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  • Non-Linear Database Retrieval

    - by pws5068
    I'm building an article system, and each article will have one more Tags associated with it (similar to the Tags on this site). The tables are set up something like this: Article_Table Article_ID | Title | Author_ID | Content | Date_Posted | IP ... Tag_Table Tag_ID | Name ... Tag_Intersect_Table Tag_ID | Article_ID Is it possible query an article and all of its associated tags in one database call? If so, how is this done?

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  • What objects would get defined in a Bridge scoring app (Javascript)

    - by Alex Mcp
    I'm writing a Bridge (card game) scoring application as practice in javascript, and am looking for suggestions on how to set up my objects. I'm pretty new to OO in general, and would love a survey of how and why people would structure a program to do this (the "survey" begets the CW mark. Additionally, I'll happily close this if it's out of range of typical SO discussion). The platform is going to be a web-app for webkit on the iPhone, so local storage is an option. My basic structure is like this: var Team = { player1: , player2: , vulnerable: , //this is a flag for whether or //not you've lost a game yet, affects scoring scoreAboveLine: , scoreBelowLine: gamesWon: }; var Game = { init: ,//function to get old scores and teams from DB currentBid: , score: , //function to accept whether bid was made and apply to Teams{} save: //auto-run that is called after each game to commit to DB }; So basically I'll instantiate two teams, and then run loops of game.currentBid() and game.score. Functionally the scoring is working fine, but I'm wondering if this is how someone else would choose to break down the scoring of Bridge, and if there are any oversights I've made with regards to OO-ness and how I've abstracted the game. Thanks!

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  • Should DAL always return business objects in MVP

    - by Chathuranga
    In Model View Presenter (MVP) pattern, it is said that our DAL always should returns business models. But let's say if I want to get just a number from database like the last ClientID (the latest clients ID) which is a string, should my DAL method returns a ClientInfo object which has about 10 other fields as well like ClientName, Address etc.? If I want to get a list of business objects from my DAL, is it acceptable to do it as follows or better to get a DataTable from DAL and then in the applications BLL, converts it a List? public List<Employee> GetNewEmployees() { string selectStatement = "SELECT Employee.Emp_ID, Employee.Initials + ' ' + Employee.Surname AS Name,..."; using (SqlConnection sqlConnection = new SqlConnection(db.GetConnectionString)) { using (SqlCommand sqlCommand = new SqlCommand(selectStatement, sqlConnection)) { sqlConnection.Open(); using (SqlDataReader dataReader = sqlCommand.ExecuteReader()) { List<Employee> list = new List<Employee>(); while (dataReader.Read()) { list.Add ( new EpfEtfMaster { EmployeeID = (int) dataReader ["emp_id"], EmployeeName = (string) dataReader ["Name"], AppointmentDate = (DateTime) dataReader["appointment_date"], }); } return list; } } } }

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  • CakePHP form $options['options']

    - by James
    Hey! Total CakePHP noob here. This is sort of a two fold question. In a view that is used for adding user objects I would like to use a drop down (selection) field in the form. Each user belongs to a group so when I add a user I want a drop down that contains all of the groups that the user could possibly join. Currently the group_id field is a textfield. I know how to force it to be a selection field, but I don't know how to populate the selection with the names of the groups programmatically. The Current method: echo $form->input('group_id', array( '1' => 'NameOfGroup1', '2' => 'NameOfGroup2', '3' => 'NameOfGroup3') ); I want to generate the options array programmatically though. echo $form->input('group_id', $this->Group->find('list')); This doesn't work though. I get an error: Undefined property: View::$Group [APP/views/users/add.ctp, line 8] To me this means that I don't have access to the Group object from inside my user view. How can I accomplish this? Again, I want to do it programmatically so that it updates as I add groups or remove them.

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  • constructors and inheritance in JS

    - by nandinga
    Hi all, This is about "inheritance" in JavaScript. Supose I create a constructor Bird(), and another called Parrot() which I make to "inherit" the props of Bird by asigning an instance of it to Parrot's prototype, like the following code shows: function Bird() { this.fly = function(){}; } function Parrot() { this.talk = function(){ alert("praa!!"); }; } Parrot.prototype = new Bird(); var p = new Parrot(); p.talk(); // Alerts "praa!!" alert(p.constructor); // Alerts the Bird function!?!?! After I've created an instance of Parrot, how comes that the .constructor property of it is Bird(), and not Parrot(), which is the constructor I've used to create the object? Thanks!!

