is if I can set up a Jpanel in one class, then somehow add labels etc to the that container, but from another class. Is this possible ? or do i have to set the entire GUI up in one class, but then I guess I would have the same issue, if I wanted to update those fields I had set up in the main class from another class? Apologies I don't really have any code that's usefull to demostrate here - I'm just trying to get the idea going, working out if its possible before I go ahead. And I'm not even sure if this is possible. Any advice would be greatly appreciated. Thanks

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  • Why a new instance uses logger from old instances?

    - by Roman
    I generate 2 instances in this way: gameManager manager1 = new CTManager(owner,players1,"en"); manager1.start(); gameManager manager2 = new CTManager(owner,players2,"en"); manager2.start(); The start() method of the gameManager looks like that: void start() { game.start(); } When I create the game instance I create a loger: log = Logger.getLogger("TestLog"); (log is a public field of the class in which the game belongs). In the game.start() I run many processes and give them a reference to the corresponding log. So, I expect that manager1 and manager2 will write to different files. But manager2 writes to its own file and to the log file of the manager1. Why can it happen?

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  • Object Oriented vs Relational Databases

    - by Dan
    Objects oriented databases seem like a really cool idea to me, no need to worry about mapping your domain model to your database model, no messing around with sql or ORM tools. The way I understand it, relational DBs offer some advantages when there is massive amounts of data, and searching an indexing need to be done. To my mind 99% of websites are not massive, and enterprise issues never need to be thought about, so why arn't OO DBs more widely used?

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  • Java : Using parent class method to access child class variable

    - by Jayant
    I have the following scenario : public class A { private int x = 5; public void print() { System.out.println(x); } } public class B extends A { private int x = 10; /*public void print() { System.out.println(x); }*/ public static void main(String[] args) { B b = new B(); b.print(); } } On executing the code, the output is : 5. How to access the child class(B's) variable(x) via the parent class method? Could this be done without overriding the print() method (i.e. uncommenting it in B)? [This is important because on overriding we will have to rewrite the whole code for the print() method again]

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  • Is there anything wrong with taking immediate actions in constructors?

    - by pestaa
    I have classes like this one: class SomeObject { public function __construct($param1, $param2) { $this->process($param1, $param2); } ... } So I can instantly "call" it as some sort of global function just like new SomeObject($arg1, $arg2); which has the benefits of staying concise, being easy to understand, but might break unwritten rules of semantics by not waiting till a method is called. Should I continue to feel bad because of a bad practice, or there's really nothing to worry about? Clarification: I do want an instance of the class. I do use internal methods of the class only. I initialize the object in the constructor, but call the "important" action-taker methods too. I am selfish in the light of these sentences.

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  • How important is it that models be consistent across project components?

    - by RonLugge
    I have a project with two components, a server-side component and a client-side component. For various reasons, the client-side device doesn't carry a fully copy of the database around. How important is it that my models have a 1:1 correlation between the two sides? And, to extend the question to my bigger concern, are there any time-bombs I'm going to run into down the line if they don't? I'm not talking about having different information on each side, but rather the way the information is encapsulated will vary. (Obviously, storage mechanisms will also vary) The server side will store each user, each review, each 'item' with seperate tables, and create links between them to gather data as necessary. The client side shouldn't have a complete user database, however, so rather than link against the user for gathering things like 'name', I'd store that on the review. In other words... --- Server Side --- Item: +id //Store stuff about the item User: +id +Name -Password Review: +id +itemId +rating +text +userId --- Device Side --- Item: +id +AverageRating Review: +id +rating +text +userId +name User: +id +Name //Stuff The basic idea is that certain 'critical' information gets moved one level 'up'. A user gets the list of 'items' relevant to their query, with certain review-orientation moved up (i. e. average rating). If they want more info, they query the detail view for the item, and the actual reviews get queried and added to the dataset (and displayed). If they query the actual review, the review gets queried and they pick up some additional user info along the way (maybe; I'm not sure if the user would have any use for any of the additional user information). My basic concern is that I don't wan't to glut the user's bandwidth or local storage with a huge variety of information that they just don't need, even if proper database normalizations suggests that information REALLY should be stored at a 'lower' level. I've phrased this as a fairly low-level conceptual issue because that's the level I'm trying to think / worry over, but if it matters I'm creating a PHP / MySQL server that provides data for a iOS / CoreData client.

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  • How to implement copy operator for such C++ structure?

