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From: dxb@genrad.com (Daniel A. Burkhard)
Newsgroups: comp.lang.objective-c
Subject: Re: Objective C vs C++
Keywords: why
Message-ID: <40804@genrad.UUCP>
Date: 19 Feb 91 14:17:43 GMT
References: <60377@eerie.acsu.Buffalo.EDU> <44957@nigel.ee.udel.edu>
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In article <44957@nigel.ee.udel.edu>, carroll@cis.udel.edu (Mark Carroll) writes:

> ... stuff deleted

> C++ is a systems language. It's very low level, very fast, etc. It's 
> optimized towards very low level programming. It's not very good
> at abstraction. It's completely impossible to implement a class in
> a way where a user cannot change the private parts of the class, or
> alter the class declaration. ............

How so ?? C++ gives you member access control private (default), public, and
protected. A user has no direct access to private members, i.e private
members can only be changed thru the public interface of a class.
[ Of course these rules can always be violated in any language that supports
  access to raw memory ...]

> C++ is almost completely statically bound;
> dynamic binding only comes into play when you start using virtual
> function, and only functions tagged virtual can be rewritten in your
> subclasses.

I'm not exactely sure what you mean by "rewritten", but of course something like

class foo
    {
	int a;
    public:
	foo(int aa=1)	{ a = aa;}
	int geta()	{ return a;}
    };

class bar: public foo
    {
	int b;
    public:
	bar(int bb=2)	{ b =bb; }
	int geta()	{ return b;}
    };

is perfectly legal in C++ [note: no "virtual" here].

> .. stuff deleted
> ..................... Also, in
> C++, it is possible to distribute object-code for classes, without the
> corresponding source. You can present objects which the user can make
> full use of, but cannot alter without implementing a subclass. The private
> parts of one of these classes can NEVER be changed by their users.

This seems to be a contradiction to your first point.

-- dan

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