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  • ruby restrict attr_accessor in subclass

    - by Arivarasan
    I want restrict the access of superclass's method in subclass class Parent attr_accessor :first_name, :last_name def initialize(first_name, last_name) @first_name, @last_name = first_name, last_name end def full_name @first_name + " " + @last_name end end class Son < Parent attr_accessor :first_name def initialize(parent, first_name) @first_name = first_name @last_name = parent.last_name end def full_name @first_name + " " + @last_name end end p = Parent.new("Bharat", "Chipli") puts p.full_name s = Son.new(p, "Harry") s.last_name= "Smith" puts s.full_name here i am getting son's full name as "Harry Smith", but i want "Harry Chipli"

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  • Subclass not seeing superclass' instance variable

    - by hyn
    I have a situation where my subclass is not seeing the superclass' instance variable x. The ivar is obviously @protected by default, so why do I get a compiler error "x undeclared"? If I make this ivar a property then I can access it by self.x. What's worse is sometimes the error disappears, so something in my code is obviously causing this error but I cannot figure it out.

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  • Can 'iterator' type just subclass 'const_iterator'?

    - by doublep
    After another question about iterators I'm having some doubts about custom containers. In my container, iterator is a subclass of const_iterator, so that I get conversion from non-const to const "for free". But is this allowed or are there any drawbacks or non-working scenarios for such a setup?

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  • c#Repository pattern: One repository per subclass?

    - by Alex
    I am wondering if you would create a repository for each subclass of a domain model. There are two classes for example: public class Person { public virtual String GivenName { set; get; } public virtual String FamilyName { set; get; } public virtual String EMailAdress { set; get; } } public class Customer : Person { public virtual DateTime RegistrationDate { get; set; } public virtual String Password { get; set; } } Would you create both a PersonRepository and a CustomerRepository or just the PersonRepository which would also be able to execute Customer related queries?

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  • Java: Why is this Subclass valid?

    - by incrediman
    Here, I have an abstract class: abstract class A<E extends A> { abstract void foo(E x); } Here's a class that extends A: class B extends A<B>{ void foo(B x){} } And here's another (E is B here on purpose): class C extends A<B>{ void foo(B x){} } Both of those classes are valid, and the reasoning for that makes sense to me. However what confuses me is how this could possibly be valid: class D extends A{ void foo(A x){} } Since when are generics optional like that? I thought the extending class (subclass) of A would be required to specify an E?

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  • android.app.Application subclass, onTerminate is not being called

    - by synic
    From the documentation for android.app.Application: "Base class for those who need to maintain global application state" I am using my own subclass to maintain an object that I'm using to query a server. Also from the documentation: "onTerminate() Called when the application is stopping." However, onTerminate() in my class is never called. I press the back button while viewing my main activity, and everything seems to shut down. My main Activity's onDestroy() method is called and isFinishing() returns true, but my android.app.Application's onTerminate() method is never called. Why is this? What am I missing? Is there something that is keeping it open?

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  • python: subclass a metaclass

    - by Michael Konietzny
    Hello, for putting methods of various classes into a global registry I'm using a decorator with a metaclass. The decorator tags, the metaclass puts the function in the registry: class ExposedMethod (object): def __init__(self, decoratedFunction): self._decoratedFunction = decoratedFunction def __call__(__self,*__args,**__kw): return __self._decoratedFunction(*__args,**__kw) class ExposedMethodDecoratorMetaclass(type): def __new__(mcs, name, bases, dct): for obj_name, obj in dct.iteritems(): if isinstance(obj, ExposedMethod): WorkerFunctionRegistry.addWorkerToWorkerFunction(obj_name, name) return type.__new__(mcs, name, bases, dct) class MyClass (object): __metaclass__ = DiscoveryExposedMethodDecoratorMetaclass @ExposeDiscoveryMethod def myCoolExposedMethod (self): pass I've now came to the point where two function registries are needed. The first thought was to subclass the metaclass and put the other registry in. For that the new method has simply to be rewritten. Since rewriting means redundant code this is not what I really want. So, it would be nice if anyone could name a way how to put an attribute inside of the metaclass which is able to be read when new is executed. With that the right registry could be put in without having to rewrite new. Thanks and Greetings, Michael

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  • How to subclass a specific jqueryui widget method ?

