inheritance

问题 I'm trying to implement abstract inheritance in Django with the following code, but it produces a MAX recursion depth error. I'm trying to override a model's save method. class BaseModel(models.Model): class Meta: abstract = True def save(self, *args, **kwargs): #i'm doing something here #i think the problem is in the return statement specifically because of the #self.__class__ expression. return super(self.__class__, self).save(*args, **kwargs) class MyModel(BaseModel): p = models.CharField

问题 I'm trying to implement abstract inheritance in Django with the following code, but it produces a MAX recursion depth error. I'm trying to override a model's save method. class BaseModel(models.Model): class Meta: abstract = True def save(self, *args, **kwargs): #i'm doing something here #i think the problem is in the return statement specifically because of the #self.__class__ expression. return super(self.__class__, self).save(*args, **kwargs) class MyModel(BaseModel): p = models.CharField

问题 Is it possible to employ some kind of prototypal inheritance in PHP like it is implemented in JavaScript ? This question came to my mind just out of curiosity, not that I have to implement such thing and go against classical inheritance. It just feels like a interesting area to explore. Are there prebuild functions to combine classical inheritance model in PHP with some sort of Prototypal inheritance with a combination of anonymous functions? Let's say I have a simple class for UserModel

问题 I must structure new model for application and I don't what is better: using inheritance or using enum as type of object: For example : Books class Book { public string Name {get;set;} public string Author {get;set;} public int NumberOfPages {get;set;} } public class Encyclopedie:Book { } public class Novel:Book { } or better use: class Book { public BookType Type {get;set;} public string Name {get;set;} public string Author {get;set;} public int NumberOfPages {get;set;} } public enum

问题 What are ways to get around the problem of only being allowed to extend at most one other class. class Bar { doBarThings() { //... } } class Bazz { doBazzThings() { //... } } class Foo extends Bar, Bazz { doBarThings() { super.doBarThings(); //... } } This is currently not possible, TypeScript will give an error. One can overcome this problem in other languages by using interfaces but solving the problem with those is not possible in TypeScript. Suggestions are welcome! 回答1: This is possible

问题 If you have Class A with an instance var "foo" which has a @property/@synthesize directive, and Class B inherits from Class A, does it also need to @property/@synthesize "foo"? The reason I ask is because when I try to use Class B's "foo", the calling class says that "foo" is not something of a structured union or a member, which makes me believe it needs to be explicitly synthesized. 回答1: No, you don't. Synthesized properties are added to class A and its subclasses automatically. 回答2: If you

问题 I'm using TypeScript to create some classes with KnockoutJS, with the data being loaded from some JSON returned by WebAPI. The problem is I wanted to copy the JSON values into my TypeScript class from the constructor: but if I do this just at the base class, the inherited properties have not been defined and so are not initialised. Example We want to create an inventory item from a JSON response: { Name: "Test", Quantity:1, Price: 100 } I have a base class Product and an inherited class

问题 I'm making a Cocos2d game for iphone, and I have my main game mode, Game , which inherits from CCLayer . I'm trying to make another game mode, MathGame , which inherits from Game , but when I try to compile, I get this error in MathGame.h : Attempting to use the forward class 'Game' as superclass of 'MathGame' I get the error even if the implementation and interface of MathGame are empty. And it only happens if I try to include MathGame.h in another file. Here's the code for the Game class: /

问题 I have the following code. class Test { int i = 0; Test() { System.out.println(this); System.out.println(this.i); } } public class Demo extends Test { int i = 10; Demo() { super(); System.out.println("calling super"); System.out.println(this); System.out.println(this.i); } public static void main(String[] args) throws IOException { Demo d = new Demo(); } } O/P : Demo@2e6e1408 0 calling super Demo@2e6e1408 10 When I execute the program and print the value of "this", in both super class

问题 I have the following ViewModel: public class DocumentViewModel : ViewModelBase { public virtual string TabHeader { get { return "Document"; } } private ObservableCollection<DATA> data; /// <summary> /// Source for Grid /// </summary> public ObservableCollection<DATA> Data { get { return data; } set { data = value; RaisePropertyChanged("Data"); } } // ...... a lot of properties and methods .... } I want ProcurementViewModel to inherit DocumentViewModel : public class ProcurementViewModel :