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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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  • 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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  • 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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  • 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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  • 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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  • 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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  • 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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  • 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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  • 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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  • Patterns to deal with with functions that can have different kinds of results.

    - by KaptajnKold
    Suppose you have an method on an object that given the some input alters the objects state if the input validates according to some complex logic. Now suppose that when the input doesn't validate, it can be due to several different things, each of which we would like to be able to deal with in different ways. I'm sure many of you are thinking: That's what exceptions are for! I've thought of this also. But my reservation against using exceptions is that in some cases there is nothing exceptional about the input not validating and I really would like to avoid using exceptions to control what is really just in the expected flow of the program. If there were only one interpretation possible, I could simply choose to return a boolean value indicating whether or not the operation resulted in a state change or not and the respond appropriately when it did not. There is of course also the option to return a status code which the client can then choose to interpret or not. I don't like this much either because there is nothing semantic about status codes. The solution I have so far is to always check for each possible situation which I am able to handle before I call the method which then returns a boolean to inform the client if the object changed state. This leaves me the flexibility to handle as few or as many as the possible situations as I wish depending on the context I am in. It also has the benefit of making the method I am calling simpler to write. The drawback is that there is quite a lot of duplication in the client code wherever I call the method. Which of these solutions do you prefer and why? What other patterns do people use for providing meaningful feedback from functions? I know that some languages support multiple return values, and I if I had that option I would surely prefer it.

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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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  • When to Use Properties & When to Use Methods?

    - by DaveDev
    Hi Guys I was looking at the following line of code foreach (PropertyInfo prop in t.GetProperties()) and I noticed that tprovides a method to return the type's properties instead of a property like t.Properties This makes me wonder why sometimes people use properties to make a type's data avilable and other times there's a method provided? Is there some logic behind the decision? Thanks Dave

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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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  • interface abstract in php real world scenario

    - by jason
    The goal is to learn whether to use abstract or interface or both... I'm designing a program which allows a user to de-duplicate all images but in the process rather then I just build classes I'd like to build a set of libraries that will allow me to re-use the code for other possible future purposes. In doing so I would like to learn interface vs abstract and was hoping someone could give me input into using either. Here is what the current program will do: recursive scan directory for all files determine file type is image type compare md5 checksum against all other files found and only keep the ones which are not duplicates Store total duplicates found at the end and display size taken up Copy files that are not duplicates into folder by date example Year, Month folder with filename is file creation date. While I could just create a bunch of classes I'd like to start learning more on interfaces and abstraction in php. So if I take the scan directory class as the first example I have several methods... ScanForFiles($path) FindMD5Checksum() FindAllImageTypes() getFileList() The scanForFiles could be public to allow anyone to access it and it stores in an object the entire directory list of files found and many details about them. example extension, size, filename, path, etc... The FindMD5Checksum runs against the fileList object created from scanForFiles and adds the md5 if needed. The FindAllImageTypes runs against the fileList object as well and adds if they are image types. The findmd5checksum and findallimagetypes are optionally run methods because the user might not intend to run these all the time or at all. The getFileList returns the fileList object itself. While I have a working copy I've revamped it a few times trying to figure out whether I need to go with an interface or abstract or both. I'd like to know how an expert OO developer would design it and why?

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  • Why does this program stop running?