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  • Generics and Constrained Polymorphism versus Subtyping

    - by Rahul G
    Hullo all. In this (Warning: PDF) presentation on Haskell Type Classes, on slide #54, there's this question: Open Question: In a language with generics and constrained polymorphism, do you need subtyping too? My questions are: How do generics and constrained polymorphism make subtyping unnecessary? If generics and constrained polymorphism make subtyping unnecessary, why does Scala have subtyping?

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  • What to name this class?

    - by orlandu63
    (This is not an interface: I simply omitted the method bodies) class _ { protected $_data = array(); function __construct($data); function set($name, $value); function get($name); function __set($name, $value); function __get($name); //aliases for their respective non-magic methods. # and some other generic methods } Essentially it's a class that provides a magical object-oriented reusable access layer to some data. I've considered DataLayer, DataObject and some others; I'd like to hear some suggestions from someone who's more terminologically savvy.

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  • objective C architecture question

    - by thekevinscott
    Hey folks, I'm currently teaching myself objective C. I've gone through the tutorials, but I find I learn best when slogging through a project of my own, so I've embarked on making a backgammon app. Now that I'm partway in, I'm realizing there's some overall architecture things I just don't understand. I've established a "player" class, a "piece" class, and a "board" class. A piece theoretically belongs to both a player and the board. For instance, a player has a color, and every turn makes a move; so the player owns his pieces. At the same time, when moving a piece, it has to check whether it's a valid move, whether there are pieces on the board, etc. From my reading it seems like it's frowned upon to reach across classes. For instance, when a player makes a move, where should the function live that moves the piece? Should it exist on board? This would be my instinct, as the board should decide whether a move is valid or not; but the piece needs to initialize that query, as its the one being moved, no? Any info to help a noob would be super appreciated. Thanks guys!

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  • use of assertions for type checking in php?

    - by user151841
    I do some checking of arguments in my classes in php using exception-throwing functions. I have functions that do a basic check ( ===, in_array etc ) and throw an exception on false. So I can do assertNumeric($argument, "\$argument is not numeric."); instead of if ( ! is_numeric($argument) ) { throw new Exception("\$argument is not numeric."); } Saves some typing I was reading in the comments of the php manual page on assert() that As noted on Wikipedia - "assertions are primarily a development tool, they are often disabled when a program is released to the public." and "Assertions should be used to document logically impossible situations and discover programming errors— if the 'impossible' occurs, then something fundamental is clearly wrong. This is distinct from error handling: most error conditions are possible, although some may be extremely unlikely to occur in practice. Using assertions as a general-purpose error handling mechanism is usually unwise: assertions do not allow for graceful recovery from errors, and an assertion failure will often halt the program's execution abruptly. Assertions also do not display a user-friendly error message." This means that the advice given by "gk at proliberty dot com" to force assertions to be enabled, even when they have been disabled manually, goes against best practices of only using them as a development tool So, am I 'doing it wrong'? What other/better ways of doing this are there?

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  • How to handle the pylint message: Warning: Method could be a function

    - by biffabacon
    Being new to Python, I decided to get some feedback on a class I'd written ASAP so I ran it against pylint. Is the message it gave "Warning: Method could be a function" telling me that it would be better to move this method out of the class because it doesn't use any instance variables? In c# I would make this a static method. What's the most pythonic thing to do here?

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  • Can a function return an object? Objective-C and NSMutableArray

    - by seaworthy
    I have an NSMutableArray. It's members eventually become members of an array instance in a class. I want to put the instantiantion of NSMutable into a function and to return an array object. If I can do this, I can make some of my code easier to read. Is this possible? Here is what I am trying to figure out. //Definition: > function Objects (float a, float b) { > NSMutableArray *array = [[NSMutableArray alloc] init]; > [array addObject:[NSNumber numberWithFloat:a]]; > [array addObject:[NSNumber numberWithFloat:b]]; > //[release array]; ???????? return array; > } //Declaration: Math *operator = [[Math alloc] init]; [operator findSum:Objects(20.0,30.0)]; My code compiles if I instantiate NSMutableArray right before I send the message to the receiver. I know I can have an array argument along with the method. What I have problem seeing is how to use a function and to replace the argument with a function call. Any help is appreciated. I am interested in the concept not in suggestions to replace the findSum method.

