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• Star rating not showing in rich snippets

  - by Danny R

  We've recently been doing a lot of work on our site's SEO (www.betterthanreviews.com). We recently did a push to update the rich snippets breadcrumb, meta description, and star rating. After giving Google some time to index the site, it has updated the breadcrumbs and meta descriptions for our review pages, but the stars are still not showing. This is currently how it appears on a Google search (link to the actual page: http://www.betterthanreviews.com/home-security/livewatch): This is what the Rich Snippets is supposed to look like, and how it appears in Google's testing tool: More context: As seen in our html, we are using schema.org language. We initially were using schema.org/Corporation for the site, but we now have the page labeled as schema.org/HomeAndConstructionBusiness because Google will not show star ratings for the Corporation language. However, in our Webmaster Tools, the Structured Data is still showing the Corporation language, which could be a potential issue. Here is a look at some of the coding that we used. But it can be looked at closer by inspecting the element: <div class="aggregate-rating" itemprop="aggregateRating" itemscope="" itemtype="http://schema.org/AggregateRating"> <div class="review row_fluid" itemprop="review" itemscope="" itemtype="http://schema.org/Review"> <div class="row_fluid rating" itemprop="reviewRating" itemscope="" itemtype="http://schema.org/Rating"> <meta content="4.5" itemprop="ratingValue" title="4.5 out of 5 stars" class="star-rating-readonly"> <meta content="2013-12-05" itemprop="datePublished"> <p class="review-headline" itemprop="headline">Way better than my previous system</p> <div> <p class="reviewer" itemprop="author">Scott H. </p> <span class="bullet">•</span> <p class="created_at">2 months ago</p> <p class="content" itemprop="description">I love it! The experience I have had so far is extremely positive. I had another alarm system before and I didn't like it but this one is really nice. I am telling everybody about it.</p> </div> </div> Any suggestions for how to fix this?

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• Clean way to use mutable implementation of Immutable interfaces for encapsulation

  - by dsollen

  My code is working on some compost relationship which creates a tree structure, class A has many children of type B, which has many children of type C etc. The lowest level class, call it bar, also points to a connected bar class. This effectively makes nearly every object in my domain inter-connected. Immutable objects would be problematic due to the expense of rebuilding almost all of my domain to make a single change to one class. I chose to go with an interface approach. Every object has an Immutable interface which only publishes the getter methods. I have controller objects which constructs the domain objects and thus has reference to the full objects, thus capable of calling the setter methods; but only ever publishes the immutable interface. Any change requested will go through the controller. So something like this: public interface ImmutableFoo{ public Bar getBar(); public Location getLocation(); } public class Foo implements ImmutableFoo{ private Bar bar; private Location location; @Override public Bar getBar(){ return Bar; } public void setBar(Bar bar){ this.bar=bar; } @Override public Location getLocation(){ return Location; } } public class Controller{ Private Map<Location, Foo> fooMap; public ImmutableFoo addBar(Bar bar){ Foo foo=fooMap.get(bar.getLocation()); if(foo!=null) foo.addBar(bar); return foo; } } I felt the basic approach seems sensible, however, when I speak to others they always seem to have trouble envisioning what I'm describing, which leaves me concerned that I may have a larger design issue then I'm aware of. Is it problematic to have domain objects so tightly coupled, or to use the quasi-mutable approach to modifying them? Assuming that the design approach itself isn't inherently flawed the particular discussion which left me wondering about my approach had to do with the presence of business logic in the domain objects. Currently I have my setter methods in the mutable objects do error checking and all other logic required to verify and make a change to the object. It was suggested that this should be pulled out into a service class, which applies all the business logic, to simplify my domain objects. I understand the advantage in mocking/testing and general separation of logic into two classes. However, with a service method/object It seems I loose some of the advantage of polymorphism, I can't override a base class to add in new error checking or business logic. It seems, if my polymorphic classes were complicated enough, I would end up with a service method that has to check a dozen flags to decide what error checking and business logic applies. So, for example, if I wanted to have a childFoo which also had a size field which should be compared to bar before adding par my current approach would look something like this. public class Foo implements ImmutableFoo{ public void addBar(Bar bar){ if(!getLocation().equals(bar.getLocation()) throw new LocationException(); this.bar=bar; } } public interface ImmutableChildFoo extends ImmutableFoo{ public int getSize(); } public ChildFoo extends Foo implements ImmutableChildFoo{ private int size; @Override public int getSize(){ return size; } @Override public void addBar(Bar bar){ if(getSize()<bar.getSize()){ throw new LocationException(); super.addBar(bar); } My colleague was suggesting instead having a service object that looks something like this (over simplified, the 'service' object would likely be more complex). public interface ImmutableFoo{ ///original interface, presumably used in other methods public Location getLocation(); public boolean isChildFoo(); } public interface ImmutableSizedFoo implements ImmutableFoo{ public int getSize(); } public class Foo implements ImmutableSizedFoo{ public Bar bar; @Override public void addBar(Bar bar){ this.bar=bar; } @Override public int getSize(){ //default size if no size is known return 0; } @Override public boolean isChildFoo return false; } } public ChildFoo extends Foo{ private int size; @Override public int getSize(){ return size; } @Override public boolean isChildFoo(); return true; } } public class Controller{ Private Map<Location, Foo> fooMap; public ImmutableSizedFoo addBar(Bar bar){ Foo foo=fooMap.get(bar.getLocation()); service.addBarToFoo(foo, bar); returned foo; } public class Service{ public static void addBarToFoo(Foo foo, Bar bar){ if(foo==null) return; if(!foo.getLocation().equals(bar.getLocation())) throw new LocationException(); if(foo.isChildFoo() && foo.getSize()<bar.getSize()) throw new LocationException(); foo.setBar(bar); } } } Is the recommended approach of using services and inversion of control inherently superior, or superior in certain cases, to overriding methods directly? If so is there a good way to go with the service approach while not loosing the power of polymorphism to override some of the behavior?