    - by designloper
    Hi everyone....I am developing a card making system...nothing fancy. Right got this far but program now stops running with no error when running after the first card sample i.e. " Enter 'OK' if this card is OK, otherwise enter an alternative border character: + ". Any suggestions Java Masters? //Ask user for input //makes use of print line method System.out.println("Enter name: "); //took the variables //called the object of the scanner 'cardOrder' //and use the Scanner objects method '.nextLine' //to read the next line of the input firstName = cardOrder.nextLine(); mInitial = cardOrder.nextLine(); lastName = cardOrder.nextLine(); //Print out the "Here is a sample card" + the first name, middle initial and last name System.out.println("Here is a sample card: \n\n" + firstName + mInitial + lastName + "**************" + "**************" + firstName + mInitial + lastName + "\n* *" + "\n*" + " " + firstName + mInitial + lastName + " *" + "\n* *\n" + firstName + mInitial + lastName +"**************" + "**************" + firstName + mInitial + lastName + "\n"); //Ask user is the card is OK to proceed to order query or if they want an alternative border character: + System.out.println("Enter 'OK' if this card is OK, otherwise enter an alternative border character: + "); //Check if user entered "OK" and store it in var optionA optionA = cardOrder.nextLine(); //test if (a == optionA){ System.out.println("\nHow many cards would you like? "); cardsOrdered = cardOrder.nextInt(); equals = (int) (cardPriceA * cardsOrdered); System.out.println("The price of " + cardsOrdered + " cards"+ " is £" + equals + ".\n"); System.out.println("No Discount given."); } else if(b == optionA) { //Print out the "Here is a sample card" + the first name, middle initial and last name System.out.println("Here is a sample card: \n\n" + firstName + mInitial + lastName + "++++++++++++++" + "++++++++++++++" + firstName + mInitial + lastName + "\n+ +" + "\n+" + " " + firstName + mInitial + lastName + " +" + "\n+ +\n" + firstName + mInitial + lastName +"++++++++++++++" + "++++++++++++++" + firstName + mInitial + lastName + "\n"); //Ask user is the card is OK to proceed to order query or if they want an alternative border character: + System.out.println("Enter 'OK' if this card is OK, otherwise enter an alternative border character: OK "); //Check if user entered "OK" and store it in var optionA optionA = cardOrder.nextLine(); if (a == optionA){ System.out.println("\nHow many cards would you like? "); cardsOrdered = cardOrder.nextInt(); equals = (int) (cardPriceA * cardsOrdered); System.out.println("The price of " + cardsOrdered + " cards"+ " is £" + equals + ".\n"); System.out.println("No Discount given."); } } else if (c == optionA) {//Print out the "Here is a sample card" + the first name, middle initial and last name System.out.println("Here is a sample card: \n\n" + firstName + mInitial + lastName + "**************" + "**************" + firstName + mInitial + lastName + "\n* *" + "\n*" + " " + firstName + mInitial + lastName + " *" + "\n* *\n" + firstName + mInitial + lastName +"**************" + "**************" + firstName + mInitial + lastName + "\n"); //Ask user is the card is OK to proceed to order query or if they want an alternative border character: + System.out.println("Enter 'OK' if this card is OK, otherwise enter an alternative border character: + "); //Check if user entered "OK" and store it in var optionA optionA = cardOrder.nextLine(); if (a == optionA){ System.out.println("\nHow many cards would you like? "); cardsOrdered = cardOrder.nextInt(); equals = (int) (cardPriceA * cardsOrdered); System.out.println("The price of " + cardsOrdered + " cards"+ " is £" + equals + ".\n"); System.out.println("No Discount given."); } }

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  • Upcasting in C#: Making a Fruit a Pear

    - by Adam Kane
    Why can't I upcast (?) a Fruit to a Pear? public static class PearGenerator { public static Pear CreatePear () { // Make a new generic fruit. Fruit genericFruit = new Fruit(); // Upcast it to a pear. (Throws exception: Can't cast a Fruit to a Pear.) Pear pear = (Pear)genericFruit; // Return freshly grown pear. return ( pear ); } } public class Fruit { // some code } public class Pear : Fruit { public void PutInPie () { // some code } } Thanks!

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  • Are there any "gotchas" to watch for in using a Class (object) within itself?

    - by Clay Nichols
    I've got a Registry class and there are a few Registry values that I want to access from within that Registry class. (There is a bit of a calculation with these values so I thought I'd just put all that code right in the Registry Class itself). So we might have something within our RegistryRoutine.cls like: Function GetMyValue() as integer Dim R as new RegistryRoutine <calculations> GetMyValue=R.GetRegisetryValue (HKEY, key, value, etc.) End Function

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  • Running a loop (such as one for a mock webserver) within a thread

    - by bob c
    I'm trying to run a mock webserver within a thread within a class. I've tried passing the class' @server property to the thread block but as soon as I try to do server.accept the thread stops. Is there some way to make this work? I want to basically be able to run a webserver off of this script while still taking user input via stdin.gets. Is this possible? class Server def initialize() @server = TCPServer.new(8080) end def run() @thread = Thread.new(@server) { |server| while true newsock = server.accept puts "some stuff after accept!" next if !newsock # some other stuff end } end end def processCommand() # some user commands here end test = Server.new while true do processCommand(STDIN.gets) end In the above sample, the thread dies on server.accept

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  • One-to-One relation classes

    - by SeyZ
    I want to have a class named ProjectDirectory and a class named MetaDirectory. Each project has a MetaDirectory which contains some meta data. Is it the good way to write the classes like this: class ProjectDirectory(object): def __init__(self, directory=None): self.directory = directory self.meta_directory = MetaDirectory(self) def __repr__(self): return self.directory class MetaDirectory(object): def __init__(self, project_directory=None): self.project_directory = project_directory self.directory = "%s/.meta/" % project_directory ProjectDirectory has a reference to MetaDirectory and MetaDirectory has a reference to ProjectDirectory. Is there an other solution or this solution is good ?

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  • Possible to add hook as android fetches XML-strings?

    - by user247245
    I'm on my first week with android and would appreciate any insight if it's possible to hook or override the default behaviour when an android application reads their values from the resource-files to the shown layouts. What I want is to over time be able to add new/updated strings OTA and store locally and then on launch of application load new values instead of the ones in the default /res. Ideally i guess, would be an override of setContentView. Files holding updates will be in same xml-format as those in /res. (Please, no advices in other ways to do this. Just need to know if it's at all possible, without hacking the SDK) regards, /t

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