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  • Multiple Inheritance Debates II: according to Stroustrup

    - 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 Stroustrup 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 ? Why Sun and Microsoft consider developers too immature to just make the choice themselves ?

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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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  • Best way to make an attribute always an array?

    - by Shadowfirebird
    I'm using my MOO project to teach myself Test Driven Design, and it's taking me interesting places. For example, I wrote a test that said an attribute on a particular object should always return an array, so -- t = Thing.new("test") p t.names #-> ["test"] t.names = nil p t.names #-> [] The code I have for this is okay, but it doesn't seem terribly ruby to me: class Thing def initialize(names) self.names = names end def names=(n) n = [] if n.nil? n = [n] unless n.instance_of?(Array) @names = n end attr_reader :names end Is there a more elegant, Ruby-ish way of doing this? (NB: if anyone wants to tell me why this is a dumb test to write, that would be interesting too...)

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  • Class member variables, methods and their state

    - by codeMonkey
    How should class member variables be used in combination with class methods? Let's say I have a class 'C' with a member variable 'someData'. I call C.getData(), which does not return a value but instead puts data in C.someData. The class that instantiated 'C' first calls C.getData and then uses the data by accessing the member variable C.someData. I call C.getData() in the class that instantiated 'C' which is a function that returns data. I myself prefer the second way. But it also depends on the situation and it's a small difference. Is it 'bad' to have class methods that depend on the classes internal state? What are the best conventions?

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  • Is fetching data from database a get-method thing?

    - by theva
    I have a small class that I call Viewer. This class is supposed to view the proper layout of each page or something like that... I have a method called getFirstPage, when called the user of this method will get a setting value for which page is currently set as the first page. I have some code here, I think it works but I am not really shure that I have done it the right way: class Viewer { private $db; private $user; private $firstPage; function __construct($db, $user) { $this->db = $db; if(isset($user)) { $this->user = $user; } else { $this->user = 'default'; } } function getFistPage() { $std = $db->prepare("SELECT firstPage FROM settings WHERE user = ':user'"); $std->execute(array(':user' => $user)); $result = $std->fetch(); $this->firstPage = $result['firstPage']; return $this->firstPage; } } My get method is fetching the setting from databse (so far so good?). The problem is that then I have to use this get method to set the private variable firstPage. It seems like I should have a set method to do this, but I cannot really have a set method that just fetch some setting from database, right? Because the user of this object should be able to assume that there already is a setting defined in the object... How should I do that?

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  • C++ Beginner - Simple block of code crashing, reason unknown.

    - by Francisco P.
    Hello everyone, Here's a block of code I'm having trouble with. string Game::tradeRandomPieces(Player & player) { string hand = player.getHand(); string piecesRemoved; size_t index; for (size_t numberOfPiecesToTrade = rand() % hand.size() + 1; numberOfPiecesToTrade != 0; --numberOfPiecesToTrade) { index = rand() % hand.size(); piecesRemoved += hand[index]; hand.erase(index,1); } player.removePiecesFromHand(piecesRemoved); player.fillHand(_deck); return piecesRemoved; } I believe the code is pretty self explanatory. fillhand and removepiecesfromhand are working fine, so that's not it. I really can't get what's wrong with this :( Thanks for your time

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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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  • What should I put into classes and what stuff I shouldnt?

    - by jpjp
    I am learning about classes right now in PHP and their examples are like.. class table { //makes a table private $tag ; function Begin($border=0, $align="center", $width='100%', $cellpadding=2, $cellspacing=2, $class='', $id='', $bgcolor='', $style='') { $this->tag = '<table ' ; if ($align) $this->tag .= 'align="' . $align . '" ' ; if ($width) $this->tag .= 'width="' . $width . '" ' ; if ($border > 0) $this->tag .= 'border="' . $border . '" ' ; if ($cellpadding > 0) $this->tag .= 'cellpadding="' . $cellpadding . '" ' ; if ($cellspacing > 0) $this->tag .= 'cellspacing="' . $cellspacing . '" ' ; if ($class) $this->tag .= 'class="' . $class . '" ' ; if ($id) $this->tag .= 'id="' . $id . '" ' ; if ($bgcolor) $this->tag .= 'bgcolor="' . $bgcolor . '" ' ; if ($style) $this->tag .= 'style="' . $style . '" ' ; $this->tag .= ">" ; return $this->tag ; } Then you just instantiate it and make a table by $table =new table; $table->$table($border=2, $align='center', etc); Should I be coding like this where html, css are in classes? i feel making tables and forms this way is more confusing then actually just typing . Should I only put like validation, getting data from db, and the logic stuff in classes? What should I use classes for and not?