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  • PHP: Array of objects is empty when I come to retrieve one from the array

    - by Tom
    Good morning, I am trying to load rows from a database and then create objects from them and add these objects to a private array. Here are my classes: <?php include("databaseconnect.php"); class stationItem { private $code = ''; private $description = ''; public function setCode($code ){ $this->code = $code; } public function getCode(){ return $this->code; } public function setDescription($description){ $this->description = $description; } public function getDescription(){ return $this->description; } } class stationList { private $stationListing; function __construct() { connect(); $stationListing = array(); $result = mysql_query('SELECT * FROM stations'); while ($row = mysql_fetch_assoc($result)) { $station = new stationItem(); $station->setCode($row['code']); $station->setDescription($row['description']); array_push($stationListing, $station); } mysql_free_result($result); } public function getStation($index){ return $stationListing[$index]; } } ?> As you can see I am creating a stationItem object per database row (which for now has a code and description) and I then push these on to the end of my array which is held as a private variable in stationList. This is code which creates this classes and attempts to access the properties on them: $stations = new stationList(); $station = $stations->getStation(0); echo $station->getCode(); I am finding that the sizeof($stationList) at the end of the constructor is 1 but then it is zero when we come to try to get an object from the array using the index. Therefore the error that I get is: Fatal error: Call to a member function getCode() on a non-object Please can someone explain to me why this is happening? I guess I am misunderstanding how object references work in PHP5.

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  • Is this a good way to expose generic base class methods through an interface?

    - by Nate Heinrich
    I am trying to provide an interface to an abstract generic base class. I want to have a method exposed on the interface that consumes the generic type, but whose implementation is ultimately handled by the classes that inherit from my abstract generic base. However I don't want the subclasses to have to downcast to work with the generic type (as they already know what the type should be). Here is a simple version of the only way I can see to get it to work at the moment. public interface IFoo { void Process(Bar_base bar); } public abstract class FooBase<T> : IFoo where T : Bar_base { abstract void Process(T bar); // Explicit IFoo Implementation void IFoo.Process(Bar_base bar) { if (bar == null) throw new ArgumentNullException(); // Downcast here in base class (less for subclasses to worry about) T downcasted_bar = bar as T; if (downcasted_bar == null) { throw new InvalidOperationException( string.Format("Expected type '{0}', not type '{1}'", T.ToString(), bar.GetType().ToString()); } //Process downcasted object. Process(downcasted_bar); } } Then subclasses of FooBase would look like this... public class Foo_impl1 : FooBase<Bar_impl1> { void override Process(Bar_impl1 bar) { //No need to downcast here! } } Obviously this won't provide me compile time Type Checking, but I think it will get the job done... Questions: 1. Will this function as I think it will? 2. Is this the best way to do this? 3. What are the issues with doing it this way? 4. Can you suggest a different approach? Thanks!

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  • How to add event listners / signals to a simple superman class?

    - by Kabumbus
    I can and would love to use boost or std for this. Sorry - I am new to C++. So I created a really simple program like: #include <iostream> #include <string> using namespace std; class superman { public: string punch(){return cout << "superman: I hit the bad guy!" << endl;}; }; int main() { superman clark; clark.punch(); cin.get(); } I want to add an event listner that would tell me when clark punched and cout something like "superman punched!". How to add such event listner and event function to my class?

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  • PHP: Recursive array function

    - by Industrial
    Hi everybody, I want to create a function that returns the full path from a set node, back to the root value. I tried to make a recursive function, but ran out of luck totally. What would be an appropriate way to do this? I assume that a recursive function is the only way? Here's the array: Array ( [0] => Array ( [id] => 1 [name] => Root category [_parent] => ) [1] => Array ( [id] => 2 [name] => Category 2 [_parent] => 1 ) [2] => Array ( [id] => 3 [name] => Category 3 [_parent] => 1 ) [3] => Array ( [id] => 4 [name] => Category 4 [_parent] => 3 ) ) The result I want my function to output when getting full path of node id#4: Array ( [0] => Array ( [id] => 1 [name] => Root category [_parent] => ) [1] => Array ( [id] => 3 [name] => Category 3 [_parent] => 1 ) [2] => Array ( [id] => 4 [name] => Category 4 [_parent] => 3 ) ) The notoriously bad example of my recursive skills: function recursive ($id, $array) { $innerarray = array(); foreach ($array as $k => $v) { if ($v['id'] === $id) { if ($v['_parent'] !== '') { $innerarray[] = $v; recursive($v['id'], $array); } } } return $innerarray; } Thanks!

