Re: What exactly is considered inherited from a base class?

From:

Pete Becker <pete@versatilecoding.com>

Newsgroups:

comp.lang.c++.moderated

Date:

Thu, 12 May 2011 09:48:15 CST

Message-ID:

<2011051207504522630-pete@versatilecodingcom>

On 2011-05-12 00:35:06 -0400, cpp4ever said:

On 12/05/11 01:06, Pete Becker wrote:

On 2011-05-11 12:07:28 -0400, Kris Prad said:

This is a Java site, yet applicable here:
http://download.oracle.com/javase/tutorial/java/IandI/subclasses.html
The site starts with a blanket statement like:
"A subclass inherits all the members (fields, methods, and nested
classes) from its super class." ---------------- (1)
and later on after a few paragraphs, narrows it down to:
=93Private Members in a Super class:
A subclass does not inherit the private members of its parent class.
However, if the super class has public or protected methods for
accessing its private fields, these can also be used by the subclass.=94
-------------- (2)

Umm, no. This talks about something that's fundamentally different from
the way that C++ works.

My question: Are private members of a base class considered inherited
or not? (That they are accessible via public accessor methods is
beside the point.)
My understanding: If the inheritance is conditional upon access ("data
hiding" aspect), then (2) is applicable - private members are not
inherited. Otherwise (1) is applicable. My understanding is that (2)
prevails. Data hiding and inheritance are orthogonal concepts in
theory, but bound together in practice. I may be wrong in interpreting
like this.
This may be splitting hairs as far as programming is concerned =96 one
just knows how they work, but the difficulty is in communicating these
as concepts.

In C++, all members are inherited. Try it. Write a base class with
private members that declares its derived class as a friend.

Personally I avoid using friend on the basis it defeats the whole point
of information hiding.

<shrug> The point of my message was to suggest a way to explore how
inheritance works, not to recommend a general coding approach.

--
  Pete
Roundhouse Consulting, Ltd. (www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
(www.petebecker.com/tr1book)

      [ See http://www.gotw.ca/resources/clcm.htm for info about ]
      [ comp.lang.c++.moderated. First time posters: Do this! ]