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• Can't adjust brightness on Samsung RV420 with fn keys

  - by nicholascamp

  Typing ls /sys/class/backlight/*/brightness outputs /sys/class/backlight/intel_backlight/brightness /sys/class/backlight/samsung/brightness The max_brightness for the second is 8, but changing it with echo 2 | sudo tee /sys/class/backlight/samsung/brightness doesn't change brightness. I can do it by using intel_backlight: echo 2000 | sudo tee /sys/class/backlight/intel_backlight/brightness (max_brightness: cat /sys/class/backlight/intel_backlight/max_brightness outputs 4648). But I want to do this work with the fn brightness keys, as I always did. I don't know what happened to stop working, maybe the use of +1 monitor and removing it in a wrong time or a system update. I'm using Ubuntu 12.04 64 bits in an Samsung RV420 notebook. Kernel Version is 3.2.0-27-generic. Could you help me? Please tell me what more info should I provide. Thanks!

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• Is this how dynamic language copes with dynamic requirement?

  - by Amumu

  The question is in the title. I want to have my thinking verified by experienced people. You can add more or disregard my opinion, but give me a reason. Here is an example requirement: Suppose you are required to implement a fighting game. Initially, the game only includes fighters, who can attack each other. Each fighter can punch, kick or block incoming attacks. Fighters can have various fighting styles: Karate, Judo, Kung Fu... That's it for the simple universe of the game. In an OO like Java, it can be implemented similar to this way: abstract class Fighter { int hp, attack; void punch(Fighter otherFighter); void kick(Fighter otherFighter); void block(Figther otherFighter); }; class KarateFighter extends Fighter { //...implementation...}; class JudoFighter extends Fighter { //...implementation... }; class KungFuFighter extends Fighter { //...implementation ... }; This is fine if the game stays like this forever. But, somehow the game designers decide to change the theme of the game: instead of a simple fighting game, the game evolves to become a RPG, in which characters can not only fight but perform other activities, i.e. the character can be a priest, an accountant, a scientist etc... At this point, to make it more generic, we have to change the structure of our original design: Fighter is not used to refer to a person anymore; it refers to a profession. The specialized classes of Fighter (KaraterFighter, JudoFighter, KungFuFighter) . Now we have to create a generic class named Person. However, to adapt this change, I have to change the method signatures of the original operations: class Person { int hp, attack; List<Profession> skillSet; }; abstract class Profession {}; class Fighter extends Profession { void punch(Person otherFighter); void kick(Person otherFighter); void block(Person otherFighter); }; class KarateFighter extends Fighter { //...implementation...}; class JudoFighter extends Fighter { //...implementation... }; class KungFuFighter extends Fighter { //...implementation ... }; class Accountant extends Profession { void calculateTax(Person p) { //...implementation...}; void calculateTax(Company c) { //...implementation...}; }; //... more professions... Here are the problems: To adapt to the method changes, I have to fix the places where the changed methods are called (refactoring). Every time a new requirement is introduced, the current structural design has to be broken to adapt the changes. This leads to the first problem. Rigid structure makes it hard for code reuse. A function can only accept the predefined types, but it cannot accept future unknown types. A written function is bound to its current universe and has no way to accommodate to the new types, without modifications or rewrite from scratch. I see Java has a lot of deprecated methods. OO is an extreme case because it has inheritance to add up the complexity, but in general for statically typed language, types are very strict. In contrast, a dynamic language can handle the above case as follow: ;;fighter1 punch fighter2 (defun perform-punch (fighter1 fighter2) ...implementation... ) ;;fighter1 kick fighter2 (defun perform-kick (fighter1 fighter2) ...implementation... ) ;;fighter1 blocks attacks from fighter2 (defun perform-block (fighter1 fighter2) ...implementation... ) fighter1 and fighter2 can be anything as long as it has the required data for calculation; or methods (duck typing). You don't have to change from the type Fighter to Person. In the case of Lisp, because Lisp only has a single data structure: list, it's even easier to adapt to changes. However, other dynamic languages can have similar behaviors as well. I work primarily with static languages (mainly C and Java, but working with Java was a long time ago). I started learning Lisp and some other dynamic languages this year. I can see how it helps improving my productivity.

