Date:	Thu, 26 Jan 1995 18:21:54 +0900
From:	Stephen Turnbull <turnbull AT shako DOT sk DOT tsukuba DOT ac DOT jp>
To:	frbelme AT coulomb DOT uwaterloo DOT ca
Cc:	djgpp AT sun DOT soe DOT clarkson DOT edu
Subject:	Pure Virtual Functions in djgpp

A pure virtual function by definition cannot be called.

Presumably you are calling an overload of that function for an object
whose type is implicitly the virtual class:

ie, here the problem is obvious, but there are devious ways to do the
same thing.

class virtual_base {
    int data;
public:
    virtual void vf () = 0;
    };

void func (virtual_base *vbp)
{
    vbp->vf();                // BZZZT!
}

Maybe you can only do polymorphism for classes with the function
defined, and its derivatives.

I don't see why this should be a problem, since you can't instantiate
a pure virtual class.  But there you go; it may be necesary to
implement this way.
-- 
Stephen Turnbull  /  Yaseppochi-gumi  <turnbull AT shako DOT sk DOT tsukuba DOT ac DOT jp>
http://turnbull.sk.tsukuba.ac.jp/   anon FTP: turnbull.sk.tsukuba.ac.jp
Check out Kansai-WWW, too ---------> http://pclsp2.kuicr.kyoto-u.ac.jp/

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