inheritance

问题 I have a hierarchy of ConfigBuilder classes which have the role of creating Config instances. My superclass is an AbstractConfigBuilder which has a method build . I want that build always calls a method validate before actually building the object. So, in the abstract super class I have val commonField: String //one of many fields common to all the hierarchy abstract def build: Config //building logic left to the subclasses def validate: Boolean = { // here some common checks commonField.size

问题 I have a class that subclasses NSMutableArray. I init it using: MyClass class = [MyClass arrayWithContentsOfFile:path]; When i try to access any of my subclass methods the app crashes with this error: -[NSCFArray loadCards]: unrecognized selector sent to instance 0x454a30 * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[NSCFArray > mymethod]: unrecognized selector sent to instance 0x454a30' app[32259:20b] Stack: ( 2524995915, I am suspecting this happens

问题 I got an issue. In Unity I want to reflect into a private field. But I always get null for the fieldinfo. what am I doing wrong? public abstract class _SerializableType { [SerializeField] private string name; } // because I am using a CustomPropertyDrawer for all inherited from _SerializeType public class SerializableType<T> : _SerializableType { } public class SerializableType : _SerializableType { } [Serializable] public class CTech : SerializableType<_CouplingTechnology> { } so using this

问题 I have read few threads and know that for sure django can have multiple abstract classes. But pretty much all the samples I saw are... class AbsOne(models.Model): pass class AbsTwo(models.Model): pass class AbsThree(AbsOne, AbsTwo): pass but what if I have something like... class AbsOne(models.Model): pass class AbsTwo(AbsOne): // this actually inheritance AbsOne pass class AbsThree(AbsOne): // this inheritance AbsOne pass What if I need to inheritance both AbsTwo, AbsThree but these two are

问题 Part 2 problem, which continues from here: EntityFramework Core - Update record fails with DbUpdateConcurrencyException Error: The derived type 'BinaryFile' cannot have KeyAttribute on property 'Id' since primary key can only be declared on the root type. I am trying to make inheritance for my entities as much as possible, so I remove duplication as much as possible. My inheritance structure: public interface IEntityMinimum { bool IsDeleted { get; set; } byte[] Version { get; set; } string

问题 I am new in swift and now i am stuck in inheritance . Here i am using two class class A, and class B . Class B is inheriting some properties of class A . Here is the code . class A { var objRunningJobs:UIViewController! var objCompletedJobs:UIViewController! init(objRunningJobs:UIViewController, objCompletedJobs: UIViewController) { self.objRunningJobs = objRunningJobs self.objCompletedJobs = objCompletedJobs } required init?(coder aDecoder: NSCoder) { fatalError("init(coder:) has not been

问题 I have an application.cfc in a subdir of my webroot: /app/application.cfc I recently added another application.cfc in a subdir of that and it extends the original application.cfc using the proxy method described here http://corfield.org/blog/index.cfm/do/blog.entry/entry/Extending_Your_Root_Applicationcfc : /app/mysubdir/application.cfc /app/applicationproxy.cfc The extends attribute for the subdir cfc looks like this: <cfcomponent extends="app.applicationProxy"> This all works fine so far

问题 Can anyone tell me if it's possible to override a use statement? My example is having an MVC setup where there is core code with the ability to override each Controller / Model with a custom version that extends the core version. The issue I face is that my core controller has a use statement telling it to use the core model, so if I extend the model, I'm not sure how to tell it to use the custom model rather than the core one I could obviously update the core controller use statement to

问题 Here is a code: class Base { public: long index; }; class Derived : public Base { public: bool value; }; void call(map<char *, Base *> *base) { map<char *, Base *>::iterator it = base->begin(); cout << it->second->index << endl; } void test(void) { map<char *, Derived *> *d = new map<char *, Derived *>; call(d); } Compiler alerts an error: error C2664: 'call' : cannot convert parameter 1 from 'std::map<_Kty,_Ty> *' to 'std::map<_Kty,_Ty> *' 1> with 1> [ 1> _Kty=char *, 1> _Ty=Derived * 1> ] 1

问题 Here is a code: class Base { public: long index; }; class Derived : public Base { public: bool value; }; void call(map<char *, Base *> *base) { map<char *, Base *>::iterator it = base->begin(); cout << it->second->index << endl; } void test(void) { map<char *, Derived *> *d = new map<char *, Derived *>; call(d); } Compiler alerts an error: error C2664: 'call' : cannot convert parameter 1 from 'std::map<_Kty,_Ty> *' to 'std::map<_Kty,_Ty> *' 1> with 1> [ 1> _Kty=char *, 1> _Ty=Derived * 1> ] 1