private

问题 EDIT: I'm not going to do this, I now realize how dangerous this can be. But, the question stays for purely academic purposes. I'm trying to implement a category on NSCollectionView that will let me access the private variable _displayedItems. I need to be able to access it in my subclass. So, I've created the following category: @interface NSCollectionView (displayedItems) - (NSMutableArray *)displayedItems; @end @implementation NSCollectionView (displayedItems) - (NSMutableArray *

问题 Well there is enough information about this subject. For example this thread was very clear to me: Difference between private, public, and protected inheritance Except one point; Why is it useful? 回答1: Use public inheritance to reflect an is-a relationship . This is the main use for inheritance, especially in combination with virtual functions. It allows re-use of interface, not just of old code by new code, but also re-use of new code by old code! (because of virtual function dispatch at

问题 Well there is enough information about this subject. For example this thread was very clear to me: Difference between private, public, and protected inheritance Except one point; Why is it useful? 回答1: Use public inheritance to reflect an is-a relationship . This is the main use for inheritance, especially in combination with virtual functions. It allows re-use of interface, not just of old code by new code, but also re-use of new code by old code! (because of virtual function dispatch at

问题 This question already has answers here : Why use getters and setters/accessors? (38 answers) What is the point of setters and getters in java? [duplicate] (14 answers) Closed 5 years ago . If I can change the value of private variable through getter-returned reference then isn't it bypassing the setter method? Doesn't it defeat the purpose of getter-setter and private variables public class Test{ private Dimension cannotBeChanged; public Test(int height, int width) { if(height!=3)

问题 I've learn C++ for some time, however there is always this question which puzzles me (for years). In school, our lecturers like to declare class variables as private. In order to access it, we have to declare an accessor to access it. Sometimes we even have to make the different classes become "friends" into order to access its elements. My question is: Why make it so troublesome? What is the true rationale behind all the private and protected stuff when we can just make our life as a

问题 using namespace std; #include <cstdio> #include <iostream> class One{ private: virtual void func(){ cout<<"bark!"<<endl; } }; class Two: public One{ public: void func(){ cout<<"two!"<<endl; } }; int main(){ One *o = new Two(); o->func(); } Why is there an error on o->func() ? I don't know the mechanism behind it... In my opinion, o->func() should call the func() in the derived class, which is public, so there wouldn't be problems, but it says: error: ‘virtual void One::func()’ is private 回答1:

问题 I need to initialize private readonly field after Deserialization. I have folowing DataContract: [DataContract] public class Item { public Item() { // Constructor not called at Deserialization // because of FormatterServices.GetUninitializedObject is used // so field will not be initialized by constructor at Deserialization _privateReadonlyField = new object(); } // Initialization will not be called at Deserialization (same reason as for constructor) private readonly object

问题 I have a Dummy class that has a private method called sayHello . I want to call sayHello from outside Dummy . I think it should be possible with reflection but I get an IllegalAccessException . Any ideas??? 回答1: use setAccessible(true) on your Method object before using its invoke method. import java.lang.reflect.*; class Dummy{ private void foo(){ System.out.println("hello foo()"); } } class Test{ public static void main(String[] args) throws Exception { Dummy d = new Dummy(); Method m =

问题 In Delphi 10 Seattle I could use the following code to work around overly strict visibility restrictions. How do I get access to private variables? type TBase = class(TObject) private FMemberVar: integer; end; And how do I get access to plain or virtual private methods? type TBase2 = class(TObject) private procedure UsefullButHidden; procedure VirtualHidden; virtual; procedure PreviouslyProtected; override; end; Previously I would use a class helper to break open the base class. type

问题 In Delphi 10 Seattle I could use the following code to work around overly strict visibility restrictions. How do I get access to private variables? type TBase = class(TObject) private FMemberVar: integer; end; And how do I get access to plain or virtual private methods? type TBase2 = class(TObject) private procedure UsefullButHidden; procedure VirtualHidden; virtual; procedure PreviouslyProtected; override; end; Previously I would use a class helper to break open the base class. type