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  • Is there a better way to handle data abstraction in this example?

    - by sigil
    I'm building an application that retrieves Sharepoint list data via a web service SPlists.Lists. To create an instance of the web service, I have the following class: class SharepointServiceCreator { public SPlists.Lists createService() { listsService.Url = "http://wss/sites/SPLists/_vti_bin/lists.asmx"; listsService.Credentials = System.Net.CredentialCache.DefaultCredentials; SPlists.Lists listsService=new SPlists.Lists(); } } I'm concerned that this isn't good OOP abstraction, though, because in order to create this service elsewhere in my application, I would need the following code: class someClass { public void someMethod() { SharepointServiceCreator s=new SharepointServiceCreator() SPlists.Lists listService=s.createService() } } Having to use declare the instance of listService in someMethod as type SPlists.Lists seems wrong, because it means that someClass needs to know about how SharepointServiceCreator is implemented. Or is this ok?

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  • Is this JS code a good way for defining class with private methods?

    - by tigrou
    I was recently browsing a open source JavaScript project. The project is a straight port from another project in C language. It mostly use static methods, packed together in classes. Most classes are implemented using this pattern : Foo = (function () { var privateField = "bar"; var publicField = "bar";     function publicMethod() { console.log('this is public');     } function privateMethod() { console.log('this is private'); } return {   publicMethod : publicMethod, publicField : publicField }; })(); This was the first time I saw private methods implemented that way. I perfectly understand how it works, using a anonymous method. Here is my question : is this pattern a good practice ? What are the actual limitations or caveats ? Usually i declare my JavaScript classes like that : Foo = new function () { var privateField = "test"; this.publicField = "test";     this.publicMethod = function()     { console.log('this method is public'); privateMethod();     } function privateMethod() { console.log('this method is private'); } }; Other than syntax, is there any difference with the pattern show above ?

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  • Is there an alternative to the term "calling object"?

    - by ybakos
    Let's suppose you've got a class defined (in pseudocode): class Puppy { // ... string sound = "Rawr!"; void bark() { print(sound); } } And say, given a Puppy instance, you call it's bark() method: Puppy p; p.bark(); Notice how bark() uses the member variable sound. In many contexts, I've seen folks describe sound as the member variable of the "calling object." My question is, what's a better term to use than "calling object?" To me, the object is not doing any calling. We know that member functions are in a way just functions with an implicit this or self parameter. I've come up with "receiving object," or "message recipient," which makes sense if you're down with the "messaging" paradigm. Do any of you happy hackers have a term that you like to use? I feel it should mean "the object upon which a method is called" and TOUWAMIC just doesn't cut it.

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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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  • Estimates, constraint and design [closed]

    - by user65964
    For your next two software projects (assuming that you're getting programming assignments, otherwise consider the program to find the min and max of a set of rational numbers) estimate how much effort they would take before doing them, then keep track of the actual time spent. How accurate were your estimates? State the requirements, constraint, design, estimate (your original estimate and the actual time it took), implementation (conventions used, implement/test path followed.

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  • Placing advice on any parameter of a given type in AspectJ

    - by user12558
    Hi, Im doing a POC using Aspectj. class BaseInfo{..} class UserInfo extends BaseInfo{..} class UserService { public void getUser(UserInfo userInfo){..} public void deleteUser(String userId){..} } I've defined an advice, that gets invoked when I pass an UserInfo instance.But when i try to pass the BaseInfo, the advice is not getting invoked. Below block executes the afterMethod as expected for getUser. &ltaop:pointcut id="aopafterMethod" expression="execution(* UserService.*(..,UserInfo,..))" / &gtaop:after pointcut-ref="aopafterMethod" method="afterMethod" / But when i try to give BaseInfo instead of UserInfo, the aspect is not getting triggered. Am i missing something? Kindly help me on this issue.

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  • Should an image be able to resize itself in OOP?

    - by ChocoDeveloper
    I'm writing an app that will have an Image entity, and I'm already having trouble deciding whose responsibility each task should be. First I have the Image class. It has a path, width, and other attributes. Then I created an ImageRepository class, for retrieving images with a single and tested method, eg: findAllImagesWithoutThumbnail(). But now I also need to be able to createThumbnail(). Who should deal with that? I was thinking about having an ImageManager class, which would be an app-specific class (there would also be a third party image manipulation reusable component of choice, I'm not reinventing the wheel). Or maybe it would be 0K to let the Image resize itself? Or let the ImageRepository and ImageManager be the same class? What do you think?