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• Engine Rendering pipeline : Making shaders generic

  - by fakhir

  I am trying to make a 2D game engine using OpenGL ES 2.0 (iOS for now). I've written Application layer in Objective C and a separate self contained RendererGLES20 in C++. No GL specific call is made outside the renderer. It is working perfectly. But I have some design issues when using shaders. Each shader has its own unique attributes and uniforms that need to be set just before the main draw call (glDrawArrays in this case). For instance, in order to draw some geometry I would do: void RendererGLES20::render(Model * model) { // Set a bunch of uniforms glUniformMatrix4fv(.......); // Enable specific attributes, can be many glEnableVertexAttribArray(......); // Set a bunch of vertex attribute pointers: glVertexAttribPointer(positionSlot, 2, GL_FLOAT, GL_FALSE, stride, m->pCoords); // Now actually Draw the geometry glDrawArrays(GL_TRIANGLES, 0, m->vertexCount); // After drawing, disable any vertex attributes: glDisableVertexAttribArray(.......); } As you can see this code is extremely rigid. If I were to use another shader, say ripple effect, i would be needing to pass extra uniforms, vertex attribs etc. In other words I would have to change the RendererGLES20 render source code just to incorporate the new shader. Is there any way to make the shader object totally generic? Like What if I just want to change the shader object and not worry about game source re-compiling? Any way to make the renderer agnostic of uniforms and attributes etc?. Even though we need to pass data to uniforms, what is the best place to do that? Model class? Is the model class aware of shader specific uniforms and attributes? Following shows Actor class: class Actor : public ISceneNode { ModelController * model; AIController * AI; }; Model controller class: class ModelController { class IShader * shader; int textureId; vec4 tint; float alpha; struct Vertex * vertexArray; }; Shader class just contains the shader object, compiling and linking sub-routines etc. In Game Logic class I am actually rendering the object: void GameLogic::update(float dt) { IRenderer * renderer = g_application->GetRenderer(); Actor * a = GetActor(id); renderer->render(a->model); } Please note that even though Actor extends ISceneNode, I haven't started implementing SceneGraph yet. I will do that as soon as I resolve this issue. Any ideas how to improve this? Related design patterns etc? Thank you for reading the question.

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• Liskov principle: violation by type-hinting

  - by Elias Van Ootegem

  According to the Liskov principle, a construction like the one below is invalid, as it strengthens a pre-condition. I know the example is pointless/nonsense, but when I last asked a question like this, and used a more elaborate code sample, it seemed to distract people too much from the actual question. //Data models abstract class Argument { protected $value = null; public function getValue() { return $this->value; } abstract public function setValue($val); } class Numeric extends Argument { public function setValue($val) { $this->value = $val + 0;//coerce to number return $this; } } //used here: abstract class Output { public function printValue(Argument $arg) { echo $this->format($arg); return $this; } abstract public function format(Argument $arg); } class OutputNumeric extends Output { public function format(Numeric $arg)//<-- VIOLATION! { $format = is_float($arg->getValue()) ? '%.3f' : '%d'; return sprintf($format, $arg->getValue()); } } My question is this: Why would this kind of "violation" be considered harmful? So much so that some languages, like the one I used in this example (PHP), don't even allow this? I'm not allowed to strengthen the type-hint of an abstract method but, by overriding the printValue method, I am allowed to write: class OutputNumeric extends Output { final public function printValue(Numeric $arg) { echo $this->format($arg); } public function format(Argument $arg) { $format = is_float($arg->getValue()) ? '%.3f' : '%d'; return sprintf($format, $arg->getValue()); } } But this would imply repeating myself for each and every child of Output, and makes my objects harder to reuse. I understand why the Liskov principle exists, don't get me wrong, but I find it somewhat difficult to fathom why the signature of an abstract method in an abstract class has to be adhered to so much stricter than a non-abstract method. Could someone explain to me why I'm not allowed to hind at a child class, in a child class? The way I see it, the child class OutputNumeric is a specific use-case of Output, and thus might need a specific instance of Argument, namely Numeric. Is it really so wrong of me to write code like this?

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• A strong component keeps everything together

