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  • How do I create a class in Javascript?

    - by William
    This is what I got so far, and it's not working at all :( <!DOCTYPE html> <html lang="en"> <head> <title>Class Test</title> <meta charset="utf-8" /> <style> body { text-align: center; background-color: #ffffff;} #box { position: absolute; left: 610px; top: 80px; height: 50px; width: 50px; background-color: #ff0000; color: #000000;} </style> <script type="text/javascript"> document.onkeydown=function(event){keyDown(event)}; document.onkeyup=function(event){keyUp(event)}; var box = 0; function Player () { var speed = 5; var x = 50; var y = 50; } function update() { box.style.left = this.x + "px"; box.style.top = this.y + "px"; box.innerHTML = "<h6 style=\"margin: 0px 0px 0px 0px; padding: 0px 0px 0px 0px;\">X: "+ this.x + "<br /> Y: " + this.y + "</h6>"; } var player = new Player(); var keys = new Array(256); var i = 0; for (i = 0;i <= 256; i++){ keys[i] = false; } function keyDown(event){ keys[event.keyCode] = true; } function keyUp(event){ keys[event.keyCode] = false; } function update(){ if(keys[37]) player.x -= player.speed; if(keys[39]) player.x += player.speed; player.update(); } setInterval(update, 1000/60); </script> </head> <body> <div id="box" ></div> <script type="text/javascript"> box = document.getElementById('box'); box.innerHTML = "<h6 style=\"margin: 0px 0px 0px 0px; padding: 0px 0px 0px 0px;\">X: "+ player.x + "<br /> Y: " + player.y + "</h6>"; </script> </body> </html>

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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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  • override __set in __construct() in php?

    - by user151841
    I have a class based on database values. I'm using __set to automatically sync database values with the class properties. Set checks an array of database fields that it is allowed to update in the database. The field 'id' isn't in the list, so __set will throw an exception if you try to do $objDbRow->id = 5;. However, there is one time when I do want to set the id property of the object, and that's on instantiation. So in __constuct, I have $this->id = $id (where $id is passed to __construct). However, __set seems to be intercepting the setting here, because an exception is being thrown on construction. What's the way to get around this? I suppose I also have a boolean flag, like $instantiated, that __set() would check before it does it's field whitelist checking. But that feels inelegant.

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  • Is there anything wrong with a class with all static methods?

    - by MatthewMartin
    I'm doing code review and came across a class that uses all static methods. The entrance method takes several arguments and then starts calling the other static methods passing along all or some of the arguments the entrance method received. It isn't like a Math class with largely unrelated utility functions. In my own normal programming, I rarely write methods where Resharper pops and says "this could be a static method", when I do, they tend to be mindless utility methods. Is there anything wrong with this pattern? Is this just a matter of personal choice if the state of a class is held in fields and properties or passed around amongst static methods using arguments?

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  • Class works without declaring variables?

    - by Maxim Droy
    I'm learned php as functional and procedure language. Right now try to start learn objective-oriented and got an important question. I have code: class car { function set_car($model) { $this->model = $model; } function check_model() { if($this->model == "Mercedes") echo "Good car"; } } $mycar = new car; $mycar->set_car("Mercedes"); echo $mycar->check_model(); Why it does work without declaration of $model? var $model; in the begin? Because in php works "auto-declaration" for any variables? I'm stuck

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  • how to pass a parameter to method with php's is_callable

    - by fayer
    i have to create a variable that is callable with php's is_callable i have done this: $callable = array(new MyClass, 'methodName'); but i want to pass a parameter to the method. how can i do that? cause using symfony's event dispatcher component will be like: $sfEventDispatcher->connect('log.write', array(new IC_Log('logfile.txt'), 'write')); the first parameter is just a event name, the second is the callable variable. but i can only call the write method, i want to pass a parameter to it. could someone help me out. thanks

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  • Object model design choice

    - by spinon
    I am currently working on a ASP.NET MVC reporting application using C#. This is a redesign from a PHP application that was just initially thrown together and is now starting to gain some more traction. SowWe are in the process of reworking the backend to have a more OO approach. One of the descisions I am currently wrestling with is how to structure the domain objects. Since 95% of the site is readonly I am not sure if the typical approaches are practical. Should I create domain objects for the primary pieces of the application (ticket, assignment, assignee) and then create static methods off of these areas to pull the reporting data? Or should I just skip that part and create the chart data classes and have some get method off of these classes? It's not a real big application and currenlty I am the only one developing on it. But I feel torn as to which approach. I feel that the first one is the better choice but maybe overkill given that the majority of uses is for aggregate reporting. Anybody have some good insight on why I should go one way or another?