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  • Sharing object between 2 classes

    - by Justin
    I am struggling to wrap my head around being able to share an object between two classes. I want to be able to create only one instance of the object, commonlib in my main class and then have the classes, foo1 and foo2, to be able to mutually share the properties of the commonlib. commonlib is a 3rd party class which has a property Queries that will be added to in each child class of bar. This is why it is vital that only one instance is created. I create two separate queries in foo1 and foo2. This is my setup: abstract class bar{ //common methods } class foo1 extends bar{ //add query to commonlib } class foo2 extends bar{ //add query to commonlib } class main { public $commonlib = new commonlib(); public function start(){ //goal is to share one instance of $this->commonlib between foo1 and foo2 //so that they can both add to the properites of $this->commonlib (global //between the two) //now execute all of the queries after foo1 and foo2 add their query $this->commonlib->RunQueries(); } }

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  • Question about design

    - by lukeluke
    Two fast questions about two design decisions: Suppose that you are checking collisions between game elements. When you find a collision between object 1 and object 2, do you play immediately a sound effect or do you insert it in a list and, in a later a stage, do you process all sound effects? Same question as above for user input. When the user presses key 'keypad left' do you insert the event in a queue and process it later or do you update character position immediately? Thx

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  • using static methods and classes

    - by vedant1811
    I know that static methods/variables are associated with the class and not the objects of the class and are useful in situations when we need to keep count of, say the number of objects of the class that were created. Non-static members on the other hand may need to work on the specific object (i.e. to use the variables initialized by the constructor) My question what should we do when we need neither of the functionalities? Say I just need a utility function that accepts value(s) and returns a value besed solely on the values passed. I want to know whether such methods should be static or not. How is programming efficiency affected and which is a better coding practice/convention and why. PS: I don't want to spark off a debate, I just want a subjective answer and/or references.

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  • Flash Website Design in Online Business

    As Adobe has owned Macromedia, use of flash in websites has increased significantly. Flash represents the information in more interesting manner enhancing the visual value of a website. Non-stop mo... [Author: Alan Smith - Web Design and Development - May 27, 2010]

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  • Is "If a method is re-used without changes, put the method in a base class, else create an interface" a good rule-of-thumb?

    - by exizt
    A colleague of mine came up with a rule-of-thumb for choosing between creating a base class or an interface. He says: Imagine every new method that you are about to implement. For each of them, consider this: will this method be implemented by more than one class in exactly this form, without any change? If the answer is "yes", create a base class. In every other situation, create an interface. For example: Consider the classes cat and dog, which extend the class mammal and have a single method pet(). We then add the class alligator, which doesn't extend anything and has a single method slither(). Now, we want to add an eat() method to all of them. If the implementation of eat() method will be exactly the same for cat, dog and alligator, we should create a base class (let's say, animal), which implements this method. However, if it's implementation in alligator differs in the slightest way, we should create an IEat interface and make mammal and alligator implement it. He insists that this method covers all cases, but it seems like over-simplification to me. Is it worth following this rule-of-thumb?

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  • Should I pass an object into a constructor, or instantiate in class?

    - by Prisoner
    Consider these two examples: Passing an object to a constructor class ExampleA { private $config; public function __construct($config) { $this->config = $config; } } $config = new Config; $exampleA = new ExampleA($config); Instantiating a class class ExampleB { private $config; public function __construct() { $this->config = new Config; } } $exampleA = new ExampleA(); Which is the correct way to handle adding an object as a property? When should I use one over the other? Does unit testing affect what I should use?

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  • OOP Structure for web application

    - by Query
    Ok so I have a website in which users complete tasks to earn points. When they earn enough points, they rise in rank. The site from my understanding is very basic and only executes one query or two queries at most a page. There is a user table, a support ticket table, and an orders table. All of these contain a relational row for username. Our class was familiarized with OOP back in highschool with Java but that was for video games and I could grasp the concept on why you would need a class player and class enemy. However I don't understand it's web application. At least not in my situation. I understand the user class might contain stuff like: getUsername getPoints getEmail setEmail addPoints (does this belong here? OR only things the user can manipulate should be here?) etc.. But I'm at a loss with everything else such as user registration. Can you help give me a wire framework that I could wrap my head around? Pointing me to a good eBook would help greatly

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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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  • Should the 12-String be in it's own class and why? Java