  - by Justin Paul-Oracle

  Most of the times you implement a WebCenter Content based system, you require some sort of customization. Sometimes these customizations need a Java class or two, or libraries (for example, the JavaMail API), or Database Objects (like new tables, views, indexes, etc). I have seen that libraries and Database Objects are usually put in place using manual steps. This means that the library jar files are copied to one of the common classes directory (set in the Content CLASSPATH variable) and/or the database scripts are executed manually. I have also seen people place the custom Java classes in the common classes directory. While this may seem like an easy solution, think about a scenario where you need to disable or uninstall the component or if you have to upgrade or migrate the system. You have to keep these manual steps documented and execute them every time you encounter the above scenarios. It is very common that some of these manual steps are missed when you have multiple teams and people working on the system. Here are a few points to ponder upon: Place all your custom Java classes within your component. Create a new directory, say ${COMPONENT_DIR}/classes, and place your code there. You can choose to bundle all your classes into a jar or you can place the entire class directory structure. Add a path entry to the Build Settings so that it is bundled with the component when you build it. You also need to update the Custom Class Path and the Custom Class Path Load Order under the Advanced Build Settings. This will ensure that the system CLASSPATH is updated to add this new directory. Create a new component for any new library that you want to add. Add the appropriate path entries to the Build Settings so that it is bundled with the component when you build it. You also need to update the Custom Class Path, Custom Class Path Load Order and/or the Custom Library Path under the Advanced Build Settings. Enter a comma separated list of features that this component will provide. When you create other components that will use the features exposed by this component, make sure that you specify a dependency to this library component by specifying the comma separated list of features in the Advanced Build Settings. The component wizard allows you to create custom install/uninstall Java code. The wizard will create a install filter class when you check the “Has Install” checkbox on the “Install/Uninstall Settings” tab. Consider using this filter class to create database objects when you install the component and drop the objects when you uninstall the component. If you do a lot of custom component development, consider creating a install/uninstall Java class, which can execute queries defined within the component. To sum up, whenever you write a new custom component, make sure that you bundle everything within the component.

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• Where should i organize my matrices in a 3D Game engine?

  - by Need4Sleep

  I'm working with a group of people from around the world to create a game engine(and hopefully a game with it) within the next upcoming years. My first task was writing a camera class for the engine to use in order to add cameras to the scene, position and follow points in the scene. The problem i have is with using matrices for transformations in the class, should i keep matrices separate to each class? such as have the model matrix in the model class, camera matrix in the camera class, or have all matrices placed in one class/chuck? I could see pros and cons for each method, but i wanted to hear some input form a more professional standpoint.

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• How should I organize my matrices in a 3D game engine?

  - by Need4Sleep

  I'm working with a group of people from around the world to create a game engine (and hopefully a game with it) within the next upcoming years. My first task is to write a camera class for the engine to use in order to add cameras to the scene, with position and follow points. The problem I have is with using matrices for transformations in the class, should I keep matrices separate to each class? Such as have the model matrix in the model class, camera matrix in the camera class, or have all matrices placed in one class/chuck? I could see pros and cons for each method, but I wanted to hear some input form a more professional standpoint.

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• Visitor-pattern vs inheritance for rendering

  - by akaltar

  I have a game engine that currently uses inheritance to provide a generic interface to do rendering: class renderable { public: void render(); }; Each class calls the gl_* functions itself, this makes the code hard to optimize and hard to implement something like setting the quality of rendering: class sphere : public renderable { public: void render() { glDrawElements(...); } }; I was thinking about implementing a system where I would create a Renderer class that would render my objects: class sphere { void render( renderer* r ) { r->renderme( *this ); } }; class renderer { renderme( sphere& sphere ) { // magically get render resources here // magically render a sphere here } }; My main problem is where should I store the VBOs and where should I Create them when using this method? Should I even use this approach or stick to the current one, perhaps something else? PS: I already asked this question on SO but got no proper answers.

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• Viewing the NetBeans Central Registry (Part 2)