    - by SBUJOLD
    Since I updated jQueryUI to 1.8 I found a couple of issues in our implementations and I could fix it myself without waiting for a fix on their end if I could find out how to subclass a specific method of the datepicker widget so I call the parent code and then execute my code. I was reading on $.widget but I just can't wrap my head around how that is suppose to work. I tried something like this: $.widget("ui.datepicker", { _showDatepicker: function(input) { alert('Yo'); $.datepicker.prototype._showDatepicker.apply(this,arguments); alert('Hey!'); } }); And all sorts of other variations and beging to think I just don't understand the 'extendability' of jQueryUI or it just can't be done. Anybody knows how I can achieve this ? Thx

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  • Use HTTParty methods in a subclass

    - by cpjolicoeur
    I'm trying to write an API wrapper in ruby and am stumped on how I can call HTTParty methods from a subclass. For instance, I want the user to create a connection to the api and then be able to query results from subclasses. module ApiWrapper class Connection include HTTParty base_uri '...' def initialize( u, p ) ... end def contacts ApiWrapper::Contact end end end module ApiWrapper class Contact def all # issue httparty get request here that is created from the Connection class end end end ## The user would do this conn = ApiWrapper::Connection.new( 'username', 'password' ) contacts = conn.contacts.all

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  • Adding ivars to NSManagedObject subclass

    - by The Crazy Chimp
    When I create an entity using core data then generate a subclass of NSManagedObject from it I get the following output (in the .h): @class Foo; @interface Foo : NSManagedObject @property (nonatomic, retain) NSString *name; @property (nonatomic, retain) NSSet *otherValues; @end However, in my .m file I want to make use of the name and otherValues values. Normally I would simply create a couple of ivars and then add the properties for them as I required. That way I can access them in my .m file easily. In this situation would it be acceptable to do this? Would adding ivars to the .h (for name and otherValues) cause any unusual behaviour in the persistance & retrieval of objects?

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  • Inherit static properties in subclass without redeclaration?

    - by David
    Hi, I'm having the same problem as this guy with the application I'm writing right now. The problem is that static properties are not being inherited in subclasses, and so if I use the static:: keyword in my main class, it sets the variable in my main class as well. It works if I redeclare the static variables in my subclass, but I expect to have a large number of static properties and subclasses and wish to avoid code duplication. The top-rated response on the page I linked has a link to a few "workarounds", but it seems to have 404'd. Can anyone lend me some help or perhaps point me in the direction of said workarounds?

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  • Jpa subclass mapping

    - by Roy Chan
    I am making a POS like system. I wonder how to map subclass using JPA (this is for my DAO). Product class has product details and OrderProduct class has information about the Product and details about the order. @Entity @Table(name="products") public class Product implements Serializable{ @Id @Column(name="id") @GeneratedValue(strategy = GenerationType.AUTO public int getId(){ return id;} /** Other get/set methods */ } @Entity @Table(name="order_products") public class OrderProduct extends Product{ @Id @Column(name="id") @GeneratedValue(strategy = GenerationType.AUTO) public int getId(){ return id;} /** Other get/set methods */ } I got complain about duplicate @Id. But OrderProduct class really need another id than the product one. How should I map this? DB is something like this Table products id int name varchar(32) Table order_product id int quantity int productid int fk referencing product table Would @IdClass or @AttributeOverride help?

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  • C++: Create abstract class with abstract method and override the method in a subclass

    - by Martijn Courteaux
    Hi, How to create in C++ an abstract class with some abstract methods that I want to override in a subclass? How should the .h file look? Is there a .cpp, if so how should it look? In Java it would look like this: abstract class GameObject { public abstract void update(); public abstract void paint(Graphics g); } class Player extends GameObject { @Override public void update() { // ... } @Override public void paint(Graphics g) { // ... } } // In my game loop: for (int i = 0; i < objects.size(); i++) { objects.get(i).update(); } for (int i = 0; i < objects.size(); i++) { objects.get(i).paint(g); } Translating this code to C++ is enough for me.

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  • How to use NSObject subclass?

    - by Jon
    So I've created a subclass of NSObject called Query @interface Query : NSObject @property (nonatomic, assign) NSNumber *weight; @property (nonatomic, assign) NSNumber *bodyFat; @property (nonatomic, assign) NSNumber *activityLevel; @end Is this correct for setting the object's property? In VC1: BodyFatViewController *aViewController = [[BodyFatViewController alloc]init]; aViewController.query = self.query; [self.navigationController pushViewController:aViewController animated:YES]; In VC2: - (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component { Query *anQuery = [[Query alloc]init]; anQuery.bodyFat = [self.bodyFatArray objectAtIndex:row]; anQuery.weight = self.query.weight; self.query = anQuery; }

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  • jpa join query on a subclass