    - by MayNotBe
    This is my first question here. I will amend it as instructed. This is regarding a homework project in my first Java programming class (online program). The assignment is to create a "stringed instrument" class using (among other things) an array of String names representing instrument string names ("A", "E", etc). The idea for the 12-string is beyond the scope of the assignment (it doesn't have to be included at all) but now that I've thought of it, I want to figure out how to make it work. Part of me feels like the 12-String should have it's own class, but another part of me feels that it should be in the guitar class because it's a guitar. I suppose this will become clear as I progress but I thought I would see what kind of response I get here. Also, why would they ask for a String[] for the instrument string names? Seems like a char[] makes more sense. Thank you for any insight. Here's my code so far (it's a work in progress): public class Guitar { private int numberOfStrings = 6; private static int numberOfGuitars = 0; private String[] stringNotes = {"E", "A", "D", "G", "B", "A"}; private boolean tuned = false; private boolean playing = false; public Guitar(){ numberOfGuitars++; } public Guitar(boolean twelveString){ if(twelveString){ stringNotes[0] = "E, E"; stringNotes[1] = "A, A"; stringNotes[2] = "D, D"; stringNotes[3] = "G, G"; stringNotes[4] = "B, B"; stringNotes[5] = "E, E"; numberOfStrings = 12; } } public int getNumberOfStrings() { return numberOfStrings; } public void setNumberOfStrings(int strings) { if(strings == 12 || strings == 6) { if(strings == 12){ stringNotes[0] = "E, E"; stringNotes[1] = "A, A"; stringNotes[2] = "D, D"; stringNotes[3] = "G, G"; stringNotes[4] = "B, B"; stringNotes[5] = "E, E"; numberOfStrings = strings; } if(strings == 6) numberOfStrings = strings; }//if else System.out.println("***ERROR***Guitar can only have 6 or 12 strings***ERROR***"); } public void getStringNotes() { for(int i = 0; i < stringNotes.length; i++){ if(i == stringNotes.length - 1) System.out.println(stringNotes[i]); else System.out.print(stringNotes[i] + ", "); }//for }

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  • Name for this antipattern? Fields as local variables

    - by JSB????
    In some code I'm reviewing, I'm seeing stuff that's the moral equivalent of the following: public class Foo { private Bar bar; public MethodA() { bar = new Bar(); bar.A(); bar = null; } public MethodB() { bar = new Bar(); bar.B(); bar = null; } } The field bar here is logically a local variable, as its value is never intended to persist across method calls. However, since many of the methods in Foo need an object of type Bar, the original code author has just made a field of type Bar. This is obviously bad, right? Is there a name for this antipattern?

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  • Web Design Philippines

    There have been many tools used to make web designing a lot easier. Compared in the past in which a designer would have to memorize all markup languages to create a website apart from their talent in... [Author: Margarette Mcbride - Web Design and Development - May 02, 2010]

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  • How should I refactor switch statements like this (Switching on type) to be more OO?

    - by Taytay
    I'm seeing some code like this in our code base, and want to refactor it: (Typescript psuedocode follows): class EntityManager{ private findEntityForServerObject(entityType:string, serverObject:any):IEntity { var existingEntity:IEntity = null; switch(entityType) { case Types.UserSetting: existingEntity = this.getUserSettingByUserIdAndSettingName(serverObject.user_id, serverObject.setting_name); break; case Types.Bar: existingEntity = this.getBarByUserIdAndId(serverObject.user_id, serverObject.id); break; //Lots more case statements here... } return existingEntity; } } The downsides of switching on type are self-explanatory. Normally, when switching behavior based on type, I try to push the behavior into subclasses so that I can reduce this to a single method call, and let polymorphism take care of the rest. However, the following two things are giving me pause: 1) I don't want to couple the serverObject with the class that is storing all of these objects. It doesn't know where to look for entities of a certain type. And unfortunately, the identity of a type of ServerObject varies with the type of ServerObject. (So sometimes it's just an ID, other times it's a combination of an id and a uniquely identifying string, etc). And this behavior doesn't belong down there on those subclasses. It is the responsibility of the EntityManager and its delegates. 2) In this case, I can't modify the ServerObject classes since they're plain old data objects. It should be mentioned that I've got other instances of the above method that take a parameter like "IEntity" and proceed to do almost the same thing (but slightly modify the name of the methods they're calling to get the identity of the entity). So, we might have: case Types.Bar: existingEntity = this.getBarByUserIdAndId(entity.getUserId(), entity.getId()); break; So in that case, I can change the entity interface and subclasses, but this isn't behavior that belongs in that class. So, I think that points me to some sort of map. So eventually I will call: private findEntityForServerObject(entityType:string, serverObject:any):IEntity { return aMapOfSomeSort[entityType].findByServerObject(serverObject); } private findEntityForEntity(someEntity:IEntity):IEntity { return aMapOfSomeSort[someEntity.entityType].findByEntity(someEntity); } Which means I need to register some sort of strategy classes/functions at runtime with this map. And again, I darn well better remember to register one for each my my types, or I'll get a runtime exception. Is there a better way to refactor this? I feel like I'm missing something really obvious here.