  - by Geertjan

  Jens Hofschröer, who has one of the very best NetBeans Platform blogs (if you more or less understand German), and who wrote, sometime ago, the initial version of the Import Statement Organizer, as well as being the main developer of a great gear design & manufacturing tool on the NetBeans Platform in Aachen, commented on my recent blog entry "Viewing the NetBeans Central Registry", where the root Node of the Central Registry is shown in a BeanTreeView, with the words: "I wrapped that Node in a FilterNode to provide the 'position' attribute and the 'file extension'. All Children are wrapped too. Then I used an OutlineView to show these two properties. Great tool to find wrong layer entries." I asked him for the code he describes above and he sent it to me. He discussed it here in his blog, while all the code involved can be read below. The result is as follows, where you can see that the OutlineView shows information that my simple implementation (via a BeanTreeView) kept hidden: And so here is the definition of the Node. class LayerPropertiesNode extends FilterNode { public LayerPropertiesNode(Node node) { super(node, isFolder(node) ? Children.create(new LayerPropertiesFactory(node), true) : Children.LEAF); } private static boolean isFolder(Node node) { return null != node.getLookup().lookup(DataFolder.class); } @Override public String getDisplayName() { return getLookup().lookup(FileObject.class).getName(); } @Override public Image getIcon(int type) { FileObject fo = getLookup().lookup(FileObject.class); try { DataObject data = DataObject.find(fo); return data.getNodeDelegate().getIcon(type); } catch (DataObjectNotFoundException ex) { Exceptions.printStackTrace(ex); } return super.getIcon(type); } @Override public Image getOpenedIcon(int type) { return getIcon(type); } @Override public PropertySet[] getPropertySets() { Set set = Sheet.createPropertiesSet(); set.put(new PropertySupport.ReadOnly<Integer>( "position", Integer.class, "Position", null) { @Override public Integer getValue() throws IllegalAccessException, InvocationTargetException { FileObject fileEntry = getLookup().lookup(FileObject.class); Integer posValue = (Integer) fileEntry.getAttribute("position"); return posValue != null ? posValue : Integer.valueOf(0); } }); set.put(new PropertySupport.ReadOnly<String>( "ext", String.class, "Extension", null) { @Override public String getValue() throws IllegalAccessException, InvocationTargetException { FileObject fileEntry = getLookup().lookup(FileObject.class); return fileEntry.getExt(); } }); PropertySet[] original = super.getPropertySets(); PropertySet[] withLayer = new PropertySet[original.length + 1]; System.arraycopy(original, 0, withLayer, 0, original.length); withLayer[withLayer.length - 1] = set; return withLayer; } private static class LayerPropertiesFactory extends ChildFactory<FileObject> { private final Node context; public LayerPropertiesFactory(Node context) { this.context = context; } @Override protected boolean createKeys(List<FileObject> list) { FileObject folder = context.getLookup().lookup(FileObject.class); FileObject[] children = folder.getChildren(); List<FileObject> ordered = FileUtil.getOrder(Arrays.asList(children), false); list.addAll(ordered); return true; } @Override protected Node createNodeForKey(FileObject key) { AbstractNode node = new AbstractNode(org.openide.nodes.Children.LEAF, key.isFolder() ? Lookups.fixed(key, DataFolder.findFolder(key)) : Lookups.singleton(key)); return new LayerPropertiesNode(node); } } } Then here is the definition of the Action, which pops up a JPanel, displaying an OutlineView: @ActionID(category = "Tools", id = "de.nigjo.nb.layerview.LayerViewAction") @ActionRegistration(displayName = "#CTL_LayerViewAction") @ActionReferences({ @ActionReference(path = "Menu/Tools", position = 1450, separatorBefore = 1425) }) @Messages("CTL_LayerViewAction=Display XML Layer") public final class LayerViewAction implements ActionListener { @Override public void actionPerformed(ActionEvent e) { try { Node node = DataObject.find(FileUtil.getConfigRoot()).getNodeDelegate(); node = new LayerPropertiesNode(node); node = new FilterNode(node) { @Override public Component getCustomizer() { LayerView view = new LayerView(); view.getExplorerManager().setRootContext(this); return view; } @Override public boolean hasCustomizer() { return true; } }; NodeOperation.getDefault().customize(node); } catch (DataObjectNotFoundException ex) { Exceptions.printStackTrace(ex); } } private static class LayerView extends JPanel implements ExplorerManager.Provider { private final ExplorerManager em; public LayerView() { super(new BorderLayout()); em = new ExplorerManager(); OutlineView view = new OutlineView("entry"); view.addPropertyColumn("position", "Position"); view.addPropertyColumn("ext", "Extension"); add(view); } @Override public ExplorerManager getExplorerManager() { return em; } } }

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• Have I mistakenly assumed that my routines are loosely coupled?

  - by Tarun

  My Selenium test structures goes as - Data Object class - public class RegistrationData { String firstName = "test first name"; String lastName = "test last name"; // Getter Setter Here } Page Object class which carries out operations on a Web Page - public class RegistrationPage { private RegistrationData regData; public void setRegistrationData(RegistrationData regData) { this.regData = regData(); public NewAccountPage fillRegForm() { enterFirstName("FirstNameTextBoxLocator", regData.getFirstName); enterLastName("LastNameTextBoxLocator", regData.getLastName); // Some more fields are filled here return NewAccountPage(); } } And test class uses them as - public class TestRegistration extends SelTestCase { @Test public void testRegNewUser() { RegistrationData regData = new RegistrationData(); RegistrationPage regPage = New RegistrationPage(); regPage.setRegistrationData(regData) regPage.fillRegForm(); // Some assertion here } } Now since fillRegForm method does not take any argument, Can I assume that it is an example of loose coupling despite I need to set RegistrationData in RegistrationPage before being able to use fillRegForm method.

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• How to access functions in extended classes efficiently?

  - by nischayn22

  In PHP I have classes as below class Animal { //some vars public function printname(){ echo $this->name; } } class AnimalMySql extends Animal { static public function getTableFields(){ return array(); } } class AnimalPostgreSql extends Animal { static public function getTableFields(){ return array(); } } Now I have an object $lion = new Animal(); and I want to do if($store == mysql) //getTableFields from class AnimalMySql else //getTableFields form class AnimalPostgreSql I am new to OOP and not sure what is the best way to call the method from the specific class P.S. Please leave a note with the answer to explain the efficiency of the approach

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• "Collection Wrapper" pattern - is this common?