    - by Brian
    I have the following relationships in JPA (hibernate). Object X has two subclasses, Y and Z. Object A has a manyToOne relationship to object X. (Note, this is a one-sided relationship so object X cannot see object A). Now, I want to get the max value of a column in object A, but only where the relationship is of a specific subtype, ie...Y. So, that equates to...get the max value of column1 in object A, across all instances of A where they have a relationship with Y. Is this possible? I'm a bit lost as how to query it. I was thinking of something like: String query = "SELECT MAX(a.columnName) FROM A a join a.x; Query query = super.entityManager.createQuery(query); query.execute(); However that doesn't take account of the subclass of X...so I'm a bit lost. Any help would be much appreciated.

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  • Check if a class is subclass of another class in Java

    - by craesh
    Hi! I'm playing around with Java's reflection API and trying to handle some fields. Now I'm stuck with identifying the type of my fields. Strings are easy, just do myField.getType().equals(String.class). The same applies for other non-derived classes. But how do I check derived classes? E.g. LinkedList as subclass of List. I can't find any isSubclassOf(...) or extends(...) method. Do I need to walk through all getSuperClass() and find my supeclass by my own? Thanks! craesh

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  • ruby subclass filter

    - by Nik
    Hey! Maybe I am getting the idea of a subclass wrong, but I have a Person model and it has an attrib called "age" so Person.first.age #=> '20' Now I want to have a model that's basically persons 55 or older so I know I can have a class like this: class Senior < Person end But how can I "pre-filter" the Senior class so that every object belonging to that class has age = 55? Senior.first.age #=> 56 Thanks!

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  • Abstract class get parameter from implementing subclass?

    - by soren.qvist
    I'm wondering if there is way to do this without breaking encapsulation, I want the abstract class to rely on parameters defined in the implementing subclass. Like so: public abstract class Parent { private int size; private List<String> someList; public Parent() { size = getSize(); someList = new ArrayList<String>(size); } public abstract int getSize(); } public class Child extends Parent { @Override public int getSize() { return 5; } } Is this ugly? Is there a better way? And perhaps more importantly, is this even a good idea?

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  • AttributeError in my Python program regarding classes

    - by Axel Finkel
    I'm doing an exercise out of the Python book that involves creating a class and a subclass. I am getting the following error when I try to run the program: AttributeError: 'Customer' object has no attribute 'name', when it tries to go through this bit of code: self.name.append(name) As this is my first time dealing with classes and objects in Python, I'm sure I am making some overt mistake somewhere, but I can't seem to figure it out. I've looked over the documentation for creating classes and writing member functions, and it looks correct, but it is obviously not. I want the Customer subclass to inherit the name, address, and telephone attributes from the Person superclass, but it doesn't seem to be doing so? Here is my code: class Person: def __init__(self): self.name = None self.address = None self.telephone = None def changeName(self, name): self.name.append(name) def changeAddress(self, address): self.address.append(address) def changeTelephone(self, telephone): self.telephone.append(telephone) class Customer(Person): def __init__(self): self.customerNumber = None self.onMailingList = False def changeCustomerNumber(self, customerNumber): self.customerNumber.append(customerNumber) def changeOnMailingList(): if onMailingList == False: onMailingList == True else: onMailingList == False def main(): customer1 = Customer() name = 'Bob Smith' address = '123 Somewhere Road' telephone = '111 222 3333' customerNumber = '12345' customer1.changeName(name) customer1.changeAddress(address) customer1.changeTelephone(telephone) customer1.changeCustomerNumber(customerNumber) print("Customer name: " + customer1.name) print("Customer address: " + customer1.address) print("Customer telephone number: " + customer1.telephone) print("Customer number: " + customer1.customerNumber) print("On mailing list: " + customer1.OnMailingList) customer1.changeOnMailingList() print("On mailing list: " + customer1.OnMailingList) main()

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  • NHibernate DuplicateMappingException when mapping abstract class and subclass

    - by stiank81
    I have an abstract class, and subclasses of this, and I want to map this to my database using NHibernate. I'm using Fluent, and read on the wiki how to do the mapping. But when I add the mapping of the subclass an NHibernate.DuplicateMappingException is thrown when it is mapping. Why? Here are my (simplified) classes: public abstract class FieldValue { public int Id { get; set; } public abstract object Value { get; set; } } public class StringFieldValue : FieldValue { public string ValueAsString { get; set; } public override object Value { get { return ValueAsString; } set { ValueAsString = (string)value; } } } And the mappings: public class FieldValueMapping : ClassMap<FieldValue> { public FieldValueMapping() { Id(m => m.Id).GeneratedBy.HiLo("1"); // DiscriminateSubClassesOnColumn("type"); } } public class StringValueMapping : SubclassMap<StringFieldValue> { public StringValueMapping() { Map(m => m.ValueAsString).Length(100); } } And the exception: NHibernate.MappingException : Could not compile the mapping document: (XmlDocument) ---- NHibernate.DuplicateMappingException : Duplicate class/entity mapping NamespacePath.StringFieldValue Any ideas?

