Hello,
I want to write a list class with an iterator class as an inner class. The
iterator class must have access to certain private members of the list
class in order to do its job. Here is a reduced code example:
class List {
private:
void *rootNode;
class Iterator {
private:
void *currentNode;
public:
Iterator( List &listRef ) : currentNode( listRef.rootNod e ) {}
};
};
I wouldn't think that this is a problem. The inner class is like a member of
the outer class. Other members of the outer class (e.g., member functions)
also have access to private members of the outer class. But surprisingly,
g++ 2.95.4 complains about the list class members being private.
The problem now is not only that I don't understand and don't want this
behaviour; the problem is also that I cannot imagine a proper workaround.
I'm happy for any comments clarifying this situation.
Wolfgang 7 9764
"Wolfgang Jeltsch" <je*****@tu-cottbus.de> wrote in message
news:bh******** ***@ID-77306.news.uni-berlin.de... Hello,
I want to write a list class with an iterator class as an inner class. The iterator class must have access to certain private members of the list class in order to do its job. Here is a reduced code example: class List { private: void *rootNode;
class Iterator { private: void *currentNode;
public: Iterator( List &listRef ) : currentNode( listRef.rootNod e ) {} }; };
I wouldn't think that this is a problem. The inner class is like a member
of the outer class. Other members of the outer class (e.g., member functions) also have access to private members of the outer class. But surprisingly, g++ 2.95.4 complains about the list class members being private.
That's correct. Member class have no special access to the enclosing class,
never have. The problem now is not only that I don't understand and don't want this behaviour; the problem is also that I cannot imagine a proper workaround.
Use friendship.
class List {
private:
class Iterator;
friend class Iterator;
class Iterator {
};
};
I'm happy for any comments clarifying this situation.
Wolfgang
john
John Harrison wrote: "Wolfgang Jeltsch" <je*****@tu-cottbus.de> wrote in message news:bh******** ***@ID-77306.news.uni-berlin.de... Hello,
I want to write a list class with an iterator class as an inner class. The iterator class must have access to certain private members of the list class in order to do its job. Here is a reduced code example: class List { private: void *rootNode;
class Iterator { private: void *currentNode;
public: Iterator( List &listRef ) : currentNode( listRef.rootNod e ) {} }; };
I wouldn't think that this is a problem. The inner class is like a member of the outer class. Other members of the outer class (e.g., member functions) also have access to private members of the outer class. But surprisingly, g++ 2.95.4 complains about the list class members being private.
That's correct. Member class have no special access to the enclosing class, never have.
So the concept of member classes is only for namespace purposes? The problem now is not only that I don't understand and don't want this behaviour; the problem is also that I cannot imagine a proper workaround.
Use friendship.
class List { private:
class Iterator; friend class Iterator; class Iterator { }; };
Oh, I didn't know that friendship is also useable for member classes. I
always thought it was only for non-member functions. I'm happy for any comments clarifying this situation.
Wolfgang
john
Thank you very much for your fast and helpful response.
Wolfgang
> > That's correct. Member class have no special access to the enclosing class, never have.
So the concept of member classes is only for namespace purposes?
That's about it. The problem now is not only that I don't understand and don't want this behaviour; the problem is also that I cannot imagine a proper
workaround.
Use friendship.
class List { private:
class Iterator; friend class Iterator; class Iterator { }; };
Oh, I didn't know that friendship is also useable for member classes. I always thought it was only for non-member functions.
Friendship is for entire classes (members or not) or for non-member
functions.
john
"John Harrison" <jo************ *@hotmail.com> wrote in message news:<bh******* ****@ID-196037.news.uni-berlin.de>... "Wolfgang Jeltsch" <je*****@tu-cottbus.de> wrote in message news:bh******** ***@ID-77306.news.uni-berlin.de... Hello,
I want to write a list class with an iterator class as an inner class. The iterator class must have access to certain private members of the list class in order to do its job. Here is a reduced code example: class List { private: void *rootNode;
class Iterator { private: void *currentNode;
public: Iterator( List &listRef ) : currentNode( listRef.rootNod e ) {} }; };
I wouldn't think that this is a problem. The inner class is like a member of the outer class. Other members of the outer class (e.g., member functions) also have access to private members of the outer class. But surprisingly, g++ 2.95.4 complains about the list class members being private.
That's correct. Member class have no special access to the enclosing class, never have.
The problem now is not only that I don't understand and don't want this behaviour; the problem is also that I cannot imagine a proper workaround.
Use friendship.
class List { private:
class Iterator; friend class Iterator; class Iterator { }; };
I'm happy for any comments clarifying this situation.
Wolfgang
john
You don't need forward class declaration in order to declare a friend class.
class List {
private:
//class Iterator; //**** This is not needed ****
friend class Iterator;
class Iterator {
};
};
foo wrote: "John Harrison" <jo************ *@hotmail.com> wrote in message news:<bh******* ****@ID-196037.news.uni-berlin.de>... [...]
Use friendship.
class List { private:
class Iterator; friend class Iterator; class Iterator { }; };
[...]
You don't need forward class declaration in order to declare a friend class.
class List { private:
//class Iterator; //**** This is not needed **** friend class Iterator; class Iterator { }; };
Yes, I assume that
friend class Iterator;
declares Iterator like
class Iterator;
does. So you can just add the "friend" to the forward declaration. You can
even get rid of the forward declaration and just add the "friend" to the
definition(?):
class List {
private:
[private members of List]
public:
friend class Iterator {
[members of Iterator]
};
};
(I thought, this could work maybe, tried it out and yes, it did.)