  - by Prog

  A different question of mine had to do with encapsulating member data structures inside classes. In order to understand this question better please read that question and look at the approach discussed. One of the guys who answered that question said that the approach is good, but if I understood him correctly - he said that there should be a class existing just for the purpose of wrapping the collection, instead of an ordinary class offering a number of public methods just to access the member collection. For example, instead of this: class SomeClass{ // downright exposing the concrete collection. Things[] someCollection; // other stuff omitted Thing[] getCollection(){return someCollection;} } Or this: class SomeClass{ // encapsulating the collection, but inflating the class' public interface. Thing[] someCollection; // class functionality omitted. public Thing getThing(int index){ return someCollection[index]; } public int getSize(){ return someCollection.length; } public void setThing(int index, Thing thing){ someCollection[index] = thing; } public void removeThing(int index){ someCollection[index] = null; } } We'll have this: // encapsulating the collection - in a different class, dedicated to this. class SomeClass{ CollectionWrapper someCollection; CollectionWrapper getCollection(){return someCollection;} } class CollectionWrapper{ Thing[] someCollection; public Thing getThing(int index){ return someCollection[index]; } public int getSize(){ return someCollection.length; } public void setThing(int index, Thing thing){ someCollection[index] = thing; } public void removeThing(int index){ someCollection[index] = null; } } This way, the inner data structure in SomeClass can change without affecting client code, and without forcing SomeClass to offer a lot of public methods just to access the inner collection. CollectionWrapper does this instead. E.g. if the collection changes from an array to a List, the internal implementation of CollectionWrapper changes, but client code stays the same. Also, the CollectionWrapper can hide certain things from the client code - from example, it can disallow mutation to the collection by not having the methods setThing and removeThing. This approach to decoupling client code from the concrete data structure seems IMHO pretty good. Is this approach common? What are it's downfalls? Is this used in practice?

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• Using PDO for Data Management

  - by edorahg

  This question is more a design oriented question than a code specific question. I am new to PHP and I am planning to use PDO as a data access layer. Say for instance I have a class called CITY. Now if I need to create an instance of this class, what is the best technique. Should have a singleton DB access class which is used to write and read data from the db layer. OR should I delegate it to the individual class object. For example if I invoke city.save() (city is a class), then the city class will handle the saving of that city object's data into the database. Excuse my ignorance but i have a java background and therefore trying to understand what is the best design principle for data management when using php.

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• jQuery val() undefined

  - by betacar

  We have the following XHTML table: <tr class="encabezado"> <th scope="col" width="2%">1</th> <th scope="col" width="2%">2</th> <th scope="col" width="2%">3</th> <th scope="col" width="2%">4</th> <th scope="col" width="2%">5</th> <th scope="col" width="2%">...</th> <th scope="col" width="2%">31</th> </tr> <tr> <th scope="row">Area 1<input name="line_config" type="hidden" value="0,5,50" /></th> <td class="gantt"> </td> <td class="gantt"> </td> <td class="gantt"> </td> <td class="gantt"> </td> <td class="gantt"> </td> <td class="gantt">...</td> <td class="gantt"> </td> </tr> <tr> <th scope="row">Area 2 <input name="line_config" type="hidden" value="0,0,10" /></th> <td class="gantt"> </td> <td class="gantt"> </td> <td class="gantt"> </td> <td class="gantt"> </td> <td class="gantt"> </td> <td class="gantt">...</td> <td class="gantt"> </td> </tr> When there is a click over a TD.gantt element, we want jQuery to get the value from input[name='line_config'] tag. We try the following jQuery code, but val() returned 'undefined': $(document).ready(function() { function sum_day(tag, status, column) { var total_day = 0; var index_pos = 0; var values = 0; values = tag.closest('tr').children("input[name='line_config']").val(); alert(values); //Return undefined return total_day; } $('td.gantt').click(function() { var gantt_tag = $('td.preop'); $(this).toggleClass('preop'); sum_day(gantt_tag, 'preop', $(this).index()); }); }); Are we getting right the value way? If anyone can help us, we appreciate... =)

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• Is there an easy way to get the Scala REPL to reload a class or package?

  - by Rex Kerr

  I almost always have a Scala REPL session or two open, which makes it very easy to give Java or Scala classes a quick test. But if I change a class and recompile it, the REPL continues with the old one loaded. Is there a way to get it to reload the class, rather than having to restart the REPL? Just to give a concrete example, suppose we have the file Test.scala: object Test { def hello = "Hello World" } We compile it and start the REPL: ~/pkg/scala-2.8.0.Beta1-prerelease$ bin/scala Welcome to Scala version 2.8.0.Beta1-prerelease (Java HotSpot(TM) Server VM, Java 1.6.0_16). Type in expressions to have them evaluated. Type :help for more information. scala> Test.hello res0: java.lang.String = Hello World Then we change the source file to object Test { def hello = "Hello World" def goodbye = "Goodbye, Cruel World" } but we can't use it: scala> Test.goodbye <console>:5: error: value goodbye is not a member of object Test Test.goodbye ^ scala> import Test; <console>:1: error: '.' expected but ';' found. import Test;

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• What is the best way to attach static methods to classes rather than to instances of a class?

  - by John Gietzen

  If I have a method for calculating the greatest common divisor of two integers as: public static int GCD(int a, int b) { return b == 0 ? a : GCD(b, a % b); } What would be the best way to attach that to the System.Math class? Here are the three ways I have come up with: public static int GCD(this int a, int b) { return b == 0 ? a : b.GCD(a % b); } // Lame... var gcd = a.GCD(b); and: public static class RationalMath { public static int GCD(int a, int b) { return b == 0 ? a : GCD(b, a % b); } } // Lame... var gcd = RationalMath.GCD(a, b); and: public static int GCD(this Type math, int a, int b) { return b == 0 ? a : typeof(Math).GCD(b, a % b); } // Neat? var gcd = typeof(Math).GCD(a, b); The desired syntax is Math.GCD since that is the standard for all mathematical functions. Any suggestions? What should I do to get the desired syntax?