    - by Kabumbus
    So having struct ResultStructure { ResultStructure(const ResultStructure& other) { // copy code in here ? using memcpy ? how??? } ResultStructure& operator=(const ResultStructure& other) { if (this != &other) { // copy code in here ? } return *this } int length; char* ptr; }; How to implement copy? (sorry - I am C++ nube)

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  • interact with an interface?

    - by ajsie
    from what i've read it seems that one can interact with an interface? eg. lets say that i've got an interface with an empty method "eat()" then 2 subclasses are implementing this interface. can my controller interact with only the interface and use it's eat() method? have a look at the picture in this link strategy

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  • Is this a reasonable way to handle getters/setters in a PHP class?

    - by Mark Biek
    I'm going to try something with the format of this question and I'm very open to suggestions about a better way to handle it. I didn't want to just dump a bunch of code in the question so I've posted the code for the class on refactormycode. base-class-for-easy-class-property-handling My thought was that people can either post code snippets here or make changes on refactormycode and post links back to their refactorings. I'll make upvotes and accept an answer (assuming there's a clear "winner") based on that. At any rate, on to the class itself: I see a lot of debate about getter/setter class methods and is it better to just access simple property variables directly or should every class have explicit get/set methods defined, blah blah blah. I like the idea of having explicit methods in case you have to add more logic later. Then you don't have to modify any code that uses the class. However I hate having a million functions that look like this: public function getFirstName() { return $this->firstName; } public function setFirstName($firstName) { return $this->firstName; } Now I'm sure I'm not the first person to do this (I'm hoping that there's a better way of doing it that someone can suggest to me). Basically, the PropertyHandler class has a __call magic method. Any methods that come through __call that start with "get" or "set" are then routed to functions that set or retrieve values into an associative array. The key into the array is the name of the calling method after get or set. So, if the method coming into __call is "getFirstName", the array key is "FirstName". I liked using __call because it will automatically take care of the case where the subclass already has a "getFirstName" method defined. My impression (and I may be wrong) is that the __get & __set magic methods don't do that. So here's an example of how it would work: class PropTest extends PropertyHandler { public function __construct() { parent::__construct(); } } $props = new PropTest(); $props->setFirstName("Mark"); echo $props->getFirstName(); Notice that PropTest doesn't actually have "setFirstName" or "getFirstName" methods and neither does PropertyHandler. All that's doing is manipulating array values. The other case would be where your subclass is already extending something else. Since you can't have true multiple inheritance in PHP, you can make your subclass have a PropertyHandler instance as a private variable. You have to add one more function but then things behave in exactly the same way. class PropTest2 { private $props; public function __construct() { $this->props = new PropertyHandler(); } public function __call($method, $arguments) { return $this->props->__call($method, $arguments); } } $props2 = new PropTest2(); $props2->setFirstName('Mark'); echo $props2->getFirstName(); Notice how the subclass has a __call method that just passes everything along to the PropertyHandler __call method. Another good argument against handling getters and setters this way is that it makes it really hard to document. In fact, it's basically impossible to use any sort of document generation tool since the explicit methods to be don't documented don't exist. I've pretty much abandoned this approach for now. It was an interesting learning exercise but I think it sacrifices too much clarity.

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  • What is an instance of a field called?

    - by waxwing
    This might be an odd question, but it has actually caused me some headache. In Object oriented programming, there are accepted names for key concepts. In our model, we have classes with methods and fields. Now, going to the data world: An instance of a class is called an object. An instance of a field is called... what? A value? Isn't the term value a little broad for this? I have been offered "property" as well, but isn't property also part of the model and not the data? (This is not purely academic, I am actually coding these concepts.)

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  • Interesting OOPS puzzle

    - by user3714387
    Recently, faced the below question from one of the interviewer. Initially thought that the question was wrong, but the interviewer mentioned there is solution for this. Quite interesting. Can anyone shed light please ? Program as below. public class BaseHome { public static void main() { Console.WriteLine("A"); } } Required output : B A C Condition : Should not make any change in the Main function. Should not create any additional class. Please advice if this can be done with the condition met.

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  • Get information from a higher class?

