protected

问题 Given the sample code: class Base { public: bool pub; protected: bool prot; }; class Derived : private Base { friend class MyFriend; }; class MyFriend { Derived _derived; void test() { // Does standard provide me access to _derived.pub and _derived.prot? cout << "Am I allowed access to this: " << _derived.pub << " and this: " << _derived.prot; } }; Does being a friend give me all access I would get as if I was a member function within the class to which I am a friend? In other words, can I

问题 Given a class with some protected members and a public interface to modify them, when is it generally accepted to access the protected members directly? I have some specific examples in mind: Unit testing Internal private methods such as __add__ or __cmp__ accessing other's protected attributes Recursive data structures (e.g. accessing next._data in a linked list) I don't want to make these attributes public as I don't want them touched publicly. My syntax IDE syntax highlighting keeps saying

问题 I am trying to work our for myself access modifiers in Ruby. I have: class Person def initialize (first_name, last_name, age) @first_name=first_name @last_name=last_name @age=age end def show() puts @first_name puts @last_name puts @age end protected def compare(other) self.instance_variable_get(:@age)<=>other.instance_variable_get(:@age) end end p1=Person.new("Some", "Body", "99") p1.show puts "\n" p2=Person.new("Who", "Ever", "21") p2.show puts "\n" p1.compare(p2) I am getting the error

问题 In general, according to the OOP paradigm, my understanding of encapsulation basically says: If a member is private, it can only be accessed by the class. If a member is protected, it can only be accessed by the base class and any derived classes. If a member is public, it can be accessed by anyone. If I have a nested class, can I declare a property to be accessible only to that class and the parent class it's nested within? For example: Public Class ContainerClass Public Class NestedClass

问题 I understand that to write python module private/protected functions you use def _func(): ... but I have an object hierarchy with specialized overrides. Also I want to hide the internal implementation(since its not meant for outside use, and so I can hopefully improve it without breaking code, not that I think anybody will use it except me). If I use class Paragraph(Tag): def _method(self): ... and try calling _method from a different class that subclasses Tag IntelliJ IDEA(and probably

问题 @interface AClass : SomeType { @protected NSMutableArray* amINotAlreadyProtected; //? } Why does this code need @protected if @protected is the default? This code was written by a very experienced programmer, but I would omit the specifier myself. 回答1: There is no need for the keyword @protected as it is the default behavior. However, some programmers tend to use it anyways incase a less experienced programmer comes along at a later date and doesn't know this. It can also be mentioned that it

问题 A Java library class I'm using declares protected getPage(): Page { ... } Now I want to make a helper Scala mixin to add features that I often use. I don't want to extend the class, because the Java class has different subclasses I want to extend at different places. The problem is that if I use getPage() in my mixin trait , I get this error: Implementation restriction: trait MyMixin accesses protected method getPage inside a concrete trait method. Is there a solution how to make it work,

问题 F# 3.0 adds stricter checks for calls to base and protected members. I have something like the following abstract class in C# that has protected static helper methods to be used by derived classes. public abstract class Processor { public abstract void Process(); protected static void Helper(object arg) { } } In F#, one of those helper methods is passed as a first-class function: type DerivedProcessor() = inherit Processor() let init f = f () override x.Process() = init Processor.Helper It

问题 Besides the normal explenation of being visible or not to derived classes, is their any other difference? If you make it more visible, is it taking more or less memory, does it slow thing down or...? 回答1: Apart from the accessibility of members outside or to the derived classes, access specifiers might affect the object layout. Quoting from my other answer: Usually, memory address for data members increases in the order they're defined in the class . But this order may be disrupted at any

问题 I'm querying for the ID of a field by accessing a class function which someone has already put in place. The result is a object returned with protected member variables. I'm struggling to see how I can access the member variable values outside the class. 回答1: Just add a "get" method to the class. class Foo { protected $bar = 'Hello World!'; public function getBar() { return $this->bar; } } $baz = new Foo(); echo $baz->getBar(); 回答2: Accessing protected or private variables from public is