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  • Should Equality be commutative within a Class Hierachy?

    - by vossad01
    It is easy to define the Equals operation in ways that are not commutative. When providing equality against other types, there are obviously situations (in most languages) were equality not being commutative is unavoidable. However, within one's own inheritance hierarchy where the root base class defines an equality member, a programmer has more control. Thus you can create situations where (A = B) ? (B = A), where A and B both derive from base class T Substituting the = with the appropriate variation for a given language. (.Equals(_), ==, etc.) That seems wrong to me, however, I recognize I may be biased by background in Mathematics. I have not been in programming long enough to know what is standard/accepted/preferred practice when programming. Do most programmers just accept .Equals(_)may not be commutative and code defensibly. Do they expect commutativity and get annoyed if it is not. In short, when working in a class hierarchy, should effort me made to ensure Equality is commutative?

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  • Did Bjarne Stroustrup create the terms constructor/destructor when talking about objects?

    - by user104971
    I was watching this keynote and Bjarne Stroustrup (Creator of C++) claims that he hadn't yet invented the words constructor and destructor yet when he was giving an example of RAII. http://www.youtube.com/watch?v=IYBLXBJr0HU I know the concept of construction and destruction has been around a lot longer (even in C, a function that allocates and returns a struct and then a function that frees it etc.), but was Bjarne really the first to invent the terms?

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  • Should the 12-String be in it's own class and why?

    - by MayNotBe
    This question is regarding a homework project in my first Java programming class (online program). The assignment is to create a "stringed instrument" class using (among other things) an array of String names representing instrument string names ("A", "E", etc). The idea for the 12-string is beyond the scope of the assignment (it doesn't have to be included at all) but now that I've thought of it, I want to figure out how to make it work. Part of me feels like the 12-String should have it's own class, but another part of me feels that it should be in the guitar class because it's a guitar. I suppose this will become clear as I progress but I thought I would see what kind of response I get here. Also, why would they ask for a String[] for the instrument string names? Seems like a char[] makes more sense. Thank you for any insight. Here's my code so far (it's a work in progress): public class Guitar { private int numberOfStrings = 6; private static int numberOfGuitars = 0; private String[] stringNotes = {"E", "A", "D", "G", "B", "A"}; private boolean tuned = false; private boolean playing = false; public Guitar(){ numberOfGuitars++; } public Guitar(boolean twelveString){ if(twelveString){ stringNotes[0] = "E, E"; stringNotes[1] = "A, A"; stringNotes[2] = "D, D"; stringNotes[3] = "G, G"; stringNotes[4] = "B, B"; stringNotes[5] = "E, E"; numberOfStrings = 12; } } public int getNumberOfStrings() { return numberOfStrings; } public void setNumberOfStrings(int strings) { if(strings == 12 || strings == 6) { if(strings == 12){ stringNotes[0] = "E, E"; stringNotes[1] = "A, A"; stringNotes[2] = "D, D"; stringNotes[3] = "G, G"; stringNotes[4] = "B, B"; stringNotes[5] = "E, E"; numberOfStrings = strings; } if(strings == 6) numberOfStrings = strings; }//if else System.out.println("***ERROR***Guitar can only have 6 or 12 strings***ERROR***"); } public void getStringNotes() { for(int i = 0; i < stringNotes.length; i++){ if(i == stringNotes.length - 1) System.out.println(stringNotes[i]); else System.out.print(stringNotes[i] + ", "); }//for }

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  • Android app, No error message but has stopped unexpectedly [migrated]

    - by user74722
    Does anyone know what is my problem. I do not have any compile error messages however when i run the app it crashes and stops unexpectedly. Here is my codes. Thank you in advance. ListView l ; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_final_project); String arr[]={"Red","Green","Blue","Yellow","Cyan"}; l=(ListView) findViewById(R.id.listView1); ArrayAdapter<String> adapter=new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, arr); l.setAdapter(adapter); Button buttonOne = (Button) findViewById(R.id.button1); buttonOne.setOnClickListener(new OnClickListener(){ @Override public void onClick(View v){ setContentView(R.layout.layout_save); // setContentView(R.layout.activity_final_project); //startActivity(new Intent("com.example.finalproject.layout_save")); } }); }

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