Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!bionet!ames!sun-barr!rutgers!att!ulysses!andante!alice!ark
From: ark@alice.UUCP (Andrew Koenig)
Newsgroups: comp.lang.c++
Subject: Re: cant use virtuals in base constructors
Message-ID: <9327@alice.UUCP>
Date: 8 May 89 22:23:25 GMT
References: <DOVE.89May4223113@rocket.stars.flab.Fujitsu.JUNET> <198@riunite.ACA.MCC.COM>
Distribution: comp
Organization: AT&T Bell Laboratories, Liberty Corner NJ
Lines: 29

In article <198@riunite.ACA.MCC.COM>, rfg@riunite.ACA.MCC.COM (Ron Guilmette) writes:

-> One question.  You said that "f must be supplanted" in all derived classes.
-> Supplanted how?  Will this be legal?  (I hope so!)

-> 	class base {
-> 	public:
-> 		virtual void f() = 0;
-> 	};

-> 	class middle : public base {
-> 	public:
-> 		virtual void f() = 0;	// force leaves to supplant f()
-> 	};

-> 	class derived : public middle {
-> 	public:
-> 		virtual void f() {}	// finally!
-> 	};

Yes.

In this particular example, the semantics will not change
if you omit the definition of middle::f().

You can also omit `virtual' in middle::f and derived::f.
-- 
				--Andrew Koenig
				  ark@europa.att.com