Re: "Inheritance break Encapsulation "

From:

"Daniel T." <daniel_t@earthlink.net>

Newsgroups:

comp.lang.c++

Date:

Wed, 16 Jul 2008 22:00:42 -0400

Message-ID:

<daniel_t-D12C9E.22004216072008@earthlink.vsrv-sjc.supernews.net>

Pallav singh <singh.pallav@gmail.com> wrote:

i find Following statement while reading Design pattern in C++
( author - Erich Gamma)
"Inheritance break Encapsulation " because inheritance exposes to
subclass the detail of its parent's Implementation
Is it correct ?

as we only expose interface ( function prototype) to derived class But
not how it being implemented

Kindly give urs View regarding it

Also from the book "With inheritance, the internals of parent classes
are often visible to subclasses." (note the use of "often".)

For example, if the parent class has protected member-variables, or if
the parent class calls virtual member-functions from within other
member-functions. In either case, the derived class must know something
about the base classes implementation in order to ensure that the
parent's member-variables are used correctly and to understand how to
implement its virtual member-functions.

I generally only use inheritance to facilitate polymorphism, my base
classes rarely have anything more than pure virtual member-functions.