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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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  • 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 an example ( without the actual database inserts ): class selfStarter { public $type; public function __construct( $type ) { $this->type = $type; } public static function create( $type ) { if ( ! empty($type) ) { $starter = & new selfStarter($type); return $starter; } } } $obj1 = selfStarter::create( "apple" ); $obj2 = & new selfStarter( "banana" ); What is this pattern called?

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  • Using Zend_Db and multiple tables

    - by Yacoby
    I have a normalized database that stores locations of files on the internet. A file may have multiple locations spread across different sites. I am storing the urls in two parts (Site.UrlStart, FileLocation.UrlEnd). The UrlEnd is the part unique to that file (for the site). Simplified Db structure: I am using Zend_Db as my ORM (If it is that), with classes for the tables inheriting from Zend_Db_Table_Abstract. The issue is that retrieving the location data (e.g. the url) requires the use of multiple tables and as far as I can make out and I would either have to use both table classes (thereby exposing my table structure) or scatter sql all over my application, neither of which sound appealing. The only solution I can see is to create a façade that acts like Zend_Db_Table_Abstract (Maybe inherits from it?) and hides the fact that the data is actually on two tables. My questions are as follows: Am I going in the right direction in creating a façade class (Are there other alternatives)? Should the facade class inherit from Zend_Db_Table_Abstract?

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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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  • Get data from Joomla jos_users table

    - by RobertR
    Hello, world! I'm trying to build a little bit advanced users system using Joomla, but I stuck at one spot. I added new field on Joomla's jos_users table, but when I wanted to get that field out, like "echo" - it didn't worked at all. Any other data, even password field I can get without problems. Of course, I added new value in /var/www/<project>/libraries/joomla/user/user.php like this after line 40. /** * The users address name * @var string */ var $address = null; What might be the problem here? Or what I did wrong, or what I didn't do at all? Thanks for replies! Cheerio

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  • [[alloc] init] as a factory method

    - by iter
    I want to initialize an instance of one of the subclasses of a superclass depending on the arguments to init: [[Vehicle alloc] initWithItinerary: shortWay]; // returns a bicycle [[Vehicle alloc] initWithItinerary: longWay]; // returns a car I can't find examples of code like this. I wonder if this is not idiomatic in Objective C, or I simply am not looking in the right places.

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  • Is it possible for a parent to use a child's constant or static variables from inside a static metho

    - by ryeguy
    Below is an example of what I'm trying to do. The parent can't access any of the child's variables. It doesn't matter what technique I use (static or constants), I just need some kind of functionality like this. class ParentClass { public static function staticFunc() { //both of these will throw a (static|const) not defined error echo self::$myStatic; echo self::MY_CONSTANT; } } class ChildClass extends ParentClass { const MY_CONSTANT = 1; public static $myStatic = 2; } ChildClass::staticFunc();

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  • JavaScript prototype(ing) question

    - by OneNerd
    Trying to grasp Prototyping in Javascript. Trying to create my own namespace to extend the String object in JavaScript. Here is what I have so far (a snippet): var ns { alert: function() { alert (this); } } String.prototype.$ns = ns; As you can see, I am trying to place what will be a series of functions into the ns namespace. So I can execute a command like this: "hello world".$ns.alert(); But the problem is, the this doesn't seem to reference the text being sent (in this case, "hello world"). What I get is an alert box with the following: [object Object] Not having a full grasp of the object-oriented nature of JavaScript, I am at a loss, but I am guessing I am missing something simple. Does anyone know how to achieve this? Thanks -

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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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  • 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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  • pass variable by reference within class? in php

    - by user151841
    I'm working on a hex color class where you can change the color values of any hex code color. In my example, I haven't finished the hex math, but it's not completely relevant to what I'm explaining here. Naively, I wanted to start to do something that I don't think can be done. I wanted to pass object properties in a method call. Is this possible? class rgb { private $r; private $b; private $g; public function __construct( $hexRgb ) { $this->r = substr($hexRgb, 0, 2 ); $this->g = substr($hexRgb, 2, 2 ); $this->b = substr($hexRgb, 4, 2 ); } private function add( & $color, $amount ) { $color += amount; // $color should be a class property, $this->r, etc. } public function addRed( $amount ) { self::add( $this->r, $amount ); } public function addGreen( $amount ) { self::add( $this->g, $amount ); } public function addBlue( $amount ) { self::add( $this->b, $amount ); } } If this is not possible in PHP, what is this called and in what languages is it possible? I know I could do something like public function add( $var, $amount ) { if ( $var == "r" ) { $this->r += $amount } else if ( $var == "g" ) { $this->g += $amount } ... } But I want to do it this cool way.

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