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  • Bind a subclass to property

    - by Neir0
    Hi i have a simple question. Ofcourse it has many answers but i cannt choose right keywords to google. How i can bind a subclass to my wpf control? for example: It's my class. public class SiteFieldInfo<T> { public string Name { get; set; } public T Value { get; set; } public List<string> PositiveXPathExpressions { get; set; } public List<string> NegativeXPathExpressions { get; set; } } public class SiteInfo { public SiteFieldInfo<string> Author { get; set; } public SiteFieldInfo<DateTime> Date { get; set; } public SiteFieldInfo<string> Source { get; set; } } And i want to bind property Value from SiteFieldInfo to Text property of TextBox control. c# code: stackPanel1.DataContext = SiteInfoInstance; xaml code: <StackPanel Name="stackPanel1"> <TextBlock Text="Author" Grid.Row="0" Grid.Column="0" /> <TextBox Grid.Row="0" Grid.Column="1" Text="{Binding Path=Author.Value}" /> </StackPanel> It's not working. What is right syntax or any alternatives?

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  • Updating UIView subclass contents

    - by Brett
    Hi; I am trying to update a UIView subclass to draw individual pixels (rectangles) after calculating if they are in the mandelbrot set. I am using the following code but am getting a blank screen: //drawingView.h ... -(void)drawRect:(CGRect)rect{ CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetRGBFillColor(context, r, g, b, 1); CGContextSetRGBStrokeColor(context, r, g, b, 1); CGRect arect = CGRectMake(x,y,1,1); CGContextFillRect(context, arect); } ... //viewController.m ... - (void)viewDidLoad { [drawingView setX:10]; [drawingView setY:10]; [drawingView setR:0.0]; [drawingView setG:0.0]; [drawingView setB:0.0]; [super viewDidLoad]; [drawingView setNeedsDisplay]; } Once I figure out how to display one pixel, I'd like to know how to go about updating the view by adding another pixel (once calculated). Once all the variables change, how do I keep the current view as is but add another pixel? Thanks, Brett

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  • NHibernate class referencing discriminator based subclass

    - by Rich
    I have a generic class Lookup which contains code/value properties. The table PK is category/code. There are subclasses for each category of lookup, and I've set the discriminator column in the base class and its value in the subclass. See example below (only key pieces shown): public class Lookup { public string Category; public string Code; public string Description; } public class LookupClassMap { CompositeId() .KeyProperty(x = x.Category, "CATEGORY_ID") .KeyProperty(x = x.Code, "CODE_ID"); DiscriminateSubclassesBasedOnColumn("CATEGORY_ID"); } public class MaritalStatus: Lookup {} public class MartialStatusClassMap: SubclassMap { DiscriminatorValue(13); } This all works. Here's the problem. When a class has a property of type MaritalStatus, I create a reference based on the contained code ID column ("MARITAL_STATUS_CODE_ID"). NHibernate doesn't like it because I didn't map both primary key columns (Category ID & Code ID). But with the Reference being of type MaritalStatus, NHibernate should already know what the value of the category ID is going to be, because of the discriminator value. What am I missing?

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  • Javascript OOP - accessing the inherited property or function from a closure within a subclass

    - by Ali
    Hi All, I am using the javascript inheritance helper provided here: http://ejohn.org/blog/simple-javascript-inheritance/ I have the following code, and I have problem accessing the inherited property or function from a closure within a subclass as illustrated below. I am new to OOP javascript code and I appreciate your advice. I suppose within the closure, the context changes to JQuery (this variable) hence the problem. I appreciate your comments. Thanks, -A PS - Using JQuery 1.5 var Users = Class.extend({ init: function(names){this.names = names;} }); var HomeUsers = Users.extend({ work:function(){ // alert(this.names.length); // PRINTS A // var names = this.names; // If I make a local alias it works $.map([1,2,3],function(){ var newName = this.names.length; //error this.names is not defined. alert(newName); }); } }); var users = new HomeUsers(["A"]); users.work();

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