Wolfgang
"foo" <ma*******@axte r.com> wrote in message
news:c1******** *************** ***@posting.goo gle.com... "John Harrison" <jo************ *@hotmail.com> wrote in message
news:<bh******* ****@ID-196037.news.uni-berlin.de>... "Wolfgang Jeltsch" <je*****@tu-cottbus.de> wrote in message news:bh******** ***@ID-77306.news.uni-berlin.de... Hello,
I want to write a list class with an iterator class as an inner class.
The iterator class must have access to certain private members of the list class in order to do its job. Here is a reduced code example: class List { private: void *rootNode;
class Iterator { private: void *currentNode;
public: Iterator( List &listRef ) : currentNode(
listRef.rootNod e ) {} }; };
I wouldn't think that this is a problem. The inner class is like a
member of the outer class. Other members of the outer class (e.g., member
functions) also have access to private members of the outer class. But
surprisingly, g++ 2.95.4 complains about the list class members being private.
That's correct. Member class have no special access to the enclosing
class, never have.
The problem now is not only that I don't understand and don't want
this behaviour; the problem is also that I cannot imagine a proper
workaround.
Use friendship.
class List { private:
class Iterator; friend class Iterator; class Iterator { }; };
I'm happy for any comments clarifying this situation.
Wolfgang
john
You don't need forward class declaration in order to declare a friend
class. class List { private:
//class Iterator; //**** This is not needed **** friend class Iterator; class Iterator { }; };
That's depends on your compiler, since it was a new concept for the OP I
thought I better be on the safe side.
john
"John Harrison" <jo************ *@hotmail.com> wrote in message
news:bh******** ***@ID-196037.news.uni-berlin.de... That's correct. Member class have no special access to the enclosing class, never have.
So the concept of member classes is only for namespace purposes?
That's about it.
Not exactly.
Namespaces merely group names into distinct areas.
Namespaces do not by themselves provide access control, whereas classes do.
So if you need to control access rights to your class then use nested
classes.
--
JS This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
by: CoolPint |
last post by:
I read in books that nested class cannot access private members of
nesting class and vice versa unless they are made friends. Somehow, my
compiler is letting my nested class member functions access private
members of nesting class.
template <typename T>
class Container {
// NO friendship given to any other
public:
class ContainerIterator;
|
by: John Harrison |
last post by:
Both gcc 3.3.1 and VC++ 7.1 compile the following code.
struct Outer
{
struct Inner
{
int f() { return c; }
};
private:
static const int c;
|
by: Fabio Rossi |
last post by:
Hi!
I'm learning C++ from the book "Thinking in C++". Now I'm reading about
nested classes and access control. I have written this code
#include <iostream>
class Outer
{
private:
int outer_data;
|
by: Dennis C. Drumm |
last post by:
Is there a way with C# to allow one class access to a method or field of
another class, without making that method or field visible to all other
classes, as would be the case when making the method or field public?
Thanks,
Dennis
|
by: Abelardo Vacca |
last post by:
Hi,
The title sums up the question pretty much.
I would like to access all private members of a class including the private
members of its base classes.( I already have the ReflectionPermission )
Is there a way to get this information ?
Thnaks in advance
| |
by: Lyle Fairfield |
last post by:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dndotnet/html/callnetfrcom.asp
The Joy of Interoperability
Sometimes a revolution in programming forces you to abandon all that's
come before. To take an extreme example, suppose you have been writing
Visual Basic applications for years now. If you're like many
developers, you will have built up a substantial inventory of code in
that time. And if you've been following...
|
by: MariusI |
last post by:
Consider the following class layout
public class Order
{
public ProductOrder AddProductOrder(/* variables required to create a
product order */)
{
/* Check if the product order can be added to the order */
}
|
by: Carlos Martinez |
last post by:
Hi all:
Supose the following classes:
class A {
class InnerA1 {
};
|
by: earthwormgaz |
last post by:
Is the following legal?
class Outer
{
class Inner
{
private:
Inner() { }
};
|
by: marktang |
last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look !
Part I. Meaning of...
|
by: Hystou |
last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it.
First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...
| |
by: jinu1996 |
last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth.
The Art of Business Website Design
Your website is...
|
by: Hystou |
last post by:
Overview:
Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For most users, this new feature is actually very convenient. If you want to control the update process,...
|
by: agi2029 |
last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own....
Now, this would greatly impact the work of software developers. The idea...
|
by: conductexam |
last post by:
I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one.
At the time of converting from word file to html my equations which are in the word document file was convert into image.
Globals.ThisAddIn.Application.ActiveDocument.Select();...
|
by: adsilva |
last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
|
by: 6302768590 |
last post by:
Hai team
i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
| |
by: bsmnconsultancy |
last post by:
In today's digital era, a well-designed website is crucial for businesses looking to succeed. Whether you're a small business owner or a large corporation in Toronto, having a strong online presence can significantly impact your brand's success. BSMN Consultancy, a leader in Website Development in Toronto offers valuable insights into creating effective websites that not only look great but also perform exceptionally well. In this comprehensive...
| |