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  • How to override part of an overload function in JavaScript

    - by Guan Yuxin
    I create a class with a function like this var Obj=function(){this.children=[];this.parent=null;}//a base class Obj.prototype.index=function(child){ // the index of current obj if(arguments.length==0){ return this.parent?this.parent.index(this):0; } // the index of a child matchs specific obj [to be override] return -1; } basically it is just an overload function composed of index() and index(child). Then I create a sub class,SubObj or whatever, inherits from Obj SubObj.prototype.prototype=Obj; Now, it's time to override the index(child) function,however, index() is also in the function an I don't want to overwrite it too. One solution is to write like this var Obj=function(){this.children=[];this.parent=null;}//a base class Obj.prototype.index=function(child){ // the index of current obj if(arguments.length==0){ return this.parent?this.parent.index(this):0; } // the index of a child matchs specific obj [to be override] return this._index(this); } Obj.prototype._index=function(this){ return -1; } SubObj.prototype._index=function(this){/* overwriteing */} But this will easily mislead other coders as _index(child) should be both private(should not be used except index() function) and public(is an overload function of index(),which is public) you guys have better idea?

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  • naming a method - using set() when *not* setting a property?

    - by user151841
    Is setX() method name appropriate for only for setting class property X? For instance, I have a class where the output is a string of an html table. Before you can you can call getTable, you have to call setTable(), which just looks at a other properties and decides how to construct the table. It doesn't actually directly set any class property -- only causes the property to be set. When it's called, the class will construct strHtmlTable, but you can't specify it. So, calling it setTable breaks the convention of get and set being interfaces for class properties. Is there another naming convention for this kind of method? Edit: in this particular class, there are at least two ( and in total 8 optional ) other methods that must be called before the class knows everything it needs to to construct the table. I chose to have the data set as separate methods rather than clutter up the __construct() with 8 optional parameters which I'll never remember the order of.

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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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  • Can't remove first node in linked list

    - by carlmonday
    I'm trying to make a linked list class in python (pointless I know, but it's a learning exercise), and the method I have written to remove a node doesn't work if I try to remove the first element of the linked list. If the node to be removed is anywhere else in the linked list the method works fine. Can someone give me some insight as to where I've gone wrong? Here's my code thus far: class Node: def __init__(self, data=None, next=None): self.data = data self.next = next def __repr__(self): return repr(self.data) def printNodes(self): while self: print self.data self = self.next def removeNode(self, datum): """removes node from linked list""" if self.data == datum: return self.next while self.next: if self.next.data == datum: self.next = self.next.next return self self = self.next

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  • Is it good practise to blank out inherited functionality that will not be used?

    - by Timo Kosig
    I'm wondering if I should change the software architecture of one of my projects. I'm developing software for a project where two sides (in fact a host and a device) use shared code. That helps because shared data, e.g. enums can be stored in one central place. I'm working with what we call a "channel" to transfer data between device and host. Each channel has to be implemented on device and host side. We have different kinds of channels, ordinary ones and special channels which transfer measurement data. My current solution has the shared code in an abstract base class. From there on code is split between the two sides. As it has turned out there are a few cases when we would have shared code but we can't share it, we have to implement it on each side. The principle of DRY (don't repeat yourself) says that you shouldn't have code twice. My thought was now to concatenate the functionality of e.g. the abstract measurement channel on the device side and the host side in an abstract class with shared code. That means though that once we create an actual class for either the device or the host side for that channel we have to hide the functionality that is used by the other side. Is this an acceptable thing to do: public abstract class MeasurementChannelAbstract { protected void MethodUsedByDeviceSide() { } protected void MethodUsedByHostSide() { } } public class DeviceMeasurementChannel : MeasurementChannelAbstract { public new void MethodUsedByDeviceSide() { base.MethodUsedByDeviceSide(); } } Now, DeviceMeasurementChannel is only using the functionality for the device side from MeasurementChannelAbstract. By declaring all methods/members of MeasurementChannelAbstract protected you have to use the new keyword to enable that functionality to be accessed from the outside. Is that acceptable or are there any pitfalls, caveats, etc. that could arise later when using the code?

