encapsulation

I've started learning Objective-C a few weeks ago and I still don't understand how to manage the encapsulation of a class correctly. What is the best way to declare a private member variable in a class? It seems that setting the right getter/setter for your member variable with "@property" is the right way to go, more than just declaring it "@private" in the interface. But it seems to me that this still gives other classes an access to these variables. Even if you declare the property "readonly", an outside class can access the reference to the member variable and modify it! So I'm guessing

We can all agree on public variables being bad for encapsulation and all that. However, I noticed a lot of code that does this type of stuff: class foo { private: int integer_; string someString_; // other variables public: int& integer() { return integer_; } string& someString() { return someString_; } // other "functions" } int main() { foo f; f.integer() = 10; f.someString() = "something"; return 0; } I have seen this being used in many places and I don't get why. Basically it returns a reference to the data and thus exposes it directly to the outside. So encapsulation is not really

class TestClass { private string _privateString = "hello"; void ChangeData() { TestClass otherTestClass = new TestClass(); otherTestClass._privateString = "world"; } } This code compiles in C# and the equivalent works in PHP, but can someone explain the reason why otherTestClass._privateString can be changed here ? I would have thought an instance of a class should not be able to change a private member variable under any circumstances, and that trying to access otherTestClass._privateString would give an 'inaccessible due to protection level' error. This is not the case though, so why does

class TestClass { private string _privateString = "hello"; void ChangeData() { TestClass otherTestClass = new TestClass(); otherTestClass._privateString = "world"; } } This code compiles in C# and the equivalent works in PHP, but can someone explain the reason why otherTestClass._privateString can be changed here ? I would have thought an instance of a class should not be able to change a private member variable under any circumstances, and that trying to access otherTestClass._privateString would give an 'inaccessible due to protection level' error. This is not the case though, so why does

After trying to access ivars using KVC, I have noticed that there was no protection on private and protected ivars. It doesn't matter what I put a in front of the ivar (private or protected keyword) - an ivar is always a public ivar when using KVC method "setValue". Here is my code where all of the seven ivars and properties are changeble outside the class instance: //************ interface file ***************// @interface MyClass : NSObject { @public NSNumber *public_num; @protected NSNumber *protected_num; @private NSNumber *private_num; NSNumber *private_property; } @property (retain)

This question already has an answer here: Why use getters and setters/accessors? [closed] 38 answers I saw a code where getters and setters methods are declared private. I am trying to figure out the logic behind it, and I am really having hard time to understand why would you declare them as private? That's exactly opposite of what we are trying to achieve through getters and setters. I can think of several reasons: you want to prevent future public access. If a different programmer sees your code and wants access to a variable, but there are no setters and getters, he might think you just

In response to What is your longest-held programming assumption that turned out to be incorrect? question, one of the wrong assumptions was: That private member variables were private to the instance and not the class. ( Link ) I couldn't catch what he's talking about, can anyone explain what is the wrong/right about that with an example? public class Example { private int a; public int getOtherA(Example other) { return other.a; } } Like this. As you can see private doesn't protect the instance member from being accessed by another instance. BTW, this is not all bad as long as you are a bit

railstutorial.org has a suggestion which strikes me as a little odd. It suggests this code : class ApplicationController < ActionController::Base protect_from_forgery include SessionsHelper end The include SessionsHelper makes the methods available from ApplicationController , yes, but it makes them available in any view, as well. I understand that authentication/authorization is cross-cutting, but is this really the best place? That seems to me to be potentially too broad of a scope. Putting code which implements, say, a before_filter which conditionally redirects (as the railstutorial.org