    - by Clint Davis
    I don't know really how to word the question so please bear with me... I have 3 classes: Server, Database, and Table. Each class has a "Name" property. How I want it to work is that each server can have multiple databases and each database can have multiple tables. So in the Server class I have this property. Private _databases As List(Of Database) Public Property Databases() As List(Of Database) Get Return _databases End Get Set(ByVal value As List(Of Database)) _databases = value End Set End Property And I have something similar in the Database class for the tables. This works fine now because I can do something like this to get all the databases in the server. For Each db In s.Databases 's being the server object Debug.Print(db.Name) Next I would like to expand these classes. I want the server class to handle all the connection information and I would like the other classes to use the server class's connection information in them. For example, I setup a server class and set the connection string to the server. Then I want the database class to use serverclass.connectionstring property to connect to the server and get a list of all the databases. But I want to keep that code in the database class. How can I do this? I've attached some code of what I want to do. Public Class Server Private _name As String Public Property Name() As String Get Return _name End Get Set(ByVal value As String) _name = value End Set End Property Private _databases As List(Of Database) Public Property Databases() As List(Of Database) Get Return _databases End Get Set(ByVal value As List(Of Database)) _databases = value End Set End Property End Class '-----New class Public Class Database Private _name As String Public Property Name() As String Get Return _name End Get Set(ByVal value As String) _name = value End Set End Property Private _tables As List(Of Table) Public Property Tables() As List(Of Table) Get Return _tables End Get Set(ByVal value As List(Of Table)) _tables = value End Set End Property 'This is where I need help! Private Sub LoadTables () dim connectionstring as string = server.connectionstring 'Possible? 'Do database stuff End Class Thanks for reading!

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  • how can I get around no arrays as class constants in php?

    - by user151841
    I have a class with a static method. There is an array to check that a string argument passed is a member of a set. But, with the static method, I can't reference the class property in an uninstantiated class, nor can I have an array as a class constant. I suppose I could hard code the array in the static method, but then if I need to change it, I'd have to remember to change it in two places. I'd like to avoid this.

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  • Generic overloading tells me this is the same function. Not agree.

    - by serhio
    base class: Class List(Of T) Function Contains(ByVal value As T) As Boolean derived class: Class Bar : List(Of Exception) ' Exception type as example ' Function Contains(Of U)(ByVal value As U) As Boolean compiler tells me that that two are the same, so I need to declare Overloads/new this second function. But I want use U to differentiate the type (one logic) like NullReferenceException, ArgumentNull Exception, etc. but want to leave the base function(no differentiation by type - other logic) as well.

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  • AS3 Passing data between objects/classes

    - by 1337holiday
    So i a building a categorized menu of different foods. I have a class for "categories" (buttons) which essentially will return a string "salads", "drinks", etc. I now have another class "menuItems" for items within categories and this handles sizes such as "small", "med", "large", etc. My problem now is that when i return "salads", i want to invoke an array which contains all the elements of salads, send it to menuItems which will populate the menu. So far i have both the category objects and the menu object setup. I just cant seem to be able to send the data that the category object is returning and pass it to the menu object. Both of which are added to the stage as shown below: If there was a way that i could say add all these classes to one class so that they can talk to each other that would be great but i dont know how to do this. Been stuck for hours, please any help is greatly appreciated.

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  • Sequential coupling in code

    - by dotnetdev
    Hi, Is sequential coupling (http://en.wikipedia.org/wiki/Sequential_coupling) really a bad thing in code? Although it's an anti-pattern, the only risk I see is calling methods in the wrong order but documentation of an API/class library with this anti-pattern should take care of that. What other problems are there from code which is sequential? Also, this pattern could easily be fixed by using a facade it seems. Thanks

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  • How to access constant defined in child class?

    - 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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  • Refactoring huge if ( ... instanceof ...)

    - by Chris
    I'm currently trying to refactor a part of a project that looks like this: Many classes B extends A; C extends A; D extends C; E extends B; F extends A; ... And somewhere in the code: if (x instanceof B){ B n = (B) x; ... }else if (x instanceof C){ C n = (C) x; ... }else if (x instanceof D){ D n = (D) x; ... }else if (x instanceof E){ E n = (E) x; ... }else if (x instanceof G){ G n = (G) x; ... }... Above if-construct currently sits in a function with a CC of 19. Now my question is: Can I split this if-construct up in mutliple functions and let Java's OO do the magic? Or are there any catches I have to look out for? My idea: private void oopMagic(C obj){ ... Do the stuff from the if(x instanceof C) here} private void oopMagic(D obj){ ... Do the stuff from the if(x instanceof D) here} private void oopMagic(E obj){ ... Do the stuff from the if(x instanceof E) here} .... and instead of the huge if: oopMagic(x);

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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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