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  • How to call object's method from constructor?

    - by Kirzilla
    Hello, var Dog = function(name) { this.name = name; this.sayName(); } Dog.prototype.sayName = function() { alert(this.name); } I'm creating new instance of Dog object, but method sayName() is undefined. Why? Or maybe I should do something like (but I can't see difference)... var Dog = function(name) { this.name = name; this.prototype.sayName = function() { alert(this.name); } } Thank you.

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  • Using PHP interfaces in Codeigniter

    - by John Stewart
    I am trying to find out how can I used PHP interfaces in my MVC design. I want to make sure that the design enforces an interface so that any new module would follow that. For example: <?php interface BaseAPI { public function postMessage($msg); } class ServiceAPI implements BaseAPI { public function postMessage($msg) { return $msg; } } class Service_Two_API implements BaseAPI { public function postMessage($msg) { return "can't do this: ".$msg; } } ?> I want to do this in CI. Is it possible? how should I design it?

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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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  • understanding the ORM models in MVC

    - by fayer
    i cant fully understand the ORM models in MVC. so i am using symfony with doctrine. the doctrine models are created. does this mean that i don't have to create any models? are the doctrine models the only models i need? where should i put the code that uses the doctrine models: eg. $phoneIds = array(); $phone1 = new Phonenumber(); $phone1['phonenumber'] = '555 202 7890'; $phone1->save(); $phoneIds[] = $phone1['id']; $phone2 = new Phonenumber(); $phone2['phonenumber'] = '555 100 7890'; $phone2->save(); $phoneIds[] = $phone2['id']; $user = new User(); $user['username'] = 'jwage'; $user['password'] = 'changeme'; $user->save(); $user->link('Phonenumbers', $phoneIds); should this code be in the controller or in another model? and where should i validate these fields (check if it exists in database, that email is email etc)? could someone please shed a light on this. thanks.

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  • Automatically selecting and creating class objects

    - by Omin
    Lets say that we have a box class: class Box { private int width; private int height; //Box Constructor public Box( int height ) { this.height = height; width = 450; } } and a series of Box objects in our main: Box Box1 = new Box(147); Box Box2 = new Box(178); Box Box3 = new Box(784); Is there a way to use a "for" loop to go through these objects? Also, how would you make the computer create class objects for us? eg. create 10 objects using: for( int i=0; i>10; i++) { //method }

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  • Ways to make (relatively) safe assumptions about the type of concrete subclasses?

    - by Kylotan
    I have an interface (defined as a abstract base class) that looks like this: class AbstractInterface { public: bool IsRelatedTo(const AbstractInterface& other) const = 0; } And I have an implementation of this (constructors etc omitted): class ConcreteThing { public: bool IsRelatedTo(const AbstractInterface& other) const { return m_ImplObject.has_relationship_to(other.m_ImplObject); } private: ImplementationObject m_ImplObject; } The AbstractInterface forms an interface in Project A, and the ConcreteThing lives in Project B as an implementation of that interface. This is so that code in Project A can access data from Project B without having a direct dependency on it - Project B just has to implement the correct interface. Obviously the line in the body of the IsRelatedTo function cannot compile - that instance of ConcreteThing has an m_ImplObject member, but it can't assume that all AbstractInterfaces do, including the other argument. In my system, I can actually assume that all implementations of AbstractInterface are instances of ConcreteThing (or subclasses thereof), but I'd prefer not to be casting the object to the concrete type in order to get at the private member, or encoding that assumption in a way that will crash without a diagnostic later if this assumption ceases to hold true. I cannot modify ImplementationObject, but I can modify AbstractInterface and ConcreteThing. I also cannot use the standard RTTI mechanism for checking a type prior to casting, or use dynamic_cast for a similar purpose. I have a feeling that I might be able to overload IsRelatedTo with a ConcreteThing argument, but I'm not sure how to call it via the base IsRelatedTo(AbstractInterface) method. It wouldn't get called automatically as it's not a strict reimplementation of that method. Is there a pattern for doing what I want here, allowing me to implement the IsRelatedTo function via ImplementationObject::has_relationship_to(ImplementationObject), without risky casts? (Also, I couldn't think of a good question title - please change it if you have a better one.)

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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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  • 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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