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• Why can't I initialize a class through a setter?

  - by Rob emenaker

  If I have a custom class called Tires: #import <Foundation/Foundation.h> @interface Tires : NSObject { @private NSString *brand; int size; } @property (nonatomic,copy) NSString *brand; @property int size; - (id)init; - (void)dealloc; @end ============================================= #import "Tires.h" @implementation Tires @synthesize brand, size; - (id)init { if (self = [super init]) { [self setBrand:[[NSString alloc] initWithString:@""]]; [self setSize:0]; } return self; } - (void)dealloc { [super dealloc]; [brand release]; } @end And I synthesize a setter and getter in my View Controller: #import <UIKit/UIKit.h> #import "Tires.h" @interface testViewController : UIViewController { Tires *frontLeft, *frontRight, *backleft, *backRight; } @property (nonatomic,copy) Tires *frontLeft, *frontRight, *backleft, *backRight; @end ==================================== #import "testViewController.h" @implementation testViewController @synthesize frontLeft, frontRight, backleft, backRight; - (void)viewDidLoad { [super viewDidLoad]; [self setFrontLeft:[[Tires alloc] init]]; } - (void)dealloc { [super dealloc]; } @end It dies after [self setFrontLeft:[[Tires alloc] init]] comes back. It compiles just fine and when I run the debugger it actually gets all the way through the init method on Tires, but once it comes back it just dies and the view never appears. However if I change the viewDidLoad method to: - (void)viewDidLoad { [super viewDidLoad]; frontLeft = [[Tires alloc] init]; } It works just fine. I could just ditch the setter and access the frontLeft variable directly, but I was under the impression I should use setters and getters as much as possible and logically it seems like the setFrontLeft method should work. This brings up an additional question that my coworkers keep asking in these regards (we are all new to Objective-C); why use a setter and getter at all if you are in the same class as those setters and getters.

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• Getting a variable into another class through properties or button tags with Iphone SDK?

  - by MarcZero

  Hello. I have been pounding my head against a wall trying to figure out what I think is a simple thing to do, but I have, so far, been unable to figure it out with the iPhone SDK. I have a view with 4 buttons. When I push the buttons, I have another view called and come up to take over the screen. I want to have a simple variable passed from the old view to the new view. The purpose of this is to know what button was pressed out of the four identical ones. (trying to get an int value of 1 through 4) Here is what I have tried so far: I initially tried to call the variable from the class itself. My understanding was that my new view was only sitting on top of the old view, so it should not have been released. I could not get access to the variable as the variable was said to not be declared. I then tried to create a method that would return the int value. Again, the view class was not seen and was being declared as a "first use" of it. I then attempted to follow another similar post on here that suggested to try and send the button tag number to some part of the new view. I attempted to do this by setting the new views button title but I still cannot figure out a way to code it without coming up with errors. I am just looking for what method would be the best for me to pursue. I have no problem going back and reading the books on Objective-C, but I'm just trying to figure out which way I should concentrate on. Thank you for any insight.

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• Can a class inherit from LambdaExpression in .NET? Or is this not recommended?

  - by d.

  Consider the following code (C# 4.0): public class Foo : LambdaExpression { } This throws the following design-time error: Foo does not implement inherited abstract member System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) There's absolutely no problem with public class Foo : Expression { } but, out of curiosity and for the sake of learning, I've searched in Google System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) and guess what: zero results returned (when was the last time you saw that?). Needless to say, I haven't found any documentation on this method anywhere else. As I said, one can easily inherit from Expression; on the other hand LambdaExpression, while not marked as sealed (Expression<TDelegate> inherits from it), seems to be designed to prevent inheriting from it. Is this actually the case? Does anyone out there know what this method is about? EDIT (1): More info based on the first answers - If you try to implement Accept, the editor (C# 2010 Express) automatically gives you the following stub: protected override Expression Accept(System.Linq.Expressions.ExpressionVisitor visitor) { return base.Accept(visitor); } But you still get the same error. If you try to use a parameter of type StackSpiller directly, the compiler throws a different error: System.Linq.Expressions.Compiler.StackSpiller is inaccessible due to its protection level. EDIT (2): Based on other answers, inheriting from LambdaExpression is not possible so the question as to whether or not it is recommended becomes irrelevant. I wonder if, in cases like this, the error message should be Foo cannot implement inherited abstract member System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) because [reasons go here]; the current error message (as some answers prove) seems to tell me that all I need to do is implement Accept (which I can't do).

