protected

问题 The class ExtendedDismaxQParser has a static member class Clause: public class ExtendedDismaxQParser { protected static Class Clause { protected String foo, bar; } public Clause getAClause { Clause c; // misc code that isn't important return c; } } I then extended this class in a different package: public class SpecialDismaxQParser extends ExtendedDismaxQParser { public void whatever() { Clause c = super.getAClause(); boolean baz = c.foo.equals("foobar"); // <-- This doesn't compile } } It

问题 I am trying to find a way to allow the user to insert rows but only in a specific range when the sheet is protected. For example, I don't want the user to be able to insert a row between the rows "1" and "2" (because it will make my macros do funny things), but I want him to be able to insert a row everywhere else. The following code allows the user to insert rows everywhere in the sheet, but that is not exactly what I want: ActiveSheet.Protect Password:="qwerty", DrawingObjects:=True,

问题 Given the following inheritance tree, what would be the best way of implementing it in a way that works? abstract class Foo<T> : IEnumerable<T> { public abstract Bar CreateBar(); } class Bar<T> : Foo<T> { // Bar's provide a proxy interface to Foo's and limit access nicely. // The general public shouldn't be making these though, they have access // via CreateBar() protected Bar(Foo base) { // snip... } } class Baz<T> : Foo<T> { public Bar CreateBar() { return new Bar(this); } } This fails with

问题 Is there a meaning to declare friendship in the protected section, rather than in public? For example in this code: class Shape { //... protected: friend ostream& operator<<(ostream& os, const Shape& s); virtual void print(ostream& os) const = 0; }; [Note that Shape is abstract] Could I have just put the friend and the function declaration in public? Thanks! 回答1: Is there a meaning to declare friendship in the protected section, rather than in public? No. The friend class has the same level

问题 I've a class defined this way: package prueba; public class OtraClase { [...] protected int num3; [...] And another class defined this way: package otro; import prueba.*; public class OtraClaseMas extends OtraClase{ But if in that last class I create an OtraClase object I cannot do something like this: createdObjectOfOtraClase.num3=1; And I think that according to the documentation I should be able to, here. It says that the protected modifier allows for access by a subclass of its class in

问题 I've created a header for optionally-lazy parameters (also visible in a GitHub repository). In my original version of the code, I provided a protected default constructor for my base-class template: template <typename VAL_TYPE> class LazyType_Base { // .... LazyType_Base(void) =default; // .... Then, in one of the derived classes: template <typename VAL_TYPE> class LazyType_Eager : public LazyType_Base<VAL_TYPE> { public: LazyType_Eager( VAL_TYPE&& final_val) : LazyType_Base<VAL_TYPE>{} , val

问题 I wrote a short program to illustrate the principles of inheritance for my school project, but I am having a weird problem. Here is my code: (I have omitted all the code that isn't the problem) class Car { protected: double fuelLevel; public: void fuelUp(double); }; void fuelUp(double fuel) { Car::fuelLevel += fuel; } and this is the build log: ||=== Build: Debug in wierdError (compiler: GNU GCC Compiler) ===| ||In function 'void fuelUp(double)':| |4|error: 'double Car::fuelLevel' is

问题 I can use at least two basic ways to access a protected class method from a child class: parent::myMethod(); $this->myMethod(); If I don't need to override it in the child class, in which case I would have to do this: function myMethod() { ... parent::myMethod(); ... } which is the most recommended way to call it? I personally feel more comfortable using parent::myMethod() rather than $this->myMethod , because the first one immediately tells me this method is being inherited. But I'm not sure

问题 I have the following classes: class Base { protected: int myint; }; class Derived : public Base { public: bool operator==(Base &obj) { if(myint == obj.myint) return true; else return false; } }; But when I compile it, it gives the following errors: int Base::myint is protected within this context I thought that protected variables are accessible from the derived class under a public inheritance. What is causing this error? 回答1: Derived can access protected members of Base on all instances of

问题 I'm reading Sybex Complete Java 2 Certification Study Guide April 2005 (ISBN0782144195). This book is for java developers who wants to pass java certification. After a chapter about access modifiers (along with other modifiers) I found the following question (#17): True or false: If class Y extends class X, the two classes are in different packages, and class X has a protected method called abby(), then any instance of Y may call the abby() method of any other instance of Y. This question