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From: abcscnge@csunb.csun.edu (Scott Neugroschl)
Newsgroups: comp.lang.c++
Subject: Inheritance and references question
Summary: TC++ and G++ are different -- who's right?
Message-ID: <1991Feb26.060459.6777@csun.edu>
Date: 26 Feb 91 06:04:59 GMT
Sender: news@csun.edu (News Administrator)
Organization: csun
Lines: 56


Hi.  I have a question about inheritance and references.

I have the following classes:

	class StackEntry {
	    public:
		StackEntry() { }
		virtual ~StackEntry() { }
	};

	class Stack {
	    public:
		// ...
		Stack& operator>(StackEntry*&);	// Stack pop operator
		// ....
	    private:
		// ...
	};

	class Disk : public StackEntry {
		// ...
	};

	// ...

	Stack s;
	Disk *dp;

	// ...
	s > dp;			// pop s into dp <<== PROBLEM HERE

Now the question.
	Turbo C++ generates a temporary variable (implicit type cast) so that
	dp never gets set.  G++, on the other hand allows the construct, and
	the code does what I expect.  Since Disk is a subclass of StackEntry,
	and a Disk* can be assigned to a StackEntry*, I think G++ is right.
	Is it?  If not, why?

Please respond via Email, as I don't get on this system too often.
Thanks,
	Scott


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--
Scott "The Pseudo-Hacker" Neugroschl		abcscnge@csuna.csun.edu
-- Beat me, Whip me, make me code in Ada
-- Disclaimers?  We don't need no stinking disclaimers!!!