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• Why can't the 'NonSerialized' attribute be used at the class level? How to prevent serialization of

  - by ck

  I have a data object that is deep-cloned using a binary serialization. This data object supports property changed events, for example, PriceChanged. Let's say I attached a handler to PriceChanged. When the code attempts to serialize PriceChanged, it throws an exception that the handler isn't marked as serializable. My alternatives: I can't easily remove all handlers from the event before serialization I don't want to mark the handler as serializable because I'd have to recursively mark all the handlers dependencies as well. I don't want to mark PriceChanged as NonSerialized - there are tens of events like this that could potentially have handlers. Ideally, I'd like .NET to just stop going down the object graph at that point and make that a 'leaf'. So why can't I just mark the handler class as 'NonSerialized'? -- I finally worked around this problem by making the handler implement ISerializable and doing nothing in the serialize constructor/ GetDataObject method. But, the handler still is serialized, just with all its dependencies set to null - so I had to account for that as well. Is there a better way to prevent serialization of an entire class?

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• Filling SWT table object using a separated thread class ...

  - by erlord

  Hi all I've got a code snippet by the swt team that does exactly what I need. However, there is a part I want to separate into another class, in particular, the whole inline stuff. In response to my former question, it has been suggested that Callable should be used in order to implement threaded objects. It is suggested to make use of an implementation of runnable or better callable, since I do need some kind of return. However, I don't get it. My problems are: In the original code, within the inline implementation of the method run, some of the parents objects are called. How would I do this when the thread is separated? Pass the object via the C'tor's parameter? In the original code, another runnable object is nested within the runnable implementation. What is it good for? How to implement this when having separated the code? Furthermore, this nested runnable again calls objects created by the main method. Please, have mercy with me, but I am still quite a beginner and my brain is near collapsing :-( All I want is to separate all the threaded stuff into another class and make the program do just the same thing as it already does. Help please! Again thank you very much in advance for any useful suggestions, hints, examples etc... Regs Me

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• Having vCam on custom classes instead of the root class.

  - by Hwang

  Maybe some of you guys know bout vCam from http://bryanheisey.com/blog/?page_id=22 I'm trying to have the script running on a custom classes instead of a MovieClip in the library. But after some trying I fail so I stick back to having the MC in the library and load the MC from the project root action-script files. Now it works fine if I run the MC on the root as files, but for more organizing purposes on my action-script files, I was thinking of calling it from a custom classes(where I can control the vCam), then call the custom classes from the root action-script files. But seems like it won't work other than the root action-script files. I'm not sure whether I'm missing any codes between the two custom classes, or its not coded to run that way. If it's not, then its fine too just that I want the things more organize. Or if you have any idea how to 'by-pass' this, please do tell me so. In case you need my code for the 2 classes, here it is: package { import flash.display.MovieClip; import classes.vCamera; public class main extends MovieClip { private var vC2:vCamera = new vCamera(); public function main():void { addChild(vC2) } } } package classes{ import flash.display.MovieClip; import flash.display.Stage; import flash.events.Event; public class vCamera extends MovieClip{ private var vC:vCam = new vCam(); public function vCamera():void{ addEventListener(Event.ADDED_TO_STAGE, add2Stage) } private function add2Stage(event:Event):void{ vC.x=stage.stageWidth/2; vC.y=stage.stageHeight/2; vC.rotation=15; addChild(vC); } } }

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• Many DIVs inside parent DIV, CSS height issue

  - by Benjamin

  Hi everyone, I am putting together a dynamic photo gallery and getting stuck trying to place thumbnails. Basically I am trying to place each thumbnail and caption in its own DIV, floated to the left. The thumbnails are working just as I want them to but for some reason the parent DIV refuses to cover the height of the thumbnail area. Here is the CSS I am using.. #galleryBox { width: 650px; background: #fff; margin: auto; padding: 5px; text-align: center; } .item { display: block; margin: 10px; padding: 10px; float: left; background: #353535; min-width: 120px; } .label { display: block; color: #fff; } I have tried height: auto and that hasn't done anything. Here is what I am trying to style: <div id="galleryBox" class="ui-corner-all"> <div class="item ui-corner-all"> <img src="http://tapp-essexvfd.org/images/ajax-loader.gif" alt="test"/><br/> <p><span class="label">Testing</span></p> </div> <div class="item ui-corner-all"> <img src="http://tapp-essexvfd.org/images/ajax-loader.gif" alt="test"/><br/> <p><span class="label">Testing</span></p> </div> <div class="item ui-corner-all"> <img src="http://tapp-essexvfd.org/images/ajax-loader.gif" alt="test"/><br/> <p><span class="label">Testing</span></p> </div> <div class="item ui-corner-all"> <img src="http://tapp-essexvfd.org/images/ajax-loader.gif" alt="test"/><br/> <p><span class="label">Testing</span></p> </div> <div class="item ui-corner-all"> <img src="http://tapp-essexvfd.org/images/ajax-loader.gif" alt="test"/><br/> <p><span class="label">Testing</span></p> </div> <div class="item ui-corner-all"> <img src="http://tapp-essexvfd.org/images/ajax-loader.gif" alt="test"/><br/> <p><span class="label">Testing</span></p> </div> <div class="item ui-corner-all"> <img src="http://tapp-essexvfd.org/images/ajax-loader.gif" alt="test"/><br/> <p><span class="label">Testing</span></p> </div> </div> Thanks!

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