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  • Python: Can subclasses overload inherited methods?

    - by Rosarch
    I'm making a shopping cart app in Google App Engine. I have many classes that derive from a base handler: class BaseHandler(webapp.RequestHandler): def get(self, CSIN=None): self.body(CSIN) Does this mean that the body() method of every descendant class needs to have the same argument? This is cumbersome. Only one descendant actually uses that argument. And what about when I add new args? Do I need to go through and change every class? class Detail(BaseHandler): def body(self, CSIN): class MainPage(BaseHandler): def body(self, CSIN=None): #@UnusedVariable class Cart(BaseHandler): def body(self, CSIN): #@UnusedVariable

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  • Passing pointer position to an object in Java.

    - by Gabriel A. Zorrilla
    I've got a JPanel class called Board with a static subclass, MouseHanlder, which tracks the mouse position along the appropriate listener in Board. My Board class has fields pointerX and pointerY. How do i pass the e.getX() and e.getY() from the MouseHandler subclass to its super class JPanel? I tried with getters, setters, super, and cant get the data transfer between subclass and parent class. I'm certain it's a concept issue, but im stuck. Thanks!

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  • can you explain this jquery method from jquery.js

    - by mrblah
    Trying to understand how jquery works under the covers, what's the difference between: jQuery.fn and jQuery.prototype jQuery = window.jQuery = window.$ = function( selector, context ) { // The jQuery object is actually just the init constructor 'enhanced' return new jQuery.fn.init( selector, context ); }, and then: jQuery.fn = jQuery.prototype = { init: function( selector, context ) {

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  • Regular Expressions: RegEx for determining valid PHP class property names?

    - by Brian Lacy
    I am using PHP's magic __set and __get methods to access a private array in a class. I want to make sure the property names requested (i.e. $myObj->FakeProperty) are valid according to PHP property name rules before accessing them. My current RegEx isn't doing the trick; with my test values, _12 always falls through the cracks. I'm not actually sure that my test values even represent a realistic representation of what is and isn't allowed for PHP class property names, but I'm not really too concerned about it, just that I have some sort of rudimentary check in place. Test Fields: albert12 12Albert _12 _Albert12 _12Albert _____a_1 RegEx: ^(?=_*[A-z]+)[A-z0-9_]+$

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  • Bug in the official Android Fragments training sample?

    - by Jeff Axelrod
    It seems to me that there must be a bug in the Android Fragments demo. As background, Fragments are apparently sometimes instantiated by the Android OS and thus need a public no-arg constructor: All subclasses of Fragment must include a public empty constructor. The framework will often re-instantiate a fragment class when needed, in particular during state restore, and needs to be able to find this constructor to instantiate it. If the empty constructor is not available, a runtime exception will occur in some cases during state restore. But the NewsReader demo from the official Android training on Fragments constructs the HeadlinesFragment class and configures it with setOnHeadlineSelectedListener(this) from NewsReaderActivity.onCreate(). If the Android OS re-instantiates this fragment, the mHeadlineSelectedListener field will be null because HeadlinesFragment doesn't save or restore its state. Is this a bug or am I missing something?

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  • What's the deal with Java's public fields?

    - by Annan
    I've been reading two articles (1)(2) on javaworld.com about how all class fields should be private and getter/setter methods are just as bad. An object should act on the data it has rather than allowing access to it. I'm currently working on a University assignment for Connect Four. In designing the program the Agents playing the Game need access to the Board's state (so they can decide what to move). They also need to pass this move to the Game so it can validate it as a legal move. And during deciding what to move pieces are grouped into Threats with a start and end Points. Board, Threat and Point objects don't really do anything. They are just there to store related data that can be accessed in a human readable way. At the start of design I was representing Points on the board as two element int arrays, however that got annoying when creating points or referencing components of them. So, the class: public class Point { public int x; public int y; public Point(int x, int y){ this.x = x; this.y = y; } } Perfect in every way I can think of. Except it breaks every rule I've learned. Have I sinned?

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